Emu Amp Sim, needs some help

[dlazzarini]

I’m getting signal in bypass. No output when engaged. When I put the slide switches in high gain mode I can ever so faintly hear high gain sounding output but it’s barely audible. I’ve inspected for cold joints and can’t find anything that jumps out at me. I’ve read the color bands on every resistor and checked all of the other components. Everything is what it’s supposed to be. I’m in the process of making an audio probe and figuring out how to use it but had to walk away for a bit to handle some family matters. In the mean time here’s the IC voltages:
IC1
1- 4.45
2- 4.45
3- 4.05
4- 0
5- 4.05
6- 4.45
7- 4.45
8- 8.92
IC2
1- 4.45
2- 4.49
3- 4.40
4- 0
5- 4.45
6- 4.47
7- 4.45
8- 8.92
IC3
1- 4.45
2- 4.45
3- 4.43
4- 0
5- 4.45
6- 4.45
7- 4.45
8- 8.92
IC4
1- 4.48
2- 4.47
3- 4.45
4- 0
5- 4.45
6- 4.45
7- 4.45
8- 8.92
Transistor
Emitter- 3.87
Base- 4.47
Collector- 8.92
Asides from the pending audio probe, I’ve checked everything that I can think of at my current pay grade. I get the same results in or out of the enclosure. Hopefully some of you way more knowledgeable guys could help me fill in all of the blanks. Any help would be greatly appreciated

 

[dlazzarini]

Anybody see anything that I’m missing?

 

[Robert]

Make sure none of the switches are touching the metal pins / solder connections of the switch breakout boards.

 

[dlazzarini]

Make sure none of the switches are touching the metal pins / solder connections of the switch breakout boards.

First thing I checked. I’ve got tons of clearance. It doesn’t matter which side of the breakouts the switch is soldered to does it? I assumed they were just extensions outward. I’m lost. Nothing stands out to me. I’ve still got to make an audio probe, haven’t had time yet.

 

[dlazzarini]

Make sure none of the switches are touching the metal pins / solder connections of the switch breakout boards.

I’ve got the the audio probe made now. I need to learn how to use it now. Just pokin around on the IC’s I’m getting sound on IC1 and IC2. It gets a touch softer on IC3 but I’ve still got sound. I’ve got nothing at IC4. I’ve swapped out IC’s but still nothing.

 

[peccary]

I’ve got the the audio probe made now. I need to learn how to use it now. Just pokin around on the IC’s I’m getting sound on IC1 and IC2. It gets a touch softer on IC3 but I’ve still got sound. I’ve got nothing at IC4. I’ve swapped out IC’s but still nothing.

You'll want to clip the ground to the ground point (DC jack is usually convenient) and then follow the audio path through the circuit using the schematic as your guide. Start at the very beginning and just work your way through. Eventually you'll hit something that doesn't work/sound right and that will give you more information as to what is wrong. Like, your IC might be making weird/no sounds, but it could be because of a faulty cap somewhere before it or something like that. You just want to be methodical in the way that you go through it from input to output so you can isolate where the problem could be. Volume changes are not always abnormal so be sure to keep the volume low.

 

[dlazzarini]

You'll want to clip the ground to the ground point (DC jack is usually convenient) and then follow the audio path through the circuit using the schematic as your guide. Start at the very beginning and just work your way through. Eventually you'll hit something that doesn't work/sound right and that will give you more information as to what is wrong. Like, your IC might be making weird/no sounds, but it could be because of a faulty cap somewhere before it or something like that. You just want to be methodical in the way that you go through it from input to output so you can isolate where the problem could be. Volume changes are not always abnormal so be sure to keep the volume low.

Thanks for the advice. This is the first time I’ve used an audio probe

 

[dlazzarini]

Make sure none of the switches are touching the metal pins / solder connections of the switch breakoutl

Here’s what I’ve got so far with the audio probe. I’ve got a nice loud signal from pin 7 on IC2. From there there’s quite a drop in volume once it goes through r19 and r20 and into pin 3 of IC3. From IC3 it progressively looses more volume as I go along. By the time it hits the volume pot it’s hardly there. My problem is that I don’t yet know enough about how the various components interact with each other so I’m not sure if this is all normal or not. Is the signal supposed to be progressively amplified the further along it goes or are there places where it’s supposed to fall off.

 

[dlazzarini]

Since I’m not getting very far with this audio probe because i don’t yet understand how parts interact with the signal at various points in the circuit. I’m thinking I’m going to order another board, build it and probe them side by side so I can learn what happens to the signal at various points. The price of a board is well worth the learning experience.