Need help with a rat clone that stopped working

[jdoughty]

So I had a working circuit, a rat with led diodes. I was putting it into an enclosure that was a bit of a tight squeeze. I realized as I was wrapping up that you couldn't see the led for it being on and moved it to be over the circuit. As I did, the led blew and the  pedal stopped making any sound. I've now redone much of the wiring to outside boards from solid core wire to weave as pulling it out of the enclosure saw some of the wires to the pots snap, but I still don't know what broke.

I don't have alot of experience, so do you guys have some ideas where I should look?

Ic voltage reading
   1. -5.3
   2. -2.7
   3. -2.3
   4. 0
   5. 0
   6. -2.67
   7. -5.3
   8. -5.25

Transistor 90% sure I have the e/c labeled right
   1. 0 emitter
   2. -3.3 base
   3. -5.3 collector

-5.4 pos entry point from battery
0 ground exit to battery

[antonis]

First of all, replace your battery..!!!

About output transistor, it's an FET (not BJT) with D-S-G pinout so voltage readings might be OK..
(Gate instead of Emitter..)

[jdoughty]

   New(we) battery readings
Ic
        1. -7.8
   2. -4
   3. -3.5
   4. 0
   5. 0
   6. -4
   7. -8
   8. -8
Trans
   1. 0
   2. -3.3
   3. -8

-8 pos
0 ground

[GGBB]

How did you measure? All of the voltages should be positive not negative. Do you connect the battery backwards? Or did you connect your meter backwards?

[antonis]

Voltage readings seem OK.. 
(despite minus which I think is just typo..)

[jdoughty]

I may have the multimeter cables plugged in backwards. It was working before so I'm fairly confident I didn't bugger anything fundamentally, but I don't even know where to start looking for a dead part 

[GGBB]

(despite minus which I think is just typo..)

Assumptions are the gateway to confusion.

[GGBB]

I may have the multimeter cables plugged in backwards. It was working before so I'm fairly confident I didn't bugger anything fundamentally, but I don't even know where to start looking for a dead part 

An audio probe would probably be your best friend at this point.

[iainpunk]

I may have the multimeter cables plugged in backwards. It was working before so I'm fairly confident I didn't bugger anything fundamentally, but I don't even know where to start looking for a dead part 

An audio probe would probably be your best friend at this point.

i echo this

is there a chance that a stray wire killed the chip and/or transistor? happened to me a few times. one time i had a tiny stray strand of stranded core wire cross a resistor once and frying a set of transistors to the point of not working (they have become a dead short at that point), almost fried an expensive inductor if it wasn't for the fuse.
the lesson here is that you need a tidy workspace.

cheers, Iain

[jdoughty]

Very possible, I have some extra transistors so I could try cleaning up and replacing it. If it's the ic that needs replaced I may be out of luck. I'll report back this evening after the deed is done!

[Marcos - Munky]

   New(we) battery readings
...
-8 pos
0 ground

Even the voltages seems to be ok based on your input voltage, your battery is also almost dead. You should read 9-ish volts on it.

Maybe there's something that's shorting voltage supply with ground and for this reason the battery is being drained. To be sure, measure this same battery outside the circuit and connected to circuit, and also check if the battery is getting hot. And also photos are very welcome.

[jdoughty]

So I made an audio probe using a quarter inch jack. I found  audio made it to pin 3, but failed to go any further. I then replaced my lm308 with a tl71 and after that, what I believe is the gain pot got signal to each lug. I checked pin 6, got a boosted signal, went to the 4.7 cap, still boosted signal, then the 1k resistor, which is where I'm not sure things are as expected. The signal goes in boosted, but comes out super faint. Just in case I replaced this, but the new one has this effect as well. I checked the signal at the base of the diodes and the minimized signal goes in, but no signal comes out. When the circuit was working, these diodes lit up, so I'm wondering where the signal is going?

[jdoughty]

Dead green diode! Tested another and now they're lighting up!

[jdoughty]

Alright, everything is back to running! I replaced the lm308 with a ca3130, and replaced the green diode. It doesn't sound as good as I remember, but that may be my tiredness talking. I can finally get sound sleep! I'll put it in an enclosure tomorrow and make a mental not to replace the chip some day!

[jdoughty]

Also HUGE thanks to everyone! Really appreciate your help!

[iainpunk]

CA3130

nice! one of my favourite sounding opamps, i prefer the CA3140 a little bit more because its a tiny bit less aggressive/fizzy.
the 3160 sounds exactly the same as the 3130.
the LM308, OP07 and uA741 sound to dull for my taste (those 3 sound the same, me and some other guitarists did double blind testing on 8 op amp types)

cheers, Iain

[Govmnt_Lacky]

Dead green diode! Tested another and now they're lighting up!

Don't forget that different color LEDs have different forward voltages. Using a Green LED may effect the clipping point. Originals used RED diffused LEDs. Just something to keep in mind