Non-working Bassballs

[Mark Hammer]

One more instance of why I dislike stripboard layouts.  If it's REALLY simple, then soldering parts to a solid copper strip is good..But once the complexity increases even a little bit - and this is by no means a "complex" circuit; we're not talking Dimension C complexity here - troubleshooting, or simply following the circuit path, becomes difficult.  Not to mention the fact that they take up far more room than they really need to.

[Baran Ismen]

Ok, I made the mentioned change of the lugs for 0.47 uf pol. cap, but it didn't work whatsoever.

I took measurements for each transistor and here they are. Black on GND and Red probe on each pin;

Q1 - all pins are 0v (P6/Q6/R6)
Q2 - all pins are 0v (S15/T15/U15)
Q3 - collector 9.05, base 7,95, emitter 0v (P22/Q22/R22)

These are going from left to right according to the layout.

IC readings are same as before.

[Rob Strand]

Ok, I made the mentioned change of the lugs for 0.47 uf pol. cap, but it didn't work whatsoever.

I took measurements for each transistor and here they are. Black on GND and Red probe on each pin;

Q1 - all pins are 0v (P6/Q6/R6)
Q2 - all pins are 0v (S15/T15/U15)
Q3 - collector 9.05, base 7,95, emitter 0v (P22/Q22/R22)

These are going from left to right according to the layout.

FYI your transistor numbers don't match the schematic.

Your Q3 is actually Q1 on the schematic.

IC readings are same as before.

IC-1 (1458)
7- 8,54

If we start with this. I would have expected pin 7 to be at 0V to 1V.

The base voltage of Q3 (actually Q1) is consistent with IC1 pin7 voltage, even though the actual voltage looks wrong to me.  So one possible problem related to IC1.

There is also a problem with the emitter voltage on Q3 (actually Q1).   This should sit at 0.65V below IC7 pin 1, ie. about 7.9V based on the *current* IC1 pin 7 voltage.  The 0V means you might have a short around the emitter.

The other transistors at 0V is simply a follow-on effect of the zero emitter voltage on  Q3 (actually Q1).

Also FYI when this thing is working you really need to check the voltages with and without signal because things can sit at 0V when there's no signal even when it is working.

[Baran Ismen]

Bit more delved into the chasm of this.

https://imgur.com/a/tGln73V

1- A red marked cap is not available on this layout, which is a 100n.
2- The orange-colored lane is merged into one instead of separate ways, I'm unsure if it's a problem or not,
3- R23 resistor do not meet the IC7 instead it meets IC1, also one of the 4n7 caps there are ill-connected as well.
4- Also the 22n caps are in the wrong place, I think they should be interchanged with 4n7 caps, because 22n's are going into IC2's 1&2, and 4n7 caps are going to IC2's 6&7, in the veroboard whereas it's vice versa.

At the moment, I'm recreating this layout on DIY Lay Gen, and I'll apply these fixes to it.

[duck_arse]

the stripboard layout has swapped IC2 A-section for B-section. I think it's all right tho. there is a 100uF cap in top right corner of the layout - it is connected to the wrong end of the 47R. it should go (-) leg to C18 and (+) leg to D18.

I don't want to look at that layout anymore.

we need to see the solder side of your build, please.

-- sorry, I only just saw your "orange" track as I was closing the image.

[duck_arse]

4- Also the 22n caps are in the wrong place, I think they should be interchanged with 4n7 caps, because 22n's are going into IC2's 1&2, and 4n7 caps are going to IC2's 6&7, in the veroboard whereas it's vice versa.

leave those, they should be right as is.

[Baran Ismen]

There you go, flipped back.

https://ibb.co/17qxPS9

[Baran Ismen]

Here's the recreation of the layout.

- Fixed the 100uf p.cap as suggested,
- Fixed the R23, now goes to 7th Leg of IC2 instead of 1st,
- Haven't exchanged the C11-C12 and C9-C10 caps,

Now it's a total clone of Mad Bean's.

But still not working. 

https://imgur.com/OPuOePw
https://imgur.com/gyL20zc

[antonis]

Sorry but is there any schematic to follow..??
(other than the one which shows IC2 pin 5 directly grounded..)

[Baran Ismen]

Sorry but is there any schematic to follow..??
(other than the one which shows IC2 pin 5 directly grounded..)

There are 2 and both seem same.

https://www.madbeanpedals.com/EP/schematics/Slurpee.gif
https://docs.pedalpcb.com/project/Lowballer-PedalPCB.pdf

Slurpee has an extra 100n cap between V+ and gnd, thats all, rest is the same.

One difference between these two is the 1n5817 diodes placement, which i dont know why.

[antonis]

OK.. Both show pin5 of IC1.2(or B) grounded..
So, what's the purpose of O-13 cut..??

[Rob Strand]

Just as a warning the part designations on the two schematics are different even though the circuit itself is basically the same.  We should stick to the pedal PCB designations otherwise there's going to be a lot of confusion 

OK.. Both show pin5 of IC1.2(or B) grounded..
So, what's the purpose of O-13 cut..??

What's the O-13 cut?

I'm pretty sure there's something wrong with the IC1b (pins 5, 6, 7 ).

As I mentioned before this measurement looks off, it should be around 0V to 1V.

IC-1 (1458)
7- 8,54

It could also explain why there's no signal in one of the switch positions (down = Distortion mode)

Last night I finished my 2nd project with great hopes, however all I got was a DI sound mixed with a rather hi-freq hiss, and nothing else. I've followed the below project. Also the dist. switch (which is an on/on, 3-pin switch) totally kills the sound when switched on one side.

The opamp is operating with the inputs are near 0V.  Perhaps the IC1 LM1458 is faulty, or doesn't work like an old-school LM1458, or isn't a real LM1458.   On some opamps pushing the input towards ground can cause a phase-inversion at the output - that might explain the 8.54V on IC1 pin 7.

Maybe you should try something like this as a test/debug workaround:


The idea is to put some DC bias on pin 5 without affecting the operation of the ckt.

[Baran Ismen]

OK.. Both show pin5 of IC1.2(or B) grounded..
So, what's the purpose of O-13 cut..??

Seems un necessary, yet pin5 is grounded anyway right now.

[Baran Ismen]

Just as a warning the part designations on the two schematics are different even though the circuit itself is basically the same.  We should stick to the pedal PCB designations otherwise there's going to be a lot of confusion 

OK.. Both show pin5 of IC1.2(or B) grounded..
So, what's the purpose of O-13 cut..??

What's the O-13 cut?

I'm pretty sure there's something wrong with the IC1b (pins 5, 6, 7 ).

As I mentioned before this measurement looks off, it should be around 0V to 1V.

IC-1 (1458)
7- 8,54

It could also explain why there's no signal in one of the switch positions (down = Distortion mode)

Last night I finished my 2nd project with great hopes, however all I got was a DI sound mixed with a rather hi-freq hiss, and nothing else. I've followed the below project. Also the dist. switch (which is an on/on, 3-pin switch) totally kills the sound when switched on one side.

The opamp is operating with the inputs are near 0V.  Perhaps the IC1 LM1458 is faulty, or doesn't work like an old-school LM1458, or isn't a real LM1458.   On some opamps pushing the input towards ground can cause a phase-inversion at the output - that might explain the 8.54V on IC1 pin 7.

Maybe you should try something like this as a test/debug workaround:


The idea is to put some DC bias on pin 5 without affecting the operation of the ckt.

The OpAmp I got for IC1 is "MC1458P CPAC 2108G". Would that matter? I guess not as all are dual opamps.

[Rob Strand]

The OpAmp I got for IC1 is "MC1458P CPAC 2108G". Would that matter? I guess not as all are dual opamps.

Your opamp is definitely a dual opamp, otherwise the voltages on the other half of IC1 would not be measuring correctly.

What I'm saying is if there is something wrong with IC1 (out of the list of things previously mentioned) it might not work correctly in that circuit since connecting pin 5 to ground like that requires certain behaviors from the opamp.   All we know is an old-school 1458 works.   The circuit I suggested might help get a 1458 that doesn't work quite like on old-school 1458 into working.

If you have any other dual opamps you could just replace the MC1458P and see what happens.   You probably don't want to use a TL072, LM833, NE5532.   A crappy LM358 might work for a test, not a great idea to leave it in there.

[Baran Ismen]

The OpAmp I got for IC1 is "MC1458P CPAC 2108G". Would that matter? I guess not as all are dual opamps.

Your opamp is definitely a dual opamp, otherwise the voltages on the other half of IC1 would not be measuring correctly.

What I'm saying is if there is something wrong with IC1 (out of the list of things previously mentioned) it might not work correctly in that circuit since connecting pin 5 to ground like that requires certain behaviors from the opamp.   All we know is an old-school 1458 works.   The circuit I suggested might help get a 1458 that doesn't work quite like on old-school 1458 into working.

If you have any other dual opamps you could just replace the MC1458P and see what happens.   You probably don't want to use a TL072, LM833, NE5532.   A crappy LM358 might work for a test, not a great idea to leave it in there.

I dont have any spare dualops at hand unfortunately, ill try to get some today tho. I also wrote this issue on madbeans forum and asked for the voltages reading on both ics.

[Rob Strand]

There's some voltages in this old thread.  Also indicates problems with the LM1458 position opamp.

https://www.diystompboxes.com/smfforum/index.php?topic=35294.0

His pin 3 voltage is lower than yours because your multimeter has a 10M input impedance and his has a 1M input impedance.  Both load down the true voltage but 1M loads it down more.  Your previous pin 3 voltage looks fine.

You won't get 0V out of pin 7 with an LM1458 it will be 0 to 1V, perhaps upto 2V.   Pin 6 will be a little lower than pin 7.

I don't doubt connecting pin 5 to ground, as per schematic, can cause issues with some opamps.

Crappy LM358's will work I'm sure.   However they are a poor choice for the first half of IC1.


Another thread here,

https://www.diystompboxes.com/smfforum/index.php?topic=76998.0

and here, (watch out different layout/schematic)

https://www.diystompboxes.com/smfforum/index.php?topic=90320.0

same problem really.

[Baran Ismen]

There's some voltages in this old thread.  Also indicates problems with the LM1458 position opamp.

https://www.diystompboxes.com/smfforum/index.php?topic=35294.0

His pin 3 voltage is lower than yours because your multimeter has a 10M input impedance and his has a 1M input impedance.  Both load down the true voltage but 1M loads it down more.  Your previous pin 3 voltage looks fine.

You won't get 0V out of pin 7 with an LM1458 it will be 0 to 1V, perhaps upto 2V.   Pin 6 will be a little lower than pin 7.

I don't doubt connecting pin 5 to ground, as per schematic, can cause issues with some opamps.

Crappy LM358's will work I'm sure.   However they are a poor choice for the first half of IC1.


Another thread here,

https://www.diystompboxes.com/smfforum/index.php?topic=76998.0

and here, (watch out different layout/schematic)

https://www.diystompboxes.com/smfforum/index.php?topic=90320.0

same problem really.

I see that this circuit is somehow cursed and works (or not) however it desires lol. All 3 threads, I read different voltage values for IC1 per pin.

Mark Hammer suggests something about being one of the diodes in opposite, I wonder it would be the case.

[Rob Strand]

I see that this circuit is somehow cursed and works (or not) however it desires lol. All 3 threads, I read different voltage values for IC1 per pin.

Not cursed it just needs some specific behaviour from the opamp.    Many circuits need specific opamps as they push certain operational boundaries.   I think the problem here is the circuit has a subtle design flaw in that only *some* LM1458's work - that's an annoyance to DIY'ers.   Back in the day EHX might have used a specific brand.

The easy way out is to use one of the opamps people have found to work.  The mod I suggested tries to make the circuit more robust and work with more opamps.   You might need to use two or three diodes.  It's worth trying.   More than three and you will probably need to design out the problem altogether.

Mark Hammer suggests something about being one of the diodes in opposite, I wonder it would be the case.

It's not a circuit "mistake".  It just life with opamps in these types of circuits.   Look up single op amp rectifier - the single supply versions all require "special" opamps.

[duck_arse]

OK.. Both show pin5 of IC1.2(or B) grounded..
So, what's the purpose of O-13 cut..??

to see who's paying attention?

the Dr Quack and the Nurse Quacky both use a 10k to +9V and a led to ground as bias.