# Informant overdrive problems



## ElReverendoRyan (Feb 20, 2022)

Hey guys.

Had some trouble with the informant. First it worked out of box, then didn’t once in box, then it did, then I’d get oscillation from the voltage doubler, then ONLY that sound + IC2 is heating up. All of this out of box now mind you.

I’m kinda running out of ideas and getting tired of looking/proving, my eyes are shot to s*** (been at it for 3 hours now). Anyone wanna take a look at these pics see if I’m missing something?


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## carlinb17 (Feb 20, 2022)

Is the back of your pot covered by something? They are notorious for shorting the back of the board once boxes


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## ElReverendoRyan (Feb 20, 2022)

carlinb17 said:


> Is the back of your pot covered by something? They are notorious for shorting the back of the board once boxes


It’s got a bumper, and while testing out of the box I made sure to have it bend away from the board


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## carlinb17 (Feb 20, 2022)

What do your connections look like


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## ElReverendoRyan (Feb 20, 2022)

carlinb17 said:


> What do your connections look like


They’re fine, getting signal through true bypass, and when engaged the knobs do have an effect on the squeal, ie can turn it down, distort it, and change the tone of it


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## Diynot (Feb 21, 2022)

Looks like you are using the tc1044scpa charge pump, did you follow these instructions?


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## ElReverendoRyan (Feb 21, 2022)

Diynot said:


> View attachment 23319Looks like you are using the tc1044scpa charge pump, did you follow these instructions?


Yes, put a blob of solder over this


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## Diynot (Feb 21, 2022)

I would need to look at the IC pinout, but you should be able to remove the charge pump ic and jumper the in/out pins of the socket so that the pedal only sees 9v, or remove the ic and jumper from the cathode of d100 and the positive leg of c104. try that and see if the squealing resolves.


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## Diynot (Feb 21, 2022)

Have you checked voltages on the tl072 pin 8 with the charge pump in?


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## ElReverendoRyan (Feb 21, 2022)

Diynot said:


> Have you checked voltages on the tl072 pin 8 with the charge pump?


17 and a bit


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## Diynot (Feb 21, 2022)

I will pull out mine after awhile and do some probing. For now though, have you tried swapping out the charge pump and the IC2 (one at a time) to make sure it’s not the IC itself? Also trying running it at 9v to see if the current IC2 still heats up. If it does, that at least eliminates the charge pump as the offender (aside from the oscillation) and maybe you can focus on the solder joints around IC2 to make sure there is proper grounding/no solder bridges


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## ElReverendoRyan (Feb 21, 2022)

Diynot said:


> I will pull out mine after awhile and do some probing. For now though, have you tried swapping out the charge pump and the IC2 (one at a time) to make sure it’s not the IC itself? Also trying running it at 9v to see if the current IC2 still heats up. If it does, that at least eliminates the charge pump as the offender (aside from the oscillation) and maybe you can focus on the solder joints around IC2 to make sure there is proper grounding/no solder bridges


I’ve tried swapping them around, same deal. I’ll try omitting the charge pump (tried two different ones) and bridging to see if at 9v it still heats. If that’s still going on I’ll try reflowing all my sockets


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## Diynot (Feb 21, 2022)

One last thing, make sure you have continuity from pin 4 to the ground plane on IC2. Hope some of this helps


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## ElReverendoRyan (Feb 21, 2022)

Diynot said:


> One last thing, make sure you have continuity from pin 4 to the ground plane on IC2. Hope some of this helps


Alright just had a go through everything, nothing conclusive to me. Here's the results:

-IC2's pin 4 definitely has ground connection.

-Reflowed everything, then check all pins on my IC sockets with a multimeter for continuity to make sure there wasn't a connection between adjacent pins

-Tried a jumper between D100 and C104 - no dice

-Went over all componenet values, everything is ok and in the right place.

I tried plugging power without the charge pump or the jumper, IC2 still heats up. I found this odd, so unsocketed it and took voltage values on the socket pins. This is without the charge pump. Might be a clue:

1 - 002 (this started off at 010 and slowly drained, i think if i kept on it it would have gone to 000)
2 - 002 (same deal as pin 1)
3 - 1.32
4 - 0
5 - 1.32
6 - 0
7 - 0
8 - 9

I find it weird that without a jumper or charge pump in place that voltage is getting to the IC's (checked IC1 and have similar results)


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## Diynot (Feb 21, 2022)

So, I just measured mine with and without the lt1054 (This is with IC2 in the socket since I couldn’t remove it with my honking pf cap in place) and here is what I get with a 7.95v source
IC2 With:
1-7.2
2-7.2
3-5.9
4-0
5-6
6-7.1
7-7.2
8-14
IC2 Without:
1-3.6
2-3.6
3-3.0
4-0
5-3.0
6-3.6
7-3.6
8-7.25
Lt1054
1-1.4
2-4
3-0
4-1.5
5-160mv
6-2.5
7-1.5
8-7.4
So, yes, your voltages look a little screwy. Where to go from here I may have to leave it in more technical hands.


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## ElReverendoRyan (Feb 21, 2022)

Just did a continuity run through between socket pins and where they should be connecting, all is good.

I’m really stumped here


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## ElReverendoRyan (Feb 22, 2022)

Refreshing thread, I still haven't had a 'eureaka' moment!


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## ElReverendoRyan (Feb 22, 2022)

Resolved, bad ic. Popped one in I knew to be good from another build and it came to life


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## ElReverendoRyan (Feb 23, 2022)

Scratch that, worked for a hot minute and was the best distortion I’ve ever played, then totally crapped the bed, started doing the same thing again minus the overheating chip


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## music6000 (Feb 23, 2022)

ElReverendoRyan said:


> Scratch that, worked for a hot minute and was the best distortion I’ve ever played, then totally crapped the bed, started doing the same thing again minus the overheating chip


As you say, all the values look good!
When you magnify the PCB there is quite a bit of flux & solder bits on the back of the Board.
Would be a good idea to Clean with Electronic Cleaner and under Cut pot, there may be a stray bit of crap or you might find a bad joint!
The other thing is we can't see your Footswitch or Jack connections on the PCB or Off the PCB???


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## ElReverendoRyan (Feb 20, 2022)

Hey guys.

Had some trouble with the informant. First it worked out of box, then didn’t once in box, then it did, then I’d get oscillation from the voltage doubler, then ONLY that sound + IC2 is heating up. All of this out of box now mind you.

I’m kinda running out of ideas and getting tired of looking/proving, my eyes are shot to s*** (been at it for 3 hours now). Anyone wanna take a look at these pics see if I’m missing something?


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## ElReverendoRyan (Feb 23, 2022)

music6000 said:


> As you say, all the values look good!
> When you magnify the PCB there is quite a bit of flux & solder bits on the back of the Board.
> Would be a good idea to Clean with Electronic Cleaner and under Tone pot, there may be a stray bit of crap or you might find a bad joint!
> The other thing is we can't see your Footswitch or Jack connections on the PCB or Off the PCB???


All that flux has been cleaned since

Here’s a bigger angle


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## ElReverendoRyan (Feb 23, 2022)

ElReverendoRyan said:


> All that flux has been cleaned since
> 
> Here’s a bigger angleView attachment 23406


What I don’t get is that it worked great, even boxed, and all of a sudden just went back to that oscillation, and I can’t bring it back. It’s definitely something power related, because when I unplug it you hear the squeal « power down »


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## music6000 (Feb 23, 2022)

It wouldn't be the first time a TC1044SCPA went south, I personally don't use them!!!
I use a 7660SCPAZ, Pull one TC1044S from a working pedal & try that!
You should have no Continuity on the IC Pins other than Pictured below:


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## ElReverendoRyan (Feb 23, 2022)

music6000 said:


> It wouldn't be the first time a TC1044SCPA went south, I personally don't use them!!!
> I use a 7660SCPAZ, Pull one from a working pedal & try that
> You should have no Continuity on the IC Pins other than Pictured below:
> 
> View attachment 23407


Cheers, will check this


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## ElReverendoRyan (Feb 23, 2022)

music6000 said:


> It wouldn't be the first time a TC1044SCPA went south, I personally don't use them!!!
> I use a 7660SCPAZ, Pull one TC1044S from a working pedal & try that!
> You should have no Continuity on the IC Pins other than Pictured below:
> 
> View attachment 23407


The 7660SCPAZ is a direct drop in? With the solder connection at the back?


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## music6000 (Feb 23, 2022)

ElReverendoRyan said:


> The 7660SCPAZ is a direct drop in? With the solder connection at the back?


Yes!


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## ElReverendoRyan (Feb 23, 2022)

music6000 said:


> It wouldn't be the first time a TC1044SCPA went south, I personally don't use them!!!
> I use a 7660SCPAZ, Pull one TC1044S from a working pedal & try that!
> You should have no Continuity on the IC Pins other than Pictured below:
> 
> View attachment 23407


Continuity test checks out


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## music6000 (Feb 23, 2022)

ElReverendoRyan said:


> Continuity test checks out


ALSO Pin 8's on IC1 & IC2 !!!


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## ADAOCE (Feb 23, 2022)

music6000 said:


> Yes!


Do you have to bridge pins 1 and 8 on the 7660 when replacing a 1044? I thought only the lt1054 needs to have the pins bridged


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## music6000 (Feb 23, 2022)

No, No Bridging for LT1054 only!


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## jesuscrisp (Feb 24, 2022)

ICL7660S needs to have the pins 1 and 8 connected.


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## ADAOCE (Feb 24, 2022)

jesuscrisp said:


> ICL7660S needs to have the pins 1 and 8 connected.


Right but PPCB circuits that call for tc1044 also accept 7660 and don’t require additional soldering only for the 1054 do you need to bridge the pads on the back. I was just checking. I’m swapping a 7660 in another build because I can’t find 1044s right now


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## ElReverendoRyan (Feb 24, 2022)

I’ve ordered new charge pump and tl072s. Everything else checks out. I’ll keep you posted


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## ElReverendoRyan (Feb 26, 2022)

Alright!

Switched the type of charge pump, and had a spare 4558 lying around. It worked, but after a while the sound would fizzle out, until i jiggled the op amp at IC1. Reflowed, same. Let it play like that (running a loop of guitar into it), and bridged connections on the op amp to adjacent parts, found a pin that would spring the circuit to life. Soldered a jumper and let the loop run for 15 minutes, didnt seem to have the issue afterwards. Gonna wait a bit before declaring victory, but its looking good


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## fig (Feb 26, 2022)

ElReverendoRyan said:


> Alright!
> 
> Switched the type of charge pump, and had a spare 4558 lying around. It worked, but after a while the sound would fizzle out, until i jiggled the op amp at IC1. Reflowed, same. Let it play like that (running a loop of guitar into it), and bridged connections on the op amp to adjacent parts, found a pin that would spring the circuit to life. Soldered a jumper and let the loop run for 15 minutes, didnt seem to have the issue afterwards. Gonna wait a bit before declaring victory, but its looking good


Hot dog!
What pin did you connect to? I'm following along in the shadows.


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## ElReverendoRyan (Feb 26, 2022)

fig said:


> Hot dog!
> What pin did you connect to? I'm following along in the shadows.


3 to the adjacent resistor


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