6100 loses HV after say 10-20 min

Jlannoo

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This is conversational at the moment since I'm not working on it at this time. Just interested in opinions.

Deflection PCB is capped, lv2000 installed. HV PCB Is capped.

When HV drops it drops from like 19.5K to around 950 volts or so. If the Tempest is unplugged for a good long time it will behave the same way again.

Game always plays blind and you can hear chatter no matter what.
 
Overvoltage shutdown or a heat sensitive connector/component..... Test the first with a voltmeter and the second with freeze spray. Also, ensure you have a good ground on your monitor as the last time I had a similar problem it was due to a bad ground.
 
what points should I check for the over voltage. I have the Manual in front of me
 
And Google says:

HV Over-Voltage Protection Circuit
The later revision HV supplies (P329) have a circuit called the HV over-voltage protection
circuit. It monitors the voltage of the focus assembly in the secondary circuit of T900. If the
high- voltage at the anode of the picture tube increases beyond the threshold set by H.V. TRIP
adjustment R930, this circuit shuts off the timer of IC901 and LED D903 turns on to indicate the
over-voltage condition. Presumably, this was added to help discourage Tempest from eating HV
transformers, as it is prone to do since they are by far the most expensive component in the
game. If you know your HV is good, adjust R930 so that it is just beyond the point where LED
D903 lights (so that the LED is off).
NOTE: The following adjustments are a 2-person job (unless you are very handy with mirrors)
because it is nearly impossible to view the screen and turn the pots at the same time. When
adjusting your monitor, all adjustments should be made exactly in the order as presented below
as many of the adjustments have effects on other qualities and will cause you to have to go back
and redo them if you change the order.
On the outside of the HV assembly are the focus and brightness adjustments. Adjust the focus
until the picture is sharp then adjust the brightness just under the point where the dot in the center
starts to show or just under the point where you can see the connecting lines between objects. Be
careful not to get carried away with the brightness as you can do permanent damage to the
phosphors in the tube.
 
Mine does have the Overvoltage protection with the LED. Would be Nice if turns out to be that simple.

So your saying that the voltage is under the threshold at first but climbs as the game is on longer till it trips that. is it normal for voltage to climb like that a little?

I honestly cant remember if that led lit when it failed so I need tocheck that
 
Yes. If you read the procedure for the vectors and setting the HV, you are supposed to let the monitor warm up for 15 minutes prior to setting the voltage as it has a habit of "drifting".

Also, without a good ground I have found monitors in the past that seem to keep building voltage in the tube until it finds another path to ground. When this happens, it can produce anything from static on the screen to an arcing anode....
 
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