Page 1 of 3 123 LastLast
Results 1 to 10 of 22

Thread: Quick techie question

  1. #1
    Join Date
    Aug 2007
    Location
    Under a rock in Cambridge UK
    Posts
    1,353

    Default Quick techie question

    I am connecting my DB25's with IDC connectors and ribbon cable.

    I assume that as you look at the cable, the first wire red is pin 1, so will the second wire be pin 14?

    As in the ribbon is ordered top row, bottom row, top row, bottom row and so on..

    kind of urgent, my QM2000 arrived today and I want to play as have to be away from home for rest of the week and can't really take a laser into my hotel room

    Thanks
    Mark

  2. #2
    Join Date
    Nov 2007
    Location
    Coming to a theatre near you!
    Posts
    521

    Default

    grab a meter, as long as the cable is one to one, you're ok.

    that being said, the red stripe usually indicates the pin one side of the connector, and indeed the red conductor is usually pin one.
    but this may not always be the case. however, on a db25, yes, the first conductor would be pin one, while the second would be pin 14. but, always check first, two minutes of troubleshooting is worth the cost of your sexy, sexy interface.

    and remember, you can always make a continuity tester.
    "TO DO IS TO BE" - Nietzsche
    "TO BE IS TO DO" - Kant
    "DO BE DO BE DO" - Sinatra

  3. #3
    Join Date
    Aug 2007
    Location
    Under a rock in Cambridge UK
    Posts
    1,353

    Default

    Thanks for that... Just wanted to check myself, I stuck a meter on it and think I am right, but would hate to kill my laser so close to the meet

  4. #4
    Join Date
    Nov 2007
    Location
    Coming to a theatre near you!
    Posts
    521

    Default

    did you check for cross-connections between adjacent conductors? when you're on a ribbon cable, that's your biggest concern. )ie, in your setup, check for contunity betweeb pins 1 and 14, etc)

    hey, no prob. any time you have a question like that, you can always plug it into google. (i was 90% certain of the red stripe thing, but a quick google query backed it up).
    "TO DO IS TO BE" - Nietzsche
    "TO BE IS TO DO" - Kant
    "DO BE DO BE DO" - Sinatra

  5. #5
    Join Date
    Aug 2007
    Location
    Under a rock in Cambridge UK
    Posts
    1,353

    Default

    hmmm, now I am not sure... I will try to myself explain better...

    I am crap at soldering, so decided to go down the crimping route. So I have a DB25 IDC and a stretch of ribbon cable. With a soldered connector I can see which wire goes where as I can colour code them.

    However, with the ribbon cable it is harder to tell and I don't want to just assume, plug it in and turn my projector into a smoke machine and not the good type

    So, I have made sure the red wire is at pin one and crimped it in. I am assuming that the next wire in the ribbon is NOT pin 2 but pin 14.. If that is the case then I can carefully count along the cable to ensure the correct wires go to the correct devices in the correct order..

    So just wanted to check my assumption was right. I'm afraid my electronics knowledge is as good as my soldering skills.

    Thanks again

    Mark

  6. #6
    Join Date
    Nov 2007
    Location
    Coming to a theatre near you!
    Posts
    521

    Default

    mark, sorry to make you nervous, everything is probably fine. here's what you need to do to check your cable out:

    if it is a single-ended cable (ie, you have one db-25 on one end, and the other end terminates in wires), then separate the 25 conductors so you have test points.

    if you have a double-ended cable (ie: each end is a db25 connector), then you can start from here:

    first off, check to make sure your cable is straight-through, ie, pin one connects to pin one and so forth.

    then, check to see if there is any crosstalk between adjacent conductors, ie pin 14 may have been set off center and could be shorting with pin 1 or 2. the quick and easy way to do this with a db25 connector is to use the bottom set of pins, and check the two pins above each pin with it. ie: for a db25 you would put one probe in pin 14, and check it against 1 and 2, then move the bottom probe to pin 15 and check it against pin 2 and 3, and so on, until you get to the end of the bottom row of pins (pin 25). using this manner, you only have to check one connector (if you have a double-ended cable). because any short will make itself known on any end of the line (you're testing for shorts between the lines of the cable, so either end will complete the circuit).

    sorry if that last bit confuses you, but if you follow the first part, and check against the bottom row, you'll be ok. if you run into problems, just reply, i'm not in bed yet, so i'll help you in any way that I can.
    "TO DO IS TO BE" - Nietzsche
    "TO BE IS TO DO" - Kant
    "DO BE DO BE DO" - Sinatra

  7. #7
    Join Date
    Aug 2007
    Location
    Under a rock in Cambridge UK
    Posts
    1,353

    Default

    Aha,,

    Got you, didn't see the continuity bit as I am supposed to be working but keep slipping in and out the forum as I go along

    That sounds easier than what I had in mind.. I was going to run signals down the cable and see where they came out at the other end with a voltmeter. Continuity testing is a much easier plan..

    Told you my electronics knowledge was rubbish...

    By the way, love the sig... Doo bi doo bi doo excellent

  8. #8
    Join Date
    Nov 2007
    Location
    Coming to a theatre near you!
    Posts
    521

    Default

    indeed, continuity testing is the quickest method to make sure what is going where, and where it isn't going.

    that will make sure that you won't fry your rig, but if you plug your system in and it still doesnt work, a possible issue is this: the cable that you have tested, that passes a dc signal (your continuity tester), may not work for high-frequency signals. in the realm of audio, this has happened to me before, and while I do not anticipate it to be an issue with this particular setup, I figured that I would mention it.

    but good luck, and have fun playing with a much better laser system than I have, you bastard ;-)
    "TO DO IS TO BE" - Nietzsche
    "TO BE IS TO DO" - Kant
    "DO BE DO BE DO" - Sinatra

  9. #9
    Join Date
    Aug 2007
    Location
    Under a rock in Cambridge UK
    Posts
    1,353

    Default

    Thanks for all the help there...

    By the way, I'm not a bastard you can ask the milkman

    About to log off now and get continuity testing...

    Thanks alot, that's what I love about this forum, you ask a question and never get ignored...

    Cheers mate
    Mark

  10. #10
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,488,500

    Cool

    Hey Mark... Quick question:

    Are you wiring the ILDA port on your projector, or are you trying to build a custom ILDA cable?

    Reason I ask is that you don't have to build custom cables. Assuming you've wired a DB-25 connector on your projector to the ILDA standard, then all you need is a parallel cable (with a male DB-25 on one end and a female DB-25 on the other, and all lines wired straight through) to connect your QM-2000 to your projector. (Or *any* controller to your projector, for that matter.)

    If you're wiring the ILDA port on your projector, then I see where you're coming from. But in that case it doesn't matter which wire on the ribbon cable you use so long as pin 1 is connected to the X+ input on the scanner amp, and Pin 14 is connected to X-, and so on...

    Adam

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •