Rebote 2 Delay - No delay-Please help

[KRK]

I'm still troubleshooting my rebote 2 delay from tonepad.com using the PCB ordered from tonepad.

When I plug in I get no delay just straight bypass.

I have wired everything to the board with no switch to eliminate the extra wiring as a cause.

All components are correct except for a 470 K resistor instead of the 510k. The only other thing is I have electrolytic caps for the .1uF caps. I set them up so that the negative is soldered to the ground trace.

My voltage in at the board is 7.7v  - the battery is 8.1v

IC1 PT2399
   
PIN  VOLTAGE
1              5
2              2.5
3              0
4              0
5              2
6              2.3
7              1.3
8              1.5
9              4.8
10            0.4
11            0.4
12            4.8
13            2.9
14            0.1
15            2.8
16            0



IC2 TL072 PC
   
PIN  VOLTAGE
1              3.6
2              3.6
3              3.6
4              0
5              7.5
6              3.6
7              3.3
8              2.7



IC3 is a 5V regulator

I/P - 7.6v
GND - 0v
O/P - 5v

Can anyone help me troubleshoot or point me in the right direction?

Cheers!

[bancika]

I have the same problem with rebote 2.5, my audio probe isn't here at the moment. Hopefully this will help 

[nelson]

Use a fresh battery.

Your TL072 voltages are wrong, are you sure its orientated correctly?

the 7.5v on pin 5 should be on pin8.

[KRK]

Use a fresh battery.

Your TL072 voltages are wrong, are you sure its orientated correctly?

the 7.5v on pin 5 should be on pin8.

No, I'm not sure.

From what I can tell from the spec sheet for the TL072CP at www.alldatasheet.com it is correct and right for the tonepad layout. I don't mean to be rude, but if pin 4 and 8 were wrong it would make sense being backwards, but if pin 5 and 8 are wrong do I need to mount it upsidedown?

I do appreciate the help and please don't think I'm being a pain (I'm not trying to be) I'm just asking about the upsidedown aspect.

Cheers!

[George Giblet]

Re PT22399 chip, I'm suspecting you have put one of the 0.1uF electros in the wrong way. Probably the one on pin 8 since you pin 9 and 10 voltage don't look right (as I remember).   Check the cap +ve terminal is indeed positive with respect to the -ve terminal using your multimeter.

Re Tl072 make you are looking at things the right way around.  I can't see how you are getting 7.5V on pin 5 if it's in the right way or wrong way unless you have soldered it to the wrong side of the board!

[KRK]

I revised the pins for my TL072 - I had them labelled incorrectly.

I'm still troubleshooting my rebote 2 delay from tonepad.com using the PCB ordered from tonepad.

When I plug in I get no delay just straight bypass.

I have wired everything to the board with no switch to eliminate the extra wiring as a cause.

All components are correct except for a 470 K resistor instead of the 510k. The only other thing is I have electrolytic caps for the .1uF caps. I set them up so that the negative is soldered to the ground trace.

My voltage in at the board is 7.7v  - the battery is 8.1v

IC1 PT2399
   
PIN  VOLTAGE
1              5
2              2.5
3              0
4              0
5              2
6              2.3
7              1.3
8              1.5
9              4.8
10            0.4
11            0.4
12            4.8
13            2.9
14            0.1
15            2.8
16            0



IC2 TL072 PC
   
PIN  VOLTAGE
1              3.6
2              3.6
3              3.6
4              0
8              7.5
7              3.6
6              3.3
5              2.7



IC3 is a 5V regulator

I/P - 7.6v
GND - 0v
O/P - 5v

Can anyone help me troubleshoot or point me in the right direction?

Cheers!

[George Giblet]

The TL072 stuff looks OK.  The fact the clean signal works only confirms this.

Based on the assumption you haven't done any silly mistakes like poor solder joints, no soldering shorts, electrolytic caps around the wrong way, pot wired incorrectly:   I think the problem is around the delay chip.

The voltages on pin 9 and 10 voltages look wrong to me.  The relation ship inverted relationship between the voltages on pin 9 and 10 make me think the opamp on these pins is OK - it may not be but it seems like it is OK.

The clock may not be working.  In this case the output of the delay chain which feeds pin 10 (more or less) is stuck on zero.  As a result the pin9/10 opamp simply saturates in the state it is now.

To check the clock you need to put an oscilloscope on pin 5.   

If you haven't got an oscilloscope: connect a 10k resistor to pin 5 then take the free end of the 10k to a 10n to 100nF capacitor to ground.  Connect you multimeter to that capacitor and ground, set the multimeter to DC volts (20V range)  If the clock is working you should see about 2.5V - I'm assuming the clock is square.  Check is stays constant over a range of delay pot settings.

If it appears there is no clock start looking at the resistor and pot connecting to pin 6.

Another thing is you might consider *not* using an electrolytic for the 100nF cap across the power supply.  Use a ceramic, or a tantalum, a greencap might work.   If the supply bypass cap isn't good enough perhaps the oscillator isn't operating properly.

[bancika]

Since I'm having exactly the same problem I must join discussion.
For 1uF and 100nf caps I used WIMA foil caps, electros are only 47u ones. In fact, all but those in pF range (those are ceramic) are poly caps.
Is this fine?
Also, I read ~2.5V at pins 9-16 of my delay chip and KRK has some very different values. Can you tell which ones are correct, it can help us both.

[George Giblet]

I don't have a unit with this specific chip in there - surely someone else must!

> Also, I read ~2.5V at pins 9-16 of my delay chip and KRK has some very different values. Can you tell which ones are correct, it can help us both.

Your values look good.

KRK's values have some problems.  Having another look at KRK's values I think there may be a short to ground on one of the parts connecting to pin 16.

On your unit I'd first check the audio is getting to pin 16, then pin 9, then pin 12 then pin 14.  If audio makes it to pin 14 then the chip is working (well a very good chance anyway).  From that point it should be straight forward to find the problem (ie. loss of audio) in the pin 14 and REP and WET pot region.

How are your opamp voltages.  KRK's look ok *but* his meter has loaded down some of the voltages around IC2B (in reality they should be at 4.5V, or 3.6 with KRK's relatively flat battery)

Here's the voltages I know:

IC1 PT2399
   
PIN  VOLTAGE
1              5
2              2.5
3              0
4              0
5              2  <---- I don't recommend connecting a multimeter directly.
                           Go through a 10k resistor at least, and preferable use the cap trick about
                           I think it should be around 2.5V, but 2V might be OK
                          Checking with CRO is the most reliable.
                          If there's no clock the device won't work!
6              2.3 to 2.5V depends on resistor value to ground off this pin.
7              ? don't know off hand
8              ? don't know off hand
9              2.5V
10            2.5V
11            2.5V
12            2.5V
13            2.5V
14            2.5V
15            2.5V
16            2.5V

[bancika]

Thanks for reply!
I'll check with audio probe ASAP, and opamp voltages are:

1: 4.74
2: 4.7
3: 4.7
4: 0
5: 3.8
6: 4.74
7: 4.74
8: 9.4

Thanks again

[bancika]

Hi George,
I checked with audio probe pins you mentioned and I get sound on 9, 12 and 14, but no sound at pin 16.
What should I do next?
Thanks

[George Giblet]

I have to appologize but that should have been pin 15 (not pin 16, pin 16 should have no detectable signal).

Sound on pin 14 is the ultimate winner, if you get sound upto there then the chip is working.  I suspect the problem is somewhere between pin 14 and the REP and WET pots.

There's a 1k resistor on pin 14  which then connects to a 10nF cap to ground.  Check you are getting signal at that point.

If OK then:

Check for signal on the clockwise pin on the REP pot when the REP pot is fully counter clockwise.

Check signal on the REP pot wiper pin when the REP pot is fully clockwise

Check for signal on the clockwise pin on the WET pot is fully counter clockwise.

Check for signal on the WET pot wiper pin when the WET pot is fully clock wise

If these all check out and there still no signal check the 1uF cap and the 10k resistor that go from the WET pot wiper and pin 2 if IC 2a.

You are nearly there.  You have your hand on the last rock to pull yourself up to the summit of the mountain - don't let go yet!

[bancika]

Thanks for great assistance, really appreciate it!
I'm using 2.5 version, there isn't 1K resistor on pin14, only on pin6!
I probed pots and if I'm not wrong there's signal on all of them. Just to make sure about pot pinout, as usual pot pins are towars bottom of enclosure where switch is. Which one is (counter)clockwise, left one or right one.
I also probed opamp, get signal only on pins 1 and 7, but again there isn't 10K resistor to pin 2, it's 33K.
Once again thanks!

[George Giblet]

>I'm using 2.5 version,
OK got ya. 

> 1K resistor on pin14, only on pin6!
The 1k/10nF I was referring to is the 2.7k/10nF on pin 14.

> I'm not wrong there's signal on all of them.

If that's the case, it's probably the 1uF/33k.

> Which one is (counter)clockwise, left one or right one.

If you are looking at the knob side counterclockwise in on the left.  If you are looking from the back where you solder the terminals counterclockwise is on the right.   You should be rotating the pots in as viewed from the front, as in normal operation.

> I also probed opamp, get signal only on pins 1 and 7, but again there isn't 10K resistor to pin 2, it's 33K.
Signal on 1 and 7 is good but it is not possible to get the delay only signal there.

On the level pot the wiper conencts to 1uF then to 33k.  When the Level pot is on full (ie. clockwise) you should see signal on both sides of the 1uF cap - that assumes you are getting signal on the both sides of the 2.7k resistor mentioned previously (it sounds like the signal is getting there).

[bancika]

It's strange, I get signal at first lead of 2.7K resistor, but no signal after it! I can't be bad joint because I probe directly to lead instead of joint. I measured it with multimeter and it's 2.7K sharp. What should I do now?

[bancika]

Solved it, yahoo!! 
There was small bridge between 10nF and 100K, after removing it it worked!
Thanks for assistance, without your help I couldn't make it.
Also thanks FP for great project. I'll post clips and pics soon

[George Giblet]

  very cool!