Help with TS808 buildq

[Kipper4]

Jim has a point looks like the IC is back to front.
If you compare the notch on the pcb it's on the diode side.

[Halp!]

I've just flipped the IC round in it's saddle and nothing changed. The actual pcb layout is a little different to the one in the instructions, not sure if that has caused any confusion


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[Kipper4]

It's hard to know. If the pcb is different.
Your ic voltages should be around V/2 (4.5v) on pins 1  2 3 5 6 7.
Pin8=9v
Pin4=0v

Transistors
C 9v
B 4.5
E 3.9
Or there abouts.

Next step is to try an audio probe.
Take your voltages again.
Double check the dot on the ic is where it should be with the given pcb.

[Keeb]

This is how I interpret your IC voltages: http://imgur.com/a/K0CI2 which looks fine. Please verify this and also check the transistor voltages again.

Make an audio probe http://www.diystompboxes.com/pedals/debug.html. Hook everything up (guitar and amp) and poke around to see where there is sound and where it disappears.

I suggest starting at the input pad, then the emitter of Q1, moving on to pin 3 and 1 on the IC. Then try pin 5 and 7. Still sound? Try lug 2 of the volume pot, then the emitter of Q2. Be carful not to short the IC pins though.

[GibsonGM]

^^  Audio probe

[Halp!]

Audio probe it is, thanks guys! I'll post back when I've tested with it.


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[Halp!]

 Transistors are now both 3.6,4,9v

You are correct about the IC voltages, and I've double checked the board dot so it's definitely the right way round! Now sitting down to make audio probe..






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[Halp!]

Audio probe has revealed that no audio is getting into the circuit past the pcb in! Oh dear....


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[Kipper4]

We've all been there.
Can you see why?
Did you say the bypassed signal works?

[Keeb]

Audio probe has revealed that no audio is getting into the circuit past the pcb in! Oh dear....

Like Kipper4 said, you ain't the first. 

So do you have sound on the PCB "in" pad? Might be redundant but have you probed the input jack (or however you're connecting it) just to make sure that the probe is working?

[Halp!]

I don't feel so alone now, thanks [emoji1]

Yeah there is sound on the in pad but nowhere after that apart from the out jack


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[Keeb]

I don't feel so alone now, thanks [emoji1]

Yeah there is sound on the in pad but nowhere after that apart from the out jack

If you have sound on the input pad then I think you also should have sound on the 47nk cap in the bottom left corner. Did you resolder the round pad for that cap went you went over the board again?

[Halp!]

I've just had a look and re-soldered anyway, there's no audio reaching that cap. I've attached some more photos of the in/out pads, I think the metal squares have come off when I've been stripping out the old solder, is this a problem?

[Keeb]

I think the metal squares have come off when I've been stripping out the old solder, is this a problem?

Use your DMM to check continuity (or resistance) between the in pad and the the centre most leg of the 47n cap underneath Q1. If it's open (no connection) then yes, it's broken.

Problem? Yes. Fixable? Yes.

The trace from the input jack goes just above the "JEDS" text. It connects to a 1M resistor and the 47n cap I mentioned above. You can use either of these points to solder the input wire.

Edit: You can use these resistor legs for alternative in- and outputs. http://imgur.com/a/D57k1

[Halp!]

It works! I used those legs as in/out and it's alive.

Thanks everyone, you all rock [emoji3]


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