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Galaxy DX-939 repair info/options? -- EL board loud buzz rot. dimmer

Discussion in 'CB and Export Equipment and Accessories' started by gecko, Jun 18, 2008.

  1. gecko

    gecko Member

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    I have a Galaxy DX-939 which I received new yesterday from
    a dealer.

    The DX-939 emits a loud high-pitched whine similar to an
    analog TV set flyback transformer type of whine -- increases in
    pitch with dimmer control rotated towards fully bright, and
    increases in amplitude as well.

    (MORE details below -- see EL BOARD in this post).

    Looking for info and repair options. The EL board is mounted
    on the dimmer board and it looks difficult to reach to swap out.

    I'm getting too old for this.


    -=-=-=

    Doesn't look especially feasible to do a return with the dealer;
    looking more towards shipping just the transciever (no
    accessories) somewhere for a repair job. I'd like to know what
    the likely fix is, how difficult it is to do the fix, and (if I
    want it done professionally) what I'm looking at for cost.

    The radio performs well and I like the feature set.

    Also: three potentiometer knobs are quite crooked; they're so
    difficult to remove I haven't checked the pot shafts to see if
    they are really bent. The packaging did not exhibit any sign of
    trauma. The pots behave correctly (makes me suspect only the
    knobs, not the pot shafts, are crooked, if that's possible).

    I'm considering buying a second radio (new) while this one's
    in for repair. The one I have is stock (no tune-up) and the
    second radio would also be ordered stock.

    Speaking of stock, the stock mic on this rig gives excellent
    audio.



    EL BOARD

    (EL Driver PCB EPT91V131Z)

    I looked on cbtricks and have positively identified the EL board
    (a small tin box situated on a horse-shoe shaped PCB in proxi-
    mity to the front panel meter).



    I assume the EL board is an electro-luminescent display driver
    of some sort -- it seems to be exciting the star-lite type face-
    plate illumination substrate. There is a loud high-pitched whine
    emitted from the radio, ostensibly from the EL board. Like the
    glue holding it down (solder, expoxy) broke loose during ship-
    ping, and now it's transmitting mechanical vibration somewhere
    else, and making my ears miserable. Though I don't see how that
    would explain it getting into the receive audio as well.

    The loud whine increases in both pitch and amplitude as the
    dimmer pot is rotated CW towards full brightness. The whine
    gets into the RX audio; the squelch squelches this (the whine
    in the audio disappears when the radio is squelched; the whine
    emitted from the chassis does not). Same with an external
    speaker plugged in.

    On-air tests report from multiple stations this sound artifact
    is not in the transmit audio.

    I haven't looked up the IC on the EL board to see exactly what
    it does; I'd appreciate a description including any HV (elec-
    trical shock) concerns. Reminds me of CCFL (backlight)
    for laptop.

    The tone 3-position switch does not seem to do anything whatso-
    ever; noticing this gave me the idea to take the panties down on
    the rig and see if a connector had worked itself loose during
    shipping. Couldn't find any problems during this inspection.

    Thanks for any thoughts you might give -- appreciated.

    gecko
     
    #1 gecko, Jun 18, 2008
    Last edited: Jun 19, 2008

  2. gecko

    gecko Member

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    Pull J406 both ends to eliminate the whine but lose feature

    Removing the small cable from J406 (BAK, GN) and from
    the electroluminescent ribbon cable end (in the corner of
    the chassis near the meter) completely silences the whine,
    but at a cost of losing the backlit feature of the front panel.
    The dimmer still functions (the LED's behind the meter,
    and the display LED segments continue to function correctly
    and dim under control of the front panel potentiometer).

    The cable seems to introduce an AF tone (the 'whine') into
    nearby wires or circuitry. It got a lot louder during trouble-
    shooting, and much louder in the connected external
    speaker (so I'm backing off my 'mechanical vibration'
    theory).

    Seems to be a proximity thing (dress this cable just right,
    and perhaps change its length, and possibly exchange it for
    a shielded version, for a permanent fix, I'd think).

    That cable probably carries a strong signal that gets into
    the audio.

    The tone switch fix is (perhaps) going to turn out to be a
    missing jumper on the (rather sparsely populated) main-
    board, or another board.

    The potentiometer issue stems from a crude fix at the
    factory, for a problem with loose or ill-fitting control knobs.
    The fix is to remove the knobs, and straighten the split
    shaft-ends of the pots, and re-knob.

    Those were the advices I got through other channels
    (mixed with some of my own). I performed the 'yank-the-
    offending-cable' fix ... and Bob's my uncle. No more of that
    sound. I zip-tied the cable into an existing cable bundle, so
    I'd have it available when (or if) I pursue a permanent fix.

    gecko
     
    #2 gecko, Jun 19, 2008
    Last edited: Jun 19, 2008
  3. loosecannon

    loosecannon Sr. Member

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    gecko, sounds like you got a lemon.

    i would return it to the dealer and not buy from them anymore.

    if that isnt an option; dtbradio is a member here and he is a galaxy repair shop.
    very good tech.
    here is his site: www.dtbradio.com

    later,
    LC
     
  4. broncoman529

    broncoman529 Active Member

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    OH YEAH!!!...OH YEAH!!..OH YEAH!. HA!!!...HA!!..HA!. AAhhhh...

    HOW BOUT IT GECKO.........YOU GOT A COPY???...

    I agree 100%. (y) 73's

    Larry T.
     
  5. gecko

    gecko Member

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    spread the love

    Yeah Larry,

    B-Man, I appreciated your inspecting the unit and agreeing with
    me the buzz sound from the dimmer was unacceptably loud. That
    was a good sanity-check.

    I phoned the dealer this morning and told him I followed cer-
    tain resolution paths he'd suggested. He was happy to get that
    phone call. I implied I consider the matter closed (my tone of
    voice strongly suggested this was the last I'd speak of the
    matter with him).

    Gotta spread a little love in this world.

    (insert homily about how the supply depot was king, in the mili-
    tary, and why)

    [edited from here down]

    LC, I appreciate your input. I'd rx the same suggestion (DTB)
    from B-man prior; that wasn't the path I wanted to take (at a
    minimum, I'd like to beat the intershipping charges, which all
    mail-order-based solutions employ). Nobody but me was going to
    eat the shipping charges, and also, I'd be without the rig.

    Initially, I thought the resolution would require a replacement
    of the dimmer board, which I did not think I wanted to tackle.

    [edit/update section]

    Update: I was able to gorilla the knobs (all of 'em) away from
    the front panel, enough for the T or 'hat-shaped' nylon washer/
    bushings to come unseated (they are loose-fits held against the
    faceplate by the proximity of the skirts of the knobs). These
    function mostly as dust seals, and so they should be secured.

    I used a combined technique of doubling up on my own fingers
    (I used one hand to augment the other's strength) but for the
    last few knobs, I used a mouse pad (neoprene rubber) to get a
    good grip on 'em). Result: knobs won't scar the faceplate with
    repeated use.

    I may find some nylon washers to space them a bit further from
    the front panel; I don't like the idea of taking pliers to the
    shafts (if necessary) to spread the steel split-shafts (they
    are splined and split; the obvious fix is to bend them straight,
    but that'd leave plier marks, the way I do things -- I'm not
    good with detailed work using steel tools in close quarters).

    By using only my hands and the mouse pad I was able to keep
    stresses on the pot shafts reasonable; I don't expect any
    damage from this technique (and haven't found any, thusfar).

    73

    the Gecko
     
    #5 gecko, Jun 19, 2008
    Last edited: Jun 19, 2008
  6. galaxyradioshop.com

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    I would return it to the place of purchase or call them back and ask them to send you a new one and you will return the old one. Or you can contact Galaxy. If you go to my website www.galaxyradioshop.com and look at my policies page for galaxy radios warranty you can get there contact information and see if they can help you.
     
  7. deadgoon

    deadgoon Member

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    Galaxy guarantees their radios for 3 years from the date of manufacture which is on the back. Something went wrong with my 929 and I called the number for service in the back of my manual. They gave me a RMA number and stated that it was valid for a year. Several months later I sent it in and just received it back after they had it about a month. They didn't include any paperwork to say if it was fixed so I'm going to try to hook it up and see if it is working tonight.

    It was a great radio when it was working. Then one day I got no modulation when I was trying to transmit. Another driver told me he could hear me keying up, but couldn't hear me talking. I was hoping it was just the mic, but when I tried a different one, that wasn't the problem.

    I'll update when I test it.

    UPDATE:
    The radio still didn't work. I guess I'll have to see what other options I have.
     
    #7 deadgoon, Oct 19, 2008
    Last edited: Oct 19, 2008
  8. psycho

    psycho Running a special on our rooms!

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    I don't understand what all the confusion is about.....Galaxy warranties the radio for 2 years. You are making a mountain out of a molehill.
     
  9. zinger827

    zinger827 Supporting Member

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    The 939s are warrantied for 3 years. Just call galaxy give them serial #s get a RMA # send in for free repair.
     
  10. jessejamesdallas

    jessejamesdallas Sr. Member

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    This must be a common problem with the 939, because I have one that does the exact same thing...I got the radio at cost from a local CB Shop, because I'm always sending him New Business, so I really don't want to bother him with the problem...

    I sent Galaxy a request for a RMA#, but haven't herd back from them yet.

    Not too sure I would ever buy another one either. The receive sounds good, but IMO the radio is "Over-Priced" for no more than what it is...
     
  11. Cityboy

    Cityboy Active Member

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    The typical hum you guys are hearing is from the transformer in the tin box is also a problem with some Cobra 29 NW radios and I have found that it was even noisier on the Galaxy models. Truthfully Gecko I would just send it back and eat the shipping charges one way to Galaxy unless there is a problem with you having proof of purchase or the seller was less than honest with the sale and you can not send it in for repair; a $10-15 shipping charge one way to Galaxy is a lot cheaper than the number of hours you will spend or have spent trying to figure it out and fix it. Did you break the seals? If you have then I can see your reluctance to return and the nylon washers that are behind the knobs are for a dust cover and also the are they exact diameter of the know and will keep the knob from scratching marks into the faceplate and should spin freely with the knob to decrease the amount of friction between the knob and faceplate. If you would like to remove knobs a little easier and safer I would suggest taking a small flathead srewdriver and take some heat shrink tubing and shrink two layers around the shaft of the screwdriver and use it to pry you knobs gently while going around the bezel area for support and will keep from scratching it up. Good luck but send the radio in.
     
  12. jazzsinger

    jazzsinger Bullshit Buster

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    The whine from the el unit is inherent in all radios with el displays,the ss3900el is rancid with it,the other problem these units have is the display dulls through time too.
     
  13. jessejamesdallas

    jessejamesdallas Sr. Member

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    Right. I talked to one of the Techs over at Galaxy on Monday, and what the problem is on the Galaxy 939, is since the Mic jack is on the same side of the radio as the transformer that operates the faceplate lights, the wires from the faceplate are too close to the wires coming off the small circuit board that the Mic jack is connected to, and then run to the main board...

    The Mic jack is picking up the hum from the transformer, and then broadcasting the hum over the air...

    To fix the problem, all you have to do, is gently pull the two wires that are connected to the little illuminating light source that connects to the faceplate away from the Mic Jacks circuit board...

    So turn on the radio, and turn on the "Talk Back", then Key the Mic and you can hear the hum in the speaker, so while you have the Mic Keyed, start moving the wires with a small screw driver, (something plastic would be best, so you don't accidentally hit something that may Bite you back!)

    You will hear the hum start to go away as you move the wires around...Once you get the noise out, then take some small plastic zip-ties and fix the wires so they are away from the wires going to the Mic Jack...

    If I remember right, the two wires going to the illuminating light source are Yellow and Black with a little heat-shrink on the ends...If you need to, you can cut the factory zip-ties that have all the wires tied back against the case of the radio, so it's easier to separate everything...Then if you want, later go back and replace the zip-tie.

    Took me every bit of maybe 5 minutes to fix my problem.;)

    note: Since the transformer that lights the faceplate operates on AC, and not DC, there will still be a very faint hum while the radio is turned ON...But that hum will not get broad-casted over the air, as long as you separated the wires like I was talking about doing earlier. And if the unit is in a mobile, you wont be able to hear the hum anyway.
     
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