Powerbook 540C memory problems

[david63]

I recently got a 32Mb memory module for my one of my PB 540Cs. After installing the module into my first 540 the machine doesn't boot up(screen stays blank but there is some hard disk activity). Without the module, the PB boots up with its basic 4Mb ram.

I then installed the module into my second 540 and it boots up okay, System Profiler shows 36Mb.

Has anybody got any possible solutions for this problem?

 

[equill]

If the expansion card works in another Mac and the 540c works without the RAM card, you have to suspect the female connector on the CPU daughtercard into which the RAM card plugs.

I've seen it. A 603e/117MHz card that I bought had the end contacts damaged, either by or before a kludged attempt to fix the contacts in the socket. The system could (erratically) 'see' only 4MB of the 32MB on the card. Getting and installing a new socket will be a challenge. If this kind of damage is the cause, a new daughtercard may be necessary. 33MHz cards are getting scarcer, but still about.

de

 

[david63]

Thanks for the reply. I thought there would be some hardware problem.

 

[wally]

I recommend you visually inspect the face wiping contacts connecting CPU and memory, especially those on the CPU board plug in that face upwards (possibly marked J700 pins 1 thru 70). It only takes one piece of lint, grit or spec of plastic to keep the gold contact pairs from connecting. A high power magnifier would be good. Any suspicious area could be cleaned with gentle wiping with an ethanol dipped wood toothpick. Conductive metal foreign bodies on either the motherboard or CPU board are another less likely possibility, these usually cause total failure but cannot be ruled out by the observed behavior. So additional inspections and careful vacuuming or air blast cleaning, while minding static discharge risk, might also help. Of course, the SMT connector soldering is also suspect, but I do not know an easy way to visually inspect or even continuity test with an ohmmeter, they are right there in front of you , but they are so *@! tiny and packed in there. [!] !]'>

 

[david63]

After posting I had a look at the CPU board connector using a magnifying glass and there seems to be a broken pin in the corner of the connector. I think that this machine has been opened up before (only one screw holding in the heatsink and none holding in the floppy drive) I got it and thats when the connector damage was done.I think I will use this machine to run LocalTalk Bridge until I can get my hands on a processor card.