Star Wars AVG board voltages -15 is .477

gatordad

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Well I finally finished fixing my monitor and tested it in my space duel, so on to the board set.

Before plugging in the monitor I wanted to test board voltages first

all main board vdc checks good

AVG board
+5 is 4.87
+12 is 11.96
+15 is 14.88
-15 is .477
I have looked at this board and don't know where the +22 and - 22vdc is? where are those?

What should I look at for the -15 being so far off?
 
Atari schematic book says that neither of the 15v's are used on Star Wars. (Whoops, looked at the wrong schematic.... was looking at the ARII)

But if it drives you nuts, or you need it for a different machine, it's almost invariably going to be Q11 witch is the 7915 regulator. Not much else on that circuit at all.

-Hans
 
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Yep the 7915 tests bad 24v in and .477 out
Dumb question are the schematics online anywhere?

I have no real board level knowledge but I can test and replace stuff
 
He's talking about the main PCB, Dez.

The +/-22 coming in through the edge connector is simply the unreg input for the +/-15 (7815/7915) regulators. The 15v lines are only used in the output section, mainly for the op-amps (TLO8x) which provide the final video output levels.

Just replace the 7915, if you still have issues, one of the op-amps will probably be pulling it down, but if you see half a volt I'd suspect the 7915 simply failed.

If you're powering this up in the cabinet, disconnect the monitor until you know all voltages are correct.
 
Yes for sure
I believe I may have made additional work for myself the first time I had the monitor working, I tried it in the game without testing the board voltages only to have to my monitor die again, I had to fix a few blown diodes, I took out 2 chassis transistors and burnt a voltage reg on the lv6100 in addition to the original full cap out and parts update.

It's been a learning experience.

On the positive side I've learned how to test diodes, transistors, voltage regulators, and resistors with this game.

I'll place my order today and hopefully have my parts soon.
 
I replaced the bad VR 7915 on the AVG Board and retested all my voltages they were fine.

I held my breath and fired it up with the monitor connected, good news bad news.

Game comes up I tested my B+ and adjusted to 180.4 thats the closest I could get to 181 with out going over.

Bad news is I have never fine tuned a vector before and if I turn the brightness down to eliminate all the retrace lines I have no image.

Grrrr.... so close but yet so far

any advice on fine tuning the monitor.

I started a new thread in the monitor section with a more appropriate title, as I believe it is now just some monitor fine tuning.
 
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