Macintosh 128K Sad Icon error Code

[macalle69]

Hello Folks ,

I found this 128K motherboard, unfortunately on start up chime is a little bit distorted and after 1 second of normal grey display , dark screen and sad icon with message 04A000 , I have tested Rom on another motherboard and are 100% working, message appear with and without floppy drive connected, I have tried "piggy" with some ram one by one on the soldered banks but message does not change , only pigging on g11 and g12 and f11 and f12 the display shows vertical strips on startup instead of normal grey with some black points.

Any suggestion ? 

thank you !

see video 

 

[BadGoldEagle]

04= Bad RAM, don't look any further, you'll have to replace them all anyway sooner or later. The RAM chips on the 128k and IIc are known for going bad after some time. Some failed even back in the day.

Your piggybacking didn't work probably because you only tried one chip at at time. You may have multiple bad chips. Again, it's best to replace them all and it won't happen again.

 

[MOS8_030]

Doesn't that code indicate the specific chip? Or is it just a general ram check failure?

 

[BadGoldEagle]

It usually does but when multiple chips are bad, the code doesn't actually indicate anything. To prove my point, macalle69's mac error code isn't on this rather handy list. When I got my faulty 128k a couple of years ago, the code it was displaying wasn't on that list either. I had it fixed by uniserver who replaced every single one of those RAM ICs. 

Single Chip Identification


Data Bit


Location


Sub Code Bits


0


F5


0001


1


F6


0002


2


F7


0004


3


F8


0008


4


F9


0010


5


F10


0020


6


F11


0040


7


F12


0080


8


G5


0100


9


G6


0200


10


G7


0400


11


G8


0800


12


G9


1000


13


G10


2000


14


G11


4000


15


G12


8000
 

 

[macalle69]

04= Bad RAM, don't look any further, you'll have to replace them all anyway sooner or later. The RAM chips on the 128k and IIc are known for going bad after some time. Some failed even back in the day.

Your piggybacking didn't work probably because you only tried one chip at at time. You may have multiple bad chips. Again, it's best to replace them all and it won't happen again.

Yes I agree  the error shown on my 128 isn't indicated in that "common error list" , I have also tried pigging all ram chips at the same time  but unsuccessfully , last time I've been able to identify 4 faulty ram , this time I think  the only way is to re-ram entirely ( it is a nasty job but I'll try when i'll be very "inspired" )

thanks everybody for your support , will update as soon as I'll do the job.

 

[macalle69]

Hello Folks 

finally received all parts , replaced all ram and now my 128K is back to life !

 

[MOS8_030]

Congrats!

That's a lot of soldering...

 

[macalle69]

Yep! a lot of Desoldering & Soldering , I have tried to save all the old rams just for curiosity and check how many failed , 8 of those were bad !

 

[beachycove]

From where did you source the ram chips?

 

[macalle69]

I live in Italy I found on eBay in Europe (Bulgaria)  object 172668289677

 

[PB145B]

Very nice! Adding sockets was definitely a good idea. I’ll do the same if I ever have to replace the RAM one of these. 

 

[macalle69]

Well... aesthetically should be better resolder like original one but I preferred socket for further “accidents “ ( hope will not happen)