520 Logic Board

[khannonnd]

Many years ago I acquired a 540c and 520c in a single eBay auction.  Both operate perfectly (the 520c screen was kind of janky), but the 540c's case was slightly beat up/required tape to keep parts on it.  So recently, I cannibalized the 520c's case and moved over the necessary parts to the 540c.  I am now left with a perfectly functional 520c motherboard, processor, floppy drive, etc.

Once the processor is removed, is the 520 motherboard identical to a 540 motherboard?  I am wondering if it makes sense to keep the 520 motherboard as a "backup" should anything happen to the 540 motherboard or if I should try to trade the 520 board.

Thanks!

 

[MikeatOSX]

I would keep it for the 540.

 

[Byrd]

Yes, the Powerbook 5x0 series all share the same motherboard - only difference is the CPU speed.  For all vintage machines you keep, I think it's a great idea to store away a spare motherboard just in case.  Same goes with RAM, LCD, fragile case parts.

 

[ArmorAlley]

Does this mean that I can take a processor board from a 540C, put it into a 520c and turn the 520c into a 540c?

 

[Byrd]

Yes, it's only the CPU daughter card (25Mhz vs 33Mhz LC040) that's different.  33Mhz '040 daughter cards used to be dirt cheap to source and upgrade to, you might have more luck finding a junker 540 for the parts these days.

 

[Charadis]

Does this mean that I can take a processor board from a 540C, put it into a 520c and turn the 520c into a 540c?

True, only the screen technology between the 540c (active matrix, tft) and 520c (passive) are different! 

 

[ArmorAlley]

But the 540c processor (running at 33Mhz) will run at 33Mhz if put into a 520c?

That is good news.

Thanks.

 

[Bolle]

But the 540c processor (running at 33Mhz) will run at 33Mhz if put into a 520c?

Definetly will. Processor speed is set by the oscillator on the CPU card.

 

[ArmorAlley]

Thanks again Bolle & Charadis!