Oberheim Matrix 6 Display Problem

[plexicube]

My Oberheim Matrix 6 has started to exhibit an odd display problem. Certain characters have an extra display segment, which is not lit on other characters. It is though the segments at 12:00 and 1:00 are now incapable of displaying separately. Thinking this may be a battery issue I replaced the battery with a new clip and battery to no avail. I reseated every IC and hit all the ribbon cables with de-oxit. I don't see any cold solder joints on the display board, but I may not be looking in the right spot. Could this somehow be a power supply issue? One other thing that may be related: when attempting to sequence the Matrix 6 via Cubase, it would occasionally lock up with all voice dots on the display showing and drone a low note until the power was cycled (sometimes a few times).

[garranimal]

Yes, make sure the power supply is putting out the required voltages within spec. Check for ripple with a scope as well. Then check the display board voltages, looks like there are both 9V AC as well as +5V DC incoming.

[cornutt]

That's a vacuum fluorescent display and it operates at rather high voltages internally. I'm guessing there is a short somewhere between two driver lines. I'm a bit pessimistic about whether it is fixable, and replacements are hard to find.

[plexicube]

The short would be in the display itself, or in the driver chip?

[cornutt]

The short would be in the display itself, or in the driver chip?

I think it's more likely to be in the display itself, but it could be either. If you are handy with a scope, and can find a pinout for the driver IC, you could check it.