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Pioneer SX-434 Dial Problem?

Discussion in 'Pioneer Audio' started by tmho, May 14, 2018.

  1. tmho

    tmho Member

    Messages:
    67
    Location:
    Richmond, BC, Canada
    Recently, I got a Pioneer SX-434. Overall, it is great after replacing some light bulb. But I notice that the dial or the dial pointer is not accurate for the FM radio. Roughly it is off by about 3 Mhz. But for the AM radio, I would say it is quite accurate. Is this normal? If not, will there be a way to fix?
    (I understand that I can shift or move the pointer by 3 Mhz to make it correct. But this will make the AM dial not accurate or off.)
    Below are some photos showing the dial when I tuned to a strong station according to the signal indicator.

    DSCN7473.JPG
    AM 650


    DSCN7477.JPG
    AM 690


    DSCN7479.JPG
    AM 1040

    DSCN7487.JPG
    AM 1470

    DSCN7493.JPG
    FM 90.9 (but from the dial, I would say 90.6)

    DSCN7495.JPG FM 93.7
    (but from the dial, I would say 93.4)


    DSCN7497.JPG
    FM 99.3 (but from the dial, I would say 99.0)
     

     

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  2. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,791
    Location:
    Glen Burnie Md.
    Turn the Tuning dial all the way to the LEFT END WITHOUT FORCING IT. The pointer should sit centered on the ZERO on the log scale. If it sits to the left approx 300kHz then it needs to be adjusted. Get inside and locate the top of the dial pointer. The string goes thru a clamp, retainer pin, clamp affair to lock it to the dial pin. The factory locked it by squeezing the clamps, and then setting them with nail polish (clear usually). The polish has to be broken up so the clamps can be forced open with a jewelers screwdriver. Once that is done, slide the dial pointer to the Right unti l the pointer is sitting on the ZERO on the Log Scale. Squeeze the clamps with needle nose pliers and apply nail polish of your choice. DON'T use the Wife's or G.F.'s favorite stuff or suffer accordingly.

    Check 1st the accuracy of the dial pointer vs. the dial pointer. If it's acceptable, then switch to AM and check dial pointer accuracy against AM stations. If off you can adjust via the board following the board instructions. Only DO THE 600kHz and 1400kHz adjustments.

    Larry
     
  3. Watthour

    Watthour Electron Rancher - JS3600

    After checking/setting the mechanical position as Larry advised above, if the AM indications are correct, the FM local oscillator trimmer may require adjustment. This is usually an EXTREMELY sensitive adjustment, so check everything else first.
     
  4. tmho

    tmho Member

    Messages:
    67
    Location:
    Richmond, BC, Canada
    Thanks for your reply.
    For the "log scale", do you mean the scale (marked 0 on the left end and 10 in the right end) located in between the FM scale and the AM scale?
    For the AM adjustment, sorry, I do understand "adjust via the board following the board instructions". Do you mean the "Aligning the AM Section" as shown on P.15 of the service manual?
     
  5. Watthour

    Watthour Electron Rancher - JS3600

    Read Larry's instructions carefully. The very first thing to do is to ascertain that the dial pointer will traverse (without forcing) from one end of the tuning scale to the other, with an equal amount of overshoot at either end. If this does not happen, the dial pointer may have slipped.. If the pointer travels end-to-end (0-10 on the relative scale) then the pointer has probably not slipped.

    Assuming this, and understanding from your first post that the AM indication is approximately correct, do NOT adjust anything in the AM tuner section. If the FM section only is off by about 3 MHz, adjustment of TC3 may be necessary to bring the tuner VC back into the correct regisration.

    However, if the AM indication is incorrect, you will need to perform the low frequency end adjustment of the AM tuner section and the high frequency end adjustment, as described in the "AM Alignment" section of the manual (Pg 15). As the manual indicates, these adjustments are to be performed several times at both ends of the scale for best overall performance. A the low end, near 600 KHz, T6 and the antenna core adjustments are made. At the high end (1,400 KHz), TC4 and TC5 are adjusted.
     
  6. tmho

    tmho Member

    Messages:
    67
    Location:
    Richmond, BC, Canada
    Thanks for your information.
    Yes, for FM, the pointer goes to the left side of the zero and the right side is okay.
    According to "Aligning the FM Section" on P.13 of the service manual, adjustment of TC3 needs some equipment which I do not have. Therefore, I think I better bear with that 3MHz off on the FM.
    Thanks again for all of you giving me suggestions.
     

     

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  7. Watthour

    Watthour Electron Rancher - JS3600

    Search the forum archives reagarding FM local oscillator adjustment. You may discover that it can be done to resolve the dial registration without any siggen equipment, provided that is the only adjustment made.
     
  8. tmho

    tmho Member

    Messages:
    67
    Location:
    Richmond, BC, Canada
    Thanks a lot. I will try that.
     

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