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Discussion Starter · #1 ·
I seem to have a love/hate relationship with my Barco 808s. I love it when its working and it hates me all the time. I have had it 2 1/2 years and it has about 1750 hours. After working perfectly for one year (just long enough for my warranty to expire) it started giving me grief. Esentially it has been in "dry dock" for almost the past year. First the level of the green tube started running away and I discovered a RGB amplifier had gone bad. I replaced it and all was ok for a week or two when the red tube started running away. I had a Barco tech come and he could not get the G2 settings properly adjusted. All three RGB amplilfier boards were tested in another machine and they work fine. We then sent the G2 board to Barco in Georgia for testing. Two months and $200 later it came back with a report that it tested out perfectly. After several trips by the Barco tech I have spent about $1200 with him and we still cant find the difficulty. With the jumpers (J3) on the RGB amplifier boards on or off we can not properly adjust the G2 settings. Now we can not get the light on the red board to come on at all, nor can we get the lights on either the green or blue board to go out. In addition , the brightness and contrast settings seem to jump around while we are trying to adjust the G2 settings. Any suggestions as to what we can try (short of relegating it to a dempsy dumpster) would be greatly appreciated. Thanks.

Paul
 

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You obviously have not been praying to the BARCO gods.
 

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Hello Paul,


sorry to hear you're having problems with your 808, but yours worked for a year...mine gave up after watching 2 movies. (also a defective RGB-amp board)

Did you use a scope to set the different voltage levels on the boards ? If you need a how-to and the correct settings, just ask.


regards Joeri
 

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Discussion Starter · #5 ·
Thanks Joeri. I think the Barco tech checked out all the boards, however you can never have enough good information. Please provide the poop to check out the RGB's and I will have him have another go to insure that they are ok. It may be that he just put them in another unit to see if they were good.


--Paul
 

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5.2.0 Sony VPL-VW95ES, AT Screen, DIY THX-650, B&W 601S2, Fi IB, Integra 3.4, Buckeye 4x, Crest 8200
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It's too bad that you've already spent as much money on repairs as it would cost to buy another used unit with burned tubes. I would sniff around for deals on used units so you can start swapping parts to find the culprit.


-Mike
 

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Hello Paul


What you can do is remove the jumpers of the RGB boards and put on a black picture set brightness to 50 contrast to 0 adjust the G2 controls till the raster is just visible on all 3 tubes by looking into the lenses

Place the jumpers back and readjust brightness and contrast and watch the picture

Forget the led's for now if the picture is ok

Don't touch the pot's on the RGB boards without a manual and decent tools


Rob
 

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Hello Paul,


Rob is right, don't touch the pots without a manual and decent tools ! If you are sure about it, here we go !!


RGB ouput board + ABL part.no R7621735 (Check this !)


Preparations :


You need a Scope meter

supply an external signal to the projector (e.g. color bar)

Connect 1st probe to TP1 video input signal (VIDEO_IN)

Connect 2nd probe to TP2 video output signal (VIDEO_OUT)


Adjust the brightness control until the DC blacklevel of the video input reaches 2V


Adjust the contrast controls until the video input information reaches an amplitude of 2.35V


Adjustment :


Remove the strap J3 for the adjustment of P1 (gain) P2 (cut off) and P30.

Adjust P2 and simultaneously P1 for an ouput blacklevel of 185V and a video output amplitude of 100 Vpp (neglect the blanking pulse)

Important : both adjustments affect each other


Adjustment of the ABL-led


(first remove the testprobe of the video output) adjust P30 until the led D30 stops lighting up.

Reinstall strap J3 to allow proper ABL operation


Verification :

connect a scope to TP2 and verifiy the presence of the blanking pulses (these pulses are situated between black level on 185V and power supply voltage on 210V)

control of the operation of the IBCL circuit : connect a resistor of 15 kOhm between TP2 and the 210V power supply. the measured voltage on the output, pin 3 of connector J1 must be around +6V DC


thats it. (with thanks to the service manual)


good luck,


Joeri
 

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I'd get a new barco tech. If this one has used up $1200 of your money and not fixed the problem, he must not be a very good tech. He sounds like the typical car mechanic that just keeps replacing parts at the owners expense until he finally solves the problem. You need to find someone local that you can swap boards with to locate the problem. For $1200, you could have probably bought another 808 with bad tubes to use for parts. If you choose to go back to this barco tech. I would set a limit up front with him. Say $400 limit to guarantee it is fixed, then he has to eat the rest for anything above that. Good Luck.....
 

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Well Pocatello, I am a technician, but not in this field. I am a car mechanic, but not the type descibed above ;-)

I just had the same problem with my Barco and had to find out what the problem was. I think it is better to get into these kinds of things myself, before I have to pay a technician for it ( Is it because I'm curious or am I cheap?)


Joeri
 

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Joeri --- I know what you mean. I do things myself because I am cheap. I have to be cheap... not many desirable alternatives to my cheapness.


what kind of cars do you work on?
 

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Pocatello, I work on all types of cars, all brands, as longs as there is a good electrical problem in it ;-). You really should see what strange things will happen if you are putting to much electronics in a car! Cars are evolving to computers on wheels. In 10 years you will not say about your car how much bHP it has but how much GFlops it can do.


Joeri
 

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Discussion Starter · #14 ·
Boy are you guys great or what! Maybe I won't have to put this old beast in the dumpster after all. BTW, Joeri, did you invent the CRT or something? Thanks all.


--Paul
 

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No Paul, I just typed what my parrot said after he ate my service manual.


Joeri
 
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