Amplifone High Voltage problem



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Hey all.

I'm working on a Blue Amplifone HV board. When I got it the board was dead
and was missing the transformer at T1 as well as the resistor at R13. I
don't have the Wintron installation instructions and its been about 4 years
since I've had to put one of these things on a board so I don't recall if
those parts were removed as part of the install or if they were just

After putting them back, I pulled them off of a beige board, and doing the
upgrades to the blue board (5 watt 50 ohm resistors and the diodes on the
outputs of the regulators) I now get HV but everything is white and there
are "drawback" lines everywhere. It really looks like the screen control is
up to high but its all the way down. I can swing the HV from 12k to 19k with
the frequency pot.

I've seen this before on a GO8 but it had something to do with the heater
voltage. I don't think that's the case here.

Any insight would be great. I'm sure I can get this if I fart around with it
some more but other ideas are always a help!


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Matt, I'm far from an expert on Amplifones, but facing the same repair
and I just read the faq on Amplifones at

It's a great document aside from a couple of typos (mislabeled
transistor locations in the document on the HV board and cap types
should all be radial on the HV board not axial).

Mike Doyle


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It takes you 1.5 hours to drive home????

Yeesh...maybe I should not complain when it takes me only 20 mins to
get to work and back where I live....and thats in rush hour traffic.

On Mon, 18 Apr 2005 19:37:08 -0700, "matt" <>

>Hey Mike.
>I was poking through that earlier today. Thanks to that doc I did the
>mandatory upgrades to the blue board but it didn't cover the problem I'm
>having. I think that diode right in front of the HV transformer might be
>where my problem lies.
>I took me an hour and a half to drive home tonight so I had lots of time to
>think about this board. If there was something wrong in the 555 circuit then
>I wouldn't have HV at all. Its got to be something on the output side of the
>transformer or the transformer itself.