Trying to repair my A600 :S

[elmasta]

Hello, first of all thanks for reading this post,

My A600 is my second computer (after a spectrum), my parents bought it for me when I was 9 in 1992. Back in that time, i remember as being the best computer around, and now it's not working.

The thing is that it isn't booting. It passes all internal tests, changes the screen color from black->dark gray->light gray->white, and the caps lock doesn't blink indicating any other error. However it stays there, in the white screen.

But it wasn't that one day stopped booting, the amiga would boot to workbench if I let it on for 10 minutes or so. That was like 4 years ago. Now it doesnt get past the white screen.

So today (being a rainy day) I opened it and commited myself to find out what was wrong. The first thing I thought was to check for a power failure, so I measured all voltages (with the amiga on) and all turned out OK. Then I thought of the processor, checked the voltages and OK, BUT I checked the _RESET pin and it was LOW!! (along with the _HALT). Then I got the service manual and seached where it was connected and I found that it was to a LM555 (U14 in the board), so I looked in the board and I found something kind of strange.

The LM555 along with the 3 capacitors above had its pins somewhat dirty, such as when you leave a battery stored for a long time. So I tried to understand what the 555 was used to and I found it was used to generate a reset pulse on power up. According to the chematics on the service manual, the 555 is in a monostable configuration.

I think the capacitor is broken. But anyways, monitoring the voltage in the capacitor I see that it rises up very slowly,but ultimately gets _RESET high after some minutes.

So now I don't know what to do, I could try to replace the capacitor (kind of risky for the board) but I need to know if there could be a problem somewhere, or if someone passed from a similar situation.

Any help is appreciated! (Sorry for my english I'm not a native speaker)


Complimentary information:

I am using an A500 PSU because the one that came with the A600 died.

Here are pictures of my board and U14 and its capacitors above.

http://img146.imageshack.us/my.php?image=p1012148sp1.jpg
http://img79.imageshack.us/my.php?image=p1012147dq7.jpg
http://img146.imageshack.us/my.php?image=p1012146ub4.jpg
http://img101.imageshack.us/my.php?image=p1012145ma2.jpg
http://img101.imageshack.us/my.php?image=p1012144vg5.jpg

[elmasta]

t looks like it probably is the capacitors. they leak their fluid on the board and it causes problems. if you check this site link you can find pretty decent instructions for replacing capacitors of this type. all of the capacitors on the a600 are correct polarity wise but most capacitors have a finite lifespan either drying out or leaking

Thanks, the instructions are highly detailed. I guess i'll try  to replace them.

I'll tell you what happens