finished stereomour II amp

Smoses01 · 5344

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Offline Smoses01

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on: October 18, 2023, 09:13:05 AM
Hello, I have a completed stereomour II amp I am trying to troubleshoot. Initially, I had B+ voltage on one side only. I reviewed my connections and re-heated and added a bit more solder to connections that looked not too secure. Now, I have no B+ power to either of the large tubes.
Also, I notice that the LEDs aren't lighting on the Cs4 board. I have gone over everything and cannot find the problem. My next step seems to be returning the unit to Bottlehead for repair. I thought I would try the forum before doing that. My resistance checks were all ok, and my voltages when testing the power supply were all normal. Any suggestions?



Offline Paul Birkeland

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Reply #1 on: October 18, 2023, 10:35:58 AM
Can you post some build photos?  Did the fuse end up blowing?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Smoses01

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Reply #2 on: October 19, 2023, 01:23:18 AM
no blown fuse. I think the problem may be with where 130 2 W resistors connect together right before B+ power occurs on circuit diagram. Will post some photos. I certainly don't want to take step of sending unit back to Washington state unless absolutely necessary!



Offline Smoses01

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Reply #3 on: October 19, 2023, 01:57:50 AM
_MG_4553 copy.jpg

Trying to post an image of where I think problem is occurring. not sure if copy of jpeg has posted correctly, but here is a link:

/Users/stephenmoses/Pictures/Photos Library.photoslibrary/originals/D/D6A28395-3008-45CC-9D61-28F3D0E8E67D.jpeg



Offline Paul Joppa

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Reply #4 on: October 19, 2023, 04:05:21 AM
To attach  a photo, click on the "Attachments and other options" just below the text box. Note the list of acceptable file formats and the maximum size. PNG files are acceptable.

Paul Joppa


Offline Smoses01

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Reply #5 on: October 20, 2023, 08:28:51 AM
Today I have reviewed every joint in my build. Re-heated questionable connections, and added a bit more solder where needed. I also performed the primary and secondary voltage test on the power supply ((all were normal).
Resistance tests all good. But when go to do voltage tests, I am getting no high voltage at all. I start at the top, getting AC 120 coming in from the plug to the first small circuit board with 45, 46’ 47, 48 terminals. Then I check dc voltage at the ultrafast rectifier and get weird readings like -1.85 or such. I keep moving towards the front of kit and check every spot where B+ high voltage should be occurring, and instead of 388 volts I once again get a weird readout like -1.85.
Then going directly to the 2A3 tube sockets I get similar( -) voltages. Also, as before, LEDs on circuit board are not glowing. A few days ago I removed the circuit board, checked for proper soldering connections and re-installed it.
I really don’t want to have to return my unit to Washington state, but I am lost as what to do next. BTW, I am using a good quality meter- a Fluke 177. Stephen Moses.



Offline Paul Joppa

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Reply #6 on: October 20, 2023, 08:53:54 AM
Don't worry yet - we have a good record of resolving problems like this through the Forum. It just takes a little time to be methodical. You have the attention of the guy who did the mechanical layout of the SII (and our chief technician) PB, as well as the circuit designer (myself). Photos of the build are usually a big help; be sure to include the area of the UF4007 rectifiers.

Paul Joppa


Offline Paul Birkeland

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Reply #7 on: October 20, 2023, 09:21:18 AM
This is going to be something missing or backwards.  Build phots will help to make the issue more obvious.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Smoses01

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Reply #8 on: October 20, 2023, 09:40:58 AM
Here are a few pics:



Offline Smoses01

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Reply #9 on: October 20, 2023, 09:43:28 AM
pics:



Offline Smoses01

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Reply #10 on: October 20, 2023, 09:51:17 AM
more pics:



Offline Smoses01

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Reply #11 on: October 20, 2023, 09:52:25 AM
more pics:



Offline Smoses01

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Reply #12 on: October 20, 2023, 09:54:35 AM
pics:



Offline Smoses01

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Reply #13 on: October 20, 2023, 09:55:56 AM
pics



Offline Smoses01

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Reply #14 on: October 20, 2023, 09:58:06 AM
pics: