[Mac Plus] Help with my RAM error code.

[keelus]

Hello ! A few weeks ago I posted here asking for help with my Mac Plus. I fixed the error by replacing the U3 Optocoupler with a 4N35. Now, everytime I turn it on, my Mac Plus does the chime sound, gives video, and displays the sad face (althought, sometimes displays a few random lines, other times this lines are different, or non existant). Tomorrow, I will recap the analog board capacitors. Could that be the problem, which is displaying the sad face 020100? Or, the analog board does not conflict with that?
Also, if the problem is the logic board itself, i looked up the Sad Mac Error Codes, and, my error has to be the RAM issue at G5? (Visually, the RAM seems OK, the connectors, I mean) Am I right? The thing is that, at G5, there's no chip (i read some post of people with different GX problems, and replacing the chip in there solved it), so, what could be happening? I attach some pictures of the error with the lines (three variations I got), the RAM itself, and the logic board solders.


Also (not related doubt). I currently don't have the floppy reader connected (I will connect it once everything is OK). Could that affect in any ways? Or, even without having it connected, I can get to the floppy interrogation part?

Thanks in advance!

All three variations I got (the error is always 020100)

That's G5 right? Did I understand it correctly?

G5 and ram bottom solders a bit more zoomed​

 

[Patrick]

maybe it means that bottom RAM sim is bad ? Do you have other sim's you can swap in ?
maybe you could try just reseating it / use some deoxit
...

my guess is one of the RAM SIMs is bad. (and not any kind of bad solder or anything)

 

[keelus]

maybe it means that bottom RAM sim is bad ? Do you have other sim's you can swap in ?
maybe you could try just reseating it / use some deoxit
...

my guess is one of the RAM SIMs is bad. (and not any kind of bad solder or anything)

I sadly don't have any other ram to swap and test..

What do you mean by reseating it / using some deoxit?

 

[Patrick]

reseating = removing it and putting it back in.

can also try to clean contacts. maybe just using alcohol or dexoit

you can also try just removing that ram. but For a Mac plus you have to modify a resistor to set at a lower amount of ram. There is some documentation out there that can show how.

But first. i wonder if you can just move it to a different slot and see if the behavior changes at all.

 

[keelus]

reseating = removing it and putting it back in.

can also try to clean contacts. maybe just using alcahole or dexoit

you can also try just removing that ram. but For a Mac plus you have to modify a resistor to set at a lower amount of ram. There is some documentation out there that can show how.

But first. i wonder if you can just move it to a different slot and see if the behavior changes at all.

Y cleaned them before, with isopropilic alcohol, the entire board and ram slots, no change.
I tried changing their placement in this way:
ABCD ram order gave me that error, 020100
DCBA ram order gave me a different error, 028000

 

[Patrick]

I think its safe to say that RAM sim is bad. As the problem seems to follow it when you put it in different slots. I'm guessing they are 256k ? i'm guessing you can't simply remove it and work. I found this memory guide that might help.

http://akarchive.digidesign.com/support/docs/memguide.pdf

But i think you would have to get replacement RAM somehow.

 

[keelus]

I think its safe to say that RAM sim is bad. As the problem seems to follow it when you put it in different slots. I'm guessing they are 256k ? i'm guessing you can't simply remove it and work. I found this memory guide that might help.

http://akarchive.digidesign.com/support/docs/memguide.pdf

But i think you would have to get replacement RAM somehow.

I've bought some used 4 RAM cards of another mac plus for 8$, will write here if they work or what happens. Will check that guide, thanks for your help

 

[lilliputian]

Obviously the problem has already been sussed out, but out of curiosity I plugged the code into Snooper 2:

RAM Test Failed initial Bank B test

It reports that the code points to memory chip 9. I'm guessing this means the first chip of SIMM 2 in Bank B? I suppose if you were adventurous you could try replacing that chip, but that would of course mean sourcing one, and then of course desoldering the old one and soldering the new one! Perhaps not worth it for 256k...