Barco 808s Powers Up, but no image.

Discussion in 'Projectors, Screens & Video Processors' started by bpasco, Feb 1, 2009.

  1. bpasco

    bpasco
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    I just replaced a bad quad in my 808s, but now I have a new problem. With the new quad it comes out of standby, but the tubes won't illuminate. I have a good video feed attached to 1, 2, and 4/5. No red LEDs at all. Green LEDs on all three tubes. Adjusting G2 pots does nothing to the green LEDs on the tubes. The controller board has the stdby, main power, and block match LEDs on for ports 1, 2, and 3/4. I swapped out the horizontal board, vertical board, port three board, RGB switcher board, and quad decoder. No change. I checked the 17v point on the SMPS, and it was high - 17.82 - and dialed it back. I've seen reference to a 48v check point, apparently referenced in the service manual, but I only have the owners and installation manuals which I don't believe discuss it. I'm not sure what else to try at this point. Any ideas are warmly appreciated!
     
    Last edited: Feb 1, 2009
  2. Tom.W

    Tom.W
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    Check the fuse on the EHT module and you can download the 808 data service manual. Should be pretty close to the 808s. See the service manual thread.
     
  3. barcoed

    barcoed
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    808S and 808Se had different HVPS bits and are incompatible (unless you mod a few things) - Are you sure the replacement part has EXACTLY the same part number?
     
    Last edited: Feb 1, 2009
  4. Tom.W

    Tom.W
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  5. bpasco

    bpasco
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    Thanks very much for the feedback. I greatly appreciate it. I've pulled the EHT board again, and retested the fuse in the black holder. It has connectivity. In any event, there have been no red lights on the EHT board since I swapped the quad - which means I'm not in EHT hold down, I think?

    I've rechecked the part number on the quad. The quad I had in the machine originally was R7722091 Index 1. The one I put in is R7622091 Index 5. I had seen the chart on Curt Palme's website, ( http://www.curtpalme.com/docs/BarcoServiceBulletin_R762716_New_EHT.pdf ) and noted that the R7722091 wasn't on the list at all. But my EHT is the old style, R7617427, which should work with a R7622091.

    Additional thoughts?
     
  6. Tom.W

    Tom.W
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    Recheck the wiring harness from the quad. Do you hear the HV come up on the tubes ?
     
  7. bpasco

    bpasco
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    Thanks for the suggestion. I've detached the quad from the projector, and reinstalled it. There are three connection points, to the HV splitter, the G2 power supply, and via a white plastic strip connector (don't know what that is properly called.) All are tight. When I power up, it comes out of standby, and I can hear the CRTs charge, but no signal. I have a DVD player hooked directly up to Port 2 using S-Video, which is on. Pressing 2 (or any other port) makes the relevant LED light on the RGB switching board, but no illumination on the tubes.

    I've downloaded the Barco Data 808s Service Manual from the service manual thread. I'll start digesting that, but in the mean time I value your willingness to help me out.
     
  8. Tom.W

    Tom.W
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    I assume the the internal test patterns are also not working. Are the filaments on the tubes lit ?
     
  9. Tom.W

    Tom.W
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    Also put the original boards back if the only thing wrong in the first place was the quad. Have you replaced the G2 board also ?
     
  10. bpasco

    bpasco
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    Okay, I've swapped out the G2 board too. No change.

    Internal test patterns do nothing (hitting the adjust button does not bring up internal menus), and the filaments on the tubes are not lit. Looking in the tubes, they look identical to when the set is turned off.

    I hope I am overlooking something obvious.
     
  11. Tom.W

    Tom.W
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    Last edited: Feb 2, 2009
  12. Roland @ B4

    Roland @ B4
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    I'm wih Tom
    By the sound of it you have EHT but one of the voltage rails is down
    There are two standard replacable fuses and whole load of fixed ones test them all.
    After that I would suspect a transistor has shorted out. Most common will be the big one next to the main fuse on the power supply.
     
  13. Tom.W

    Tom.W
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    See page 267 of the service manual for the fuse locations. You will need an ohm meter to test the fuses.
     
  14. bpasco

    bpasco
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    Bingo - That did it. :clap: That is an interesting one for me. In the past, if I've had trouble with the SMPS, I had no eht. Thanks a lot for the generous assistance!

    I've been reading through the service manual for the 47v adjustment. I've found where it says to adjust it, but I'm not really sure I understand what the adjustment is for. What symptoms indicate a problem in that area?

    Thanks again!
     
  15. Roland @ B4

    Roland @ B4
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    I love a happy ending
     
  16. Roland @ B4

    Roland @ B4
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    48 volt adjustment is P2 genrally used to contol Max screen width.
    It is rarely measured as most of us are pushing the projectors into the higher frequencies and need to get the most width out them so genrally they are turned up full.

    However on a lower frequency particulary 15Khz video this can be over loaded and the screen width will dramatically start opening and closing about twice a second if P2 is set too high. Eventually forcing the PJ into scan fail.

    I tend to set it like this. select your maximum resolution you are sensibly going to watch. set the H width in the Geometry screen to about 90-95 then turn P2 up so that the width fills the screen required. (making sure all the things like keeping it off the crt faceplate sides have been observed and the correct projection distance etc)
    That way you still have 5-10 to play with.
    If you come down to a 15khz source or test pattern and it starts doing an impression of an accordian try to reduce the width with the geomenty menu else get that P2 pot turned down again
     
  17. Tom.W

    Tom.W
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    So is all up and running ?

    I'f so :thumbsup:

    Tom
     
  18. bpasco

    bpasco
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    I didn't quite go far enough. Once it came on, I declared victory and powered off. Another glitch, although a different one.

    Well, not quite a Stephen King cult classic, but the blue CRT is in wild Maximum Overdrive. If I put a lens cap on blue, I can see and make adjustments through the menus, but with the cap removed everything is completely washed out. Thoughts on the likely culprets? (I mean, other than operator error...:rolleyes:)

    Thanks for the benefit of your thinking!
     
  19. Tom.W

    Tom.W
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    Sounds like a bad video amp on blue. Try swapping the Blue and Green video amps or try a replacement if you have one,
     
  20. bpasco

    bpasco
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    Is a good thought, but no dice.

    I have one extra video amp, and swapped it out. No change. Since these old boards could easily have faults on them, when that didn't work I swapped it for the one on Green, which was working fine. While it worked on Green, on Blue it is still in Max Overdrive. :confused: Thoughts on the next step warmly welcomed...
     
  21. Tom.W

    Tom.W
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    See page two of this PDF...

    http://www.thegleam.com/ke5fx/crt/sencrt.pdf

    Whats strange is first you lose the quad,then a fuse on the SMPS and now another problem such as a possible shorted tube.

    Did the projector work OK until you lost the quad ?
     
  22. Tom.W

    Tom.W
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    Do you have Sony CRT's ?
     
  23. bpasco

    bpasco
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    Yes, the set was working fine. I've had this projector for a couple of years. This is the 2nd quad I've replaced. The blue tube is 7626576, which is I believe a Sony tube.

    Do I likely need a new tube?

    Not sure what has launched this cascade of problems. But I do appreciate your bending your pick to help me figure it out!
     
  24. Tom.W

    Tom.W
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    Check for a filament to cathode short using an ohm meter or a cathode to control grid short.Page 2 of the above pdf.
     
  25. Tom.W

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  26. Roland @ B4

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    Faulty tubes are realy rare but they do of course happen.
    This could still be a G2 issue. Turn the blue G2 voltage right down
    Try swapping the focus leads for the blue and Red.

    (Green tubes are dificult to come by as they go first)
     
  27. bpasco

    bpasco
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    Roland:

    First, I greatly appreciate your help. Forgive me, because I am more fearless then full of wisdom when it comes to projector repair. Can you provide, or point me to, the specific guidance that tells me how to do what you suggest? Forgive me, I'm a competent lawyer (which just means I can read and apply guidance), and I flatter myself not too bad an auto mechanic (which perhaps suggests the limits of my ability to apply guidance...), but the electronics stretch me to the outer edge of my comfort zone. I grasp the gist of what you suggest, but don't really have the nuance of how to implement it.
     
  28. Tom.W

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    Last edited: Feb 9, 2009
  29. Roland @ B4

    Roland @ B4
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    The Focus leads are the thinner red leads attached to the G2 diagnosics card Ie the one with all the greeen leds on.They then feed onto the Amps on the end of the tube.

    If the G2 voltage is working correctly your bright blue screen should normalise as yu turn down the G2 volage adjusting as per tomes post. Ifit just gets dimmer but constaly lit with a video type pictire the RGB amp has gone bad.

    I know you have given this a BG808s with sony tubes but are the amps on the end of the tube black with raised heat sinks held on by two silver screws?
     
  30. bpasco

    bpasco
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    Thanks for the input, all. I've trimmed the G2 pots, no luck. And no, the amps don't have the 2 screws typical to the Data 808s. I think I've just got a shorted tube. Grr :mad:

    Rather than buy a new tube, i picked up a Data 808s (with the 2 afore mentioned screws) but which has been retubed. This one was working find when I left with it, but 300 miles of driving has a red led on the Sync + Vertical Deflection Board. It won't come out of standby, per the leds on the controller. Grr again.

    I pulled the Sync Deflector Board from the BG 808s (which is, I believe, the same unit.) I had no red led in the BG, but in the BD, the led came on.

    Anyone have wisdom as to what makes that LED come on that isn't on the board?
     

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