Amiga 500 Hardware Problem - Advice Please

[paul1981]

I've just removed and socketed 1 of the RAM chips but its not that one (15 to go...), but does this sound like it could be a RAM problem? What I am puzzled by is that when fastram is there turrican loads, but I thought chipram and fastram were used for very different things within the system - ie. CPU has only access to fast ram, which could mean that fast ram takes priority for code over chipram, and possibly having fastram connected means I am skipping the CPU loading code into dodgy ram perhaps, is that what I am seeing here?
 
I thought the A500 was supposed to test RAM on boot and give a green screen if there's a problem?

It doesn't test the ram byte by byte, as that would take far too long. You'll need a memory testing program for that, and aminet would be a good place to look for obtaining one (there are many). Someone else can perhaps point you in the right direction for the best program to use.

And on the A500, any trapdoor ram expansion isn't Fast ram at all, despite being known as Fast ram by the system. It's actually as slow as Chip ram and is known as "slow ram", as it's connected to the same bus as Chip ram. It's quite useless really, so many people do the modification on their A500's to turn that 512k slow ram into Chip ram that can used as Chip ram (more sound samples, more screens open etc etc).

[paul1981]

EDIT: Forgot to mention, that corrosion on the metal shielding - all dealt with early on, using metal polish (Brasso). Wiped down afterwards with paper towels to remove residue, then wiped again with a very fine oil in order stop future corrosion (don't use something like WD40, unless you want it to smell like a car engine forever lol).

That's a brilliant job done Gadget. I'd have slung that A500 in the bin! Nice to see a lobster rescued.
I've had corrosion on an A1200 shield that was so bad that there was a hole in the shield. I admit, when I was younger I spilt drinks in my 1200...not deliberately of course.