Recent content by fjm_48

The board that I photographed is the one that I purchased on eBay. I'm thinking that the melted adhesive may be a sign of overheating of the processor. I think I should ask for a refund before it's too late. I assume from prior posts that the 180MHz core clocking would not be the root of the...

The R1, R2, R3, R9 configuration seems to be 1010. The melted adhesive obscures those a little, but they're still visible. My cpu card seems to be the second (newer) one shown on your attachment. I see a 45MHz oscillator on my card. I assume that is the bus frequency. That would make the...

Your reply led me to some further investigation. On the back of the card is a number 600-4830-A. A search if this number brought up only the eBay listing from which I purchased the card. Nothing else on the card resembles an Apple part number. But I detected that the label (600-4830-A) seems...

This is a cross post of a message that I put on Vintage Computers Federation Forums: Can anyone tell me for sure whether a Model 8500/9500 cpu card, 820-0849-A, is compatible with the 7500 logic board?

Thanks for the reply (s_pupp too). Yes, I'm aware of ceramic cap issues... dc bias, dielectric re-crystallization, etc. I've sized the replacements accordingly. As these devices are for power rail holdup/bypassing, precise capacitance is not critical as long as it is enough.

I've ordered ceramic caps to replace all of the aluminum electrolytics on both the logic board and the processor card. I'll post again with the results in probably about a week.

Phipli, the voltages on the HDD power connectors (with one HDD connected) are 5.06 and 11.81. Both of those are easily within +/- 5%. But, I do suspect the PSU also. Sometimes during power up, the power LED comes on for a second or two then shuts down. I'm going to replace the PSU and try...

I've removed all plugged components from the motherboard, cleaned the contacts, and reinstalled. I thoroughly cleaned everything with solvent cleaner. Still no joy. I get about 3 seconds of hash (white noise) from the speaker right after power up. Then nothing else. Do you know what the...

The spreadsheet shows the clip on the wrong side of the connector. It should be on the same side (top with respect to the PM motherboard) as the +5V trickle (yellow wire).

Phipli, the voltages on the HDD power connectors (with one HDD connected) are 5.06 and 11.81. Both of those are easily within +/- 5%. But, I do suspect the PSU also. Sometimes during power up, the power LED comes on for a second or two then shuts down. I'm going to replace the PSU and try...

Well, since I'm tearing into it anyway, I'll clean all the connections. Thanks

I pulled an old PM 7500/100 out of storage a couple of weeks ago, and I found that I had lost/thrown out the keyboard, mouse, and Apple monitor. Using a DB15 to VGA adapter, I connected the Mac to a monitor. It powered up to the welcome screen showing system 8.(something). I ordered a Wombat...