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Barco Convergence Controls Dead

Discussion in 'Projectors, Screens & Video Processors' started by cosaw, May 4, 2005.

  1. cosaw

    cosaw
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    Hello all,

    Playing with my new Barco 500 via pc and rgbhv. For anyone with an 800 - I beleive the 500 is a very similar chassi just with smaller less bright tubes. It has a digital chassi.

    Before I contact the seller - who seems to know his stuff when it comes to servicing the things I thought I'd ask here first just in case I'm missing something simple.

    The Problem: When in convergence via guided or random access menus the arrow buttons on the remote have stopped functioning properly. The bar scale indicator moves but the cross hatch pattern within the current convergence square does not. This function was working when I received the pj as did 2 rough convergences.

    Wondering if the convergene board is dead. Re-seated it plus all the other boards. No difference.

    Before the problem developed I set everything to midpositions and activated "convergence off" plus deleted all memory blocks. After this convergence still worked but a few hours later it did not.

    Any ideas anyone before I contact the seller for advice.

    Thanks all,

    Simon
     
  2. flibble

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    If I'm reading it right, the buttons (physically) are fine but using them causes all the software related things to happen (moving between squares, and seeing the settings change), but the actually converging (moving of the two colours together) isn't happening at all ?

    I've got an 800, but I've not seen anything like this before. I hope someone else has more idea than me :)
     
  3. cosaw

    cosaw
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    You've got it spot on! Thanks for clarifying my explanation further - and let's hope someone knows what's up.
     
  4. Person99

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    I had this problem with my blue on all the zones on the right had side of the screen even after inverting the scan on my 1208/2. Scale would move, but not the grid. It did turn out to be the convergence board that was bad.

    As a side note, my convergence board was knocked out by internal arcing of a bad VDC rebuilt green tube that evenually went completely bad. I've also heard of internal tube arcing knocking out the convergence board on an 800.

    So, if I had to bet, yes you convergence board is bad. But the question is, did it just go bad or did something else knock it out?

    Dave
     
  5. cosaw

    cosaw
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    Thanks for your input Dave. I've got it on all zones on all tubes so hopefully its one part high up in the chain which needs fixing to bring all zones working again. Yes would be interesting to know what knoked it out but probably unlikely I'll find what.

    You say it was the same after inverting the scan? Would you expect it to swap sides when doing this?
     
  6. Roland @ B4

    Roland @ B4
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    Inverting scan will do nothing, but do it you like.
    Pull the convergence board and look of the SR* resistors SR1 and SR2 if I recall and check that they are ok.
    Has any of your geometry stopped responding?
    Do you get any IC2 errors (will be displayed where the text/ adjust box on screen appears)?
    You may have the test option in ther service menu for IC2 errors.
    Look for bent pins in the big connectors on your convergence board.
    This could still be your power supply
     
  7. cosaw

    cosaw
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    Thanks Roland - will get on to that and get back to you.
     
  8. cosaw

    cosaw
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    Roland followed your instructions. This is what I can report - I have no way of electrically testing them by the way:

    SR1 looks fine front and back - it appears to be just a piece of bridging wire bridging part of the circuit.

    SR2 and SR3 (which is close to SR2) are both pinky red and look like resistors mounted in what looks like white porcelain. The solder joints on the back show some signs of discoloration (browning) which I can't see anywhere eles on the board. All four joints are probably the worst on the the board - one on SR3 particularly so - as seems to be a little sparse on solder in places. If it is these would they both need replacing or just resoldering?

    On your other points: All geometry works fine and their are no IC2 erros on any field of convergence on all three tubes. All brass coloured pins on the con board connectors are straight and fine. Can't find the IC2 test option in service menu unless its the run in cycle test thingy.

    Another thing I found a loose bit of silver wire (like the bridging stuff I described) about a cm long and just sitting loose on a part of the board. There are more than a couple of places for parts which are empty and some of the big black chips have their 5th pin removed - presume this is normal?

    You said could be power supply - I asked the seller about the power supply and whether he had resoldered any joints - he said they didn't need it - he showed me and they all looked fine (to my uneducated eye though).

    I can tell this isn't the origninal con board from the serial number - all the other boards seem original.

    Any thoughts?
     
  9. Roland @ B4

    Roland @ B4
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    Odd that this is JUST the convergence, I think your power supply is ok or you would have lost something like side bow or north/south keystone etc.

    The blanks for extra chips are normal (reseved for further options like convergence on green etc)

    If you could find someone to test those resistors that would be helpfull.

    Apart from that I think it is time to try another Conv board or better still your board in another PJ.
     
  10. cosaw

    cosaw
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    Thanks Roland - you have given me a plan of action to follow up on. Should be able to get hold of another board as the seller has more than a few 500s. Will also get those resistors checked - the solder joints certainly look suspect.

    So what you're saying is that even if the fuses went on the psu which controled the con board these fuses would also affect some parts of geometry?
     
  11. Roland @ B4

    Roland @ B4
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    Usually yes. I've not worked on a 500 but it should be the same as the 801.
     
  12. cosaw

    cosaw
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    Roland am waiting on digital multimeter and soldering iron. In the meantime I've tested the resistors (SR2 and SR3) with an analogue multimeter while still in the board (can you do this or should they be out of the board?).

    SR2 reads between .5 and 1 ohm. SR3 reads anwhere between 15k and infinity (difficult to tell as the scale runs out).

    In the 800 service manual the model number for both resistors is: 1012997 SR* R CFFH E10K 0W7, where *= 2 or 3

    Can't work out the rating on the resistors as the colour bands are worn/discoloured. What is E10K? Is it 10 kilo ohms or somehting else - don't know what the E is. Whats 0W7 mean?

    Will the 500 take exactly the same con board as the 800 (for which I have service manual). 800 con board model number is 761772. Mine has an 8 on the end - 7617728 - will parts (resistors) on the boards be interchangeable?

    Gonna test again (out of board) when digital multimeter arrives. Can you get hold of these resistors and how much do they cost?

    Many thanks in advance to you Roland!

    Simon
     
  13. cosaw

    cosaw
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    Roland,

    SR3 was blown - replaced both SR3 and SR2 for good measure. Convergence working again - for about 20 mins! The con board just keeps switching off now - it seems heat related.

    The new resistor is same ohmage but higher wattage so instead of blowing it just seems to rise in heat until resistance is too much for the board and the board stops running.

    The resistor was hot when I removed the board - hotter than SR2. Now when the con board turns off I can put pj on standby for a few minutes and then when I turn on again convergene board is running again for a couple of mins until heat buildup in the resitor - one would presume - gets too high and stops the board.

    Where do I go from here? Could the psu be overloading the resistor by sending the wrong voltage/current?

    Thanks Roland,

    Simon
     
  14. Roland @ B4

    Roland @ B4
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    It is possibel that the PSU is faultly but more likley that the Convergence drivers are drawing too much current.
    Do you get any IC2 errors whe you try to adjust? (from cold)
     
  15. cosaw

    cosaw
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    I'm totally free of IC2 errors at any point hot or cold. +/- 17v leds are lit yellow and indicate no problems with or without fault though suppose this still does not rule out totally the psu. Wondering if it might now be the new resistors being of a different composition.

    I hope I worked out correctly that the original resisors are carbon film 0.1 ohm, 0.7 watt. Does this sound right - wondering if it was 7 watt instead of 0.7?

    Can't get hold of these easily (at 0.1 ohm) so replaced with wirewound resistors (bath tub style ceramic). They are the same ohmage but can take 3 watt at 70 degrees c - wondering though if they need a heatsink physically bonded to them to dissipate this wattage. I'm thinking that the resistor is overheating and becoming non linear when convergence board now goes down after about 15 minutes.

    I have heard that wirewounds should not be used in applications where frequency is important. Don't know what this means. Does this sound like it could be a problem?

    Hoping to get spare con board and psu off seller shortly so this should help in diagnosis.

    Thanks as ever Roland!

    Simon
     
  16. briandinazareth

    briandinazareth
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    Hi,
    i have same convergence problem on my barco 800...(your old problem with barco)
    Sr3 resistor burn and burn again when i replace it.
    I tried also with another convergence board and burn the same...

    Any idea?

    Thanks
     
  17. cosaw

    cosaw
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    I never got to the bottom of this. When I used a different covnergence board everything was fine. That's where my fault differst to yours. Suppose it is possible that both convergence boards could have the same fault. The closest I got was Rolands help - refer back to the last page where he talked about the "drivers". That is the path I would follow if I knew it was restricted to one board but with you having it happen on 2 convergence boards it would seem like a freak coincidence or the fault is somewhere else in the machine.

    Although - to let you know I've seen quite a few convergence boards with these particular safety resistors blown or have been replaced. As far as I understood there intended purpose is to do just that (blow)and act like fuses to protect the board from overcurrent. Once the circuit and additional components have been fixed the safety resistors will not blow. I mean't to go back to this fault and get it fixed (to have the board as a spare) and I studdied the schematics alot but am only reasonable at analogue electronics. My personal guess would be that one of the active components (transistors) along the heatsink bar on the convergence board has failed in some way - gone short or come loose from the sink or some other mode of failure. You'd have to study the schematic to see which are most likely and then check em. Maybe I'll have another look too but no promises as I'm busy with other things at the moment and also my fault finding skills are only above average with electronics.

    If you can find out what the "drivers" were to which Roland reffered you may be onto something.

    You may also like to know for your fault finding purposes that you can run the machine without the convergence board and it will power up and work safely. This is not the case with other boards in the machine. It may be of help, it may not but it's worth knowing.
     
    Last edited: Feb 10, 2009
  18. briandinazareth

    briandinazareth
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    Thanks Simon, i will try to find all the transistors and replace....

    Maurizio
     
  19. cosaw

    cosaw
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    Whoa not so fast! :)

    There are alot of transitors on that sink and probably many are hard to get hold of. Unless you know what you are doing don't go at it like a bull in a china shop.

    My suggestions are only based on my experience and all in all may not be very good - I'm not an electronics wizz. Consider that I may have sent you in the wrong direction - it's more than possible. I'm going off memory from over 2 years ago.

    Do you at least have a schematic or knowledge of how to do basic tests on transistors?

    There is the pottential (if you're not sure what you're doing) to do alot more harm than good.

    I don't know you're electronics experience or expertise so forgive me if it sounds like I'm patronising you. Remember these machines can be very dangerous to your health in the wrong hands. You can't test the convergence board with the set on without the proper equipment anyway but if you did go poking while the machine is on remember these machines can quite easily kill you.
     
  20. briandinazareth

    briandinazareth
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    Hi,
    I joke, i will check and try a lot of things before replace, but if is transistors is quickly replace than test....
    My electronic knowledge is basic but i don't risk my life...;)
    Transistors fault was my first idea but i think is rare that 2 boards have the same defect.
    I think that other boards can short convergence board, but a don't found anything wrong in other boards.
    Problems starts with smps problem, i replace this and all works fine except convergence.

    Thanks
     
  21. cosaw

    cosaw
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    Let me know how you get on. Might have a look at the schematics tonight.
     
  22. briandinazareth

    briandinazareth
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    This evening i replace burn resistor and try to start the projector without other boards then i will add boards once a time and verify resistor... if one other board short the convercence board i will find this.


    Thank you Simon
     
  23. cosaw

    cosaw
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    It may turn out ok but I wouldn't personally advise this. The only board that I know of that it is definitely safe to power up the projector without is the convergence board. I had this on good advice as well and is the only board I would be happy to try without unless I was advised by the likes of Roland on this forum. I haven't been active on this forum for a few years so I don't even know if Roland is about.

    P.S. I seem to remember it was on SR3 that was blowing - is that the same with you?
     
    Last edited: Feb 10, 2009
  24. briandinazareth

    briandinazareth
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    In other forum i found a "testing mode":all boards can be disconnected to test, and when i have a smps problem i try this without problem.
    But i could search other info before do this...
    Thank you for advice.
    I will try to contact Roland.

    Resistor is the same, sr3...

    Thanks
     
  25. cosaw

    cosaw
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    Ok, as long as you're happy with the board swapping that's fine.

    Just been looking at the manual and the notes I made at the time.

    My next line of testing was gonna be the "Slow Start" circuit that is connected to the collector of Q2.

    As far as I gather - when there is a heavy load on the -17volt line the current through S3 will increase and if nothing stops it S3 will blow. However under normal opperation the conduction of Q50 stops S3 blowing.

    Quoting from the manual:

    So for certain under these circumstances if Q50 was dead SR3 would blow but that still doesn't rule out other possibilities.

    I remember at the time now I was gonna try and check Q50, Q51 and the diodes and passive components in this area (C151, R565, R566, R564, D60). If I was to try again this is probably what I'd do.

    The only thing that makes me doubt all this is the fact it is happening with 2 different convergence boards.

    Are all your led lights lit correctly - how about the -17volt and the +17volt leds, they should be lit yellow and the red "scan fail" led in the same area should not be lit. For that matter all your yellow leds should be lit.
     
    Last edited: Feb 10, 2009
  26. briandinazareth

    briandinazareth
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    Hi, i could try your suggestion and test the components.
    Who sell me the convergence board says that working fine... your doubt are reasonable, it's also my doubt.
    I try to understand if SMPS can burn sr3 resistor, but i don't found nothing (using service manuals). All yellow leds are lit and the red one is off...

    Thanks a lot for your time and help

    Maurizio
     
  27. cosaw

    cosaw
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    Did you try swapping other boards like you said you were gonna do?

    Have you varified the 48v setting on the SMPS? Thinking blindly here but the pot which controls the master horizontal amplitude of the picture (on the SMPS) if set incorrectly could theoretically put a greater load on the whole system and in turn possibly the -17volt line and SR3 - it's worth checking this is correct. Also worth checking the R,G,B width coils are set correctly - but do not use a metal screwdriver - it will pottentially melt! If you are gonna adjust these I found it best to shape and file down a wooden clothes peg or a piece of hardwood till you have a handmade tool which fits the slots on the plastic screws of the coils exactly - this works a treat. I've found on all the sets I've come across the coils have been set incorrectly acording to the Barco safety rules.

    Just things that are worth getting right in your set or to rule out. I can PM you links to the procedures - but I'm guessing you might have come across em already.
     
  28. briandinazareth

    briandinazareth
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    I have tested smps in any way... 48v and 17v is ok.
    But convergence boards still burns security resistor...

    Yesterday i have solved the problem!

    It's smps board.... i have the old smps, i replace some components and some solders... now work fine and don't burn convergence security resistor and all is ok!

    I don't know what is the fault on smps (all led is ok, all seems work except convergence board..)... but smps failure can cause convergence board problem.

    Thanks for support.
     
  29. Roland @ B4

    Roland @ B4
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    in 2005

    Powersupply !!!!
    (couldn't spell then either)
    The resistors would only normally blow when they are drawing too much current.
    So I guess an under or even over voltage could cause that.
     
  30. cosaw

    cosaw
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    Good work, as we suspected 2 con boards doing the same thing pretty much ruled the con board out on the basis of odds.

    My fault is obviously differrent then as I'm running the same SMPS with a different con board.

    May pull the old con board out of the loft to try and find what's making S3 blow on mine.

    I'm guessing the IR receiver has died on my current con board as I've lost control of everything and the unit only responds to the address button of any remote I use. If anyone has any ideas on that then let me know!!

    I had it in floor mount and kept hitting the front of the convergence tray with the hoover. Doh!
     

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