Mach 1 no sound when engaged

[ADAOCE]

Have a Mach 1 that has no sound at all when engaged. Bypass and LED work fine. I’ve checked my solder joints. Didn’t see any cold looking joints. I touched up a few resistors so that the solder penetrated both sides. I even tried a different opa2134 and a tl072.

I’ve recorded the following IC voltages with the opa2134

1: 4.46
2: 5.03
3: 0
4: 0
5: 0.16
6: 0.59
7: 4.46
8: 8.2

I’ve attached some pictures of the board from the top side. I know it could use an IPA wipe down but to be honest that’s never resulted in an issue like this for me and I’ve done ones that looked worse.

mill have to wait til tomorrow to get a picture of the underside (I stupidly didn’t take a picture when I pulled it out to reflow joints). Underside looks better than top though since that’s the side I soldered from.

anyways I’m just hoping these ic voltages are enlightening. TIA

 

[ADAOCE]

Hmm so replace D100,R101 and R102?

 

[Chas Grant]

Have you got a 9V battery and 2 alligator clip leads?

 

[ADAOCE]

Have you got a 9V battery and 2 alligator clip leads?

I’ll grab some clip leads from work tomorrow

 

[Chas Grant]

I want to go in through the back door to try and find where you are losing the voltage. If you remove the op amp you can back feed power from the socket, it may show us where the issue is. Using a battery is much safer than a wall wart, thats why I want to use a battery. If there is a short, you can feel the battery as it gets hot and remove it, plus a battery won't damage the circuit as long as the IC is out

 

[ADAOCE]

I want to go in through the back door to try and find where you are losing the voltage. If you remove the op amp you can back feed power from the socket, it may show us where the issue is. Using a battery is much safer than a wall wart, thats why I want to use a battery. If there is a short, you can feel the battery as it gets hot and remove it, plus a battery won't damage the circuit as long as the IC is out

Ok sounds good. You can leave me some instructions to try or I’ll just holler when I’m home from work and can get to my bench and we can go from there

Edit: just realized tomorrow is NYE. Happy new year!

 

[Chas Grant]

Happy New Year, about what time will you be able to get on, I have the day off! And Happy New Year to you!

 

[ADAOCE]

I’ll be home around 330 but will be busy until 7 when I put my son to bed. I’ll send you a PM tomorrow evening

 

[ADAOCE]

Rigged this up at lunch. Will this be good? Only thing I had was this cable with a BNC connector on the other end.

 

[Chas Grant]

That’s perfect!!!

 

[ADAOCE]

I have some time if you do

 

[Chas Grant]

I got a little, working on a Caesar chorus

 

[Chas Grant]

The hardest part about this is hooking on the battery, the easy way is if you have an extra socket, you can plug it in the one on the board. If not then you need to be careful so you don’t mess up socket. Just need to hook up battery - lead to pin 4 and the + lead to pin 6 to start then we see what voltages are back to divider, hopefully we can find where you are losing it

 

[ADAOCE]

Ok it’s plugged in and I’m getting .64v after the divider

 

[Chas Grant]

What do you have on R3 both sides

 

[ADAOCE]

0 on both sides

 

[Chas Grant]

Where’s the battery plugged in at

 

[ADAOCE]

- on 4 and + on 6

 

[ADAOCE]

Wait do I need two batteries?

 

[Chas Grant]

No just one

 

[ADAOCE]

Ok good yeah I have it hooked like you said and I’ve confirmed I got 9.3v from the battery