Aura CA200 dim LCD display

[Chrisr3521]

Just got round to fixing the output on this but have noticed that the LCD display is very dim. I've checked the +5v and -32v supply and they are fine, what should I check next?

 

[huggygood]

I won't be surprised if the tube runs out.
if you don't already have it, I have a CD50 to go with your CA200.

 

[Mooly]

It sounds like a VFD display rather than LCD given those negative 32 volt rails.

A low emission tube is always a possibility although it is worth actually replacing the caps related to the negative rail to the display as they are a common failure point on just about anything using VFD's. Depending on the PSU there could be various arrangements including capacitor voltage doublers.

Also give the display a clean (be careful not to break the glass 'pip' on the display and also clean and polish the inside of the window as they can often attract a layer of grime.

 

[Chrisr3521]

Thanks Mooly,

I take it that'll be these caps. ( highlighted in red)

 

[Mooly]

Yes... and it does use a doubler. They have to be worth a look if only to eliminate them. The 220uF's are the ones that would usually give trouble in these kind of circuits.

 

[Chrisr3521]

I've replaced and just the same, unfortunately! Must be the display then, direct replacement seems unobtainable are there any work around for these old displays?

 

[Mooly]

There isn't much you can do unfortunately once they go low emission.

You can search for reviving and rejuvenating vacuum fluorescents but its very iffy and you can end up destroying what you have. There are such things as over running the heaters for a short time to try and burn off any surface coating that is hampering emission... all at your own risk though. I haven't tried any of these kind of hacks fwiw.