Help with Menatone Red Snapper please

[sonolink]

You're right. No GND on any of the chips.

Could all the positive voltages be because the chips are fried/shorted?

I'll check ground continuity, but maybe I should take the chips out of the board before?

Thanks for your help
Cheers
Sono

 

[sonolink]

Thinking out loud here: I've taken the pedal out of the enclosure. Could it be that the enclosure is necessary for grounding purposes and that's why I'm having those readings?

Cheers
Sono

 

[analogguru]

Thinking out loud here: .....

Maybe it is just a missing jack in the input socket ?

 

[sonolink]

Maybe it is just a missing jack in the input socket ?

What do you mean?

 

[radardoug]

Pedals commonly use the ring contact on a stereo jack to ground the negative side of the battery, thus making a power switch by plugging the jack in.

 

[sonolink]

Oh I see what you mean. That is not the problem.

So I put the pedal back into the enclosure and clearly the designer/builder is using the latter as a grounding spot.

I've measured again voltages and this is the result:
1044

9
0.5
0
0.5
0.8
4
5.6
9

4558

8.2
8.2
0.9
0.86
0
1.9
8.2
9

Still all positive voltages and no sign of 18v....

Any ideas please?
Thanks for your help
Sono

 

[radardoug]

How many batteries in there? Most pedals only use one.

 

[sonolink]

How many batteries in there? Most pedals only use one.

One 9v battery.

I've measured again voltages and this is the result:
Still all positive voltages and no sign of 18v....

I think the voltage doubler is fried...
Any other sugestions apart from replacing the 1044?

Thanks for your time and help
Cheers
Sono

 

[sonolink]

Can someone confirm I can replace the 1044 with a ICL7660SCPA, please? I just found a couple among my stuff...

Cheers
Sono

 

[radardoug]

The 4558 is sitting outputs at rail, so is possibly faulty. Remove both ics and fit sockets. Buy some new ics. Either find a circuit or draw it out Its not difficult. Working blind as you are is just wasting everybodies time.

 

[sonolink]

The 4558 is sitting outputs at rail

Sorry, what do you mean exactly? Excuse my language barrier

Cheers
Sono

 

[sonolink]

Working blind as you are is just wasting everybodies time.

If I'm wasting anybody's time, I'm pretty sure they will let me know that I'm doing such thing. If YOU feel I am wasting your time, please don't feel obliged to follow this thread and accept my most sincere apologies for that. It was never my intention to waste your time.

Cheers
Sono

 

[radardoug]

Your supply rail is 9 volts, and the opamp outputs are sitting at 9 volts. They should be sitting at about half rail.

 

[sonolink]

Your supply rail is 9 volts, and the opamp outputs are sitting at 9 volts. They should be sitting at about half rail.

Sorry I don't understand "sitting at half rail"
Do you mean 4.5v? (half of 9v)

Cheers
Sono

 

[radardoug]

YES!

 

[sonolink]

Well, I think you're right, "the 4558 is sitting outputs at rails" and as Jon said before the charge pump and/or the 4558 are probably fried.

I have 4558s but don't have 1044 or 1054. I do have ICL7660SCPAs.
Can I sub the 1044 with that even if it's for testing only?

I have checked the datasheet and they seem the same and looks like nothing would be damaged but I'd like to be sure....

Thanks again for your help and time

Cheers
Sono

 

[radardoug]

LT1054s are available from the usual suppliers, Digikey, Mouser, Newark.
If you put in the 4558 you have at least you can see if the voltages come right for that. You could probably do without the doubler anyway.

 

[sonolink]

I took the chips out already

 

[Whoops]

use also these forums, they are dedicated to stomp boxes:

https://www.diystompboxes.com/smfforum/index.php

https://www.freestompboxes.org

 

[sonolink]

Thanks for your input, Whoops. At this point I just needed to be sure that an ICL7660SCPAs is a direct sub for a 1044

Cheers
Sono