Unhappy ST Mega 2 Mainboard

[Bee]

Need a little help.  I bought this probably 20 years ago.  I used it a few times back then.  When I last booted it 17 years ago it was flakey.    Flakey means it would white screen and hang.

 

Have pushed all socketed chips down.

 

Power on = Fans spins

Black screen

On floppy activity

 

Tested with a second power supply same results.

 

I noticed it has a piggyback socket on the CPU.  Anyone know why you would do that? 

 

 

 

I have a working 1040 but was going to use this for games and my Superchrger IBM emulator.

 

Any advice is appreciated.

 

Thank you

[ParanoidLittleMan]

My advice would be to let repair to some electronic/computer expert, who has necessary equipment too.

 

Piggyback was for sure because some expansion, what is removed . Really not relevant here.

[Bee]

So I may reboot the Case and power supply.  I found a way to get a Mega 4 mainboard and bring this back up. 

 

More to follow

 

Thank you

[+tf_hh]

On 3/28/2020 at 8:47 PM, Bee said:

I noticed it has a piggyback socket on the CPU.  Anyone know why you would do that? 

Any advice is appreciated.

 

Do you know which kind of expansion was placed on top of the CPU? What may happen... if this board have had the blitter correction patch (a little PCB with a 74LS74 on it and one yellow wire to one pad near by the blitter) installed and this patch was placed on the removed expansion, then the whole system won´t start. Check the traces around the blitter with a magnifier, maybe you will find one spot where a trace is broken. Close is with a small wire and some solder - 90% of all blitters works without this patch.