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Hoffman Amps Forum image Author Topic: VVR defective under load  (Read 2505 times)

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Offline Colas LeGrippa

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VVR defective under load
« on: September 19, 2012, 07:01:09 pm »
Hi buddies ,

VVr installed in a new build. When taking the reading onto the standby switch, when off, VVR works perfectly. When standby is thrown to ON, VVR reading decreases to 15 V or so. Whitout VVr, amp works just fine but I'd prefer to lower the voltage to a certain degree. Any idea with this issue ?

 Colas
Don't miss the Woodstock experience : ''FORTY YEARS AFTER'' at Club Soda,  in Montreal, august the 17th and 18th and october the 27th. Fifteen musicians onstage.  AWESOME !
P.S.: call me Alvin.

Offline Willabe

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Re: VVR defective under load
« Reply #1 on: September 19, 2012, 09:44:34 pm »
1'st off, where you been buddy? I've been worried about you.    :icon_biggrin:

2'nd not enough information. Output stage, PP or SE, cathode or grid bias, B+ voltage at plate and screen. What is the set up you have for the VVR, what's the mosfet, how's it wired, is it heat sinked....?

Please post a schemo with all the #'s and how you have it wired up, including what is VVR'ed.


              Brad     :think1:  

Offline kagliostro

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Re: VVR defective under load
« Reply #2 on: September 20, 2012, 02:25:00 am »
Hi Colas

are you sure the VVR is by itself in good shape ?

K
The world is a nice place if there is health and there are friends

Offline Colas LeGrippa

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Re: VVR defective under load
« Reply #3 on: September 20, 2012, 07:09:01 am »
Thanx for worrying, guys. You are so great and experienced ( not the Hendrix way, I hope ) that because of all you all of my builds are trouble free!  :worthy1:

The VVR was working in that particular amp until i swap the OT for a stronger one. Then the VVR busted.  When I put back the original OT, VVR was still out of order.

I have followed installation instructions with diodes at the B+ in and out and as I said, everythiong was working fine. I think the mosfet can't supply enough current ( rated at 10A, but my amp doesn't draw even 1 A ). I will swap the mosfet and get back to you. For now I am running this SE with too high a voltage ( 420V )

Regards

Colas

P.S. did you kiss your wife this morning ? don't get no bad habbit: she'll get frustrated and start throwing peanut butter jars to you. By chance , they're made of plastic now.
Don't miss the Woodstock experience : ''FORTY YEARS AFTER'' at Club Soda,  in Montreal, august the 17th and 18th and october the 27th. Fifteen musicians onstage.  AWESOME !
P.S.: call me Alvin.

Offline Colas LeGrippa

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Re: VVR defective under load
« Reply #4 on: September 20, 2012, 07:14:26 pm »
Hi, I just checked the SS post about the NE2973 mosfet transistor. No reliable device, it seems !

Colas Coca.
Don't miss the Woodstock experience : ''FORTY YEARS AFTER'' at Club Soda,  in Montreal, august the 17th and 18th and october the 27th. Fifteen musicians onstage.  AWESOME !
P.S.: call me Alvin.

 


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