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VSM ouput and S$Y

Discussion in 'TAG McLaren Audio Owners' Forum' started by GrahamMG, Jun 16, 2005.

  1. GrahamMG

    GrahamMG
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    Hi guys.

    As my brain is fried, I wish to share this one with you for ideas:-

    DVD connected to RGB1 on the AV192R, DVI VSM output connected to DLP projector.
    SKY box RGB output connected to RGB2, same DVI to projector link.

    Picture is absolutely fine on the DVD, all set up and fne colour balance etc.

    Picture form S$Y has the white balance far too high and washes detail out of any white area of the picture (very over saturated).

    Now before I knocked seven bells out of the room the picture from both was fine and the S$Y RGB output to the standard CRT TV is also still fine so I think the VSM/PSM is doing something that it didn't do before. All VSM settings for colour etc. are all set at default as I didn't need to mess with them before, any ideas what could have changed :lease:

    The only thing I added to the S$Y box was a loop through RF feed but I can't see how that can make any difference to the RGB output? After all the TV picture is still fine.... Oh and the HTPC to the DVI input but that is off so can't bugger things surely....

    Projector uses the same input so nothing alters there either.......

    Ideas?
     
  2. Stevesky

    Stevesky
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    Probably a large DC offset on the output of the $ky box, get Mr Scope out and have a quick look. AV192R doesn't do automatic gain control so won't crank the signal back to where it should be.
     
  3. GrahamMG

    GrahamMG
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    Cure??????
     
  4. PhilB1234

    PhilB1234
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    An obvious one.... but you have connected the Sync lead as well as the RGB haven't you? That's the only difference I can think of between a DVD player's RGB output and a Sky box.
     
  5. GrahamMG

    GrahamMG
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    Yep....... Won't work too well without a sync really, this is just purely overblown whites on this source compared with DVD.
    If it is DC offset, I'm open to the easiest fix ideas....
     
  6. Stevesky

    Stevesky
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    Filthy hack is shove a couple of signal diodes in series with the video. Other mucky ways are lob a low voltage 470uF electrolytic capacitor in series with the video. All bits you should have knocking around the bench so easy to bodge something up to see if it works.
     
  7. Stevesky

    Stevesky
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    ... having said this if the box used to work and just started to fail then it's probably something else :eek:)
     
  8. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Have you also checked the contrast setting on the Sky box is set to LOW not HIGH. Not trying to teach granny to suck eggs but Ive seen the same effect with that on other equipment

    Gordon
     
  9. GrahamMG

    GrahamMG
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    Yes Gordon, I did check that out and it was set to mid as it has always been, I've set it to low but it is still well off, always worth stating the simple though, Ta...... The only thing I can think of is that somehow I have improved the signal path since I last plugged it all up and the losses are now very low so I need to "create" some.......

    First thought was the usual 75ohm resistor in series with the signal wires and another 75ohm resistor from the signal wire to the screen, all in the scart end.....

    Of course it could be Pace getting their own back for us pointing out that their SPDIF is crap..... :mad:
     
  10. sijones

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    Hi Graham,

    My Sky box is connected in the same way as yours. I can remember that I needed to adjust the White and Black levels quite dramatically in the RGB2 picture settings to get the picture looking right. Have you tried changing the picture settings on the RGB2 input?

    Regards,

    Steve
     
  11. GrahamMG

    GrahamMG
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    Hi Steve.

    I am about to sit here all afternoon and fiddle with various ideas, what I don't get is that before I unplugged it all to nuke the room the picture was fine and so nothing ought to have changed, being the curious type I'd like to know what happened before I go and "put it right" agian...
    The scope puts the volts at 3V peak to peak......which is quite a lot really for a signal that should be 1V...... Has $ky+ had a firmware update recently and cocked it up once again? I must admit that looking closely at the normal CRT picture it also does look a bit overblown in the whites the more I look but on a 7ft screen it is bleeding obvious adn really wasn't like that before...

    Question for the other Steve, As the AV192R had a little cough when it all got first powered up (the VSM PSU sulked just the once) I donlt suppose the VSM could be in a bit of a muddle and needs to be re-set, not sure this can be done without giving the whole thing the three fingered salute but I'm open to ideas just to see if the picture snaps back. Personally my money is on the $ky box as the DVD output on RGB1 is terrific. ANy bright (sorry) ideas before I go and fiddle with settings, soldering iron and a handful of resistors and diodes/caps etc.....
     
  12. Stevesky

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    Assuming you shoved a 75ohm terminator on Mr Scope and you're not measuring a factor of x10 out due to scope/probe setup then it sounds like Mr $ky box has gone a bit ding dong. See if you can find another box and see what that does. If it's cranking out those kind of levels I'm not surprised the picture is big time saturated.
     
  13. GrahamMG

    GrahamMG
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    Cheeky sod..... :rotfl:

    Yep $ky box looks buggered but here is the laugh, I swiped one from the ringmain bay and that is exactly the same give or take .5V, I think someone at PACE is trying to improve contrast a little too much...... I've dug out an old crap scart lead and it makes a huge difference as it almost halves the signal..... :devil: What a mess.... So chuck away all those expensive active scart switchers adn just use a passive splitter, I've managed to drive 4 TV's off one $ky RGB scart output and they all look fine.... Off to find just how many times I can split the signal before I get an iffy picture. BTW if I feed our portable direct from the $ky box it has a real rolling session, I wonder if I can sell the excess signal back to $ky :rotfl: :rotfl:
     
  14. Stevesky

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    Hmmm, that sounds very dodgy. I can't believe that a Scart lead has that much loss in it though. Go on, poke around abit more as this one sounds like there is more to it than meets the eye...
     
  15. GrahamMG

    GrahamMG
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    It gets better.......

    The nackered old scart lead actually had several broken wires in it and the signal was still getting through, so looking far deeper into this I discover that my multiswitch/launch amp is giving enough signal to power the whole street well over 50dB of gain...... giving over 100dB at the $ky box input despite the attenuators being wound right down..............I'm amazed it worked at all...... So off to crawl in the loft and shove another one in. Or find a standard quad LNB to swap on the dish and then bypass the multiswitch completely...adn se if the picture gets back to normal.

    For info for anyone reading this and wondering what a quad or quattro LNB is, well a "quad" has four identical outputs (the one $ky+ man fits) and they go direct to the STB. The other is also four outputs but they are not identical, namely high-horzional, low-horizontal, high-vertical and low vertical, the latter type has to be used with a multiswitch which can have almost unlimited outputs as it intellegently swiches to the right polarity for each connected STB so no limit to the STB's you can use (just like hotels etc.), so if you have ever wondered how to run more than 2 $ky+ boxes from one dish, now you know (same goes for ordinary $ky boxes...)

    Steve, I'm still curios if the three fingered salute also re-boots the VSM just in case I get all desparate Sunday morning......
     
  16. Stevesky

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    VSM - nah, not convinced it needs a reset. Leave the poor thing alone :eek:)

    From reading this thread more carefully sure it's not your active Scart switchers mucking about? Was the 3v Pk-Pk measurement made directly from the SCART out of the STB or the other end just before it goes into the AV192R?
     

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