Repairing Vacuum Fluorescent Display Driver on IRD 245

[blowerman]

Is there anyone out there who has dealt with vacuum fluorescent drivers? I'm working on an IRD 245 dynamic balancer instrument, which is one of the earliest digital balancers, and having finally got some life into the unit I seem to have a problem with the display which has both pixels missing and is clearly not reading correctly. Any experience out there??

Many thanks

James

 

[Nigel Goodwin]

Almost certainly the display itself, they are basically a type of valve, and have a very limited lifespan.

 

[blowerman]

Well the driver board for it suffered a lot of water damage at some point in its history. I'm going to try testing the input to this board using a known working display and then if that's ok at least I'll know it's down to the driver. I have another four complete units which are all working so if I can't cure this display at least I can use the unit for spares.

 

[Nigel Goodwin]

Well the driver board for it suffered a lot of water damage at some point in its history. I'm going to try testing the input to this board using a known working display and then if that's ok at least I'll know it's down to the driver. I have another four complete units which are all working so if I can't cure this display at least I can use the unit for spares.

That's the best thing to do, but in my experience, on a LOT of such products - VCR's, DVD Players, Satellite Receivers etc. in the vast majority of cases it was the display.

Very occasionally, on particular models, it was down to electrolytic capacitors in the supply to the display - but even then, while it might have been fixed, the display was generally pale and worn out.

They look quite pretty, but are really a very poor idea.

 

[blowerman]

Got it!!! After major stripping down of the board, cleaning, testing boost power supply and checking chips plus replacing capacitors....i.e. a whole saga......put in decent new chip sockets for every chip, not easy as I'm not sure they make some of the sizes anymore, and built the board back up monitoring the supply load. Found a suspect chip, replaced and it is now all back up and running perfectly. Unlike stereo displays or clock displays these units don't tend to get heavy use so the display is bright and legible which is a very happy result! I guess the answer is perseverance and being bloody minded.