CurtPalme.com Home Theater Forum

aelius · Joined: 19 Feb 2023 Posts: 7

The story so far:

I recently acquired a "working" Barco Graphics 800.
I suspect it was working before the seller let it sit somewhere mice could get inside it.

I took the time to clean what I could see, fired it up and, oops, one of the cards started arcing and smoking - probably the horizontal deflection card.

I turned it off and, cursing myself for not having done this before, removed each card and thoroughly cleaned every nook and cranny beneath them - definitely had mice living in there.

But it wouldn't power on again. When I try, I just hear a "chirp" every few seconds. The status lights indicate there's standby power but no main power.

I took to ebay to look for parts. Through sheer luck, I stumbled across some mystery barco cards listed for $20. They turned out to (probably) be a Barco Vision horizontal deflection, and RGB decoder + amp cards.

In a moment of "what have I got to lose" impatience, I installed the Vision horizontal deflection card and powered it up. After all, it looks almost identical to the one in my unit...

Main power is on! But the tubes aren't projecting anything and I see the 'sync fail' indicator light on the right side. The horiz deflection card also has a red light. I did try feeding some composite video and switching inputs to/from that- but the end result is the same.

I'm hoping, then, that I only need to repair or replace the original horizontal deflection card.

How screwed am I? Is it viable to repair the card if I know where to look? Is there someone here or elsewhere willing to spare a Barco Graphics 800: card # 761766 ?

Thanks

My skill level is for working on electronics repair is decidedly novice. I have zero prior experience with CRT projectors, but I am well versed with regular CRT TVs and monitors.

virusc · Joined: 11 Apr 2007 Posts: 358 Location: Massachusetts

I would wait for a replacement used card. Luckily Barco Graphics 800's are the most common Barco CRT projector ever made. You will find some cards if you wait. I would clean the entire projector and inspect each card.

aelius · Joined: 19 Feb 2023 Posts: 7

I took the time to probe the mosfets today, on both my dead card and the one Vision card I got from ebay.

While it is my first time doing this, it seems like there are at least 3 dead mosfets on my card- the multimeter diode test gets a voltage to/from any pin in any direction.

None of them behave like youtube tutorials say they should- having some capacitance to hold a gate open. I can't seem to get that to work at all. Not even on the good card.

I might take the time to swap over some of these mosfets, provided they're actually the same. Is there anything else I should watch out and test for?

thanks

**Curt Palme** · Posted: Wed Mar 15, 2023 10:48 pm Post subject:

Really the only thing to check for is dead shorts. In all of the H boards I repaired in the various Barcos, any bad MOSFET was shorted. The gates are so sensitive that the small voltage can hang them to partial continuity but if you reverse the meter leads, they will usually go open again. Test them in circuit for dead shorts, and those will be the bad ones out of circuit.

aelius · Joined: 19 Feb 2023 Posts: 7

Thanks for the continued help.

I haven't done the procedure yet, but I have one more question.

This unit has an odd smell I've never smelled before. At first I thought it was just a smell from being stored the way it was. But it has been in my climate-controlled garage for months and I'm still getting the same powerful smell coming from it. I'm beginning to worry some gas might be leaking. Any insight on this would be appreciated.

thanks again.

km987654 · Posted: Thu Apr 20, 2023 8:44 pm Post subject:

aelius · Joined: 19 Feb 2023 Posts: 7

As I understand it, the tubes aren't necessarily full vacuum, and may be partially filled with an inert gas.

Additionally, it has not been powered on for months, has been thoroughly cleaned months ago, and the smell is still strong.

**kal** · Posted: Thu Apr 20, 2023 9:43 pm Post subject:

What kind of smell?

Plastic?
Dust?
High voltage / ozone?

Kal

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

The tubes wouldn't work if they weren't a near-complete vacuum. You're not smelling anything coming out of the tubes.

Kal has the right idea. What does it smell like? That might give us a clue what it is.

aelius · Joined: 19 Feb 2023 Posts: 7

> a near-complete vacuum

Yep, and the "near complete" part is the inert gas that was flushed into the tube before being evacuated. I've read the phosphor itself has a distinct smell, too.

However I was (and still am) just spitballing ideas for the smell. If that seems too outlandish, disregard.

As for what it smells like, what I initially said is the best I can offer.
"odd smell I've never smelled before"

**kal** · Posted: Fri Apr 21, 2023 12:18 pm Post subject:

aelius · Joined: 19 Feb 2023 Posts: 7

**kal** · Posted: Fri Apr 21, 2023 6:00 pm Post subject:

Sorry, I skimmed quickly and read that you had a working unit. I didn't see that it wasn't working.

No idea the smell could be as we have nothing to go by. Sorry.

Kal

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

Most likely the tubes are still sealed, in which case no smell could escape. It's certainly possible that one or more tubes lost their seal, but I really doubt any noticeable smell could escape. There would be a dramatic INrush of air when the seal broke, but (assuming the tube doesn't implode) there's no reason gas would flow OUT. So even if there was something stinky in there (which I somewhat doubt), I think it would tend to stay inside the glass.

**kal** · Posted: Sat Apr 22, 2023 12:42 pm Post subject:

aelius · Joined: 19 Feb 2023 Posts: 7

thanks all- consensus seems to be the mystery smell has no likely projection/CRT origin (especially if "we don't know what smells you recognize" is reached for before a list of possibilities ;]), so it's unlikely I need to worry about consulting any material safety data sheets Smile