Power on right channel not quite right. Need suggestions

last lemming · 1441

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Offline last lemming

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Reply #15 on: March 15, 2021, 02:25:53 PM
Well, I ordered most the parts to replace the board (just in case), because I pulled the two LEDs that wouldn’t light and bench tested them. Guess what, they both worked.
« Last Edit: March 15, 2021, 03:25:58 PM by last lemming »



Offline last lemming

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Reply #16 on: March 15, 2021, 02:27:36 PM
in retesting my outputs and inputs I couldn’t get a stable reading on the output center pin, it kept going into the negative readings.

Also which side is conductive on a PCB. In trying to remove QC2 I nicked the eyelet on the top side pulling away a piece of the eye so it wasn’t a complete circle anymore. The bottom of the eye is fine and the trace on top going to the eye is still intact. Is this still serviceable?
« Last Edit: March 15, 2021, 03:14:30 PM by last lemming »



Offline last lemming

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Reply #17 on: March 19, 2021, 03:00:18 PM
Ok. I’m about to give up. I’m about to give up!!!

I replaced many of the components on the audio board out of frustration and I double checked EVERY connection solder and where they are supposed to run to and from and I see NOTHING wrong. Yet no none of the LEDs in the audio board on the right channel light at all.

I’m stumped. My last readings on the audio board are:

IA = 216V
IB = 210V
OA = 214V
OB = 158V
OC = 7V
OD = 95V
OKA = 15V
OKB = 97V
OKC = .6V
OKD = 1.63V



Online Paul Birkeland

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Reply #18 on: March 19, 2021, 04:05:06 PM
The 0.6V at OKC would have me wonder if there's a solder bridge on the 2N2222 pins that have turned it into a diode.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline last lemming

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Reply #19 on: March 19, 2021, 04:12:19 PM
No solder bridge. Looked under a 10x loop.

I ran a resistance check on all the component



Online Paul Birkeland

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Reply #20 on: March 19, 2021, 05:06:10 PM
We can set you up with a flat rate repair if necessary. 

The 7V at OC is a really bad sign.  That would basically mean no current is flowing through the 6922 half on that channel.  The 0.6V would be typical base emitter voltage which makes me wonder what's going on with the servo on that side.  PJ might have some good ideas here.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline last lemming

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Reply #21 on: March 19, 2021, 05:30:16 PM
I’ll pack up the unit and send it to you.  I’ll call about the rate Monday.

Thanks.



Offline last lemming

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Reply #22 on: March 20, 2021, 06:56:05 AM
Package sent to ya!



Online Paul Birkeland

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Reply #23 on: March 20, 2021, 06:58:18 AM
We will not accept kits sent in your packing materials.  We have to send you the materials to do this.   You need to call about the service on Monday.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline last lemming

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Reply #24 on: March 20, 2021, 07:55:41 AM
Oh crap. Did not know that. I dropped it off at the UPS already. I’ll need to go pick it up



Offline last lemming

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Reply #25 on: March 20, 2021, 08:45:21 AM
Ok. Got the package back. I’ll call Monday.



Online Paul Birkeland

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Reply #26 on: March 20, 2021, 10:11:38 AM
Thank you so much.  We used to allow people to send their own amps in, but the failure rate from poor packaging was over 90%, so we now send instructions and a proper box.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man