Hold Down EHT LED indicator / Barco 701

mypisit · 31-10-2009, 3:24 AM

I am in Thailand. I have a barco 701MM. My problem is when I turn on the projector, the picture is bright but not sharp. I tried turn it on and off several times, and the screen went on but very dark. And the white lettering on the screen has red and blue shadow, then after 3-4 seconds the picture disappear. Red light indicator comes on at HOLD DOWN EHT. Is this the problem with the board? Can this be repair by replacing some boards?

Thank you.

Tom.W · 31-10-2009, 7:51 PM

I would suspect the problem is on the horizontal or vertical deflection board that would shut down the high voltage to the CRTs causing EHT hold down. You could also have a shorted tube or a problem in the high voltage section.

Never owned a 701 though.

Read this.....

Barco 701/708/Cine7 Tips and Manuals

Welcome to the forum !

mypisit · 01-11-2009, 5:32 AM

Thanks Tom. I'll try replacing the board after I read the tips and maunual you suggested. Hopefully it's just that.

Roland @ B4 · 01-11-2009, 9:47 AM

I think this is going to be a bad focus board.

You may not get a chance to adjust as you only have a couple of seconds but try turning the contrast and bright ness down. to see if the picture will stay up.

If t will do the focus adjustments on the side of the focus board have any effect?

mypisit · 02-11-2009, 2:10 AM

I didn't get a chance to adjust anything because now when I turn on the power the screen went blank. No display at all! My brother has the same barco model with a blown tubes. Which boards from his projector should I borrow to test out on my projector?

Thanks for all the help and suggestions.

mypisit · 02-11-2009, 5:46 AM

Is this the focus board? I took out this board. I thought this board might be bad because there is something melting on the board. Could this liquid cause the board to be shorted? If so, maybe I can try to replace this board. Here are some pictures of the mentioned board:

Tom.W · 02-11-2009, 8:09 AM

I can't see the fluid in the picture. Is it fluid as in glycol or just shiny ?

Tom.W · 02-11-2009, 8:13 AM

Try replacing the HV quad and see what happens. I also assume you have checked all the fuses...

Roland @ B4 · 02-11-2009, 9:46 AM

That fluid mark is not normal but they do put a fair bit of varnish on the coils to stop them singing.
Tube fluid could get to that point if the projector is ceiling hung.Can you check around the REDtube. Particularly look to see if the front glass is cracked.

mypisit · 03-11-2009, 2:51 AM

The fluid is kind of brownish not so shiny. Projector is ceiling hung, I will check the front glass. I replaced this board with the one from my brother's projector and the picture came on for 3-4 seconds, then the screen went blank. So, I guess it's not this board. There are about ten boards in the projector. Which board should I try next? I am not technically advance.

How do I locate the HV Quad? Hopefully I will find the defective board before I go thru all of them. And I haven't check the fuses because I couldn't locate any of them.

Thanks for your help and for being patient with me.

Tom.W · 03-11-2009, 3:30 AM

Look at this again. The arrow points to the location of the high voltage quadrupler.

Barco 701/708/Cine7 Tips and Manuals

Tom.W · 03-11-2009, 7:42 AM

Is the fluid you see wet or dry ? If you have a glycol leak from a CRT it changes the whole ball game so to speak...

Glycol is VERY corrosive to circuit boards !

Also read this.......

Barco Troubleshooting Tips

Roland @ B4 · 03-11-2009, 9:59 AM

I still think this a Focus board issue.
Esspcially with that gunk on the board
Try turning down the G2 pots (the black ones on your no 7 photo) turn all three puts anticlockwise. will the projector fire up

Tom.W · 03-11-2009, 8:15 PM

Quote:

Originally Posted by Roland @ B4

I still think this a Focus board issue.
Esspcially with that gunk on the board
Try turning down the G2 pots (the black ones on your no 7 photo) turn all three puts anticlockwise. will the projector fire up

A bad focus board could overload the high voltage power supply and cause EHT hold down. Still unclear if there is truly a glycol leak though...

Also could take out the quad,EHT or a fuse.

mypisit · 04-11-2009, 10:18 AM

Tom / Roland much thanks. I still couldn't figured out which board is bad. It did check all the fuses. I failed to mention that the first time this happened, there was a crackling sound about 5-6 times. Then, the screen went blank and there was burned smell.

I did replace this board with the one from my brother's projector but no go. The display went on for 3-4 second and the display was gone.

Thanks guys.

mypisit · 17-11-2009, 2:40 AM

Hey guys, I think that I almost narrow down on the problem. I'll update this post as soon as I found out for sure.

mypisit · 08-01-2010, 1:31 AM

Hi! TOM/ROLAND IT still old problem , that is the Tack sound and Green light come at a trace solder at the corner of the HV splitter ,the dislay is gone with EHT indicator . Is the HV splitter bad ? THANKS PISIT