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CNC video display problem: DFP video cable extension

Discussion in 'Electronic Design' started by Existential Angst, Apr 18, 2013.

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  1. Awl --

    I had to relocate the pendant on a Haas GR-510 cnc gantry mill, which
    required extending 4 cables, one of them a 26-pin DFP cable, an apparently
    old-style video cable.
    A pic of the control display is here:

    The cable I purchased is here, notably thicker (and longer -- 35 ft vs.
    10-15 ft) than the original,

    and the oem mfr is this company: (the E164618 cable, "power limited circuit
    cable", type CL2):

    The display quality is substantially degraded, with shadows and
    color-bleeding like what you'd see on an old color TV with poor antenna
    reception. However, some areas/background colors of the screen are much
    better than others. Irksome, but still usable, and the placement of pendant
    is more important than the screen quality, so I'll have to deal with it, but
    I'm wondering if there is a solution. We seated/re-seated the cable,
    reversed ends, ran it away from AC wiring, etc, no real change.

    Is this to be expected in simply lengthening a video cable? Does the signal
    need boosting? A problem if a booster does not have dfp connectors.
    Could shielding be a problem? If so, could I make my own shielding, with
    alum foil? Both ends grounded??
    Is the cable poss. defective?? I'd think a defective cable would simply
    just not work at all!

    Also, could I be harming the display? LCD type, it seems.

    These cables are hard to find, and the oem mfr hasn't responded, and
    probably won't (china). I was hoping for a longer cable from them, or a
    female-female adatpter (coupler), and another duplicate cable.

    Options? Haas proper appears not to be a useful resource.... they have
    difficulty dealing with SIMPLE problems!!
  2. Oh, a male-male DFP cable has "squeeze locks" on the sides, as opposed to
    thumb-screw locks.
    The pins themselves are not the literal pins you see on a VGA cable, but
    rather on the sides of a central block, less risk of bending.
    A good pic is here: altho that top
    tab appears to be some artifact, or just a pc of tape.

    Shorter cables are more available, the problem was long cables, or
    If I could find a fem-fem adapter, I suppose I could just order another
    cable from haas.
    Or a male-female cable, to extend the original, rather than replace it.

  3. Don't know.
    Don't know.
    There is a mother-type board in the main electric panel, and then there a
    board in the pendant/controller (pictured in the mackaay link).
    The dfp connects the two boards.

    That's all I know. So the new cable (about twice as long and about 4x the
    cross-sectional area, for some reason) works, it just doesn't work well.

    If impedance is the primary issue, then conceivably even a longer cable by
    the same company might prove to be a problem.... altho mebbe less of a
    Christ, even WIRES are turning out to be complicated.....[/QUOTE]

    With renishaw probing, programmable coolant, rigid tap, macros, blast air,
    21 tool carousel, some other stuff. Custom coolant tank from, great company.

    The pendant/controller you see there on that arm has been moved to the foot
    of the machine (toward you), because the machine is next to a wall on that
    A bit of a miracle installation. I am already a legend at Haas.... lol

    But this cable/screen problem is a bit of a bummer.
  5. vinny

    vinny Guest

    35 feet for a video cable? Thats too long. Video cables are short for a
  6. Just accommodating reading levels, is all.... lol
    The price was a knee-buckler, but they went down some. And in this
    situation, would have been worth it, had it worked.
    As it stands now, it works but irksomely so.
    Actually a dicey situation, cuz then it gets back to the local people, a
    whole hierarchy/turf who's-doin-what who-knows-what issue.... really a

    The most practical thing right now, given the scarcity of this cable type,
    is to finagle one from Haas, and kluge together a female-female coupler via
    two female circuit board receptacles. I assume those are available, since
    the boards are made with them, but that might be another needle in a

    The other poss. is dfp-dvi conversion, and hope the pin-outs stay

    Very enlightening if not sobering thread, appreciate all the input. I have
    a new respect for g-d WIRES!!!!
  7. I ordered two adapters, DVI (fem) to DFP(26 pin male), which will plug into
    each circuit board.
    Then between them I'll run a DVI cable (m to m). We'll see how that works
    out. Cables arrive in a cupla days.
    The adapters were hellishly expensive, $42 each, and the 25 ft cable a whole
    $10. Just *moving* this effing pendant/controller has so far cost HUNDREDS
    of dollars, $200+ in cables alone..... goodgawd.....[/QUOTE]
  8. Jasen Betts

    Jasen Betts Guest

    it sounds like an impedance matching problem, like you'd get if you
    tried to run VGA or component video through a ribbon cable, cat5,
    (or other inapropriate cable)

    extending the original cable with an identical cable it likely to make
    the picture no more than twice as bad as the original picture was.

    the video degradation you see suggests to me that analogue signale are
    being sent over this cable, and the original is not a DFP cable, it
    just has DFP connectors on each end.
  9. Bob La Londe

    Bob La Londe Guest

    Want to gamble? Shorten the cable to the absolute minimum length by
    cutting, individually soldering, and shrink tubing each conductor.

    Also, check the gage of the conductors of the new cable. Gage and length
    can have a huge effect on low power and/or low gain analog signals.
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