Power Supply - C4PMF with additional 527 board

[lowrybt1]

Question -- I'm getting ready to add a second, fully-populated 527 board to a C4PMF to achieve 48K. Does anyone know if the two PSU's that came installed with the original C4PMF's provide sufficient current to power all that RAM?

[BillO]

What are the specs on the transformers?
What are the pass elements in the regulators?
How much current does a fully populated 527 board draw?

We should be able to figure this out.

[lowrybt1]

I get the specs on the transformers. One of them is definitely committed to just the 527 board and the other one supplies the backplane -- and through the backplane both the 505 and 540 boards.

A 2114L draws a max of 100ma. With 48 2114's on a fully populated 527 board, the theoretical max current could be something like 4.8A?!

[BillO]

Call it 5 amps to account for any other logic on the board.

I'd say, in order to keep things reasonably cool you would need 7 amps reserve on that power supply to add another 527 board.

[Jeff]

Originally my C4PMF had two 5 amp power supplies to power the two 527 boards in the system. One 5 amp for the CPU and the first 527, and another 5 amp for the second 527 and the view board. HOWEVER, I replaced the original power supplies with a new, 10 amp regulated switching one that is tremendously more reliable, and cooler. It was not expensive.

Here is a photo:

C4P Power Supply.jpg (153.21 KiB) Viewed 8483 times

/Jeff