VT-131 prints?

[Allison]

>
>Subject: VT-131 prints?
>   From: Dennis Boone <drb at msu.edu>
>   Date: Sat, 02 Jul 2005 00:57:43 -0400
>     To: cctech at classiccmp.org
>
>I have a VT-131 suffering from video circuit problems.  The logic
>seems to be ok -- does a self test, led dance, emits a normal beep,
>and ends with the on-line led lit.  The crt filament is glowing.
>Key click happens when keys are pressed.  No screen display.
>I've turned up brightness in set-up, flying blind.  Haven't twiddled
>the pot yet.  So far, I've just taken the lid off, and am looking
>into the still-assembled chassis.
>
>The video board has some very charred-looking spots around the solder
>pads of one component (cap?  spherical white ceramic-like device with
>two stout leads) down and to the right of the brightness adjustment.
>
>The tech manuals from bitsavers and vt100.net don't give me enough
>info to identify the component in question.
>
>Anyone have prints they'd be willing to scan bits of for me?  Or read
>off to me by e-mail?  Or have "replace this, kid" or "you're screwed"
>specific knowledge of this scenario?
>
>TIA,
>
>De

Common VT1xx part failure.  Seemed they made the video board with a 
50V cap where a 100V cap should be.  Huge numbers of them were made 
and failed but amazingly there are still many in use that havent.. Yet.
It is repairable as it cooks a cap, diode and resistor.

The Video board is common to most VT1xx.  Mine are deeply burried.


Allison