2 Paramount Voltages Problem

AudioDave · 2017

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Offline AudioDave

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on: February 10, 2016, 02:40:00 PM
Doing the voltage check on my first completed 300B Paramount and have 2 voltages that are not right.  Terminal strip #10 reads 0 VDC and should be 233 VDC.  Terminal strip #13 reads 0 VDC and should read 94 VDC.   All other voltages are perfect.  All solder connections look good visually.  Any suggestions?
Thanks!
Dave



Offline AudioDave

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Reply #1 on: February 11, 2016, 01:55:23 AM
I forgot to add that terminal strip #11 is also a tad bit high and reads 229 VDC and should be 164 VDC.    I forgot to mention that these readings are with the Soft Start board installed.
Thanks for any help you can provide
Dav



Offline AudioDave

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Reply #2 on: February 11, 2016, 04:40:12 AM
In doing further research on this forum I found a couple posts by folks with the same question I had about terminals 10, 13, and 11 and it sounds like I am good with my voltage readings.   Does anyone have the most current listing of voltages that I can check against just to make sure I won't damage anything?  The list I am using from my soft start manual apparently is not correct!
Thanks!
Dave



Offline Paul Birkeland

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Reply #3 on: February 11, 2016, 08:44:54 AM
It looks like the soft start manual has some errors. 

T10 should be 0V.
T9 will be whatever OB is, and is adjustable with the trim pot.

If you believe there is an error, you can post the IA, OA, IB, OB, KregA, and KregB voltages here and we can assist you.  Beyond that, the terminal strip voltages are a small sampling of these voltages.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline AudioDave

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Reply #4 on: February 11, 2016, 09:19:40 AM
Thanks Paul,  yes T9 reads 175 VDC the same as OB.   The only voltage that is questionable is T11 which reads 230 VDC and my soft start manual shows 164 VDC.
Can you provide me the recommended voltages for IA, OA, IB, OB, KregA, and KregB?
I really appreciate your help!
Dave



Offline Paul Birkeland

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Reply #5 on: February 12, 2016, 10:39:19 AM
It seems that we need to revise the manual a bit.  There will be little to no current flowing through those Zeners once the amp is running and warmed up.  If you have 300V at OA/IB/+regB, then the voltage at terminal 11 is unimportant.  (In the Kaiju, we do not have voltage measurements on these terminals for this very reason)

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline AudioDave

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Reply #6 on: February 12, 2016, 02:06:12 PM
Thanks Paul !!