Pioneer RT-1020L sound output problems

Discussion in 'Tape' started by thelonerider, Apr 17, 2018.

  1. thelonerider

    thelonerider New Member

    Messages:
    31
    Location:
    Mont Tremblant, QC
    Hi all,
    I recently purchased a Pioneer RT-1020L and after cleaning and lubricating, I gave it a test. Well, not surprising, the 1973 machine was not without problems. I checked the threads here as well as Google and also downloaded the service manual.
    My question is this; when recording, there is a big difference in volume between source and tape, there is hardly any output from the tape. To get sufficient volume, I would have to pin the VU meters from the source.

    Second, when playing back a previously recorded tape from my Akai 4000ds, the sound is distorted as well as low.

    I looked at the service manual, and I am not sure what these symptoms fall under "insufficient sound" ie P.B. circuit or "recorded sound insufficient or distorted" ie oscillator circuit.

    Any pointers or suggestions before I swap out half of this fine looking machine for nothing.
    Edmund.
     

     

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  2. pustelniakr

    pustelniakr Silver Miner at Large Staff Member Super Mod Subscriber

    Messages:
    7,326
    Location:
    Tucson, AZ
    There are a variety of potential causes. If tapes that are recorded elsewhere sound good, then your record head could be bad, or positioned incorrectly. If such tapes play back weakly, then the playback head could be bad, or not positioned correctly, or its associated circuitry will need troubleshooting.

    Tape requires a high frequency foundation signal, called bias, imposed on the music signal, to cause the tape to become more susceptible to recording. If it is not there, little music will be stored on the tape. The same high frequency signal is generally used to drive the erase head. If the deck will not erase material already on the tape, and it will not store much music on the tape, then, I would suggest that your bias oscillator is the place to look.

    Be aware that, at this age, many switches and relay contacts will be dirty/corroded, causing a variety of issues.

    There are more possibilities, but those should be enough to get you started.

    Good luck,
    Rich P
     
  3. thelonerider

    thelonerider New Member

    Messages:
    31
    Location:
    Mont Tremblant, QC
    Thanks Rich P,
    I already gave all switches a good cleaning, but I did not yet do the bias pots on the circuit boards (found these on the bottom while exploring)
    Though my issue could be both the P.B. circuit amp and the oscillator circuit, I was hoping someone might have some experience with the Pioneer and point me to only one.
    Edmund
     
  4. r_brumett61

    r_brumett61 Active Member

    Messages:
    306
    Location:
    Ct
    Hopefully it could be just dirty heads or heads out of alignment also try another tape or tapes. Pictures of the tape path on the heads would help.
     
  5. thelonerider

    thelonerider New Member

    Messages:
    31
    Location:
    Mont Tremblant, QC
    Heads are clean, several times as there was a buildup. Will check tape path, but service manual points to either the P.B. circuit or oscillator circuit as well as some semi fixed resistors and capacitors prior to the circuit itself.
     

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