One of my favourite machines is the PC XT that landed on my desk in 1986. I really didn’t need another one, but this one came to me together with a couple of other machines.
The machine had been poorly stored and had suffered some corrosion.
I pulled it all down for inspection. The damage was fairly superficial, which was good news. I treated the corrosion on the case and resprayed with a colour that is “close enough”. One day somebody may like to better replicate the original finish, but cosmetics are not my priority.
The power supply had some water stains on the exterior, but inside it looked to be in good shape. I have previously recapped an xt power supply due to capacitor leakage, but i have left this one as-is for now.
The seller had a couple of monitors that i bought at the same time. One turned out to be quite specific to an Olivetti machine, so i passed it on to an Olivetti owner. The other was a Taxan amber MDA screen, which was curious because this machine had a CGA card. The screen works well.
There were several RAM errors from the motherboard, but they were quickly resolved. With that, the system booted up using the Tandon TM262 21MB hard disk.
Initially i used a spare monochrome adapter and then i tried the CGA adapter with a CGA screen. This also worked fine.
The Persyst Time Spectrum multifunction card included a battery for the real-time clock. Alas, the leakage had been quite severe.
With several sockets to be replaced and many more possibly hiding corroded tracks, and programmable logic that has potentially been penetrated, i considered this card a write-off. I put out a call to the Adelaide Retro Computer Group for a suitable replacement and Andrew came through as he so often does.
The system worked fine with a spare 360k drive, but the TM100 was not playing the game. Checking with an oscilloscope, there was no data output during a read and this was traced to the LM311 5B at I9.
This had clearly seen some water but, curiously, the rest of the drive seemed fine. Replacing it did not resolve the problem; the inductor L4 on the power line was open. Perhaps it had acted as a fuse. Once the inductor was replaced, the drive was fine.
Although the hard drive is still functioning, there is a certain inevitability about its failure. In this situation, i always add a XTIDE solid state drive for normal use. With DOS 5.0 an 8GB card can be used, yielding 4x 2GB drives. That allows a bucket load of software to be loaded. For whatever reason, though, i have not been able to access the original drive from DOS 5.0 – a surprise given that i have similar setups where this works fine.
The case cleaned up well despite the water ingress.
I settled on using a monochrome display for now, but because the IBM monochrome adapter is a little limited, i swapped it out for Hercules style card which gives nice sharp graphics and also maintains the crisp text mode. I squeezed it all back into the enclosure.
Autocad 2 provides a nice demonstration of the graphics.
