Hi guys! My name is Dima, and I am their Belarus. So sorry for my incorrect English)
I am the owner japanese BOSS CE-3. And the problem is that when you turn on the effect, the output A: signal from the output sags on the volume.
The output B: signal from the output -such a problem does not have, with him everything is in order.
The pedal is completely original, the only thing I changed electrolytic capacitors there to eliminate the background.
I think to check the oscillograms and compare with the factory ones, but I heard that they often have this drawback. And can i play around with the denomination of the elements and eliminate this drawback?
Thank you all in advance!)
(https://i.postimg.cc/K1GPkqJv/BOSS-CE-3.jpg) (https://postimg.cc/K1GPkqJv)
(http://www.synthdiy.com/files/2007/bossce-3.jpg)
up
Welcome!
There's a similar discussion to your problem over on this thread:
https://www.diystompboxes.com/smfforum/index.php?topic=118991.0
Mark Hammer gives a good explanation of why a good reliable fix isn't simple, and why a simple fix isn't going to be that good. Without wanting to belittle anyone, the other posters are just experimenting, and their advice to "remove this" or "desolder that" can be ignored. It'd be *nice* if just lifting R18 solved the problem, but it's not that simple.
Tom
I'm assuming the problem is only in Mode I ?
Lifting R18 isn't too bad. There's plenty of chorus and flanger pedals out there which don't bother trying to correct for the level.
I suspect there's a little more going on here to make the level of A and B sound different. That would be due to the fact A Out = Delay + Effect and B Out = Delay - Effect.
For the overall level:
If you change R18 from 120k to 270k the change in volume will be less pronounced. If you want even less drop use 470k.
For the balance between A and B:
If you are still unhappy with A and B not being balance, add a 470K resistor across R29. If B is still too loud try 270k.
Quote from: Rob Strand on February 23, 2019, 09:03:06 PM
I'm assuming the problem is only in Mode I ?
Lifting R18 isn't too bad. There's plenty of chorus and flanger pedals out there which don't bother trying to correct for the level.
I suspect there's a little more going on here to make the level of A and B sound different. That would be due to the fact A Out = Delay + Effect and B Out = Delay - Effect.
For the overall level:
If you change R18 from 120k to 270k the change in volume will be less pronounced. If you want even less drop use 470k.
oooh thanks!!
For the balance between A and B:
If you are still unhappy with A and B not being balance, add a 470K resistor across R29. If B is still too loud try 270k.
I want to make a signal from the output A louder. So that it is the same as the input signal.
That's all)
P.S. no matter which mode. in mode II (vibrato) the sound is also quieter...
QuoteI want to make a signal from the output A louder. So that it is the same as the input signal.
That's all)
P.S. no matter which mode. in mode II (vibrato) the sound is also quieter...
That's a little strange. If could be a fault. By doing a mod you could be hiding a problem.
If output A has the correct level when the output is *clean* (that is Mode I + Effect bypassed) then there is less chance of a significant fault. In that case, to increase the level of A try putting 470k across R36. You could go as low as 270k. However, if you need to go down to 270k or lower I would start thinking the pedal has a fault. A possible fault would be something wrong with Q4.
If output A does not have the correct level when the output is *clean* (that is Mode I + Effect bypassed) then you may have a faulty opamp (IC1, pin 1, 2, 3), a faulty socket "OUTPUT A", or a faulty cap C7, or a bad solder joint in that area of the circuit.
--------------------------------------
[EDIT: Don't do these mods yet. I'm going to check exactly what JFET switches are on in each mode.]
OK I got the same conclusion that I wrote above. So there's something odd about output A.
I went through the schematic and found the schematic has a bug.
Boss CE-3
----------------------------------------------------------------------
From real unit
https://www.youtube.com/watch?v=0AJfndh4Ip4
Switch:
Mode I is counter-clockwise
Mode II is clockwise
Mode II:
Effect on A = Vibrato, B = Clean
Bypass A = Clean, B = Clean
----------------------------------------------------------------------
From manual
Effect on:
Mode I Mode II
A = D + E A = E
B = D - E B = D
Bypassed:
Mode I Mode II
A=D A=D (Not documented)
B=D B=D (Not documented)
----------------------------------------------------------------------
Circuit
Bugs on schematic:
The Mode I and Mode II *labels* on the schematic are wrong.
Mode II is when mode switch is closed; not Mode I as shown on the schematic.
JFETs off when gate low.
Q11/C31 Q12/C9
Bypass lo hi
Effect hi lo
JFET conditions: (corrected Mode I & Mode II schematic labels)
Q2 and Q5 have the same control signals.
Always off in Mode II.
Only on in Effect mode + Mode I.
Q4 Only on in Effect mode (Mode I or Mode II)
Q3 always on in Mode I, or on when Mode II + Bypass mode
JFET state according to Mode Switch and Foot Switch:
(Table shows corrected Mode I & Mode II schematic labels)
State Sw C31(Q11) C9(Q12) Q2 Q3 Q4 Q5 Result
Bypass Mode I lo hi off on off off A=D, B=D
Effect Mode I hi lo on on on on A=D+E, B=D-E, gain reduced (A and B)
Bypass Mode II lo hi off on off off A=D, B=D
Effect Mode II hi lo off off on off A=E, B=D
Conclusions:
- The gain is only reduced (Q2 on and R18 in circuit) in Mode I when the effect is on.
- The Mode I/Mode II switch is shown with the wrong labels on the schematic.
----------------------------------------------------------------------
guys, thank you for supporting me with advice)
So, I poked a soldering iron, and here are the results:
dropped out of the scheme Q4 and make jumper source-drain. anyway the sound sags on the output a:(
replaced C7-It seems nothing has changed...
HERE! I think I won it) I dropped out, listened, and again soldered R18. Then I decided for prophylaxis to dissolve all the sockets and wires leading to the board .... and voila! the drawdown disappeared)
But there was one oddity, about which I probably forgot ...
when in output A is turned on in the chorus mode (position 2), pressing the pedal on button the sound disappears for half a second and reappears.
So it should not be?
Pancake. in the vibrato mode, there is no sound at all (and if there is, then it is loaded ...
On the board, it feels good, I washed it with alcohol ...
QuoteHERE! I think I won it) I dropped out, listened, and again soldered R18. Then I decided for prophylaxis to dissolve all the sockets and wires leading to the board .... and voila! the drawdown disappeared)
OK. Great.
QuoteBut there was one oddity, about which I probably forgot ...
when in output A is turned on in the chorus mode (position 2), pressing the pedal on button the sound disappears for half a second and reappears.
So it should not be?
That is not normal. I suspect there might be a fault in the circuit.
Do you have a multimeter?
Quotein the vibrato mode, there is no sound at all (and if there is, then it is loaded ...
That's not good. No vibrato means Q4 is not working. Maybe you reversed Q4?, check the orientation of
Q4 using this diagram,
https://postimg.cc/K1GPkqJv
If the orientation is OK, check the solder on Q4 (not connecting or solder bridge).
I have a multimeter.
Just in case I tried to replace it with Q2.
problem still exists
dropped out P18. The signal became a little louder than the wedge!))
But it seems that a load has started to appear, or have I already had hallucinations?))
I think I need to put 470k, so the chorus will sound better!)
Or leave it as it is?
By the way, if I replaced my native electrolytic capacitors with ... Capxon, G-luxon, maybe because of this the vibrato mode does not immediately turn on?)
In general, it makes sense to change the native electrolytes in the old lotions? I heard that they dry up. and in this pedal I clearly heard pulsations at high volume.
Quotedropped out P18. The signal became a little louder than the wedge!))
But it seems that a load has started to appear, or have I already had hallucinations?))
I think I need to put 470k, so the chorus will sound better!)
Or leave it as it is?
Most chorus pedals are equivalent to removing R18, however the level does increase. If you replace R18 with 470k it should drop the volume a small amount to make it more balanced.
QuoteJust in case I tried to replace it with Q2.
problem still exists
Do you mean Q4?
QuoteBy the way, if I replaced my native electrolytic capacitors with ... Capxon, G-luxon, maybe because of this the vibrato mode does not immediately turn on?).
Normally changing the capacitor would not cause that problem. If you put the capacitor in the wrong way around it could cause a problem.
QuoteIn general, it makes sense to change the native electrolytes in the old lotions? I heard that they dry up. and in this pedal I clearly heard pulsations at high volume.
Hard to say. I don't hear a lot of reports of bad capacitors in Boss pedals. I would only replace capacitors I know are faulty.
QuoteI have a multimeter.
I suggest measuring the voltages at
- IC1 pin 7
- IC1 pin 1
- IC1 pin 2
Check the voltages in each case of:
- Mode I + Bypass
- Mode I + Effect
- Mode II + Bypass
- Mode II + Effect
The aim is to see if the DC voltage in one of these cases is different to the others. Make a note of which case is different as this will help diagnoze the the problem.
When you measure the voltages see if any of the voltage measurements have the delay when you change between bypass and effect in Mode II.
Another thing you can check is the voltages at C31 and C9 when you change between bypass and effect in Mode II. See if any of these voltages show a delay.
That is, r18 is needed so that both outputs have the same volume?
Yes, q4 and q2-are the same.
look, I want a multimeter(check IC1), a black puppy is attached to the body, the red one poked at the right points ... everywhere it was 5.26, without delay.
But on С31 in the bypass 0, and when turned on, 2.93 rushes pretty quickly.
C9: bypass:0.78, when I turn "on"-quickly 5.69v.
QuoteBut on С31 in the bypass 0, and when turned on, 2.93 rushes pretty quickly.
C9: bypass:0.78, when I turn "on"-quickly 5.69v.
The C9 voltage looks normal.
The C31 voltage looks bad. I would expect the C31 voltage to go from 0 to 5.69V (maybe up to 6V). If it only gets to 2.93V the delay signal will not pass - that is exactly the problem you are seeing. To solve the problem we need to work out what is loading C31.
It might be worth checking the voltage on the collector of Q11. That should change from 0V to 5.69V (maybe up to 6V).
If the collector of Q11 is good then only the voltage on C31 is bad. Possible causes are,
- contamination on the PCB. try cleaning the PCB.
- faulty diodes
The only parts connecting to C31 are R61, D3, D4, D6. Try this
- Switch the bypass switch so C31 is at 2.93V.
- Using the multimeter measure the voltage on the *anode* of D3, D4, D6. The anode is the point that connects to the JFET. I suspect one of those voltages will the different to the others. The JFET connecting to the diode with the different voltage might be damaged.
collector voltage Q11: 5.82v.
D3=D4=2.93v.
D6=5.25v!!!
Quotecollector voltage Q11: 5.82v.
OK, that looks good.
Quote
D3=D4=2.93v.
D6=5.25v!!!
There's definitely something wrong here but I can quite see what the problem is.
Previously you measured C31 at 2.93V, the same voltage as D3, D4. That could be because no current is flowing through the diode, or, the diodes are shorted. Check the diodes D3 and D4 are not shorted.
Do you know the input impedance of your multimeter? Normally it is 10Meg but some multimeters are 1Meg. The reason I ask is the voltage at Q11 is 5.82V, and if you multimeter is 1Meg it will form a voltage divider with R61 and produce half the voltage. 5.82 / 2 = 2.91V, which is very close to 2.93V, so perhaps your meter is loading C31.
Some other things to check are the voltages on the drain and source of Q4, Q2, Q5. You will need to check the voltage in effect and bypass mode.
I have one of these pedals. I'll try it out tonight to see how much of a volume difference there.
QuoteI have one of these pedals. I'll try it out tonight to see how much of a volume difference there.
From what I can see the Q2 thing only reduces the gain when Effect=ON and Mode I. It affects both output A and B (A=D+E, B=D-E); see JFET state table in post #6. It's achieves the same gain reduction as R37 on the MXR flanger,
https://photobucket.com/gallery/user/bainzy007/media/bWVkaWFJZDo1MDU3MzE2/?ref=
The Boss BF-2 and CE-2 on the other hand don't bother reducing the gain and just mixes both the Dry and Effect with gain = 1.
I think the original problem is fixed but now we have a secondary problem where the delay signal is not coming through.
I checked everything near D2 and D3. Everywhere is clean.
I don't know the impedance of my multimeter ..
I checked Q4, Q2, Q5, and write results.
QuoteI checked everything near D2 and D3. Everywhere is clean.
I don't know the impedance of my multimeter ..
I checked Q4, Q2, Q5, and write results.
What combination of Modes (I or II) and Outputs (A and B) actually produce a chorus or vibrato effect?
vibrato- A output, II.
Chorus- A output, I and B, also mode I.
Quotevibrato- A output, II.
Chorus- A output, I and B, also mode I.
So it's all working normally *except* for the strange turn-on delay?
Well yes..
Q2: S: 5.26(byp/eff), D:4.7(byp/eff)
Q4: S: 5.26, D: 4.82/5.26(byp/eff)
Q5: S: 5.02(byp/eff), D: 5.26(byp/eff)
QuoteQ2: S: 5.26(byp/eff), D:4.7(byp/eff)
Q4: S: 5.26, D: 4.82/5.26(byp/eff)
Q5: S: 5.02(byp/eff), D: 5.26(byp/eff)
I am now sure your multimeter has a 1MEG ohm input impedance.
I carefully analysed the circuit accounting for the 1MEG meter impedance and my calculated voltages
matched your voltage measurements very closely.
I am not 100% sure the problem only exists in mode II. The problem might be still present in Mode I but it is more difficult to hear because in Mode I the clean signal is always present.
Can you try this test:
- Set the Chorus settings to Rate = Full , Depth = Full. That will make Chorus sound very exaggerated and easier to hear.
- Set the Mode switch to Mode I (not II)
- Switch the pedal between Bypass and Effect.
- On Output A, can you determine if the chorus sound is delayed (the 0.5 second delay problem). The clean sound is present all the time so you need to listen carefully for the chorus sound.
- Repeat the same test for Output B (mode I)
Is the chorus sound delayed in Mode I on Output A, Output B, both A and B, or not delayed?
My thoughts: The original problem had some sort of loading due to contamination on the PCB. I think there may be some contamination still on the board. If the problem is in Mode I and Mode II it might help us narrow down the problem.
Did as Нou said, there is no signal interruption.
It is only in mode II, well, respectively, in output A :)
the fee was washed thoroughly. no snot or dirt. On both sides. The diodes are all clean, neatly soldered.
QuoteDid as Нou said, there is no signal interruption.
It is only in mode II, well, respectively, in output A :)
OK, thanks for confirming that.
Have you confirmed all the diodes D2, D3, D4, D5, D6, D7 are all OK? You can use the diode check on your multimeter. Check the voltage is good and that the diodes are not shorted.
This issue is very subtle. The problem is related to Q4, or the signals driving Q4. However, the thing that makes is more difficult to debug is the signals driving Q4 are not directly affected by the Mode switch!
From Reply 8:
Quotewhen in output A is turned on in the chorus mode (position 2), pressing the pedal on button the sound disappears for half a second and reappears.
Because there is no sound we know Q3 is turning off immediately but Q4 is turning on slowly.
In Mode II the mode switch is *closed* (the schematic is wrong, see Reply 6). That only affects Q3, the dry signal. Q3 will turn on quicker. In Mode II, R11 (1M) is added to the output of R12 (100k) which makes the voltage to the gates of Q3 and Q5 increase by about 0.26V. That makes the JFETs turn on harder and quicker.
I have a theory what might be happening:
In order for the BBD IC (IC3) to work correct the voltage on C20, which is set by VR3, must be adjusted to the correct value. *** I am assuming this voltage is currently set to the correct voltage ***. The voltage on C20 also goes to the JFETs. The voltages from the switching circuit (Q11, Q12 upto C31, C9) are not affected by VR3. So the problem is, if the voltage on C20 must be set high to a high voltage (for IC3) the switching signal to the JFETs is effectively reduced. This means the turn on for the JFETs could be delayed, or, they might not turn on fully.
The high voltage from R11 and the smaller value of R12 (100k) compared to R61 may be adding to the problem. One side of the JFETs is switching fast and one side is switching slow which causes a gap in the switching.
So we have a few possibilities:
1) VR3 is set *too* high. However, if the delayed signal is not distorted we cannot assume this. We can only assume IC3 needs the high voltage. So at this point don't change VR3. (It might fix the switching but it will break the signal quality of the BBD.)
2) The output from the switching circuit at C31 does not switch high enough to turn on the JFETs.
3) The small R12 value making the problem worse.
I think the next step is to try adding a 270k (or 220k) resistor in parallel with R58 (56k which goes to Q11). This will increase the drive signal to the JFETs and fix possibility #2. If you can see an improvement but it is not enough try reducing the added resistor in parallel with R57 to 120k (or 100k).
Now, if those changes improve things but it is still not good enough I suggest adding a 1MEG or 470k resistor across R61. This compensates for possibility #3. Ideally we don't want to make R61 too small because you might get 'tick' sounds when switching.
If those changes work you could remove the parallel resistors are replace the original resistors with lower values. I'll let you decide what to do here.
Good luck!
I set the correct value on the oscilloscope(vr3), and everything sounds great by ear)
I forgot to say that I redid the pedal to supply 9 volts by soldering a jumper between points 2 and 3 on the board
Further. At the same points on the board where R57 is soldered and resistor is soldered at 220k. And it gave nothing (
Then I soldered a 1M resistor to the R61, nothing has changed either (
I looked under the pcb glass board, I did not see anything bad.
QuoteAt the same points on the board where R57 is soldered and resistor is soldered at 220k. And it gave nothing (
Just to confirm was it R58 or R57? The correct resistor is R58.
I think we need to try a more "heavy handed" approach. We need to find out what affects that switch-on delay at all.
QuoteThen I soldered a 1M resistor to the R61, nothing has changed either (
Try a crazy value like 47k and see if there is *any* effect.
QuoteI set the correct value on the oscilloscope(vr3), and everything sounds great by ear)
Measure the voltage across C20 then record it on paper so you can set it back to that voltage later.
Now, try setting VR3 so the voltage across C20 is a low as possible where the delay is signal working but optimal. Does this have an effect on the 0.5sec switch-on delay between bypass and effect in Mode II on output A? In other words does it fix or improve the problem? Are there any positions of VR3 that improve the problem? If yes measure the voltage across C20 at the bets position.
OK, I didn't realize you had an oscilloscope. At this point it might be very useful.
Do you have oscilloscope probes with a "x10" switch?
If you don't have a x10 probe it might be better to leave the 47k across R61 as this will prevent the oscilloscope loading down the circuit.
Yes, to R58.
I tried to turn vr3. voltage turned 5.24v. only in the extreme position was it possible to avoid a delay. But there was no virbrato effect)) It's probably easier to live with this problem than to try to solve it.
QuoteI tried to turn vr3. voltage turned 5.24v. only in the extreme position was it possible to avoid a delay. But there was no virbrato effect)) It's probably easier to live with this problem than to try to solve it.
It's up to you if you want to continue. For me a 0.5sec delay would be very annoying. It's not normal so the unit does still have a fault.
I think the way forward is to put a constant signal like a sine wave on the input then probe the points around Q3, D3, R36, IC1 (pins 1,2,3). Do that in Mode I and Mode II, then try to see a difference between Mode I and Mode II. If Mode I works and Mode II doesn't something must be changing. If you can find out what is changing you might be able to work out what is causing the change, then after you can fix it.
One thing about the Boss circuit is if you probe the gates of the JFETs you can get strange readings because the gates float when the JFET is on. As soon as you put a probe there the probe will cut-off the gate. Any leakage or contamination on the PCB can affect the gate signal and I would not be surprised if the problem is caused by leakage between gate of Q4 and the Mode switch.
The oscilloscope is at the university and quite difficult to access it.
Can a simple way: replace any components with new ones?
QuoteThe oscilloscope is at the university and quite difficult to access it.
Can a simple way: replace any components with new ones?
The problem is a difficult one to solve and it is not obvious what components are at fault. The oscilloscope would help trying to diagnose the problem. We could change many parts and still not solve the real issue.
What we know is the problem is related to:
- The Mode switch set to Mode II
- Output A
- Changing from Bypass to Effect.
One idea is to:
- Remove Q4
- Solder a new JFET in place of Q4. Only solder the source and the drain.
Leave the gate hanging in the air.
- Get parts: 1M, 47n, and a small silicon diode. Wire them together in the same way
as R61, C31, D3. Don't replace the existing parts. Just wire the new parts together.
- With all the new parts off the board, solder the following wires:
- a wire from the collector of Q11 to the new R61
- a wire from the new C31 to ground
- a wire from the anode of the new D3 to the gate of the new Q4
What we are doing is creating a new switch circuit for Q4.
Check the new circuit works in Mode I. Then see if the 0.5 sec delay problem with Mode II and Output A is still present.
Hello again!) At the rehearsal I found out that the vibrato mode sounds very interesting in several songs, so I decided to finish our work)
Once again, I carefully re-read everything, and something became incomprehensible to me:
I need to drop one leg in the gate transistor.
and put 3 new parts instead of the existing ones?
then solder the wiring to them, as You said?
QuoteHello again!) At the rehearsal I found out that the vibrato mode sounds very interesting in several songs, so I decided to finish our work)
Once again, I carefully re-read everything, and something became incomprehensible to me:
I need to drop one leg in the gate transistor.
and put 3 new parts instead of the existing ones?
then solder the wiring to them, as You said?
You need the gate lead of the new Q4 JFET to be bent out into the air. The gate for the new Q4 is not soldered to PCB. The source and drain are soldered to the existing PCB points for Q4.
The old R61, C31, D3 are left in the PCB. The new parts R61, C31, D3 are mounted in the air. The ground side of the new C31 is solder to a ground the PCB. The new D3 goes to the new Q4 gate.
The added part duplictate what is already on the PCB.
I asked one owner, he said that he, too, has an interrupt signal ... Maybe this is a mistake in the early pedals?
I thought, suddenly they had a series of defective parts. And so I tried to solder instead of Q4 2SK117, and it gave nothing. (Of course I took into account its polarity)
Ok, but I still don’t understand how to connect with what.
I did as you advised, everything worked, but ... The problem remained !!!!
I do not know what else can be done with this pedal ....
QuoteI asked one owner, he said that he, too, has an interrupt signal ... Maybe this is a mistake in the early pedals?
Interesting someone else has the problem.
I don't know if there is a problem with the board. The Boss schematic and the Boss documents I have for CE3 are for the "First Version". I do not know if there exists Boss documents for a "Second Version" and if those later documents have a fix/mod for the issues.
Sometimes with difficult problems like this the schematic is correct but the PCB does not match the schematic. I have looked at the PCB, not everything, and it does seem to follow the schematic. I think for now we have to assume the board is OK but there is a fault.
QuoteI thought, suddenly they had a series of defective parts. And so I tried to solder instead of Q4 2SK117, and it gave nothing. (Of course I took into account its polarity)
Ok, but I still don't understand how to connect with what.
I did as you advised, everything worked, but ... The problem remained !!!!
Even though the problem still remains the result is good! That means the original parts and circuit on the PCB for Q4, R61, C31, D3 are probably working correctly. It also means the problem is probably not around those parts.
OK so replace Q4 and remove all the added parts so the unit is back to normal.
I'll try to summarise what we know:
- The problem is: when switching from Bypass to Effect in Mode II the (delayed) signal is muted for 0.5 second.
- The problem is only in Mode II. Mode I works correctly.
- Changing the RC time constant for the JFET gates does not change the problem (reply #30)
- Changing the gate voltages to the JFET does not change the problem (reply #30 and #32).
- The delay was removed when the bias trimpot was set to an extreme setting; but the delay signal is lost.
- Replacing the JFET switch Q4 and the RC network did not change the problem.
So the main points here are:
- Mode I behaves different to Mode II.
- Q4 and the switching circuit appears to be working.
So what is different between Mode I and Mode II? One difference is Q3. So maybe there is a problem with Q3 or IC1b (pins 5, 6, 7).
So the next step would be,
- measure the voltages on IC1b (pins 5, 6, 7) and IC1a (pins 1,2 3) in both Mode I and Mode II
- then try removing Q3 and see if the 0.5 sec mute in Mode II is affected . (you will get no sound in bypass)
- then try putting a wire across Q3 drain and source and see if the 0.5 sec mute in Mode II is affected.
I measured voltages, and they turned out to be the same in both modes.
The most amazing thing is that after removing K3, the delay disappeared!))))
With the wire the same result !!!
We almost won this problem!)
I tried to solder 2sk117 ... the problem remained :-\
I forgot to say that, in addition to the delay, cotton is perceived as if it were heard. it's very quiet and barely noticeable, but it sounds like a sound True-bypass.
QuoteI measured voltages, and they turned out to be the same in both modes.
The most amazing thing is that after removing K3, the delay disappeared!))))
With the wire the same result !!!
We almost won this problem!)
Yes, we are very close. The problem occurs when Q3 *changes* between off and on, which only happens in Mode II. However, it is not obvious what the problem is.
It would be useful if you could report the voltages on all pins of IC1. Maybe report the DC voltage on the source of Q1, where it connects to R3.
I think there is a DC problem around the Q3 switch. Notice Q3 is DC coupled to IC1 pin7 (ie. no cap). So that's why it would be useful to report the voltages. When Q3 changes state the circuit must find a new DC equilibrium. Somehow the signal gets blocked when this is happening.
Normally all the opamps and JFETs all sit at the bias voltage. The bias voltage is the voltage across C20.
If DC output of IC1 pin 7 not the same as that at IC1 pin 1 the JFET Q3 will have DC across it and that might be creating problems with the switch. There are many ways DC problems can arise:
- IC1 faulty. That causes DC offsets. It can also cause DC currents to flow in or out of the opamp inputs.
- Bad solder joint on IC1. If IC1 has any open input pins the circuit's DC state can wander.
Try resoldering the pins of IC1
- C3 leaking. Initially I thought C3 could be leaking. The high bias voltage setting could make the voltage across C3 go negative. That puts a small amount of DC current into IC1. However, since your measurements show no DC voltage change on IC1 pin 7 so I no longer believe that is the cause.
So where to go next?
Reporting DC voltage measurements would help me see a DC issue.
However, I can suggest a possible fix. However be warned this fix could hide the fault causing the DC problem. The idea is:
- Connect a capacitor between IC1 7 pin and R15. Maybe a 1uF non-polar capacitor.
- If that doesn't work 100% try further adding a 1M resistor. One side of the 1M connects to the point where R15 and the added 1uF capacitor joint together. The other side of the 1M connects to the positive side of C20 (anywhere on that track is OK, like IC1 pin 3).
Ic1a 1(5,27v) 2(5,27v) 3(5,24 or 5,25v)
Ic1b 5(5,20v) 6(5,27v) 7(5,27v)
I solder contact on IC1!
I'll try with a capacitor today)
QuoteIc1a 1(5,27v) 2(5,27v) 3(5,24 or 5,25v)
Ic1b 5(5,20v) 6(5,27v) 7(5,27v)
When I allow for the 1M input impedance of your multimeter those voltages look correct.
QuoteI solder contact on IC1!
I'll try with a capacitor today)
Yes try the capacitor.
This is a very hard problem to solve. I've been on this forum for nearly 20 years and this problem is one of the most difficult to solve. So many measurements look correct but we know it doesn't work!
I'm a little confused ...
I first soldered the capacitor, it seems to be better. Then i soldered the resistor, and nothing seemed to change. Then I otpayal everything, and I realized that nothing seemed to have changed ... There's no subsidence. But! Over the ears beats the sound of the pedal. Ok Like a click, but he is very deaf.
QuoteI'm a little confused ...
I first soldered the capacitor, it seems to be better. Then i soldered the resistor, and nothing seemed to change. Then I otpayal everything, and I realized that nothing seemed to have changed ... There's no subsidence.
The easy answer is that might not fix the problem!
QuoteBut! Over the ears beats the sound of the pedal. Ok Like a click, but he is very deaf.
I don't quite understand you here. Are you saying
1) after you do the mod the pedal stops working? and you can only hear a very quiet chorus sound?
or,
(2) After you removed all the changes the pedal *now* doesn't work?
Either way something is wrong.
If you remove the resistor and the capacitor circuit works. She also works with them.
But about the delay, I myself was confused.
I'd rather write it down and drop the link to the file, and we'll see graphically what is happening there !!
Because I began to pay attention to cotton.
https://soundcloud.com/user-703662903/chorus
The first couple of times I turned on in mode 1. Then in vibrato mode.
I hope this will clarify ..
This track you can download and load it into the editor..
QuoteIf you remove the resistor and the capacitor circuit works. She also works with them.
OK thanks for clarifying that. So the conclusion is adding the resistor and capacitor does not change the problem.
Quotehttps://soundcloud.com/user-703662903/chorus
The first couple of times I turned on in mode 1. Then in vibrato mode.
I hope this will clarify ..
This track you can download and load it into the editor..
Excellent idea!
That's great. I can see the gap when going from clean to vibrato. I can measure the gap in samples and it is 50ms (not 0.5s = 500ms). One thing that makes me suspicious is the 50mS is the time constant of the RC nework (R61 =1M, C31=47n, RC = 47ms). That might be a fluke.
When you have a small gap of 50ms it is very difficult to know if there is problem is Mode I. In Mode I the sound switches from Clean + Delay to Clean. You always hear sound. If the Delay signal did not appear until 50mS after pressing the footswitch it might be hard to know it was delayed by 50ms. In Mode II the signal switches from Clean to Delay. If Delay is delayed by 50mS there is a gap of no signal so that makes the gap easy to hear.
Mode I: Clean, Clean for an extra 50mS, Clean + Delay ; always has sound
Mode II: Clean, No sound for 50mS, Delay ; gap easy to hear.
So if we go back to Reply #29 and Reply #30. When you added a 1M resistor across R61 the delay should have changed from 50ms to 25ms. With the 1M added in parallel R61 becomes 1M in parallel with 1M = 500k, then R61 * C31 = 23.5ms. Even though the gap is smaller it is still audible as a gap and that's perhaps why it did not do anything.
So removed all the mods.
One issue with the existing circuit, which I noticed before, is the RC time constant of R61 and C31 does not match the time constant of C9 and R12. However, the problem is more than that: The voltage where the JFET turns on and off is at around 4.5V on the gate this makes the JFET turn-on slower than the turn-off. So even if the RC time constants match there may still be a mismatch when one JFET turns on and the other turns off.
(There is a way to fix this but wait until the result of the next test)
Put a 470nF (0.47uF) capacitor across C9. A film cap will be better but an electrolytic cap will also work provided you connect the + side to R12. What this change does is it delays the turn off Q3. If you can make that change see what effect it has. Also it would be very useful to do another recording to see if the size of the gap has changed.
One *very* interesting thing I noticed: The Boss VB2 Vibrato pedal does not use JFET switching! It must be the only Boss pedal not to use JFET switching. That must be done for a reason. I suspect they could not get the turn-on and turn-off to match and gave up.
------------------
If you have time you could try R61 = 100k, (C31, C9, R12 all normal values, 470nF cap removed). A recording would be useful.
I simulated the circuit with different values of the voltage on C20 set using the Bias Adjustment trimpot. I have called the voltage on C20 "Vb".
Click twice to enlarge:
(https://i.postimg.cc/YjqQtvD7/CE3-JFETSW-vs-VB-setting.png) (https://postimg.cc/YjqQtvD7)
This diagram shows the signal gap at one end and overlap or a gap at the other end. When the voltage is more than 100mV that means both switches are on at the same time. When the signal is zero that means both switches are off at the same time.
When I set the trimpot voltage to 5.3V I get similar behaviour to what you are seeing.
When the trimpot is set to a high voltage the gaps gets larger at *both* ends. At the end, there is overlap but if Vb is increased the overlap decreases then at some point you will get a gap also.
So I think what you are seeing is "normal" for that circuit. Also I do believe the problem does occur in Mode I but it is hard to hear the problem because there is no gap like in Mode II.
I will work on a fix. The problem is the gap and overlap depends on the trimpot setting.
QuoteIf you have time you could try R61 = 100k, (C31, C9, R12 all normal values, 470nF cap removed). A recording would be useful.
I think you should try this mod. Record the results so we can see the reduction in the delay. If the reduction in the delay agrees with the simulation then we are on the right path.
If we are on the right path I have a number of solutions to the problem. The problem is it may require changing about 5 parts and adding a resistor and diode. The "right" part values depend on the setting of the trimpot and the JFET characteristics.
I can decrease the gap without so many changes. That will be an improvement but not 100% fix, you might still have a very small gap.
so! I replaced p61 with 100k.
C31, C9, R12 left unchanged.
Here is the result of this mod:
https://soundcloud.com/user-703662903/chorus-r61
Quoteso! I replaced p61 with 100k.
C31, C9, R12 left unchanged.
Here is the result of this mod:
https://soundcloud.com/user-703662903/chorus-r61
Thanks for doing that. I'm now convinced the switching overlap/underlap is the cause of the problem.
(Not sure why the level is going up and down. The change from 1M to 100k won't cause that. Maybe it's your hand moving closer to the enclosure when you press the footswitch.)
To me it is better than before.
So the problem now is *sometimes* you get a click. The click is actually a small gap (or a bad join), probably about 10ms. It's small enough that we don't perceive it as a gap like the 50ms case. I can't actually see it on the waveforms.
The question is how many mods do you want to do to reduce that gap? Also, there a small risk after those mods you might still have small tick. It is a delicate operation to swap waveforms without any ticks. The reason is part tolerances can cause a gap even when "in theory" there is a small overlap (no gap).
I had three mods:
- The one you did. Very simple.
- A slightly more complex one. In practice I don't know if it will have less click than the first.
- A more complex one. However this one lets you adjust the parts to tweak the overlap/gap.
Are you happy with it as is?
How many mods are you prepared to do?
OK here's the simplest circuit which lets you tweak the timing.
It should do the job.
Please let me know if you think that is too many changes.
Click twice to enlarge:
(https://i.postimg.cc/BjvkPdhh/CE3-switch-mod-V1-0.png) (https://postimg.cc/BjvkPdhh)
So,
Change R11 from 1M to 10M
Change R12 from 100k to 1M
Add two series networks 270k + 1N4148 across R61 and R12.
What is the first one? Only with the replacement of r61?
tell the other two, we will try!)
The one that was attached to me below, now I will test!
oh/ not sure that i have a resistor on 10M resistor...
And instead 270k, i solder a 240k!
"Change R11 from 1M to 10M
Change R12 from 100k to 1M
Add two series networks 270k + 1N4148 across R61 and R12."
I did like this.
True, I'm not sure that the resistor is 10M, since my multimeter measures a maximum of 2000K.
(https://pp.userapi.com/c848628/v848628622/158f49/_oSLavY3dJI.jpg)
QuoteWhat is the first one? Only with the replacement of r61?
tell the other two, we will try!)
The one that was attached to me below, now I will test!
Yes.
I tried about 10 ways. At first I tried to only change a small number of parts but the solution was not reliable. So I went with solution #2 which can be adjusted. It should be possible to get #2 working.
#1) Change R61 only
#2) Attached schematic "V1.0" , 2019/03/27
#3) Minor improvement, similar to #2 except change also R58 and R59 from 56k to 33k and change 2x 270k to 2x1M.
In case 2 and case 3 you might need to adjust the resistors in series with the diodes. The reason is the values I showed are theoretical but you can do better by adjusting on the real unit. The resistors in series with the diode don't both need to be the same value. You can adjust each one separately to reduce gaps.
Quote
oh/ not sure that i have a resistor on 10M resistor...
And instead 270k, i solder a 240k!
There is a trick,
If you have a 1M resistor, measure the 1M resistor, call that measurement R1.
Then measure the "10M" (R2) and the 1M in parallel, call that measurement R3.
Then calculate R2,
R2 = 1 /( (1/R3) - (1/R1) )
So if you measure R1 = 1M and R3 = 909k, R2 = 1/(1/909k - 1/1M) = 9.99M
and if you measured R1 = 1M and R3 = 825k, R2 = 1/(1/825k - 1/1M) = 4.71M
QuoteI did like this.
Do you hear any problems? gaps or ticks.
It would be good if you could post an mp3. It is hard for me to use the waveform plot. At "Vb" it looks like the waveform has a small gap.
https://soundcloud.com/user-703662903/chorus2803
Quotehttps://soundcloud.com/user-703662903/chorus2803
Is that test in Mode II only?
For me, I interpret the results as:
The first change from clean to effect has a glitch which starts at about sample 85000. However it is not a simple glitch. It is a fizziness that lasts about 100ms or more.
At about 160000 I hear another fizz but the change from effect to clean doesn't actually occur until sample 185000. I'm not sure when you pressed the footswitch at 160000 or at 185000?
Also what if you power-up the pedal and wait 10 second before using it do you still get the fizzy sound?
After that the switching seems to work perfectly. I don't understand what is different about the first two.
Do you interpret the results like me or do you see/hear something slightly different?
If you want to try something you could try changing the 2x56k's to 2x33k.
Another question:
What power supply are you using? is it regulated to unregulated?
Look, I feed the pedal with a good stabilized current of 9 volts. The first 10 seconds after power-up, the pedal behaves inadequately, switching on as it came.
Then everything seems fine, but there is no difference between the modes after the last one!) And the problem seems to have disappeared, everything turns on well.
I wrote everything clearly?
QuoteI wrote everything clearly?
Are you happy with it like that or do you want to try to fix it?
Modes give the same sound!
QuoteModes give the same sound!
Not good but it should be solvable.
You should first check for soldering shorts, especially around the JFETs.
I suspect the problem is related to R11 and/or leakage on the PCB.
Some questions:
- Does the footswitch switch between effect and clean on both output A and output B?
- Is output B also stuck when you set Mode I and Mode II?
- What signal do you hear from Output A: Clean + Effect, Effect only?
- What signal do you hear from Output B: Clean + Effect, Effect only, or Clean only?
After the last one, the mod pedal got stuck in a vibrato position. In any position of the handle, the pedal was turned on for vibrato, tested it only at output A.
Now we are talking about: "#2) Attached schematic "V1.0" , 2019/03/27"
I did not quite understand how to make mod number 3.
/////////////////////////////////////////////////////////
Upd! I found the reason for the failures!) Because I touched the tip of the jack with my finger, and did not insert the guitar, then probably clicks appeared.
Since I need a pedal, I decided to just replace R61 with 510k (because I didn’t have exactly 500k)
I played and realized it was almost what I needed! So I measured the delay in the editor, and it makes 20 milliseconds. The human ear does not distinguish a gap of 13 ms ....
Will we finish the delay to 13ms or leave it like this?
(https://pp.userapi.com/c852220/v852220249/ebcab/2nVtEbTLLIg.jpg)
QuoteI played and realized it was almost what I needed! So I measured the delay in the editor, and it makes 20 milliseconds. The human ear does not distinguish a gap of 13 ms ....
Will we finish the delay to 13ms or leave it like this?
If you changed R61 to 510k you can reduce the gap by changing the 270k near R12 to 100k. So, not the 270k near R61 but the other one near R12.
(https://i.postimg.cc/zbtbyf3L/CE3-switch-mod-V1-1.png) (https://postimg.cc/zbtbyf3L)
QuoteI did not quite understand how to make mod number 3.
Mod #3 is very similar to mod #2. It just has two more changes:
- Change R58 from 56k to 33k
- Change R59 from 56k to 33k
If you do mod #3 you might have to adjust the 270k and 100k again.
My advice is if mod #2 works don't worry about mod #3.
You did not understand me!) Mod #2 did not work correctly for me.
Therefore, I returned the pedal to its original state and simply replaced the R61 with 510k.
And the delay decreased to 20ms.
What other resistor should be changed so that it becomes even smaller? (for example 13 ms)
QuoteMod #2 did not work correctly for me.
The *idea* for Mod #2 *must* to work. The problem is likely to be because of the large R11 value.
QuoteWhat other resistor should be changed so that it becomes even smaller? (for example 13 ms)
If you only decrease R61 you will will reduce the gap from Dry -> Effect but eventually you will *create* a gap between Effect -> Dry.
Another problem is if you make the R12/R61 resistors too low the switching circuit (Q11, Q12) will not work properly.
There is more to switching than just having no gaps. When you decrease the resistor values it makes the switching faster. If you switch too fast you will hear a 'tick' even when there is no gap (because the two signals don't join smoothly). The reason JFET switch is normally silent is because it switches slowly. Normally that isn't a problem but for the CE3 in Mode II more care is required because there is a chance of a gap. Mod #2 tries to fix all the gaps *and* still switch slowly.
Without fixing Mod #2 I can only suggest this circuit. It reduces the gap when switching Dry -> Effect as much as possible but it will not create a new gap when switching Effect -> Dry. The Dry -> Effect gap is reduced to 5 to 6ms. It is not a 100% fix but it is the best you can do (without fixing Mod #2). You might still hear a small 'tick' and sometimes the tick might be louder than other times (try switching 20 times).
(https://i.postimg.cc/tZf1fk1g/CE3-switch-mod-V2-0.png) (https://postimg.cc/tZf1fk1g)
that's it, I fixed it!) I added a resistor with a diode, drilled out holes, inserted them. The delay turned out 5ms, which does not affect the hearing, I'm happy!))
Thanks You!
Quotethat's it, I fixed it!) I added a resistor with a diode, drilled out holes, inserted them. The delay turned out 5ms, which does not affect the hearing, I'm happy!))
Thanks You!
Good to hear it worked out!
I'm going to send the bill to Boss for shipping out unfinished designs :icon_mrgreen:.
that's right! What do they have... for example, OD-2 signal squandering, people complain?
Quotefor example, OD-2 signal squandering, people complain?
I'm not aware of that one.
I know there's an issue (or two) with the SD-1.
Overall I think Boss products are well engineered and they do try to fix bugs in their designs.
Hello again, guys!)
We here argued with a friend, how to connect this pedal correctly, and in what mode is the correct stereo?
in the first mode there is a signal + effect and a signal-effect.
in the second mode, there is a direct signal, and a slow signal ("vibrato").
What position can be called stereo and why?
Quote from: midiez1997 on May 04, 2019, 03:31:51 PM
Hello again, guys!)
We here argued with a friend, how to connect this pedal correctly, and in what mode is the correct stereo?
in the first mode there is a signal + effect and a signal-effect.
in the second mode, there is a direct signal, and a slow signal ("vibrato").
What position can be called stereo and why?
*Both* of those two options have been called "stereo chorus" at one time or another in various units.