Atari 800xl problems. HELP!

[Paul Westphal]

Hi all. The problem I have: Tried two power supplies... the power light comes on when I have used both. The first PS gives me a garbled screen, and the second PS gives me a solid white bar on the left side of the screen. I am hoping it IS the power supply, but if not, which chips could I try replacing? ( I have an extra populated 800xl board ) Is there any way to test the PS to see if it is working? Any Ideas would be greatly appreciated.

[+bob1200xl]

The only practical way to test a power supply is on a good system. Problem with that is that it may make it a bad system...

 

Measure the voltage and ripple under load works. I made a little load resistor out of two 10ohm, 5watt power resistors in parallel. Check the output on a scope.

 

Most folks don't have a scope, so you can measure the DC voltage (5v) and the AC voltage (0v). "Bad" power supplies will read 7 or 8 volts. Don't ever plug one of those into a system.

 

Bob

[SIO99]

There are custom made replacement power supplies now on eBay, such as http://www.ebay.co.uk/itm/330883848120?_trksid=p5197.c0.m619 and http://www.ebay.co.uk/itm/330882589411?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649 (both by the same seller). One possible fault is some of the RAM chips, which are the same type as used by some other computers, so these may be easier to replace than the Atari custom chips. The type of chips are 4164 or 41256. More details in the topic http://www.atariage.com/forums/topic/186470-atari-800xl-memory-faulty/ .