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VGA cable prob...which wire for which pin?

Discussion in 'Cables & Switches' started by WEIRDWOLF, Jun 11, 2003.

  1. WEIRDWOLF

    WEIRDWOLF
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    Hiya

    To cut a long story short, I've got a 25M VGA cable that i'm using to connect my computer in the loft to my plasma in the lounge below. I buried the wire under the floorboards a while ago along with other cables but unfortunately had to cut one of the ends off it because the holes used to feed the cables were not big enough.

    Anyway, when I tried to solder the end back on I realised I didn't allow enough wire on the head to do the soldering so had to chuck it away and use another piece of VGA cable.

    The trouble is I've worked out which of the internal wires go to which pin on the new 'end' by taking apart that wire, but on the 25M length I can't tell because I through away the end (duh!) and I don't want to cut up the other end to check. The two cables don't have matching wire colour co-ordination which is the problem, otherwise it would be easy.

    My question is....how can I find out which wire relates to which pin??

    Three of the wires are obvious (large Red, Green & blue) but the trouble is with the 6 or so thinner ones, and the fact that one of the VGA cables has one less of the thinner wires than the other.

    Any help would be marvellous!!
     
  2. bxd

    bxd
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    Hi,

    I'll pick up on this since no one else has.

    I think that you're going to have to do this the hard way by making a circuit.

    If you bare the signal wires (and grounds) at the cut end you should be able to tie two (e.g two signal wires) together. You can then use a circuit tester (or you can improvise one from a torch) to check which pins (on the vga plug in the attic) make the connection. By changing the various combinations around you should be able (by a process of elimination) to identify which wire is associated with each pin.

    Depending on the type of cable, there is probably an overall ground connection. This probably runs from the outer 'surround' on the vga connector and runs down the cable either as a single unsheathed strand or as an outer sheath. You should be able to use this as one side of your 'circuit' to identify individual pins.

    brian.
     
  3. hornydragon

    hornydragon
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    To implement the system BXD is talking about you can use a 12v battery and a bulb. Connect battery to a pin on the VGA plug and a bulb to the bare wires until it lights up. Maplin will have all the relavent kit.
     
  4. bxd

    bxd
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    Hi,

    *******
    .... you can use a 12v battery and a bulb.
    *******

    Yup ..... I'd call that a torch !!

    Actually, Hornydragon would have been talking about a 12v bulb...... not a lightbulb !
    It's the sort of thing you can also get together as a simple 'car electrics' tester from somewhere like Halfords.

    Brian
     
  5. WEIRDWOLF

    WEIRDWOLF
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    Nice one lads...

    I'll have a look into that this weekend....can't wait to have the PC up on me plasma cuz at the mo I've got the 19'' CRT stuck on the floor of the lounge as a temporary solution but it's not wife -friendly!

    Ta very much me muckers.
     
  6. hornydragon

    hornydragon
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    :p
    Well its cheaper than dismantling a torch!!! PLus a 1.5V torch over 25m of cable aint giong to be very bright. You could of course use a peizo electric sounder. Thats how you rewire flak damaged aircraft looms dont you know ( fancy wrist strap operation mind) you just touch the bare ends!!!
     
  7. bxd

    bxd
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    Hi,

    I'd just suggested the torch approach because, it was something that you'd probably have around the house. It wouldn't be too difficult to rig up something with a couple of bits of wire and a paper clip (or two) which would do the job without completely destroying the torch. Given the individual cable strands in question I would have thought that you'd still be OK with 1.5 v.

    I've never had to rewire an aircraft loom.... but I'm a dab hand at EPS Power conduits where you just grab either end in each hand and stuff them back together...... power restored ! .... warp drive back on line ! ..... phasers and crts ready on all tubes !!!!

    ...... so much for only doing sensible suggestions !

    I give up !!!

    brian
     
  8. WEIRDWOLF

    WEIRDWOLF
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    Nice one lads...

    I'll have a look into that this weekend....can't wait to have the PC up on me plasma cuz at the mo I've got the 19'' CRT stuck on the floor of the lounge as a temporary solution but it's not wife -friendly!

    Ta very much me muckers.
     
  9. WEIRDWOLF

    WEIRDWOLF
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    Hi Chaps,

    Tried the deconstucting torch and completing the circuit thing but it does not work as hornydragon suggests due to the 25m length...there is no light.
    Will try a 12V battery when I can...
    Just a thought...is it worth soldering the ones I definitely know about (red, green, blue and their respective grounds) and 'testing' the others one at a time to see if they help the picture while it is wired to the computer...or is this liable to end in tears??
     
  10. hornydragon

    hornydragon
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    Depends how confident you are in the pins being correct mate, a VGA diagram should be on the web.
     
  11. WEIRDWOLF

    WEIRDWOLF
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    I found a VGA diagram a while ago, but doesn't help here since I need to know which colour wires on this particular cable correspond to which pin...

    I think I'll look to getting an electrics tester thingy.

    Cheers anyway!
     
  12. dts_boy

    dts_boy
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    you don't need to worry about thr colour of the wires - label each cable with a number and solder to the pin. you will have to re-solder the pins on the other end as well and shouldn't have to take a torch/light/battery type thing to it.
     
  13. WEIRDWOLF

    WEIRDWOLF
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    Mr DTS....

    That's a good suggestion...I'll try that.
    I have contacted Belkin recently who make the cables and managed to get PDF files of the specs for these.
    They wrer helpful (except one which didn't correspond at all with the wires actually there) but after soldering I get sweet f.a. on the screen.

    I'll try what you say as that way I'll know for sure what's what.

    Cheers
     
  14. WEIRDWOLF

    WEIRDWOLF
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    Me again,

    It's been a while, but I decided to get a multimeter to test absolutely what wire goes where.

    After doing a solder job, the plasma comes up with 'no signal' message again. I am getting pretty discondent now I'm afraid.

    A couple of questions....
    Should I go with dts_boy's idea and solder the wires to the pin directly??? On one cable there are two 'free' wires...one goes to pin 12 which doesn't have a corresponding wire on the other cable, so should this hang free?? Another wire for pin 15 says it is for the 'shell' which could mean the shielding??

    Should the shielding be soldered together too??? I've done this and nothing again.

    Any other suggestions would be helpful...am I missing something here??
     
  15. hornydragon

    hornydragon
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    unfortunatley it could be one of many reasons just an idea get a cheapy 2m lead and connect to screen via a laptop or similar just to check the input on the plasma....
    If that works then back to square one i am afraid I have cripped many a net work cable perfectly to the naked eye but sweet FA in terms of connection so that could cause some greif!!!
     
  16. WEIRDWOLF

    WEIRDWOLF
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    Hello Horney....

    I think the connection is OK as I did connect it all up before I put them under the flooring and they were OK, but I'll try that anyway.

    Another thing is that at one point when I was laying it down I had to kind of squeeze it round a tight bend to get it in a particular hole and maybe this could account for the lack of signal.
    Tomorrow I think I'll test the cable from the computer to make sure i'm getting a signal full-stop just in case and if i'm not then i'll know the problem.

    Just odd that i'm not getting any signal at all.....black screen only.
    You'd have thought that after connecting all the wires up correctly you'd get something???

    Cheers
     
  17. WEIRDWOLF

    WEIRDWOLF
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    Well, well....

    Checked to see if the cable from the computer is OK today, and seemed fine, but as I did this I stumbled across the fact that 2 of the wires are in fact swapped the wrong way around....i.e. the wire supposedly for pin 13 should be for 14 and vice versa.
    This was down to an incorrect schematic drawing sent to me by Belkin!!!!
    This may make a difference because they just so happen to be the V & H syncs...

    I'm working at mo so shall re-solder them tomorrow....wish me luck!!
     
  18. WEIRDWOLF

    WEIRDWOLF
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    Hoorah!!!

    Just tried re-soldering with the 2 wires swapped and it's there!!!!!

    However, the picture that comes up is pinky coloured....like some monitors go when there is a dodgy lead. I did not do a particularly good job on the soldering, so I'll try redoing it.

    Ah well, at least I'm getting a picture!!!

    Cheers for all your help lads!!!
     
  19. hornydragon

    hornydragon
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    At last mate well done!!!! I would have a rant at Belkin if i was you!!!
     
  20. WEIRDWOLF

    WEIRDWOLF
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    Oh Horney one....

    Yeh I'm well chuffed...it's been quite a while!!!!

    Just did a search on pink screens like mine and found it may be to do with the green signal not getting there, so I fiddled a bit and the pink has gone too!!!

    All sorted....but I'm not one to complain about it...life's too short.

    Long may my plasma PC viewing continue!!

    Thanks again Horneydragon, you've been a star!
     

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