130XE acting up!

[atari8warez]

My daily use 130XE, modified to include a U1MB and an internal SIO2PC just started to act strangely. It started to happen after I played with my IDE+2 for a while and I left it ON overnight last night. When I started to use it today I noticed SDX in U1MB does not boot properly but gives all sorts of error messages. First I thought it may be due to U1MB so I disconnected it to see if the machine will work properly without it, but it didn't. The video shows what happens when I try to boot SD 3.2 from a 1050. If you watch and listen carefully you will see that the machine beeps twice towards the end of the boot process and then drops to BASIC. I then type DOS and go to the dos prompt. I then try to type DIR but the machine types DHR instead, the I key is typed as H. Some other keys also malfunction, for instance 1 is typed as 0, but if i hold the 1 key down then the key repeats as 1,0,1,0,1,0 etc... Also note that when I try to type DIR at the DOS prompt I sometimes get it right, but when I press ENTER the computer does nothing, at this point the machine is useless.

 

I performed all self-test routines (including an extended RAM test) and everything including the keyboard checks OK during self-test.

I thought maybe POKEY is malfunctioning, but if it is so then I should have seen problems during self-test too, but i don't, so I am quite clueless at this point as to what might be wrong with this 130XE?

 

Did anybody experience something similar or have any ideas on what to check next?

 

http://youtu.be/PYs7Te6tNUw

Edited September 26, 2013 by atari8warez

[atari8warez]

And this is what happens when I drop into BASIC (happens the same way every time)

 

 

 

[Van]

Can't help much, but have a 600xl that has a similar flu. After several hours of use (temp related?) wrong characters read/displayed; I think there was also an issue with stored values in ram changing (flakey DRAM chip?). Didn't spend too much time testing it; no access to a logic analyzer or even a scope, so not too much I can do aside from replacing parts.

At first I thought that it might be a POKEY problem, but that wouldn't account for the corruption of mem values. So thinking it is a DRAM refresh issue.

Yogi

[atari8warez]

Turns out it was a case of a flaky RAM module and a loose capacitor (C1). So the 130XE is back to daily duty