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December 07, 2021, 09:58:45 AM

Author Topic: Help with voltage [resolved]  (Read 1772 times)

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Offline kill_surf_city

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Re: Help with voltage
« Reply #30 on: December 30, 2019, 12:10:45 PM »
The LED should not turn on when you power up the amp.

Does this also happen with no tubes in the amp at all?

Can you post a fresh photo of just the 9 pin socket wiring?

When I take the tubes out the LED doesn't turn on at all. Here’s pics of the sockets as well. I’m about to take out the bad capacitor.
« Last Edit: December 30, 2019, 12:12:55 PM by kill_surf_city »

Offline Paul Birkeland

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Re: Help with voltage
« Reply #31 on: December 30, 2019, 12:42:13 PM »
On the 9 pin socket, it looks like maybe the end of the LED going to A8 is touching the wire at A7. 

On the 8 pin socket, it looks like some of the ends of the green wires need to be trimmed that are sticking out. 

Do both halves of the 12AU7 still glow when the amp is running?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline kill_surf_city

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Re: Help with voltage
« Reply #32 on: December 30, 2019, 12:57:53 PM »
On the 9 pin socket, it looks like maybe the end of the LED going to A8 is touching the wire at A7. 

On the 8 pin socket, it looks like some of the ends of the green wires need to be trimmed that are sticking out. 

Do both halves of the 12AU7 still glow when the amp is running?


I’ll get to trimming! Also, yes both halves the the 12AU7 still glow. I have removed the bad cap.

Offline Paul Birkeland

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Re: Help with voltage
« Reply #33 on: December 30, 2019, 12:59:12 PM »
Can you also carefully measure the voltages at A3 and A8?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline kill_surf_city

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Re: Help with voltage
« Reply #34 on: December 30, 2019, 01:09:25 PM »
Can you also carefully measure the voltages at A3 and A8?

A3 - 02.7

A8 - 01.9

Offline kill_surf_city

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Re: Help with voltage
« Reply #35 on: December 30, 2019, 01:16:16 PM »
Can you also carefully measure the voltages at A3 and A8?

Also after doing the trimming I’ve gotten terminal 9 to come down to 115-116 and terminal 5 down to 92.1
« Last Edit: December 30, 2019, 02:30:53 PM by kill_surf_city »

Offline Paul Birkeland

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Re: Help with voltage
« Reply #36 on: December 30, 2019, 04:44:08 PM »
A3 - 02.7

A8 - 01.9
And they aren't glowing?!

I suspect that you have many cold solder joints.  If I had this amp on the bench for repair, I would reheat each one and let the solder flow out again. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline kill_surf_city

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Re: Help with voltage
« Reply #37 on: December 30, 2019, 05:29:27 PM »
And they aren't glowing?!

I suspect that you have many cold solder joints.  If I had this amp on the bench for repair, I would reheat each one and let the solder flow out again.

The tube is glowing on both sides yes. But neither LED is lighting up. So are you saying i should re-solder the joints where the LEDs are connected?

Offline kill_surf_city

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Re: Help with voltage
« Reply #38 on: December 30, 2019, 05:48:50 PM »
And they aren't glowing?!

I suspect that you have many cold solder joints.  If I had this amp on the bench for repair, I would reheat each one and let the solder flow out again.

Ok I resoldered the joint on the LEDs and got A8 to light up but broke A3 in the process. Something tells me that the A3 LED wasn’t in there very well to begin with. So I’ll have to order a new LED for that joint unless there’s some kind of work around for that. Thanks Paul!

Offline Paul Birkeland

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Re: Help with voltage
« Reply #39 on: December 30, 2019, 06:54:11 PM »
You can install a wire jumper between A3 and A8.

I would resolder all of the joints in the amp, not just the ones where the LEDs connect.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline kill_surf_city

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Re: Help with voltage
« Reply #40 on: December 31, 2019, 02:19:56 AM »
You can install a wire jumper between A3 and A8.

I would resolder all of the joints in the amp, not just the ones where the LEDs connect.

Okay. How long should the jumper be? I’ll install that later tonight and then do a recheck of the voltages and post them here.

Offline Paul Birkeland

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Re: Help with voltage
« Reply #41 on: December 31, 2019, 09:47:34 AM »
Okay. How long should the jumper be?
Long enough to reach between A3 and A8 and not touch anything else.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline kill_surf_city

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Re: Help with voltage
« Reply #42 on: January 02, 2020, 01:44:37 PM »
Long enough to reach between A3 and A8 and not touch anything else.

Okay, put the jumper cable in, the remaining LED is strongly lit, and I put in the replacement cap. The one I got is 160v 100uf but it’s a bit smaller looking. Either way, here’s my voltages. Should I be safe to try it out? 2,4,7, and 9 are on the high end but within 10% of the goal.

1. 94.8
2. 176.1
3. 0
4. 176.3
5. 93.6
6. 0
7. 115.0
8. 0
9.  117.1
10. 0

Offline Paul Birkeland

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Re: Help with voltage
« Reply #43 on: January 02, 2020, 02:00:31 PM »
Those are functional voltages. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline kill_surf_city

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Re: Help with voltage
« Reply #44 on: January 02, 2020, 02:11:36 PM »
Those are functional voltages.

Works and sounds incredible! Thanks a lot for you help Paul and everyone else here!! Im sure I’ll be back when the times comes to install the Speedball