Author: Zaphod (host-69-145-29-132.hln-mt.client.bresnan.net)
Date: 05-14-2006 11:43
What causes the 810 to vary speed often is the voltage regulators have gone out of whack due to overheat (yeah, the 3 legged thingies on the heatsink on that lower back board.) Believe there is a 7805 and 7812. Try replacing both.
Yeah, I said 7812, there is a voltage doubler in that drive that takes the 9VAC 50/60 Hz, doubles it to 18VAC 25/30 Hz, then rectifies, and regulates it. What a kludge.
If yer kinky, you can run a 12V mini-muffin (like the ones that come in RAM coolers for PCs) right off the rectified 9V (just after the full wave bridge), and knock out the rear sticker on the top of the drive case for a place to mount it.
Also, the 810 uses a cruddy DC motor for drive spinning, with an electromagnetic brake for speed regulation... Maybe, or maybe not there is a problem with hysterisis buildup involved there. Curing that, could be a drag, and I am not an authority on that.
Your best bet, is to get an XF551, 1050, Indus GT, or Rana 1000 drive. Beware, the indus takes DC power, and I am not sure about the rana. Best of all would be a 1050 w/ a US doubler if you can find one.
Good luck, and I admire your courage! And remember 60/40 lead-tin solder goes off the market July 6th. Stock up now!
Zaphod B
http://zaphodb.dyndns.org
Filetopia #Adult Good Things
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RE: Atari 810 drive speed problems