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November 26, 2021, 04:08:37 PM

Author Topic: Help with voltage [resolved]  (Read 1756 times)

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Offline kill_surf_city

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Help with voltage [resolved]
« on: December 26, 2019, 01:51:24 PM »
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

« Last Edit: January 02, 2020, 02:50:23 PM by Paul Birkeland »

Offline Paul Birkeland

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Re: Help with voltage
« Reply #1 on: December 26, 2019, 02:42:43 PM »
Terminals 2 and 4 are wired together with a jumper wire.  I would guess that yours is missing or not well soldered.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline kill_surf_city

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Re: Help with voltage
« Reply #2 on: December 26, 2019, 02:58:03 PM »
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.

Offline kill_surf_city

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Re: Help with voltage
« Reply #3 on: December 27, 2019, 08:09:51 AM »
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.
« Last Edit: December 27, 2019, 08:46:33 AM by kill_surf_city »

Offline Paul Birkeland

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Re: Help with voltage
« Reply #4 on: December 27, 2019, 08:51:56 AM »
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.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline kill_surf_city

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Re: Help with voltage
« Reply #5 on: December 27, 2019, 09:08:02 AM »
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

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Re: Help with voltage
« Reply #6 on: December 27, 2019, 09:28:25 AM »
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

Offline kill_surf_city

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Re: Help with voltage
« Reply #7 on: December 27, 2019, 09:35:34 AM »
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.

Offline Paul Birkeland

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Re: Help with voltage
« Reply #8 on: December 27, 2019, 09:39:44 AM »
A blue cap that gets hot could be in backwards, but I can't see that from your photos.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline kill_surf_city

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Re: Help with voltage
« Reply #9 on: December 27, 2019, 09:41:24 AM »
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

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Re: Help with voltage
« Reply #10 on: December 27, 2019, 09:43:01 AM »
From the photo it looks like the top of the cap is already bulging. PB can tell you if it's still usable.

Offline kill_surf_city

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Re: Help with voltage
« Reply #11 on: December 27, 2019, 09:54:14 AM »
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
« Last Edit: December 27, 2019, 09:56:30 AM by kill_surf_city »

Offline kill_surf_city

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Re: Help with voltage
« Reply #12 on: December 27, 2019, 10:24:41 AM »
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?

Offline oguinn

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Re: Help with voltage
« Reply #13 on: December 27, 2019, 10:39:34 AM »
You really ought not try to listen to the amp with the voltages out of spec.

Mouser will carry those capacitors, as will digikey
Jameson O’Guinn

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Offline kill_surf_city

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Re: Help with voltage
« Reply #14 on: December 27, 2019, 10:47:25 AM »
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?