atari 800xl dead

[thecaver99]

my atari 800xl seems dead,

when powered up and switched on the screen has no output at all(monitor or rf).

all chips have there 5v, i have tested nearly all the custom chips in another machine(130XE) only 5 left to remove, socket and test(PIA, Pokey, OS, Basic, MMU)

all ram has been tested.

would any of the transistors cause a similar issue?

Edited July 29 by thecaver99

[Peri Noid]

You must test the other chips. From my own experience - each of the chips you mentioned can cause such symptoms. I once repaired an XE in which I finally desoldered and socketed all the chips - the lat one was faulty (Pokey) in such way that it was causing a short on one of the address or data lines and the machine was able to ony generate a black screen. No diagnostic tool like SysCheck was able to work. 

[thecaver99]

32 minutes ago, Peri Noid said:

You must test the other chips. From my own experience - each of the chips you mentioned can cause such symptoms. I once repaired an XE in which I finally desoldered and socketed all the chips - the lat one was faulty (Pokey) in such way that it was causing a short on one of the address or data lines and the machine was able to ony generate a black screen. No diagnostic tool like SysCheck was able to work. 

i should have them finished this evening for sockets and testing

[Beeblebrox]

Remember, where possible, never socket more than one chip at a time before testing. There is little point socketing many chips at once, then testing, as if an issue is introduced with socketing one chip, you'll have a hell of a time figuring out the issue. Plus, of course you won't know which chip or chips were the issue.

 

Were possible always put the bad machine's chips into a good known to work machine, avoid the other way around - (or you risk damaging the good chips). 

 

I take images of the pcb vias once a chip is removed, then install the socket. This is helped many times where then - if my socketing introduced an issue - I can check connections that are obscurred by the socket.

 

Make sure you clean the area of any debris before installing a socket, and make sure the socket it flat/flush with the board.

 

Last week I had a 800XLF which had a bad Start button. After much checking I found pin 12 of GTIA was not engaging 100% with the socket it was in for whatever reason to do with the leg not connecting with the socket wipe.