Re: Tempest Troubles...

Well, I missed it - sorry ;-)

If you unplug the yoke then you can use a voltmeter to see if the
monitor is working properly. Do NOT unplug and transistors!!!
Unplugging the yoke removes the load from the output transistors and
thus they are unlikely to be able to self destruct even if one is
shorted.

It you next put the game into self test, then hook your voltmeter
negative to the monitor chassis you can now turn the game on. Check
the X and Y outputs on the motherboard. They should show roughly 0VDC
or about 2 - 5VAC (lower than 5VAC is likely - going from memory
here). If that is the case, then the monitor YOKE pins should also
show about 0VDC and roughly 10 times the PCB outputs on the AC scale
(at a guess - I'll test later this afternoon on a Tempest we are
firing up for the first time in 25 years - from the time travel
warehouse (last Tempest though and it's sold).

Hope that gives some guidance.

Oh, and DO use the voltage regulator upgrade LV2000 kit! Well worth
the tiny investment!
http://www.geocities.com/jeffhendrix67/lv2000/
I use them in every Tempest that passes through the shop!
That, resolder the MOLEX pins on the monitor PCB, replace the HV caps
with 105C ones, and a solid common connection between the MPU, Power
Supply and Monitor makes the machines almost invulnerable.

John :-#)#

At 5:54 PM -0400 6/9/06, Al Warner wrote:
>So I take it that this was a tough question...
>
>Al Warner wrote:
>
>>Hey Everyone,
>>
>>I have been trying to restore a Tempest for a friend of mine and
>>I've hit a barrier. I have 2 boardsets. One was described as
>>working and the other was dead. The machine that one set of the
>>boards were in must have spent some time outside because the
>>cabinet looked it. I took the monitor and wiring out and put it
>>into a nicer cabinet. The monitor was capped with a Zanen kit and
>>tested fine in my Tempest.
>>
>>I hooked up the first PCB set and it ran but there were math board
>>problems (missing things, etc). Then I hooked up the second board
>>set and it smoked the Low Voltage. I replaced the Low Voltage
>>section with an LV-2000 (older kit type) and it was good to go. I
>>tested it with the first boardset and it looked like before. Then
>>I moved the smaller board from the other set to the "Mostly
>>Working" set and it came up and looked fine.
>>
>>I left it running for 15 minutes and brought my Wife down to see
>>it. While we were watching it, the vectors turned to blobs on the
>>screen and the spot killer started kicking off and on. I moved the
>>monitor over to my working Tempest and it was fine.
>>
>>Now I'm back to the board that blew out the monitor. I looked at
>>the pots to adjust the monitor and one of them (the Y-LIN) was
>>missing the adjustment knob. The part that is soldered to the PCB
>>is still there, but the part you turn is missing. Could this have
>>been what blew out the LV on the monitor?
>>
>>I don't have an Oscilloscope, is there a way to test whether the
>>the board would damage the monitor again?
>>
>>Thanks,
>>
>>-Al-
>>
>
>
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