Does your board have JP4 open/closed? Open = Parity enabled and needs the parity chips (P0, P1 on the board).

Is the RAM 256k or 1MB?

Clean connections? Oxidisation can be on all RAM pins, seatable chips.

MikeSG wrote on 2024-08-13, 12:36:

Does your board have JP4 open/closed? Open = Parity enabled and needs the parity chips (P0, P1 on the board).

Is the RAM 256k or 1MB?

Clean connections? Oxidisation can be on all RAM pins, seatable chips.

thank you for your answer.

I have 256kB RAM seated in the BANK2 and BANK3.
As for the jumper settings, this is confusing, the manual does not match the board. In the manual, the location of JP2, JP3, JP4 is different on the board. The board has J3, J4 and J5 there where J3 is shorted from factory, J4 is missing headers from factory, J5 is shorted since it was like that when I got the board. The rest of the jumpers are not matching as well, I do not feel to try my luck and short them randomly right now, heh.

Anyway, the board passes the RAM check according to the sound from the speaker, and therefore I would say it boots up, just no signal on the POST card or Monitor.
I have cleaned the contacts where the ICs are sitting already, can try it once more. I have noticed one CAP to be "shaved", on the picture above the ISA slots next to the "made in ... " label and next to the two transistors, I will replace it but not sure if this could cause no POST on the board.

tomas

Hi,

I have replaced the faulty capacitor but there is no change in the behaviour. I have tried to swap one Jumper and it controls the parity, so this is set fine and still the board boots with beep codes but without any POST. The beep codes are changing if the GPU is in or not, and while in, the board checks the memory and wait - I guess.

One thing I have noticed, I have one GPU that went faulty, was working but went faulty a moment after, all boards will freeze with this GPU with no output on the monitor but on the POST card. While having this faulty GPU there, the board and debug card will start posting but freeze after some time, no beep codes however. This makes me wonder why it starts to POST with this card but not with a good one.

Is there any way to debug the verify if the SN74LS245N or similar ICs next to the ISA slots are good or bad?

thx, tomas

Hi,

a small update, I have noticed a few more suspicious capacitors, and replaced them but there were all good at the end and no change to the behaviour of how the board acts.
Also, I have found an auction where someone sold this board and compared the jumper settings, it is the same as by my board so I can conclude the jumpers are set the good way.

Now, I am a bit lost and not sure how to proceed. The last thing I want is to replace the ICs one after each other without knowing which could be good or bad.
Any suggestion?

br, tomas

How much total RAM is in the motherboard, and how much total RAM is in the GPUs?

The motherboard may work with 1MB for the faulty GPU, but need at least 2-4MB for the good GPU. ?

MikeSG wrote on 2024-08-22, 07:43:

How much total RAM is in the motherboard, and how much total RAM is in the GPUs?

The motherboard may work with 1MB for the faulty GPU, but need at least 2-4MB for the good GPU. ?

How is that related to anything?

vstrakh wrote on 2024-08-22, 08:11:

MikeSG wrote on 2024-08-22, 07:43:

How much total RAM is in the motherboard, and how much total RAM is in the GPUs?

The motherboard may work with 1MB for the faulty GPU, but need at least 2-4MB for the good GPU. ?

How is that related to anything?

thx both for your answer,

at first, I am pretty confident that I have tried the board with a GPU before, with no picture and nothing on the post card. Today, by just trying to swap the memory (original there was 4x 256kB, I have tried as well 4x 1MB) but with nothing on the post card again... however, I have tried a good GPU today, just in case, and the board gave picture 😀 and seems to work. Maybe some of the C were bad although my multimeter is showing them as good, or I dont know.

To wrap this up:

- nothing on the post card only if I have tried it with the bad GPU
- the board boots with a good GPU, however, nothing on the post card - not that this is important now
- the board works with either 4x256kB or 4x1MB
- i have enclosed the BIOS

thx for your help, br. Tomas