Re: TECH: Voltage Problems - 15V2000

-----Original Message-----
From: "Commander Dave" <cmdr-dave@spamcop.net>
To: <vectorlist@synthcom.com>
Date: Tue, 12 Nov 2002 22:02:28 -0600
Subject: VECTOR: TECH: Voltage Problems - 15V2000

>
> Greetings all,
>
> Once again, I am back to working on a 15V2000 out of a BZ Cabaret. It has a
> voltage problem somewhere in the HV cage. The symptoms are that when cold,
> all is well and voltages are near nominal on all pins of the P900 connector.
>
> After about 20 minutes of warm-up, however, all the output voltage pins on
> P900 drop significantly, along with the voltage at the tube anode (example:
> 12.5 KV to 9.2 KV). The voltage on pin 8 of P900 (voltage to the HV cage)
> does not drop. The main symptom of all this is the monitor blooming (a
> little more vertical than horizontal it seems).
>
> Since all the other voltages coming from the HV cage seem to be derived from
> the HV transformer, I am thinking (hoping) that a component is "thermally
> challenged" between P900 pin 8 and the HV transformer causing all the
> voltage to drop all over (anode, P900 pin 1, 2, 4 & 5). Oh, and the freeze
> spray trick did not work this time on any of the components.
>
>
did you remember to freeze the transistors on the cage aswell as the parts on the pcb?

i have noticed while working on those boxes that the silicone grease dries and cracks when they are old causing bad thermal contact.

if that is the case then clean the cage and transisors and replace the mica washer/silicone grease with a gray thermal pad, they work better.

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Received on Tue Nov 12 21:52:19 2002