Help with voltage [resolved]

[kill_surf_city]

Both tubes light up completely and one LED lights up (A8).

Here’s my readings:

1. 94.5
2. 183.3
3. 0.0
4. -00.1
5. -00.1
6. Starts at 95 then gradually drops
7. 144.7
8. 0.0
9. 67.7
10. 93 then gradually drops

[Paul Birkeland]

Terminals 2 and 4 are wired together with a jumper wire.  I would guess that yours is missing or not well soldered.

[kill_surf_city]

Terminals 2 and 4 are wired together with a jumper wire.  I would guess that yours is missing or not well soldered.

Thank you, Paul. I’ll check it out.

[kill_surf_city]

Terminals 2 and 4 are wired together with a jumper wire.  I would guess that yours is missing or not well soldered.

Yep, turns out I had missed that step completely. Just put it in and rechecked the voltage. Only terminals that are out of range are 6 and 10. Both should be zero but 6 floats around 100 then gradually starts to drop. 10 starts at 101 then floats between 99.3-99.4. Any idea what the problem is here?

Edit: google search came up with my headphone jack being miswired. Fixed it but now my voltages are all too low.

[Paul Birkeland]

Edit: google search came up with my headphone jack being miswired. Fixed it but now my voltages are all too low.

What was miswired?  What did you change?

"Too low" is not a number and doesn't tell me much about what's going on.

Please post build photos at your earliest convenience.

[kill_surf_city]

What was miswired?  What did you change?

"Too low" is not a number and doesn't tell me much about what's going on.

Please post build photos at your earliest convenience.

The black wire that goes from 3L to the headphone jack wasn’t wired all the way up, so I removed the wire and replaced it correctly. Now the one LED that was turning on, turns on initially then goes out. Here’s my readings now.

1. 45
2. 72.6
3. 0
4. 73.4
5. 17.1
6. 0
7. 49.9
8. 0
9. 14.3
10. 0

[Deke609]

Not sure if this is related to the problems you're having, but you have some leads that need trimming, particularly the one circled in the attached. It looks like it might be creating a short to chassis ground.

cheers, Derek

[kill_surf_city]

Not sure if this is related to the problems you're having, but you have some leads that need trimming, particularly the one circled in the attached. It looks like it might be creating a short to chassis ground.

cheers, Derek

Thanks. Also just realized the right blue capacitor is getting warm but the left one is not. Hmmm.

[Paul Birkeland]

A blue cap that gets hot could be in backwards, but I can't see that from your photos.

[kill_surf_city]

A blue cap that gets hot could be in backwards, but I can't see that from your photos.

Oh shit you’re right! I feel so dumb. Thanks Paul. I’ll turn it around and report back soon

[Deke609]

From the photo it looks like the top of the cap is already bulging. PB can tell you if it's still usable.

[kill_surf_city]

Ok I got both the caps in the right orientation now. Here’s my new readings. Neither LEDs are turning on.

1. 134.2
2. 169.2
3. 0
4. 169
5. 124
6. 0
7. 140.7
8. 0
9. 135.2
10. 0

[kill_surf_city]

From the photo it looks like the top of the cap is already bulging. PB can tell you if it's still usable.

I think the cap is blown. I re-did the voltage checks and the numbers are all in range except for terminals 5 and 7 which I’m pretty sure is the left channel. So I thought what the hell, and decided to plug it in and see how it sounds. Right channel is absolutely silent and when I played music it sounds incredible - like absolutely perfect.  The left channel however, barely any music came through if any at all and it’s mainly a loud hiss with some crackles here and there. Does that sound like the cap needs replaced? If so how do I go about ordering a new one?

[oguinn]

You really ought not try to listen to the amp with the voltages out of spec.

Mouser will carry those capacitors, as will digikey

[kill_surf_city]

You really ought not try to listen to the amp with the voltages out of spec.

Mouser will carry those capacitors, as will digikey

Thank you. Does what I’m describing sound like a blown capacitor?