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Seleco SVD500 No picture fault

Discussion in 'Projectors, Screens & Video Processors' started by Julian, Jan 29, 2004.

  1. Julian

    Julian
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    Hi there

    I have a problem with my Seleco SVD500 (1988).

    The fault is that although the projector will turn on, the tubes do not come on. This fault was intermittent, but now appears to be all of the time. I have tried removing and replacing various boards and connectors (as I remember this being mentioned in a previous reply about a similar fault) but with no success.

    About a week ago I 'dropped' the projector (only front end from about 1") basically in annoyance and exasperation at it. It was turned on at the time - and lo and behold, the tubes sprung into life. Before anyone comments, I'm sure that 'dropping it' was a VERY BAD IDEA :nono: which I would not admit unless I thought it added some information(!) It worked that evening, but not again since.

    I assume that there must be a bad connection somewhere? But if so where? I have a lot of PC experience, but not really any with projectors. I do understand the high voltage issues, etc.

    The tubes have about 4000 hours and the chassis about 10000. At this stage I don't feel that it is worth spending large sums for manufacturer service, but when operating the picture is really rather good - and I would hate to have to give up on it.

    Any help would be fantastic.

    Cheers

    Julian
     
  2. Roland @ B4

    Roland @ B4
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    Probably EHT failure. Normally when this happens to a projector you will not here the EHT crackle when it starts up but the fans etc keep running.

    There are four areas that could cause the failure.
    Power supply,
    Quadrupler (turns 240v into 30K)
    Splitter (splits high voltage into three)
    EHT regulator (keeps the high voltage at the right level)

    Can you see any light at all in the tubes when it is running?
     
  3. Julian

    Julian
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    No light in front of tubes. The heaters are on (can see the glow).

    I guessed no eht, otherwise would assume minimum of a spot in centre of screen(?)


    Is there anything you recommend that I can do? Could try and get access to a scope via a friend. Bit difficult without the service manual.

    (edited the post - didn't read your reply properly - sorry!)

    Thanks
     
  4. Julian

    Julian
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    OK, I have given this a bit more thought and listened to it when it starts up.

    Yes the fans, etc come on. All green leds on the (power?) board under the front of the tubes come on, there is a short noise which (to my untutored ears) sounds like a power supply switching on. At this stage a red led on the small board adjacent to the high voltage potentiometers comes on briefly then goes out. As the tubes do not come on I am unsure what should happen next - but I believe there would normally be a noise (which I guess is what Roland refers to as the eht crackle?) when the tubes actually come on. This is not happening.

    The unit then sits there in this state.

    Is it going to be possible to measure output voltages from the various stages and locate the point in the chain where there is a fault? What about the eht regulator?

    Bearing in mind my experience with 'disturbing' the circuits physically, is it possible that there is a bad connection which can be located, or is this a red herring with a component actually failing internally in a non-repairable manner?

    I do not have spare components to swap out.

    Failing something that I can do myself - what about repair (who, likely costs, etc.) - I am in NW London.

    Thanks.
     
  5. AD Roser

    AD Roser
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    Julian,

    There are a couple of things you can try.

    located to the side of the blue tube is the protection board, which is the one that has the red LEDs on it. Completely remove it and re- insert it, making sure it is pushed fully home.

    Also there are two plug in boards on the power supply, again remove and re insert.

    Basically reseat any plug-in module. If this fails to cure the problem the unit needs to be returned to Owl Video Systems who are looking after all CRT repairs for Seleco branded products. You can contact them on 01825 766123.

    Of course please ensure the unit is diconnected from the mains before attempting any internal inspection

    Regards


    Alan Roser
    Managing Director
    SIM2 UK Ltd
     
  6. Julian

    Julian
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    Thanks for the reply Alan, I have already tried removing and replacing these components, but with no effect (remembered a previous reply by you about a similar problem).
     
  7. AD Roser

    AD Roser
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    Probably a deflection board problem, which is the main board below the blue tube.

    Looks like it needs to be returned to Owl,

    Alan
     
  8. klr10

    klr10
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    Hi Julian, I'm sure Alan's boys down at Owl will be best able to fix your problem. Just have a quick suggestion that may save you a few quid. From the symptoms it sounds very much as though this fault is mechanically related - ie it is some form of loose connection. In many cases this can be tracked down to a dry solder joint, especially on boards that get quite hot. It may be worth your while to get hold of a magnifying glass and a strong lamp and just go over the suspect boards looking for bad or cracked solder joints, then retouching any that look suspect.
     
  9. Julian

    Julian
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    Thanks klr10

    I am now a bit confused! And I am also aware that this forum is probably not really the place to discuss repair issues in depth.

    However, I think it could be mechanically related as you say, but in this thread we have Roland saying it is likely to be an eht component and Alan saying it is likely to be a problem with the deflection board (presumably this could include a bad connection on that board). I may be wrong, but it looks like quite a lot of dismantling may be required to get to most of the soldered connections.

    I am not wholly averse to the idea of sending it to owl, but am concerned that, at this stage ot its life, this may not be particularly sensible (presumably quite expensive) as it may now be approaching the upwards slope of the bathtub (chassis 10,000 hours, tubes 4000+) - and this could be the first of many problems. I did wonder whether there may be a cheaper repair option (eg Roland??) Sadly financial circumstances do not allow purchase of another good crt projector at this moment, so failing a repair I will probably be going down the lcd route.

    I assume that there is no eht supply to the tube anodes, but the question is whether this is either a (low voltage) switching/regulation issue - or whether it relates to eht components (power supply, etc)? I can get hold of test equipment. My father was involved in high voltage engineering (power station design and protection switchgear) and I have done a lot of work on car engines (including ignition systems) - so I won't kill myself!!

    I have tried, but failed, to get hold of a service manual. These seem to be available for other makes of projector - but not Seleco. If someone knows where to buy one that would be fantastic.

    Cheers to everyone for their advice.
     
  10. AD Roser

    AD Roser
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    Julian,

    I would strongly recommend you don't take the DIY approach.

    If you can get the unit to me at SIM2 (nothing to do with OWL these days) for £45 we can tell you what the problem is and give you an estimate.

    Please contact me at alan.roser@sim2.co.uk.

    Regards


    Alan Roser
    Managing Director
    SIM2 UK Ltd (formerly Seleco)
     

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