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New project!!! Help me fix this Seleco SVP350

Discussion in 'Projectors, Screens & Video Processors' started by Boy Lex, May 19, 2005.

  1. Boy Lex

    Boy Lex
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    To give myself something to do, I've bought this:-

    http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=5773609454

    It's a fairly knackered SVP350 that has been on a pub ceiling for a long time! It really makes my existing SVP350+ look mint. Lots of grimey nicotine stained dust etc inside.

    Switiching it on produces LEDs on the protection board for the V and H deflection. First thing that struck me is that the little fan on the convergence board has become so full of grime that it has stopped spinning, so my first thoughts are an overheated ic on the convergence board (where the heatsink is clamped). I'm going to pull my good board out and see if I can get any life out of it - I'll keep you up-to-date. Any thoughts on what to check and thoughts on which components maybe faulty is extremely appreciated. My intention is to completely clean it up and sell it on - not looking for huge profit, just fun along the way!
     
  2. Chris Frost

    Chris Frost
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    get the lens/front cover off and open the power supply cover. There are two daughter boards that plug in edge on to the main PSU board. JUst make sure they are seated properly.

    Next, check the seating of the protection board.

    All of these boards hang down when the pj is ceiling mounted. Over time they can work loose which is when you start to get intermittent power-up problems.

    Regards
     
  3. Boy Lex

    Boy Lex
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    thanks chris... i'll check that tomorrow before I start pulling bits out of my good projector!
     
  4. Boy Lex

    Boy Lex
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    Ok. I opened up the high voltage bits (tubes look ok actually - nice even burn - worst being green at 5/10, blue and red 6/10), and the two boards are seated pretty snug, no obvious dry joints when I pulled them out either. The fan has packed in though, so the only one running is the one behind the blue tube.

    Is it possible to infer anything from the green led's i'm seeing on the high voltage board?
     
  5. Chris Frost

    Chris Frost
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    I've never seen the green LEDs lit - I try to avoid being anywhere near a powered up pj with the HV boards uncovered :rotfl:

    How about comparing the two HV sections to see if the same LEDs are lit up. Beyond that you'd really need to speak to an engineer.

    Good luck

    Chris
     
  6. Boy Lex

    Boy Lex
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    I don't blame you! The high voltages sound very close when I'm turning it on!!! There are 3 LEDs that try to come on before failing, so I guess we're looking at a problem with the HV board or a problem elsewhere that these LEDs are trying to indicate. One way or the other, it looks like I'm going to have to pull some bits out of the good projector.

    Thanks for your advice Chris - I'll keep you posted. The noises it's making sound healthy enough and the tubes look ok - I'm determined that this old beast has still got some life left in it!
     
  7. Boy Lex

    Boy Lex
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    Okay! Have not yet pulled apart my working projector (am conscious that I will have to reconverge when I put it back together!!). However, I got some piccies for y'all!

    I think tonight I will pull out the HV board from the good projector and plug it into this one.

    The pictures show the HV board (I've pulled it out to inspect it). There is a suspiscious burn mark underneath one of the big resistors, which I am hoping will be indicative of the problem, so if the good board makes it work, then I will try replacing this resistor and if that smokes then I will see if I can't locate a faulty IC. The resisot in question is the one in front of the large heatsink.

    Watch this space!
     

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  8. Boy Lex

    Boy Lex
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    Phew!!! It's been a long week - hence haven't had a chance to swap the boards until now.

    Right... I took the HV board out of my good machine and tried it in the bad machine. Same leds light up and same symptoms appear, so at the moment I've got quite a good indication that there is nothing wrong with the HV board... I could try the board from the bad machine in my good machine to check it's definately ok, but that would involve taking it back home (the dead machine is at the office!!).

    So... I'm going back to my original assumption that there is a problem with the convergence board.... Back to the harvester then!! I'll refit the hv board to my good machine and pull out the convergence board next chance I get.
     
  9. Boy Lex

    Boy Lex
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    Ok. Scratch that... I was unplugging the convergence board from my good machine when I thought, 'I wonder if it works without the convergence board'. It does. The bad machine doesn't work with the board disconnected, so swapping them would be futile... I guess it's going to be the deflection board then.
     
  10. Boy Lex

    Boy Lex
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    Right then!! :rolleyes:

    So I have swapped the deflection boards and am still getting the same problem. Both the H and the V on the protection board coming up and a couple of LEDs on the HV board.

    Anyway. While I was digging about, I found something that may be the cause of the problems. The high voltage section under the blue lens has got a hefty scortch mark from the chunky red connector towards the chassis of the projector. It looks as if it has somehow arced and sparked like something else before failing.

    Here are the photos. Nice bit of melting, surprised I didn't see it before. So perhaps I've been looking a bit too far down the line. I'm beginning to think that the green LEDs on the HV board are telling me that it's not getting any high voltage?

    I think I'll try swapping this bit then... Wary of being frazzled though... Am treading very carefully!!
     

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  11. Kjelli

    Kjelli
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    what kind of tubes are in this set?

    K
     
  12. Boy Lex

    Boy Lex
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    I believe they are Sony 07ms
     
  13. Chris Frost

    Chris Frost
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    I think you'll find that they're actually Toshiba tubes. These were better suited to having the smoke proof lens seal. The exception is the last couple of batches of 350s. They had Sony tubes fitted because Tosh had run out of stock.

    Hope that is of some help.

    Regards
     
  14. Boy Lex

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    fair enough Chris. I've definately got Sonys in the 350+, but they probably are tosh's in the 350 - couldn't see any obvious labels on them.
     
  15. gazzzman

    gazzzman
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    hi all!
    first.. be carefull swapping boards in 350s!
    pre 9806 serial numbered 350s use 65v supply for line output stage
    post 9806 uses 125 v supply for line op!!!
    sony tubed 350 OF ALL AGES use the 65 v supply put a later supply board in a sony tubed 350 and you WILL get smoke!!!
    also there are detail differences in the deflection processor and convergence
    boards not to mention the software!
    if you tell me the serial numbers of the two projectors and what tubes are fitted
    (the sony tubes have some black foam behind the lenses the tosh dont)
    I will gladly tell you what is compatible (and more importantly what is NOT)
    hope I can be of help
    gazzzman
     
  16. Boy Lex

    Boy Lex
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    Thanks for that gazzzman.

    The serial number on the 350 (duff pj) starts 9902 and is dated Feb 99
    Can't tell you what my 350+ serial is cos its at home, but it definately has sony tubes in it.
    I can't see anything in the 350 on the tubes to indicate what they are, but there was no foam inbetween the tubes and the lenses, just some kind of rubber seal.

    My 350+ is currently sat at home operational and I would like it to remain that way!! So any advice on what I can/can't try swapping would be great! From what you've said I guess swapping this transformer ? section would be pointless as they are running at different voltages?
     
  17. gazzzman

    gazzzman
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    hi again.. sorry for the delay!
    first the boards that are different and must NOT be swapped!
    delection board.. the one with the protection board with all those red led's on ;-)
    power supply.. quite a few detailed differences there including..
    the switched 120/65 rail ;-) and the standby pcb on the power supply is different too
    lastly.. the sync processor board the one standing up in the middle of the set
    with a little blank peice of board soldered to the back

    ok from what i can see of the fault.. there are three likely problems
    firstly a failed diode on the power supply (probably the stta8)
    secondly the eht transformer (dont worry I can help)
    thirdly the eht splitter...
    if you mail me at seleco@assvid.co.uk and let me know what expierence you have in this sort of stuff I will try and talk you through it
    in my oppinion I would leave your working 350 well alone!
    I will try my best to help anyway!
    if you can give me the full serial I can most probably tell you its history ;-)
    hope to hear from you soon
    gazzzman
     
  18. Boy Lex

    Boy Lex
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    Thanks!!! Am emailing you now.

    I've put the 350+ back together now and am firmly leaving it alone until I move and mount it on the ceiling!
     
  19. Boy Lex

    Boy Lex
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    Update:-

    Garry has helped me diagnose a faulty EHT transformer and transistor and is helping to find a replacement. Thanks a mill by the way mate! Fingers crossed it'll be back in action before too long. Will keep posted.
     
  20. Boy Lex

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    1 new EHT transformer and transistor later...

    This seleco is back up and running! Thanks a million to Garry for helping me to diagnose it and get it back into action.

    For those interested, the fault finding was a check of the EHT transistor (under the transformer) which showed continuity through all of its pins and had therefore fried. Checking the resistance between the big red EHT lead and the ground lead to see if there was a damaged tube or splitter. Infinate resistance was measured which indicated no shorts and so ok tubes and splitters. All this (and the scortch mark on the transformer) indicated a leak in the transformer. Had we replaced just the EHT transistor, we may have been able to see where it was leaking as 30000 volts found a path to the chassis... I didn't go down this path for reasons that escape me!

    Thanks all especially Garry!
     

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