Hunter Alignment Machine

I just picked up a 1990 vintage Hunter F111 4 wheel computerized
alignment machine....price was right it was free. Cost 30K new, and
has EPROM upgrade from '06 when it was last used. It's a fairly
compact and portable system so I'd like to fix it, but it's no longer
supported by Hunter. Supposed to beep on power up and show a curser
on the CRT screen. If I could find schematics for it would probably
be a simple fix. Possibly just a DC power supply issue. Nice card
rack inside with everything easy to get at. Display section seems
okay, but no beep from the CPU board on power up, and no response to
front panel push buttons. Wheel sensors and remote console power up
okay. Tried cold start button on CPU board, with no luck. Pulled
boards and cleaned card edges. Was working before being stored
according to former owner. Anyone ever have or use one of these? If
nothing else I got some nice sliding wheel turntables to use with my
hand held camber gauge.
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Well, there's some general hints for troubleshooting such that I can give. Locate where the power supply feeds the card rack and start measuring voltages. If no voltage, remove cards one by one, power down before removing, of course. If you get voltage back, you've found a short. Then you get the fun of trying to repair an item with no info other than what's on the card. '90s vintage should have some identifiable chips that you can backtrack and find pinouts on, then it's logic probe and/or O-scope time. If you pull ALL the cards and don't get juice, you've got a bum PS. That vintage could be linear, could be switching. You could probably adapt an AT computer supply if it's a switching unit, a linear supply is fairly easy to repair. Probably filter caps gone bad sitting there.
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Yeah still trying to find schematics from somewhere. Hunter and local rep no help yet. The PS is linear, the regulated voltages that are marked look good, +5, +/-12, but there are two outputs that are reading -18V and +20V which seem to be unregulated. I need to do some wire tracing to see what goes where....Regarding chips, the rep said thats why Hunter quit supporting the older units..many of the chips were no longer available. Generally the reps only exchanged boards until the units worked, they never did any board level repairs, so hence no schematics left over laying around.
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