Voltage Testing and Monitor Adjustment Safety

csa3d

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I have been installing cap kits and repairing parts on my Asteroids Cocktail cab. I'm just about ready to start hooking it all back together and plug it in for the first time, and had some questions on how to go about doing this properly. The last thing I want to do is hurry it and have all the parts I just swapped out blow up once again.

Some questions:

1.) When I get to the point where I plug in the power supply and test voltages, do i want to have all the other components/boards plugged in or do I leave certain parts disconnected until power is verified, etc? Any advice on this topic would be great.

2.) I had to replace a trim pot on the G05. Not that I trust that the other pots on the monitor boards aren't set incorrectly, but how should I go about adjusting all the pots should they need it? I assume this is a "adjust as needed" thing, and there's probably a systematic way to go about adjusting one at a time until it looks right. Any advice on this topic as appreciated.

I'm also curious how one adjusts a monitor in regards to it being powered on. It has a scary warning sticker in there, and it seems possible that you have to poke around in there with tools to do the job. How does one do this safely/correctly?

3.) There are 4 transistors on the bottom of the monitor which I've replaced with new transistor pads. The old pads had white gunk around the pads, the new ones are clean and new. I'm guessing that gunk was/is some sort of heat protecting cream? Is this a gunk necessary and should I put an order in to get some for the new transistor parts?

Thanks so much!

-csa
 
My suggestions:

If you did some work to the power supply, you should check the voltages before you plug anything else in. You may still need to adjust, but at least you won't send too much voltage through the other components if something is wrong.

Order the paste (non conducting) and reinstall the transistors.

Set the trim pot in the middle. What trim pot was it? Check the manual and check what it was for. Check here for your monitor type.

http://arcarc.xmission.com/PDF_Monitors/

Use a mirror to check what you are doing. Set it up so you can see the screen from behind the machine. Don't try and reach around, this is when things get dangerous.
 
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The trim pot was the 905 shown here on the HV board, labeled as the EHT Adjust. It's since been replaced with a quick order from Bob Roberts.

index.php


I've sent an order in for some paste, that's an easy fix.

This might seem like a dumb question, but when I test just the power supply without any other components hooked up, I will need to ensure that power is plugged into the power supply and the cab is turned on, yes? I'm thinking that's correct but I want to be super sure before poking around with live wires.

Thanks again!
-csa

EDIT: The monitor is an elecrohome 805-g05
 
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R905 adjusts the HV going to the anode. The trim pot adjusts the voltage from 10kv to 14kv and the nominal voltage should be 12kv. Starting in the middle should be fine.

Yes the power needs to be plugged in to the power supply to test the voltages from the power supply.
 
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