A500: Green Screen/11 blinks, reseating chips didn't help...

[Zac67]

The temperature test is a good trick to start with but it doesn't work all the time. (It's surprisingly good though - I've repaired a couple of machines w/o any schematics that way!)

If everything else fails, there's no hint of bad contact on Agnus' socket, no bad solder points on the RAMs or the buffers (U34/35 - thermal?) you'll be left with desoldering each RAM chip and test it elsewhere...

Dunno if it's been covered before: doing the 1 MB chipram mod doesn't require you to have the RAM expansion in place all the time. If it's not present there's simply no difference to an unmodded board.

Then you must do 40 unsolderings and 40 solderings (20pins on both sides of mb=40)!

Don't really get that - you desolder und resolder from both sides?
Actually, 20 pins is pretty fast if the vias aren't too tight and you've got a bit of practice - once you know which one's wrong.

[Zac67]

Every pin is soldered on BOTH sides of motherboard,so you must unsolder/solder each pin twice.

No. The pin's soldered into the via. The through hole has a metal rivet inside, connecting all layers (there may be more than two). For a reliable solder joint you need to solder a pin in one piece. Anything else may trap air in the via and/or cause a cold joint, leading to various trouble!

I can't even imagine desoldering in one step - how do you get a clean via without heating it thoroughly? And how do you desolder from the component side? :confused: No offense, but I've never ever seen that before.

For unsoldering, maybe you can heat up with soldering gun many pins together (since they are very close to eachother) and then push the ram chip underneath with a small flat screwdriver to get it off.

Wouldn't exactly try that either. It's a good way to tear off traces that haven't completely separated yet. If you're using a special desoldering tip or an air gun, that's something completely different of course.

To tell you the truth, it wasn't the unsolder/solder procedure, but rather  the tedious task of unscrewing/rescrewing all the connectors on the back of the amiga, in order to remove the aluminum back plate! Amiga really has a "hell of an armor" around her!

Yeah - and then disassemble an A3000 for a change - and you'll never complain about the 500 again...

[Zac67]

Reread the post: I said unless using special tooling I wouldn't recommend the methods you described...

I've been working with a suction pump for most of my 'career' - a 20€ iron and a 5€ pump - and think I'm fairly acquainted with it. And I can't really make out what you're doing...

Doing it the right way, desoldering with a suction pump isn't overly dangerous or crappy. Provided the solder points in question are somewhat cooperative is doesn't take too long either, you won't need more than maybe 10 seconds per point.