SpidersWeb
Veteran Member
So I grabbed another pair of genuine XT's, the 256Kb models. Unknown condition, and hard drive info I estimate they've been turned off for 17 years and left in a garage. Both hard drives and all cards work fine.
Anyway board #1:
- after removing a cap on the 12V line (which I'd had to remove off my existing 5160 too) the resistance on the 12V line went back in to the kOhm range
- applied power and another 12V cap exploded but the machine booted.
- machine was running fine for hours, I'd fully screwed the machine back together and was just using it casually and went to reboot, after the reboot the RAM test stopped at 64K and the machine locked up, reboot and now it's 'dead'.
- there was no odour or hot components or weird noises
- installing the Lansoft 27256 ROM in U18 made no change
- on my diags card I get clock and all the voltage signals.
- PSU tested, all values within 5% including -5V
- replaced intel 8088 with an AMD 8088 - no change
Board #2
- had to remove the same cap on the 12V line so the PSU could start
- no sign of life
- removed EPROM and tested, verified OK
- installed LanSoft ROM in U18, continuous beep
- reinstalled original EPROM, no beep or life.
- reinstalled LanSoft ROM in U18, continuous beep
- diags card LEDs show clock and voltages
- using the same PSU as for board 1
Have tried with and without expansion cards, even bare, I get no beeps (except board 2 + LanSoft continuous tone)
I also have a 5150 board behaving the exact same way, and another 5150 board I ended up giving away that was the same.
So I really want to know what is going on here.
I just realised my UV eraser has blown it's bulb, so making more EPROMs may be tricky unless I find some more 27256 chips, but I plan to try out the test1/2/3 bin files.
Beyond that, any ideas??
Anyway board #1:
- after removing a cap on the 12V line (which I'd had to remove off my existing 5160 too) the resistance on the 12V line went back in to the kOhm range
- applied power and another 12V cap exploded but the machine booted.
- machine was running fine for hours, I'd fully screwed the machine back together and was just using it casually and went to reboot, after the reboot the RAM test stopped at 64K and the machine locked up, reboot and now it's 'dead'.
- there was no odour or hot components or weird noises
- installing the Lansoft 27256 ROM in U18 made no change
- on my diags card I get clock and all the voltage signals.
- PSU tested, all values within 5% including -5V
- replaced intel 8088 with an AMD 8088 - no change
Board #2
- had to remove the same cap on the 12V line so the PSU could start
- no sign of life
- removed EPROM and tested, verified OK
- installed LanSoft ROM in U18, continuous beep
- reinstalled original EPROM, no beep or life.
- reinstalled LanSoft ROM in U18, continuous beep
- diags card LEDs show clock and voltages
- using the same PSU as for board 1
Have tried with and without expansion cards, even bare, I get no beeps (except board 2 + LanSoft continuous tone)
I also have a 5150 board behaving the exact same way, and another 5150 board I ended up giving away that was the same.
So I really want to know what is going on here.
I just realised my UV eraser has blown it's bulb, so making more EPROMs may be tricky unless I find some more 27256 chips, but I plan to try out the test1/2/3 bin files.
Beyond that, any ideas??