Queen of Bone 2 troubleshooting

[t0omas]

Hi everyone,

I am new to the world of DIY pedal building and new to this forum, and have a question about my first (semi-successful) build. After one failed attempt I now sort of got the Queen of Bone 2 (KoT style) working. However, every time I turn up the gain on the left side, I experience an extreme volume drop and hardly any sound. After I replace the opamp (JRC 4558D), the issue disappears but as soon as I start using the pedal and crank up the gain the opamp dies again. Anybody has a clue what I am doing wrong here?

Thanks!

[Govmnt_Lacky]

Welcome to the forum!

My first suggestion would be to double check ALL of your resistor and capacitor values. This is the most likely cause of your issue. After that, you should check carefully for solder bridges especially around the potentiometer in question (Gain2) and the op amp in question.

Report back and... Good Luck!

[t0omas]

Thank you for the suggestions. I checked my resistor values this morning and everything seems to be correct.. Also, I do not spot any solder bridges (in general and) near the gain pot or the socket for the op amp.

I attached some pictures, maybe a set of experienced eyes sees something different?

[bluebunny]

. . . the opamp dies again.

How do you know the op amp "dies"?

Check out the sticky Debugging thread - it really works.

And welcome from me too!   

[t0omas]

You're right, I don't know for sure. But if I replace the op amp (i put sockets in), it magically works again. So that was just my trial&error conclusion. I put some extra insulation on the back of the tone pot, and it seems to work properly again.. maybe it was shorting out against the pcb? Will check the debugging thread though, and report back if I run into issues again. Thanks for the support!

By the way: any tips for properly protecting the back of the pots from the pcb? I have searched everywhere for these covers, but can't seem to find them..

[Slowpoke101]

Welcome to the madhouse....It's a great place.

Check R15
Your picture seems to show that you may have a 10R resistor installed and not a 1M.
This may just be a lighting problem with the picture but check it out anyway.

[antonis]

any tips for properly protecting the back of the pots from the pcb? I have searched everywhere for these covers, but can't seem to find them..

You can't find them as "spare" part..
(many pots manufactures sell their products with or without plastic covers, although "without cover" concerns the majority of PCB mounted pots..)

You can easily isolate them by electrical tape or any non-conductive self-adhesive material..

[ElectricDruid]

You can't find them as "spare" part..

Yes, you can! You just need to know what to  search for - "pot dust covers" or "dust seal" or something. They're often not obvious.

http://www.banzaimusic.com/Dust-Seal-Cover-16-BLK.html

You can easily isolate them by electrical tape or any non-conductive self-adhesive material..

Definitely a good idea. The dust covers are expensive...

[t0omas]

Welcome to the madhouse....It's a great place.

Check R15
Your picture seems to show that you may have a 10R resistor installed and not a 1M.
This may just be a lighting problem with the picture but check it out anyway.

I checked the resistor and its really black (was indeed a lighting problem!) The pedal is still working as it should (also with the gain maxed out) so hopefully it was just the pot shorting out against the PCB

You can't find them as "spare" part..

Yes, you can! You just need to know what to  search for - "pot dust covers" or "dust seal" or something. They're often not obvious.

http://www.banzaimusic.com/Dust-Seal-Cover-16-BLK.html

You can easily isolate them by electrical tape or any non-conductive self-adhesive material..

Definitely a good idea. The dust covers are expensive...

Alright, guess I'll stick with some good old electrical tape then! Many thanks for the support!!

[Slowpoke101]

The red arrow points towards R15 and not to a specific colour band.



The resistor in the picture seems to have the following bands;
Brown, Black, Black, SILVER, Brown which indicates that it is a 10R (10 Ohm ) resistor.

A 1M resistor (which R15 is supposed to be, unless I misread the dodo - which happens all too often ) should
have the following colour bands;
Brown, Black, Black, YELLOW, Brown

Again, its probably just lighting issues or a digital artefact from the image compression algorithm.

[bluebunny]

I think the "silver" is actually yellow?  Compare with the 47K between the two red caps.

[t0omas]

The red arrow points towards R15 and not to a specific colour band.



The resistor in the picture seems to have the following bands;
Brown, Black, Black, SILVER, Brown which indicates that it is a 10R (10 Ohm ) resistor.

A 1M resistor (which R15 is supposed to be, unless I misread the dodo - which happens all too often ) should
have the following colour bands;
Brown, Black, Black, YELLOW, Brown

Again, its probably just lighting issues or a digital artefact from the image compression algorithm.

I think the "silver" is actually yellow?  Compare with the 47K between the two red caps.

I can confirm that it's yellow!

[Slowpoke101]

I can confirm that it's yellow!

That is good news, thank you.
That has got to be one of the weirdest colour errors I've seen in a digital picture. Not to worry.
Thanks also to bluebunny for noting the similar colour problem with the 47K resistor.

It's great news that you have got the pedal to work properly. Enjoy 

[bluebunny]

Definitely a good idea. The dust covers are expensive...

Small Bear does covers for the 16mm Alpha pots for 11¢.      And most of Tayda's 16mm pots have them pre-fitted.

[ElectricDruid]

Definitely a good idea. The dust covers are expensive...

Small Bear does covers for the 16mm Alpha pots for 11¢.      And most of Tayda's 16mm pots have them pre-fitted.

Ok, the pot dust covers are expensive *in Europe* but somehow are much less expensive when sent from much further away!!

I'm happy to be wrong about such a thing.

Thanks,
Tom

[bluebunny]

Ha ha!  Yes, Banzai's are a bit steep!      And knowing Banzai, they're not actually in stock and they will take an age to arrive...