ajp166 at bellatlantic.net
Sat Jul 2 09:26:50 CDT 2005
>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?
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.
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