Alright, Star Wars experts chime in on Power Supply Questions

Maxstang

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Alright, Star Wars experts chime in on Power Supply Questions

Hey guys, as you can see by my other posts, I'm trying to get my pieced together SW working. I've worked on Atari Vectors before, but have a few questions.

Firstly, I borrowed the power brick from my Space Duel to test my test my ARII-02 board and notice that while the +5 and +12 are fine, the -5 reads as -9.7. This is without load as I didn't have the game board plugged in. None of my other games run this -02 revision of the ARII board, so I'm not used to testing the -5 circuit. I understand its for the audio. I'm wondering, is the AR board needing repair, or is my power block causing the trouble. I know the SW power block is different, but I though it was only in the AC plug arrangement (one extra for the fan). I'm leafing through the schematics now, but I though I'd post and ask if anyone knows what's up.
 
Thanks for the reply. Bob Roberts says that that regulator may put out as much as -15 when unloaded. I my be worrying too much.
 
You may have a toasty resistor or a cold solder joint or both. I would do a thorough visual on both sides or the ARII to start.

There's no toasty resistor or cold solder joint the -22 unregulated goes directly to a 7905 to generate the -5.... unloaded, it may lose regulation, so I wouldn't worry much about the -9.7.... -22 (ie shorted regulator) would be worrisome.

-5 is only used as the negative rail for opamps anyway, so it doesn't need to be 'perfect'.
 
Thanks for the help guys. I ended up using a 35ohm resistor to load it and it dropped to 4.7 V. Plugged in gameboard and was greeted with "May the Force be with you!".
 
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