Denniske1976
Experienced Member
Hi Guys...
First off: Best wishes to everyone for 2014!
Second: I was fiddling around yesterday evening (the GF was working until 22:30 anyway) with an IBM XT (5160) that I picked up some time ago. It's from September 1985 and I was gonna fire it up after I had cleaned everything...
I switched the red lever and nothing happened :-( The fan from the PSU turns just slightly and that it, next to hearing a click. I took out the PSU and cleaned it, it looks like new now and nothing seems to be wrong with it. I connected an old Seagate ST-251 to it and it works! I had it running for about 30 minutes without any strange smells or sparks ;-) Then I put it back in the XT case, connected the old ST-412 that's in it and it still fires up... connected the full-height 360K floppy too and tried again: fires up. Then connected P8 and P9 to the mainboard and nothing again. Checked the mainboard for shorts and everything seemed fine, so I connected an old "normal" PSU (from a 486) to just the mainboard and fired it up, nothing again. After I also connected the ST-412 and fired it up again, there was a big POOF, some smoke and the top of C56 flying through the room ;-) So (as usual) it looked that's the problem and I snipped off C56 and it fired up with the AT/486 PSU. Then I connected the original XT PSU back to the ST-412, floppy drive and mainboard and tried again and it powered on as well...
So thinking all was OK now, I switched off the power and put in the cards that I had removed to check the mainboard out. Nothing fancy, just your average IBM MDA adapter, one Xebec HD controller and the standard IBM floppy controller (as seen in your local 5150 as well). Connected the floppy and HD cables, connected a keyboard and 5151 monitor and fired it up again... nothing!
So I started the whole process of removing the cards etc etc but it seems the mainboard is the culprit again. Everything works until I connect the mainboard, this happens with the XT PSU as well as the AT/486 PSU. Just a click and a minor turn of the fan and nothing. I checked the mainboard visually but all the other caps and tantalums etc seem fine: no cracks, no blackening or anything.
So, is this board dead and gone or is there anything I can do to test this with my multimeter over the 12V line or something? I think it might have something to do with C56 blowing up, but I've had that happen before and if I just remove it usually the boards seem fine then...
Can any of you help please? I'd hate to see this go to waiste :-(
First off: Best wishes to everyone for 2014!
Second: I was fiddling around yesterday evening (the GF was working until 22:30 anyway) with an IBM XT (5160) that I picked up some time ago. It's from September 1985 and I was gonna fire it up after I had cleaned everything...
I switched the red lever and nothing happened :-( The fan from the PSU turns just slightly and that it, next to hearing a click. I took out the PSU and cleaned it, it looks like new now and nothing seems to be wrong with it. I connected an old Seagate ST-251 to it and it works! I had it running for about 30 minutes without any strange smells or sparks ;-) Then I put it back in the XT case, connected the old ST-412 that's in it and it still fires up... connected the full-height 360K floppy too and tried again: fires up. Then connected P8 and P9 to the mainboard and nothing again. Checked the mainboard for shorts and everything seemed fine, so I connected an old "normal" PSU (from a 486) to just the mainboard and fired it up, nothing again. After I also connected the ST-412 and fired it up again, there was a big POOF, some smoke and the top of C56 flying through the room ;-) So (as usual) it looked that's the problem and I snipped off C56 and it fired up with the AT/486 PSU. Then I connected the original XT PSU back to the ST-412, floppy drive and mainboard and tried again and it powered on as well...
So thinking all was OK now, I switched off the power and put in the cards that I had removed to check the mainboard out. Nothing fancy, just your average IBM MDA adapter, one Xebec HD controller and the standard IBM floppy controller (as seen in your local 5150 as well). Connected the floppy and HD cables, connected a keyboard and 5151 monitor and fired it up again... nothing!
So I started the whole process of removing the cards etc etc but it seems the mainboard is the culprit again. Everything works until I connect the mainboard, this happens with the XT PSU as well as the AT/486 PSU. Just a click and a minor turn of the fan and nothing. I checked the mainboard visually but all the other caps and tantalums etc seem fine: no cracks, no blackening or anything.
So, is this board dead and gone or is there anything I can do to test this with my multimeter over the 12V line or something? I think it might have something to do with C56 blowing up, but I've had that happen before and if I just remove it usually the boards seem fine then...
Can any of you help please? I'd hate to see this go to waiste :-(