Beepre 2 Coarse Attenuator resistance measurement [resolved]

denteom · 4163

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Offline denteom

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Reply #45 on: December 23, 2022, 04:10:00 AM
I also checked these terminals with the C4S
Black Terminal at 4U

Terminal 1= 170 VDC
Terminal 11= 170 VDC
Terminal 6= 120 VDC
Terminal 16= 65 VDC




Offline Paul Birkeland

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Reply #46 on: December 23, 2022, 06:22:42 AM
The first BeePre upgrade will slightly raise that voltage.

I would suggest rechecking that the problematic DC resistances you found originally aren't still there.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline denteom

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Reply #47 on: December 23, 2022, 01:31:05 PM
All of my resistance problems are fully resolved. I've went through the list.



Offline Paul Birkeland

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Reply #48 on: December 23, 2022, 01:34:32 PM
The 65V at terminal 16 is troubling.  Could you post some build photos?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline denteom

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Reply #49 on: December 23, 2022, 03:38:56 PM
These are the photos near the build



Offline Paul Birkeland

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Reply #50 on: December 24, 2022, 05:23:51 AM
What I would do next is to remove the connections to the large C4S board, rotate it 180 degrees, then reinstall it.  If the 65V voltage moves to the other side of the amp, then you have an issue with your C4S board.

Also you should not have to use the isolating parts for the BeeQuiet, and I still believe you have contact between the switch terminals and the metal body of the switch somewhere that's causing issues with that portion of your build.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline denteom

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Reply #51 on: December 24, 2022, 08:20:17 AM
I flipped the C4S and re installed it (mirror image from previous).  The 65V still on the same side terminal 16. So the C4S  is good. Still not sure what's causing the low voltage in 16.
How about the voltages on Terminal 1 and 11 which reads 170v is that okay?  Manual says 150V



Offline Paul Birkeland

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Reply #52 on: December 24, 2022, 08:23:09 AM
The 170V isn't particularly concerning. 

Can you post the voltages on pins 1 and 4 of each 4 pin socket?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline denteom

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Reply #53 on: December 24, 2022, 08:53:45 AM
with the 300b on? where do I connect the black lead of the tester? What ranges do I expect? So I can set the DC voltage range.



Offline Paul Birkeland

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Reply #54 on: December 24, 2022, 09:22:40 AM
DC voltage, 300Bs installed, black probe can be on terminal 4.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline denteom

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Reply #55 on: December 24, 2022, 09:40:29 AM
A1= 18 V
A4= 13 V
B1=13 V
B4= 18 V
Did I reversed a connection somewhere?  heheh...



Offline Paul Birkeland

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Reply #56 on: December 24, 2022, 10:02:33 AM
No, there's nothing wrong with those voltages.

I suspect that the grid on the offending side isn't seeing a good ground reference.  Did you see 65V when testing the installation of the C4S board?  I would suspect that you have a loose resistor on the terminal strip next to the input selector switch, or possibly a loose wire on that terminal strip.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline denteom

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Reply #57 on: December 24, 2022, 10:14:30 AM
During the first installation of the C4S everything was fine. I think it is solder loosening, cause even the filament board that was the problem. My friend help me look for the joints that did not have enough lead.  Think problems came out when kept on tapping and shaking the chassis after trimming joints.  So you suggest re inspect terminals 16-20 and 26-30, N1-N5. Add more soldering lead to it.
But the voltage problem is at Terminal 16 and probably B2 since a red wire is connected between the two



Offline denteom

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Reply #58 on: December 25, 2022, 04:27:19 AM
I finally found the problem, yes it was the terminals near the the line selectors, the white wire connected to N1L got disconnected.  I think it got snagged by the metal plate holding the attenuators.  That wire most likely caused the shorts that I experienced when I was building the resistors at the coarse attenuators.  I followed your recommendation and removed the paper washers and returned the #6 washers included in the kit.  Did voltage and resistance checks all are in perfect ranges.  Connected my DAC to Line 2 then to my headphone amp, sounds great no his or hum, both headphone cups have equal volume, no channel imbalance. Thanks for being patient with me, pointing out my mistakes, also a big thanks to my electrical engineer friend who was willing to help me and trouble shoot the pre-amp during Christmas day.
Still have no sound on my left speaker though, when the DAC was connected to Line 1.  I think it is is just the speaker wire connection or again a loose Line 1 solder, but it most likely the former. I can handle it from here.  I'll check Line 1 and 3 tomorrow.
Guess this problem is resolved.
I'll work on upgrade 2 mid 2023, meantime relishing upgrade 1.



Offline Paul Birkeland

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Reply #59 on: December 25, 2022, 07:52:48 AM
I'm glad you stuck with it and got it sorted out!

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man