Hi,
Thanks again for the ideas on the sad 128k mac -
Pesky work and life concerns have kept me from opening up the 128, but I hope to do so within the next few days.
I got my copy of Dead Mac Scrolls, and as mentioned before on p. 65 it discusses a problem that sounds very much like this (vertical lines, no startup bong). It does mention, though, that the particular problem happens on a 512k logic board. Perhaps this mac was upgraded in the past. No way to know until it's opened up, so here's hoping I can find an empty table and a few spare hours in the very near future!
Sorry to say it doesn't look like there are any ribbon cables or DB-25 connectors, but I will certainly check for them when I get to open up the machine.
Also, was doing some investigation on various 64kbit DRAMS, and wanted to share my findings in case anyone was interested. As Mac128 mentioned, Larry Pina indicates that 4164 DRAMS work in the 128k and just wanted to check the pinouts and specs to confirm this -
Found a datasheet for the MT4264 (micron) DRAMS here: http://www.datasheetdownload.com/download.php?id=559895
And here's a 4164, which you can get from Jameco: http://www.jameco.com/Jameco/Products/ProdDS/41662.pdf
The pinouts are the same so it definitely seems like they would be interchangeable. Looks like the 41256 is the same except that pin 1 is the high address bit instead of no connection like in the 4164. Not sure what affect if any this would have in the use of it as a replacement.
Just wanted to share that in case it's useful to anyone. Will be back with details when I open up the 128. Thanks again!
Thanks again for the ideas on the sad 128k mac -
Pesky work and life concerns have kept me from opening up the 128, but I hope to do so within the next few days.
I got my copy of Dead Mac Scrolls, and as mentioned before on p. 65 it discusses a problem that sounds very much like this (vertical lines, no startup bong). It does mention, though, that the particular problem happens on a 512k logic board. Perhaps this mac was upgraded in the past. No way to know until it's opened up, so here's hoping I can find an empty table and a few spare hours in the very near future!
Sorry to say it doesn't look like there are any ribbon cables or DB-25 connectors, but I will certainly check for them when I get to open up the machine.
Also, was doing some investigation on various 64kbit DRAMS, and wanted to share my findings in case anyone was interested. As Mac128 mentioned, Larry Pina indicates that 4164 DRAMS work in the 128k and just wanted to check the pinouts and specs to confirm this -
Found a datasheet for the MT4264 (micron) DRAMS here: http://www.datasheetdownload.com/download.php?id=559895
And here's a 4164, which you can get from Jameco: http://www.jameco.com/Jameco/Products/ProdDS/41662.pdf
The pinouts are the same so it definitely seems like they would be interchangeable. Looks like the 41256 is the same except that pin 1 is the high address bit instead of no connection like in the 4164. Not sure what affect if any this would have in the use of it as a replacement.
Just wanted to share that in case it's useful to anyone. Will be back with details when I open up the 128. Thanks again!