6100 HV box repair log...

hi all..

 Well, i was successful powering up the WG6100 HV outside of the monitor
tube/frame, and not connected to anthing thanks to the confident words i got
from people on here :) I made up a pair of transistors on a plug-in harness
bolted to some heatsinks, this meant the LV supply on the deflection was
powered and running to the HV box throughthe normal connections.

 This HV box did nothing when powered up, +/-28v input was fine, there was
no B+ output (and therefore no HV).

 I firstly replaced all the caps (someone had capkitted it in the past with
horrible cheap 85' caps very badly), C901 had vented in the recent past, and
i found its corresponding 2.2ohm resistor (R901) to be measuring 160k... so
i replaced it and the box jumped into life, but I was reading 30kv at the
anode. The HV pot would not adjust this, the B+ was actually stuck at 290v
but steady.

 I found Q901 was shorted emitter to collector, and Q902 was measuring with
leaky junctions... So I replaced those and the anode voltage dropped almost
in half, it was now adjustable between 14.8kv and 17.3kv (B+ was 158v @
17.3kv maximum) ...

 So, the B+ is a bit lower than it should be, i went straight to ZD901 (13v
Zener) and replaced it on a whim, and bingo... the HV now adjusts between
17kv and 23kv. I cranked it back to 19.5kv as it should be...

All fixed! I'm very pleased with myself, just thought i'd share, and say
thanks to those of you who encouraged me to hook up the HV to my probe
inside a Branston Pickle (glass) jar out of harms way :)

enjoy...

--
Andrew Welburn
http://www.andys-arcade.com 
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