A4000 capcaitors

[Loedown]

Originally Posted by orange

well I replaced most of caps, but there is a problem with audio. output connectors have both left and right channel. (they are mono now). also, on power up large bang comes from speakers.


edit:
oh, I see
"The RCA jacks contain switches which join the independant left and right audio channels together if a single (mono) RCA cable is plugged into the computer."
so its ok, I used just one cable to test. IIRC, that was not the case in A500.


but, there is still a brief yellow screen after the 'rainbow' on boot.

Amiga doesn't have dethump circuitry, you get a spike in the audio on power up.

[8bitbubsy]

Can you take some pictures of the was-horrible-areas of the motherboard now? I love to see before- and now- pictures

[orange]

ahh, sorry, I forgot to take pictures after. it took me a lot of time to get PIV working, so I'd rather not take it out again. that thing flexes daughterboard too much on de/installation.

it does look much better now, washed it with IPA a lot. few legs on LF347 are still dark. I covered that area (and copper trace) with plastic spray.

still, I'm not sure if everything works. whichamiga reports nofpu. (not sure if it ever did have fpu) and there is no CPU card in earlystartup. (probably normal, too?)
There are gurus, but hopefully its software problem.

I did destroy a pad (lifted it partially) under one capacitor (C198). and that was when trying to get the board back in case. oh well..

[8bitbubsy]

Make sure that you bridge *all* broken traces! There is always another place to beep your way to find another soldering point. If the trace is in the middle of the board, it might be very hard to find it... Check the schematics.

[orange]

there were no broken traces, so I didn't bridge any.
this is driving me nuts. is there a definite way of telling if CPU is ok or not?

[stachu100]

Originally Posted by 8bitbubsy

Can you take some pictures of the was-horrible-areas of the motherboard now? I love to see before- and now- pictures

You can see mine:
In fact there are two board:
One received as faulty is just just cleaned so far (pictures 1-5 shows board once received).
Second is with caps replaced already (pictures 6-9). Details here:
http://picasaweb.google.com/stacho100/A4000DCapacitors#

Conclusion is the same:
Check your electrolitic capacitors in A4000 mobo to avoid .

[orange]

I had to remove PIV, so I took some photos.
first here are few more before:
http://www.fileden.com/files/2006/9/...o/pa310004.jpg
http://www.fileden.com/files/2006/9/...o/pa310010.jpg
http://www.fileden.com/files/2006/9/...o/pa310013.jpg
http://www.fileden.com/files/2006/9/...o/pa310017.jpg

these are after:
http://www.fileden.com/files/2006/9/...o/pb080033.jpg
http://www.fileden.com/files/2006/9/...o/pb080034.jpg

PIV gives blue screen on boot and won't scandouble workbench.
I ditched CF adapter and used standard hdd again.

[Loedown]

Originally Posted by orange

there were no broken traces, so I didn't bridge any.
this is driving me nuts. is there a definite way of telling if CPU is ok or not?

Let's use some logic here. If the computer starts to do things then chances are that the CPU will be ok or at least partially working. I did forget that I too had to resolder the socket on my old A500. More likely fault is going to be a stuck or faulty address line.

Finally, if you're still unsure about your CPU, simply take it out and find a friend who has a working A500 and drop it in.

[orange]

A500? this CPU card is CS MK1 '060.. there aren't many A500 with them
but I see your point. perhaps I need to clean Z3 connector on PIV some more.

oh, I noticed one strange thing, one of XTALs is missing on motherboard.

[Loedown]

Originally Posted by orange

A500? this CPU card is CS MK1 '060.. there aren't many A500 with them
but I see your point. perhaps I need to clean Z3 connector on PIV some more.

oh, I noticed one strange thing, one of XTALs is missing on motherboard.

You never know, new age hackery and alike

You need someone with an accelerator but if the CPU isn't getting even remotely hot chances are it's ok, I think Alexh mentioned that certain '060 masks don't get hot at all and from what I have read they seem to stay cooler that the older '040. Verify that from Cosmos or Stachu100.

[8bitbubsy]

Originally Posted by orange

these are after:
http://www.fileden.com/files/2006/9/...o/pb080033.jpg
http://www.fileden.com/files/2006/9/...o/pb080034.jpg

Some of the caps are marked with a red dot, some of them are not?
Please change *all* the capacitors if you're first doing it, even not-bad-looking ones can be faulty. Also, changing all of them prevents a big change in the inrush current (good).

[orange]

it seems (fingers crossed) that most of the guru problems were due to missing 68060/40.library

installed os3.9 and it works much better now with those libs.
off to find a good guide on system patches/upgrades.

yes, I changed only those marked with red dot. I just can't spend any more time on them now, sorry.

btw, what do you think about damage done by heat from custom chips? its on one of photos. that plastic insulating sheet has deformed a bit.
didn't know they get so hot.