Do you hear any beeps when you start the computer?

Try another RAM if you have any spares. Try another CPU or swap a VGA card. Is the connection from VGA cable to the monitor OK?

Disconnect floppy, HDD, CD/DVD ROM and start the computer If you haven't done that already.

Do you have Slot 1 computer or socket 7 computer? If it is Socket 1, then remove it again and clean the connectors with alcohol. If socket 7, remove the CPU and see if any pins are bend, and then install it again.

Good luck!

Thanks fir the reply Turbo. I've switched out the RAM with some from my P3 machine (PC133 128mb) but had no luck, the socket 7 might not take that much RAM in its single 72 pin ram slot. The other slots are all 30 pin. What was more telling is that the 32mb PC 100 stick of RAM that was in the socket 7 machine, didn't work (black screen and no POST) when put in the P3 machine, I tried both ram slots. I believe PC 100 ram should work with the P3.
I have a new power supply coming this week and I will check the CPU pins again. I reseated everything on the motherboard including the CPU but i'm still getting a black screen at startup. I'll pick up another stick of 70 pin ram and 30 pin ram if possible. I'll let you know how that goes.

I'll put a pic of the motherboard below. The other problem is that I can't find a manual for this exact model (Luckystar 5V-2) online, on stason or any place.

Thanks again for your help.

Here is a pic of the motherboard with the RAM and the faulty fan + heatsink. CPU (SL27J) is in its socket.

In the worst case scenario, you should consider that the motherboard has gone faulty. If you're "lucky", only the CPU is dead. However that is quite unlikely. The only way to determine what doesn't work anymore is to find similar RAM's, motherboard, CPU and test working components with suspicious ones.

Is it possible that you slipped when removing the old heatsink or installing the new one?

Post very close up pics of the area surrounding the heatsink. Maybe you knocked something loose or bent a leg or leg on the chipset.

ethanyq61 wrote:

Here is a pic of the motherboard with the RAM and the faulty fan + heatsink. CPU (SL27J) is in its socket.

Could you please check the top most 72p SIMM slot (the one right below the black DIMM slot) at the red circle?
It could be some weird pixel or a spec of dust or something totally innocent but it could also be something with the ram slot connector.

ethanyq61 wrote:

Thanks fir the reply Turbo. I've switched out the RAM with some from my P3 machine (PC133 128mb) but had no luck, the socket 7 m […]
Show full quote

Thanks fir the reply Turbo. I've switched out the RAM with some from my P3 machine (PC133 128mb) but had no luck, the socket 7 might not take that much RAM in its single 72 pin ram slot. The other slots are all 30 pin. What was more telling is that the 32mb PC 100 stick of RAM that was in the socket 7 machine, didn't work (black screen and no POST) when put in the P3 machine, I tried both ram slots. I believe PC 100 ram should work with the P3.
I have a new power supply coming this week and I will check the CPU pins again. I reseated everything on the motherboard including the CPU but i'm still getting a black screen at startup. I'll pick up another stick of 70 pin ram and 30 pin ram if possible. I'll let you know how that goes.

I'll put a pic of the motherboard below. The other problem is that I can't find a manual for this exact model (Luckystar 5V-2) online, on stason or any place.

Thanks again for your help.

You mean, 168 Pin and 72 Pin.

Thanks for the replies all. It seems like i've accidentally knocked a capacitor, it's standing on one leg and is much easier to wobble than the others of the same type on the board. When its stood up it seems to make contact with where it was soldered to but I still get a black screen when the computer is started. I have a friend who makes electronics so i'll ask him if he can solder it back or get a new capacitor if need be (i'm a bit green here and not sure if that one can be salvaged). The black spec on the RAM slot looks like grease or mud, its only on that one plastic tooth which is interesting. I havn't got any of that kind of RAM to test the slot with though. Thanks again for the help all, i'll leave the board in the hands of the solderer and go from there, but i'm pretty certain that it's that capacitor that's the problem. I'll post some pics below of the RAM slot and capacitor.

Windows 9566, whoops sorry got them mixed up 😀

Thanks Cyclone3d, after I read your comment I checked and yes, i'd knocked the capacitor over while connecting the fan, whoops again 🤣

Tetrium, the first pic I posted, that you circled the dark area on the RAM slot in, was taken before i'd used it. It was the ebay pic, it was a nicer pic than I could take so I used that. I've had the computer working since I recieved it, but i'll keep an eye on that slot in the future, it's something I hadn't noticed. Thanks 😀

Hi guys. The capacitor has been soldered back and the computer is booting but I still have problems. When I move the power cable that runs from the PSU to the motherboard, the computer powers on. I also had to change the S3 Virge DX for a S3 Vision 868, the picture on the DX had lines through it and the computer booted once the Vision 868 was installed (picture is much better too). However when using the game 'Raptor' as a test it would suddenly quit out of game with an error message that covered the whole screen. It mentioned granular bytes, something to that affect but it was really distorted and in a weird res with a lot of numbers. So i'm still trying to get the PC to work
reliably. If anyone has any ideas regarding the power issue that'd be great. Thanks.

Specs:
Pentium 200MMX
S3 Vision 898 PCI
Es1689 audiodrive ISA
CF card IDE adaptor (8gb 200x 'Silicon Power' CF)
32MB Ram
Dos 6.22

ethanyq61 wrote:

When I move the power cable that runs from the PSU to the motherboard, the computer powers on.

Such intermittent power supply fault might be caused by corroded AT power header contacts on the motherboard or contacts in the PSU's connectors, especially if the +5V rail contacts are affected. There's also a possibility that PG (power good) signal wire is broken or corresponding contacts are corroded.

Thanks for the reply, i'll have a look at the power header contacts. The AT to ATX power supply adaptor was really cheap so perhaps the quality isn't great. Just now, the computer boot up but didn't post and all I had to do was jiggle the cable and start it again and it posted, so yes the problem seems to have to do with the power. I hope its the ATX to AT adaptor, or the PSU, I know how to replace those. If it's corroded power header contacts on the motherboard then i've got no idea. Is there a way to fix corroded power headers?

Hmmm.. could also be cracked solder connections on the motherboard power connection. Some flux and a bit of new solder should fix that right up if that is the case.

Since you're using an ATX to AT adapter (and not a good quality one, as you say), there are more possibilities of a bad contact somewhere from power supply to the motherboard, via this adapter. Try to find an AT power supply that works and connect it with motherboard and see what it does.