PowerBook 540c w/ Apple 603e Upgrade RAM Issues

[ajacocks]

I've got a PowerBook 540c that I'm having fits with. I have 3 different RAM cards for it: a 32mb card, a 32mb card, and an 8mb card. The 8mb card causes the machine to not POST, even preventing any sort of startup chime. The 2 32mb cards at least allow the machine to boot, and start the installed MacOS (7.5.3, ATM), but both produce "The built-in memory test has detected a problem." errors.

I've taken all the cards out, and checked the pins, but I don't see anything wrong. I also don't see anything wrong with the PPC upgrade card's pins.

I'll believe that one of the cards is dead, but not both, at the same time. Are there any known compatibility issues with 3rd party RAM cards and PPC upgrades for the 500 series? Does anyone have any other suggestions?

Thanks!

- Alex

 

[Byrd]

So if you replace the Apple PPC upgrade with the 68K CPU, do RAM errors still result? I'd try cleaning the RAM pins and motherboard connector with electronic cleaning solvent spray. I've dabbled with various RAM modules in Apple PPC and Newertech CPU upgrades, no issues like yours.

 

[techknight]

i had this same exact problem with my setup. Turned out to be the PPC card, there was a pin on the RAM connector that had bent over. But the machine is seriously unstable until its warmed completely up. I still havent ironed out this issue yet, because the 68k card is rock solid with no stability issues. only the PPC card.

the PPC card does tax the power supply on the logic board alot more than the 68k chip, so if there are any weak caps at all, the PPC will drag it down into the unstable range.

 

[ajacocks]

Interesting...after cleaning contacts, the 8mb RAM card does post, but reports the same memory errors as the two 32mb cards.

Interestingly, if I put the 68040LC back in, none of the RAM cards will allow the machine to POST. The machine does boot fine, however, with no added RAM card.

Sound like bad caps?

- Alex

 

[Byrd]

... faulty motherboard, I'd say. Don't recall too many caps on a 5x0 board that need replacing.

Press down hard on the memory module when turning it on, could be a fine stress fracture/bad solder pad on the motherboard. The good thing is that you can buy any crappy Powerbook 5x0 and the motherboard is the same across the model line.

 

[ajacocks]

Byrd,

Well, the one interesting thing that tends to point otherwise is the fact that my 520c also has issues, using the same 2 CPU modules. With the 68LC040, the 520 boots fine with no memory card installed. However, install any of the 3 cards that I have, and the hard drive spins up, the machine powers on, but does not POST. I get no startup chime, and no sad Mac.

- Alex

 

[techknight]

use a magnifying lense and bright light, double-triple-quadruple check the pins inside the connectors. both the RAM and mobo connectors of the CPU cards.