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Zinwell 6x8 switch--functional question

Discussion in 'DIRECTV Installation/MDU Discussion' started by TigerDriver, Dec 18, 2010.

  1. TigerDriver

    TigerDriver Electronics Engineer

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    My Zinwell 6x8 Multi-Switch just went Tango-Uniform. I get no channels whatsoever; that is, my three HD DVRS do the "searching for satellites" shuffle forever.

    I measured the DC output voltage of the switch at the grounding block during "searching for satellites." Two of the cables are stepping through voltages up to +18v, but the other two cables are nailed at about 1.5v (+/- 500mv). At no time did the stingers on any cable go negative with respect to the shield (I don't know whether they're supposed to...just reporting facts <g>).

    Now: I noticed that there are two unused outputs on the Zinwell switch, and they too are switching up to 18V.. My question: should I move the cables from the defective switch outputs to the unused ones?

    Thanks in advance.

    P.S.
    Ordinarily, I would have just tried this swap, but: the grounding block is in my toasty warm basement, while all my electronics are in my unheated garage where the current temperature is about 30F. I just don't want to FMAO if the proposed cable-switching is futile.
     
  2. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    If you think the switch's outputs have gone Tango Uniform, and you have others not in use, moving over to them should show if the switch can work at all.
    You may have problems between the dish and the switch [input side] and "barreling" a receiver's coax across the switch to one of the inputs might help you narrow down what/where the problem is.
     
  3. TigerDriver

    TigerDriver Electronics Engineer

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    Funny...I think of the switch-->dish as the output side, and the receiver(s)--> to switch as the input side. I confess, however, to not having the foggiest idea how this switching system actually works.

    I measured outputs of the switch open-circuit under the assumption that if the switch couldn't drive an infinite impedance it couldn't drive an LNB<g>. The two good switch outputs continued to switch with the dish side connected--albeit with slightly lower voltages due to the load. The static 1.5V on the 'bad' outputs is suspicious, because it's about two diode-drops--which is what occurs when output is clamped by an internal circuitry failure.

    I'm pretty confident about the wiring because I did it myself. The dish itself is mounted on a small out-building about 50 ft from the house. The wires between the grounding block and the dish are continuous (i.e., unspliced) and live underground inside glued 2" PVC. Nevertheless, I checked the connectors at the LNBs and at the grounding block for corrosion and/or broken stingers--all fine. The basement wiring from the grounding block is a straight shot along the joists (fastened with standoffs) right into the garage.

    So, I guess I put on my FMAO duds and head out to the garage.
     
  4. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    I have the feeling things are backwards here.

    Starting with the DC power source [the receiver] ---> switch outputs [RF] -- inputs [passing voltage from the receiver] --> dish
     
  5. AntAltMike

    AntAltMike Hall Of Fame

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    College...
    LNBs ports that see no voltage or substandard voltage usually put out Sat A odds if they any port is getting virtually any voltage or not. In most applications, it takes a doozie of a short to suck down an RF signal to a level of where it will not be seen by a receiver, but with long cable lengths. it can happen. What are we looking at for cable lengths here?

    Some multiswitches will also pass through Sat A odds if there is no voltage on their inputs, but other switches, like the Holland 3x4 PIN diode switches I sometimes use, will not put out anything if no DC control voltage is present.

    You should probably set each tuner on a test of a single, even numbered transponder to make sure that it will be trying to send out 18 volts while you are trying to measure it. It is difficult for most do-it-yourselfers to put a resistive load comparable to that of a switch or LNB across the end of a coax to make the test voltage measurement indicative of what the switch sees as the input voltage. The cheapest way to do that might be to obtain a high frequency splitter that passes voltage on both ports but which doesn't have any blocking diodes in it and insert it just below the switch outputs, and take your voltage measurement off the other port.
     
  6. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "Even cheaper" is to open up a piece of coax so you can get to the center conductor while it's connected to the LNB. ;)
     
  7. Richierich

    Richierich Hall Of Fame

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    I had a Bad Port on my Zinwell 6X8 Multiswitch and I switched it over to another Port and it worked fine so I have kept it there until I went with SWM and Directv Replaced my Zinwell with 2 SWM8 Multiswitches.
     
  8. TigerDriver

    TigerDriver Electronics Engineer

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    Jul 27, 2007
    120-150 ft.

    Whatever this failure was, it was sudden and precipitous. All three receivers suddenly showed "Searching for Signal on Satellite in 2..(771)."

    I purchase the service/protection option from DirecTV, so ultimately this is their problem. My appointment is on Wednesday. Maybe swapping the "control input" to the switch will get me back on the air in the meantime.
     
  9. TigerDriver

    TigerDriver Electronics Engineer

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    What were your symptoms?
     
  10. TigerDriver

    TigerDriver Electronics Engineer

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    My kinda guy.

    Where in Norcal do you live?
     
  11. Richierich

    Richierich Hall Of Fame

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    It just quit working and it took awhile for me to finally figure out that lightning or something zapped it and it quit working but I was Ecstatic when I switched it over to another unused Port and it worked.

    I thought at first it was a Bad Tuner on my DVR.
     
  12. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Up around [outside of] Grass Valley, in the old Gold country.
     
  13. joe diamond

    joe diamond Hall Of Fame

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    An issue to add...the slimelines had a problem with failure in cold weather. Not all failed but many from one specific manufacturer. Try heating the LNB & tapping on it...see if anything improves. Then replace the LNB.

    This may not be it but is EZ to try.

    Joe
     
  14. HoTat2

    HoTat2 Hall Of Fame

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    Given that the OP in his initial post referred to "two unused ports" on the "output side" of the multiswitch, which he interprets as the side between the switch and dish. I thought maybe he was referring to the flexports.

    If so then no you may not use those as substitutes for the other two bad lines reading 1.5v. They are only for the 72.5 WL (now obsolete) and 95 WL international dishes.
     
  15. RobertE

    RobertE New Member

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    Won't work for his problem

    He has an issue with his multiswitch. The cold weather issue was with the SWiM LNBs made by WNC. The two won't work at all together...ever.
     
  16. joe diamond

    joe diamond Hall Of Fame

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    Thanks,
    I don't keep up. Understood it was with the Slimlines before the SWiMs were out. I learn more than I teach here.

    I still tap anything that doesn't work...can't help it.

    Joe
     
  17. TigerDriver

    TigerDriver Electronics Engineer

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    I just went to swap the ports and saw that they were labeled Flexport1 and Flexport2. I decided to check this out before plugging anything into them. Am I glad I did!

    So I guess I'm screwed until the D* tech gets here on Wednesday.

    In the mean time, I'd like to test the lines from the protection block to the dish--99% of which is underground. I have a little two-part toner gadget. One part part screws onto an RJ-6 and injects audio @ 2KHz; the other part is a little speaker that attaches to the other end of the cable. Come to think of it, I don't know whether a simple audio signal is injected into the cable, or an RF signal modulated by audio. I know this is a crude test, but it's all I got.
     
  18. TigerDriver

    TigerDriver Electronics Engineer

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    I know it well. I've flown my 4-seater into almost every little airport in NorCal. I lived in Berkeley for 40 years; retired to VA in 2006.
     
  19. joe diamond

    joe diamond Hall Of Fame

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    The toner will help identify the end of each run but will also jump shorts and opens.. To test the cables once they are identified: Know that the voltage from the receiver goes TO the LNB on the center electrode. The Low Noise Blockdown Converter (LNB) signal returns to the receiver on the outside web(coaxial) cable. So you want to test for opens & shorts between the center & the outer shield. This can be done at the fitting while examining the fittings. An ohm meter will do it.
    If there is any flow between the inside and outside you gotta find the ding or rerun the line. If you connect the center to the outside at one end there should be a complete circuit at the other.

    The other way to identify the cables on dual coax is to know that the manufacturers put the specifications on only one side of the "siamese" dual cables. The little line is a ground that should be attached to the dish and the house bond.

    Joe
     
  20. RobertE

    RobertE New Member

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    The signal from the LNB is not carried on the shield of the cable. It is carried, along with voltage, on the center conductor of the cable.
     

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