CNC video display problem: DFP video cable extension

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:

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The cable I purchased is here, notably thicker (and longer -- 35 ft vs.

10-15 ft) than the original,
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and the oem mfr is this company: (the E164618 cable, "power limited circuit cable", type CL2):

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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!!

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EA
Reply to
Existential Angst
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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:

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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 adapters/couplers. 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.

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EA 




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Reply to
Existential Angst

Show us the mill!

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John Larkin                  Highland Technology Inc 
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Reply to
John Larkin

On a sunny day (Thu, 18 Apr 2013 10:01:13 -0400) it happened "Existential Angst" wrote in :

Is the cable correctly terminated at the end? Is it driven by the correct impedance?

If the 26 pin cable is just to feed an LCD directly, that will likely not work due to reflections and cable capacitance. The LCD driver needs to be AT the LCD.

Reply to
Jan Panteltje

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 problem. Christ, even WIRES are turning out to be complicated.....

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EA 


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Reply to
Existential Angst

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With renishaw probing, programmable coolant, rigid tap, macros, blast air,

21 tool carousel, some other stuff. Custom coolant tank from ronco-plastics.com, 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 side. 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.

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EA 


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Reply to
Existential Angst

Well, I don't know if this has any relation, but I got some VGA cables years ago, and had horrible blurring of the video. I cut one of the cables open and it was just a bundle of wires in an overall shield! I got disgusted and made my own cables with

5 pieces of RG-178 (I think that's the sub-mini 75 Ohm coax designation). These work great, but are rather time-consuming to make by hand.

I'm guessing these DFP cables are supposed to be twisted pairs for LVDS signals. Either the monitor doesn't have the right termination or the cable is poorly made, and maybe has the wrong impedance, causing reflections.

Jon

Reply to
Jon Elson

The weird thing is this is a digital cable and the artifacts you describe sound like analog problems. I would suspect that there might be too much voltage drop on the 5V in the cable so the display itself is not getting quite enough voltage to work properly. If you can take the back off your pendant without voiding the warranty, you could measure this.

Reply to
anorton

35 feet for a video cable? Thats too long. Video cables are short for a reason.
Reply to
vinny

This post is legible. I dunno WTF you did with EA, but..

It seems Apples use these cables (I never heard of 'em), so you might try Apple user groups or forums to see what they use that works well.

The 35ft distance isn't trivial.. you may need a wired transmitter/receiver pair of gizmos, in addition to a proper/better cable.

The other replies are likely correct that the particular cabling used to fabricate this cable assembly isn't suited to your purpose.

Many of Arcade's products are typical China/generic quality, and I guess they thought a long, fat cable was worth $120+.

I don't know where you'd get the cable you need, but it might be very similar to a VGA monitor cable but with those digital connectors.. OR, your monitor really is digital, and the cable you have is a half-assed attempt at a non-compatible product (sound familiar?).

If the folks at Haas haven't been able to tell you what specific type of monitor you have, you probably need to try entering random phone extension numbers when calling. And ask for a pin-out of the connectors.

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Reply to
Wild_Bill

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 pita....

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 haystack.

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

Very enlightening if not sobering thread, appreciate all the input. I have a new respect for g-d WIRES!!!!

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EA 




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Reply to
Existential Angst

Buy a cheap cell phone and call Europe or Asia reps, maybe.

Companies go to great effort to keep customers (who pay the bills) in the dark.

The comment I received from a company "Level II" support rep last week was "those (SD cards) should be (work) fine. The device (was $1200) has a capacity of 6 cards.. there are 4 classes of SD which are like Generation 1 thru 4, all slightly different.

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Reply to
Wild_Bill

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.....

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EA 


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Reply to
Existential Angst

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.

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Reply to
Jasen Betts

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.

Reply to
Bob La Londe

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