CurtPalme.com Home Theater Forum

SimTech · Joined: 27 Aug 2008 Posts: 3 Location: Alaska

Hello, new to the forum. Only been reading it for a couple of days and picked up quite a bit of info - thanks!

Two questions:

Is anyone aware of a general theory of operation/diagram of the Barco 808S? Looking for something that explains how the power goes through the machine... explanation of signals and processing, etc.

Does anyone know of a way to check/test quadrupler, EHT, SMPS and G2. I need to find out which of these are bad, and get them repaired/replaced (if possible).

Currently; have a Barco 808S that is eating G2 cards.

Symptoms:
Initial power-on all is well. Cycle power - get a very dim raster, with a slightly lighter 'box' in the center. No display (graphics or text), can't see the warm-up warning, etc.
Replace G2 card, same as before - initial power up, all is great! Graphics in place as needed - required warm up warning displayed, etc. Cycle power, back to original problem. Tried both G2s in another projector - does not work; this time instead of faint green CRT, all three CRTs show bright line along bottom of tube.
We have changed the quadrupler and EHT to no avail. I'm guessing the SMPS is the next approach, but can't afford to keep throwing card$ at the projector.

So, oscilloscope, multimeter, tongue against two prongs - some sort of 'test' would be greatly appreciated!

Rob

SimTech · Joined: 27 Aug 2008 Posts: 3 Location: Alaska

Bump to the top... any help?

**Curt Palme** · Posted: Fri Sep 19, 2008 9:22 pm Post subject:

Sorry, missed this post.

1) THe only place that has the theory of info that you want is the service manual, and I don't post those as that's how I make my money, servicing boards.

2) If you get ANY light out of ANY tube, you do not have HV issues.

3) If this is a G808s, it's quite possible that the tubes are shot. For some reason the Sony tubes in the BG808s can have low output after 10K hours on the chassis. I've seen this before. The emission drops right down to almost nothing. You could also have video issues in the set though, causing low light output. the SMPS can do this as well if it's faulty.

4) Sounds like you've been buying boards/parts off eBay. you can do that, but as you've seen, you're out the money if you don't guess right. THe alternative is to send me a number of boards in the set to test. I'll test them in a set here, repair/replace as required, and then you know the set will work when you get the boards back.

Cheers!

SimTech · Joined: 27 Aug 2008 Posts: 3 Location: Alaska

Thanks for the reply.

I fully understand your reluctance to post information that would hurt your bottom line.

I believe the tubes are good... if a new G2 board is installed, the picture is perfect.
Until you cycle power. Then I notice the tubes are dim, and the G2 appears to be shot.

Changed EHT, Quadrupler and G2... looks super!
Power off, power on. Dead.

I assume the SMPS is the final culprit.
I just don't have any extra parts to replace the SMPS and G2, then see if it works.

Is there any way to check the SMPS to be sure it is doing ... ?

**Curt Palme** · Posted: Wed Sep 24, 2008 2:59 am Post subject:

Check the filament voltage. THis is a new problem with me, haven't seen it before.

The filament voltage should be 6 volts. If it lowers under say 5.5, then the tubes will be weak and dim.

You can probably see this by the orange glow at the back of the set.

Otherwise you might have an AKB (auto brightness) issue in the video section somewhere.

Z-Photo · Posted: Thu Sep 25, 2008 1:18 pm Post subject:

If you had replaced the SMPS - there are different voltage setting between a sony model and a MEC model.

As Curt suggest the AKB can be turned on/off in a number of spots -