Re: Tempest monitor severe jaggies R901 hot

----- Original Message -----
From: "Dan Rasmussen" <sscanf@yahoo.com>
To: <vectorlist@synthcom.com>
Sent: Thursday, October 19, 2000 9:05 AM
Subject: VECTOR: Tempest monitor severe jaggies R901 hot

> Hi All,
>
> Well, I'm back again with another tempest problem (you see,
> I bought the game to work and it is on _all_ the time).
> This is the second failure in about two months. Last time
> I burnt Q901, and R903. Replaced both of them and put in a
> Bob Roberts cap/upgrade/reliability kit (though I only
> installed the HV part). Monitor does have an LV2000
> installed.
>
> Anyway, I came in a couple of week ago and the HV was gone
> again. I finally pulled the monitor yesterday and found
> that R901 was open. Replaced it, got HV back but now every
> vector is severely jagged and R901 is running hot (it
> started to smell shortly after powering up, another 30
> seconds and it would have burnt open).
>
> A while back I posted that my HV cage ticks. I was hoping
> the work I did before would fix that but it still ticks and
> I was wondering if this could be related.

All symptoms point to runaway HV!!! The "ticks" are arcs either THROUGH the
insulation of the secondary anode wire to the HV cage/cover or from the HV
trasnfomers pins to the monitor chassis. THIS IS VERY BAD and can be very
dangerous!!! At a minimum it will kill your HV transformer in fairly short
order. Check the 7-9ish pin connector for B+ which should be around 180V
(check the schematic). My guess is that your is 300V+. Why? Well that's
the kicker; it could be many things. Start with the 3 cap-kit transistors
as these FREQUENTY short out causing this condition. Basicly look at any
current paths in front of the resistor which is burning up. Look for
shorted transistors and/or shorted diodes. Trust me, you will find them.

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Received on Thu Oct 19 20:52:21 2000