TS-808

[Coda]

I’ve had this on a breadboarding for two weeks. Finally decided to box it up. Sounded off; very muffled, and the gain pot does nothing. Found two mistakes: I had two resistors swapped (R6 and R16). Fixed them and now I get nothing, except sometimes I get this roaring sound,
As if the circuit works briefly. I have found that if I press the op amp down and to the left I can replicate my initial sound, but the gain pot still does nothing.

Pics are attached, I’ll grab some voltages now and edit.

JRC4558D:
1: 1.448
2: .568
3: 5.17
4: 0
5: 2.365
6: 2.367
7: 2.365
8: 8.88

 

[Diynot]

Isn’t your relay board upside down?
Sorry, not a relay board. Ignore me

 

[Coda]

I neglected to mention the following: I have a C-buffer installed. Maybe that’s the issue? Also, with a probe I found that the signal hits the opamp fine at pin 3, but is a buzzy thud by pin 1…

 

[Coda]

Bit of a bump: anyone else think the c-buffer is causing the issue?…

 

[steviejr92]

I don’t think it’s your buffer. Your opamp is giving some weird reading at pins 1 and 2

Have you made sure your opamp is seated properly. This happened to me when I was breadboarding sometimes the pins don’t make good contact with the socket.

 

[Mcknib]

Your vref voltages on the op amp input and output pins are way off apart from pins 3, 4 and 8

Check what voltage you get at the junction of R16 and 17 right hand side of either one

It's difficult to see the colour bands on your resistors the pics a wee bit out of focus

 

[Coda]

Your vref voltages on the op amp input and output pins are way off apart from pins 3, 4 and 8

Check what voltage you get at the junction of R16 and 17 right hand side of either one

It's difficult to see the colour bands on your resistors the pics a wee bit out of focus

R16 and 17 are brown-black-black-red-brown: 10k. Junction of R16/17 reads 3.8v…

 

[Mcknib]

Nice and clear now, lovely

R9 should be 1K I think

 

[Coda]

Nice and clear now, lovely

R9 should be 1K I think

Well, a 10k is ten times more good than 1k, isn’t it?…I’ll get that swapped out…

 

[Mcknib]

Well, a 10k is ten times more good than 1k, isn’t it?…I’ll get that swapped out…

Haha sure is

Easy done

Now I'm sure I've bored everyone with this before on various forums, so yawn away, but

Back in the day when we didn't have shoes and we had to wear old books tied to our feet

I put not 1 but 3 incorrect values in a deep blue delay.....I did! once I realised and couldn't afford the correct values I just consoled myself with a bowl of gruel

I had to pick a pocket or 2 to purchase the correct values obviously

You kids just don't know how easy you've got it these days

 

[Coda]

R9 replaced and no change. I tried it with a new 4558 too, and same thing. I think next I’ll try to reflow as much as possible, because it sounds like a connection issue. I can press the opamp and get signal. Maybe the socket isn’t seated fully?…

 

[steviejr92]

Thats my thought initially!

 

[Coda]

Reflowed everything, and still no change. I’m starting to suspect the gain pot. It only measures 174k when maxed out…

 

[steviejr92]

But that wouldn’t explain the gain pot not doing anything would it?

 

[Coda]

Depends on why/if it failed, I suppose. The gain control is between pins 1 and 2...which is where my signal goes shit.

 

[steviejr92]

Have you audio probed D1, D2, and C3?

 

[Flying]

Clipping diode orientation?

Ignore me, I was looking at the wrong 808 on Pedal PCB!

 

[steviejr92]

Thatll do it If that diode is backwards.

 

[Coda]

Thatll do it If that diode is backwards.

It’s not…

 

[steviejr92]

Looking at the schematic they should be going opposite directions....

Not saying you're wrong but the black band on both diodes seem to be in the same direction.