rolierop wrote on 2025-05-26, 15:45:

I cleaned the slot again thoroughly, reseated the CPU a bunch of times. The post-analyzer card gets pased C0 and C1, so memory i […]
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I cleaned the slot again thoroughly, reseated the CPU a bunch of times.
The post-analyzer card gets pased C0 and C1, so memory is seen. If I remove the memory it hangs on code C1. But after C1 the next code is 00 and it stays at that.
So to me it seems the processor is working or else the post analyzer card could not do anything. Processor also gets warm.
Code 00 does not seem to mean anything??

Hmm have you also cleaned the ram slots the same way ? give that a shot and while you are there inspect each slot to see if there are any bad pins.

Ok, so I also did extra cleaning of the memory slots. No succes. So or there is still a problem with one or more traces (although I checked for continuity multiple times) or there is another problem.

My plan B is now slowly coming in sight, because it takes to much time now.

Plan B is to remove the regulator chip for the CPU voltage and swap the one on my P2B board.
My P2B is in prestine condition and serves me for many years already. With the other regulator I could use CPU's with lower voltages on that board instead on the P3B-F. Another advantage is that the P2B has 2 ISA slots, where my P3B-F only has one.

So, Please let me know what you think.

rolierop wrote on 2025-04-25, 19:42:

Update: […]
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Update:

Board got a good clean.
Received all missing parts this week and placed them on the board.
Also did a repair on a broken trace at the underside off the board, under simm slot 2.
No shorts found anywhere on the board after thorough inspection.

Inserted post-analyzer card, first without CPU and memory for a smoke test. Succesful.
Then inserted a Celeron in a slotket and, yes postcodes appeared stopping at C1.
Added 1 memory bank and post code stopped at 00.
Also with a graphics card it stays at 00.
I rebooted couple off times and only once ended up with a booting system getting me in bios. It recognized the CPU and memory correctly!!!!
After that.....keeps hanging at post code 00.
Wiggled the slotket adapter, resoldered the joints, reseated several times.

So system showed me it is capable of booting, but something is holding it back. Dunno what, so love to get your thoughts on it!

Someone had posted a video previously on this issue. The board would go through a post and just get to a black screen. They mention C151 had to be replaced.

See this Thread

You've tried 66mhz everything, yes?
Got an isa vga card?

Worth booting your other board, swapping the bios chip, dumping the contents and hot flashing too.

Tried to find C151 and it's in a large group of very small SMD parts. Not even sure which one is must be.

Yes, I tried 66 MHz too, even a Celeron CPU. There is no difference in behaviour. Sadly I do not have a ISA video card. Tried a PCI, but no difference.

I could swap the bios and safe it to a file on the P2B.

rolierop wrote on 2025-06-01, 17:07:

Tried to find C151 and it's in a large group of very small SMD parts. Not even sure which one is must be.

Someone on another forum posted these pictures of the location.

I had to remove a CMS capacitor with 8 pins, the one named C151, right next to the PS / 2 ports.

romdump wrote on 2025-06-14, 17:26:

rolierop wrote on 2025-06-01, 17:07:

Tried to find C151 and it's in a large group of very small SMD parts. Not even sure which one is must be.

Someone on another forum posted these pictures of the location.

I had to remove a CMS capacitor with 8 pins, the one named C151, right next to the PS / 2 ports.

Can you tell what is the correct partnumber?

The only p3b-f leak I've found is a barely readable pdf.

Assuming those 4 smd caps are the same as the P2b, they're 150pf 50v 0603

myne wrote on 2025-06-15, 09:29:

The only p3b-f leak I've found is a barely readable pdf.

Assuming those 4 smd caps are the same as the P2b, they're 150pf 50v 0603

The SMD caps turn out to be ok. I will go over all solderjoints of all power transistors, because I understand that these can crack due to age and warming up. After that I'm out of ideas and I need to think about sending it to someone who has better skills than I do.......