Searching for IBM Datamaster owners

Posted by Bits_Passats@reddit | retrobattlestations | View on Reddit | 1 comments

I came here at Reddit pursuing an user with a broken 5322 in order to help him. My goal was to provide him support and to invite him to a small community we are creating with the remaining users and owners of this computer. I succeed in both: he has joined and he is receiving support. I have also taken that as an opportunity to share part of my knowledge through several posts I made here.

Aside from the benefits of being in a community, I would like to offer my knowledge about the hardware. Let it be as repair advice or as a patch/extension. At the same time, I would like to ask collaboration from users with expansion cards and external drives, as those are still undocumented, please.

I am also investigating and saving the different firmware versions in order to be able to restore any Datamaster to its previous working state. Versions 1.03 and 1.05 of its ROS are still missing from the spreadsheet. If acquired, I think the mandatory ROS mission would be complete.

My goal is to leave as many System/23 as possible in working condition.

Please, if you have an IBM Datamaster, independently of the model, would you join and share your knowledge?

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Urban-Flats-Tech@reddit

I have a dead (at this time) 5322. Mostly all there. The bottom back cover is missing. The power supply is/was functional. I had the power supply out of the case. It powered on and all voltages looked decent enough for a linear supply. After reinstalling the fan comes on, power good light doesn't, no output on CRT at all. No beeps, bloops, or otherwise. I pulled the power supply out enough to check the fuses and find the +12 is blown. Measuring between the 12+ and GND on the planar board it's nearly a dead short. 3 or 4 ohm is I recall right. Out comes the planar board, pulled all the cards, short goes away. I've narrowed it down to the CRTC board. The info I've found I'm still trying to decipher.

I found some of the datasheets on the 8275 looking to see if I could figure out where the +12 is used on that card. Maybe missing the obvious but, as of yet can't figure out where/how that +12 is used.

Now that I know the short is in the CRTC board will throw the planar board back in the case and see if it makes any beeps or other noises.

I won't be back to this physically until Tue. or later. I was just going to let it sit as a museum piece. A friends prodding has me thinking it should see life again.