HDR LCD panel - broken or not?

[John T]

So I've been fixing up an HDR, and I'm not sure whether I've killed the LCD panel or not. It's attached correctly, but doesn't light up at all. It did a couple of days ago, and I'm not sure whether I've done something to it in my tinkering.

Anyone encountered this? Is it maybe something to do with the fact that the panel has variable contrast? (even though the Mackie design doesn't implement that, it could still in principle be changed).

Cheers

John

[Jondav1120]

Hi John,

Is the display not working at all, or is it just the backlight that has stopped working. If the backlight has failed you should be just able to see the text on the screen under certain lighting conditions.
Does the HDR boot and function correctly apart from the display?

Regards

John

[John T]

Hi there, thanks for the reply.

I did indeed discover it is actually working, just that the text is *extremely* faint. So yes, I think you're right that it's a back-light issue. Everything else is working fine so far.

I've discovered that the panel is a generic part you can still buy - Powertip PC2404A.A - so I might just replace it if it comes to that. Though of course, fixing the backlight would be cheaper, and possibly more interesting in a nerdy sort of way. Any ideas about doing that?

[Jondav1120]

Hi John,

The backlight is powered from the brain board, it's a small two pin plug (J3) at the top left of the board when viewed from the rear. If this is disconnected then everything will work apart from the backlight.
It's very easy to miss this cable as it tends to drop down out of sight, whilst working on the HDR...

Regards

John

[John T]

Yeah, that is plugged in and giving power. Basically, without it, it's blank, as you'd expect, and with it, it shows very very faint text. I think something's just worn out over the years.

The service manual refers to it as a "VFD" (vacuum fluorescent display), but I don't think it actually is. Or at least, I've never seen one like it. Nothing to lose, really, so I'm going to crack it open when I get a spare hour or two and take a look. I have a suspicion it needs some of that luminescent foil stuff.