Re: More Star Wars HV problems, help please?

I've gotta say it sounds like the sensible thing to send the HVT
back to Wintron to be sure.
Probably a shorted turn from the HV output back to the B+ out.

Looking at the schematics it could be the seperate focus block
though as a long shot, so if you can check and/or replace the focus block that
would be about the last thing to test.
The focus block is the feedback loop from the bottom of the HV winding
back to the overvoltage detection circuit, and is also the ground path from
the HVT output.
You could short the connection between the HVT to the focus block directly to
GND as a test, you won't get a picture, but if the HVT still makes
noise you'll know it's the HVT.

Is the DAG GND connection good from the HV board to the tube and wiring?
It's the final grounding path from the HVT and focus block, through the
HV overvoltage adjust pot.

Have you replaced the W1 jumper with wire?

HVT's do fail sometimes regardless of age, there's a lot of high voltage
there to break a minor production fault.

Do you have a HV probe? When the noise is going are you getting any voltage out of the HVT?

Cheers,

Marc

----- Original Message -----
From: "Jonathan Stanley" <jstanley1@cfl.rr.com>
To: <vectorlist@synthcom.com>
Sent: Monday, May 26, 2003 1:11 PM
Subject: Re: VECTOR: More Star Wars HV problems, help please?

> Recap: No display - no high voltage - recently rebuilt HV board and
> installed new Wintron HVT. Worked fine for a month. When it stopped
> working I could briefly hear a strange noise. There was no smoke or
> smell.
>
> OK, here is the latest:
>
> Test results: My BU406D is fine. All my resistors are fine.
> Q1/3/4/5 are fine. My +30/-30 and +24/-24 are fine. VR1/2 are fine.
>
> But I have no display, and the red overvoltage LED comes on. I read
> that I might be getting false readings since the overvoltage was not
> allowing my tests to be under load, so I pulled one leg of CR1 by R7
> (DANGER - XRAYS!) to run my tests since I had tried everything else I
> could think of...
>
> THE NOISE IS BACK! After pulling CR1 the noise is back big time! I
> am 99% sure it is coming from the Wintron HVT. It sounds like
> somebody slowly shutting a squeaky door in between 2 power lines
> (lots of static and popping at changing frequencies). With the
> overvoltage disabled, it will make noise for as long as I dare leave
> it on. I checked my voltages and they are still good. I seem to
> have no high voltage even with the overvoltage disabled.
>
> There is no smoke, no smell, and the HVT is cold to the touch.
>
> Sound like a bad HVT? It is practically brand new. Has anybody had
> any other part of the board make that sound? I really don't want to
> start putting my ear up to parts on the board. It sure seems like
> the HVT as near as I can tell.
>
> I'd rather not have to build a LOPT tester. Would somebody consider
> renting me one? Or, I might just send back the HVT to Wintron and
> let them test it.
>
> Any advice appreciated!

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Received on Sun May 25 20:50:22 2003