Witchy
Experienced Member
Hi folks,
Only 4 threads? Strewth.
Anyway, after rediscovering my original 520ST with external power brick I cleaned it all up and hooked it up to a mono monitor from a MegaST4. It ran for long enough for me to start cleaning the heads on the SF354 floppy then I watched the screen flicker, fade and eventually die. Suspecting the monitor since it hadn't been powered up for $years I dug a similarly old SM124 out of the garage and got similar amounts of nothing. It wasn't till then I noticed the power light on the ST itself hadn't actually come back on so I switched over supplies from the floppy drive and the machine sprang into life again.
I've managed to get the power brick apart and it's a nasty looking NORTEL board run by an NE5561. All the caps test ok with a DMM but seem to defeat my basic ESR meter, I suspect it can't deal with 4700uF caps.
Is this worth repairing? It's a simple +5@3A and +12/-12@30ma brick and I've got an old Cisco PIX supply that fits the bill perfectly. I did plug it into the floppy drive and the motor spins so it's only the 5V rail that's gone but helpful stuff like schematics don't seem to exist online.
Cheers!
Only 4 threads? Strewth.
Anyway, after rediscovering my original 520ST with external power brick I cleaned it all up and hooked it up to a mono monitor from a MegaST4. It ran for long enough for me to start cleaning the heads on the SF354 floppy then I watched the screen flicker, fade and eventually die. Suspecting the monitor since it hadn't been powered up for $years I dug a similarly old SM124 out of the garage and got similar amounts of nothing. It wasn't till then I noticed the power light on the ST itself hadn't actually come back on so I switched over supplies from the floppy drive and the machine sprang into life again.
I've managed to get the power brick apart and it's a nasty looking NORTEL board run by an NE5561. All the caps test ok with a DMM but seem to defeat my basic ESR meter, I suspect it can't deal with 4700uF caps.
Is this worth repairing? It's a simple +5@3A and +12/-12@30ma brick and I've got an old Cisco PIX supply that fits the bill perfectly. I did plug it into the floppy drive and the motor spins so it's only the 5V rail that's gone but helpful stuff like schematics don't seem to exist online.
Cheers!