Amiga motherboard (A3000) cleanup with Isopropyl alcohol: weird results

[da9000]

Castellen wrote:
You could probably still get reliable soldered joints from a blind gorilla weilding a flame thrower.

Actually, I've just been working on some boards which appear to have been soldered by such a beast, but that's another story...

LOL!!!!!  :roflmao:

I wanted to just update the thread about the whole "battery acid" thing. It's not acid. Zac67 is right:

http://www.amiga.org/forums/showthread.php?t=30657

Doh! You're completely right - the caustic stuff in a NiCd battery is NiOH, obviously a base and no acid. Old "zinc-carbon" batteries use ammonium chloride, which is an acid.

There's always something left to learn...

Further update on my case:
Nothing exciting. All chips seem to be fine, except my Agnus. It seems fried. I also spotted some problems with my soldering on the Chip RAM, but those are fixed. Perhaps there are more, or the problem remains elsewhere

[da9000]

@amiga92570:

I've cleaned the board up some time ago. I had a couple of questions for your previous (top of page) suggestions:

1) I don't know if my solder is "acid core". It says "Rosin-Core, Silver-Bearing Solder". I guess that's not "acid core", is it?

2) I've tested all suspicious looking tracks and they seem ok with continuity testing. Any suggestions at which points I should be testing voltages at?

3) And how can I test the oscillators (I don't have replacements)?

4) Finally when you say "verify data, address, etc line", are you talking about the ECS chips or the Chip RAM itself?

Thanks!

[da9000]

rkauer wrote:
 When my A2k fried, I discovered the Agnus was bust. And an associated TTL was busted, too.

 Wonder if the 3000 don't have the very same associated IC (TTL 74HCT244 OR 74ALS244), it seats very near to Agnus. Major RAM problems comes from Agnus.

Very interesting!!! I will look into this. Not sure if they have the same chips, but easy enough to check. Thanks!

amiga92570 wrote:
 If you do not have one, I would suggest you at least get a logic probe. You will at least be able to check for shorts and opens. Checking data address and control lines you can verify you have a clock and that the oscillator is working. Do you have a schematic, or a logic diagram. It is almost a necessity to narrow down a fault.

Yeah, I really want to get one, and a scope too. Too expensive, or too many models and not sure which is "better" to get because they have so many features I don't understand

Yes, I have the schematics, I'm just not too good at reading them... yet.

As for the chips you mentioned, I'll locate them. Do you think they could damage the Agnus, because I'm thinking of what rkauer said, and now if I get a new Agnus, I don't want her blowing a cap if those are malfunctioning.

I really wonder if they have been damaged or their traces messed up due to the leak. I guess I'll just have to start with testing them first... Now that I know these chips are related to the Agnus, I'll be checking the schematics and following their traces. Before I didn't know which traces to follow. Thanks Mr. 92570

@weirdami:
A, I didn't know. Glad I didn't put anything too explicit up there