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Fixed Broken Wheel Of Tuning Needle In National Panasonic RX-5100F

By on November 10, 2020
National Panasonic RX-5100F













Those of you who have not seen the previous history of this unit published in September, 2015, can view this: [I have now included better pictures without re-sizing in this article, for those who are interested to see the inside clearly] This unit was brought back to me in September, 2020, exactly after FIVE YEARS of use, with the complaint that the needle was stuck at the left side and it does not come out. I presumed it could be due to a loose cord or overlapped winding of cord. Anyhow, I opened the set and did a thorough cleaning of inside using blower and dismantled the Tuner PCB.

tuner pcb repair national

tuner pcb repair national panasonic

how to fix national panasonic cassette radio

I observed that the cord on the twin-sized wheel that supplies it to the needle and collects it back, had come out of its lower large sized wheel and got wound on the smaller portion.

Then noticed that one of the two tips that hold the cord to the large wheel was broken, as a result of which, it got slipped and got wound on the other. So, there was no grip and the wheel was rotating without pulling the cord! I am giving below a picture of another similar wheel near the drum for you all to have a comparison, along with the broken one:

how to fix tuner

So, I used my hot soldering iron to insert two cut steel pins to its place. It went in and held firmly as the wheel was solid and not hollow. Then kept the needle at the extreme left and routed the cord through the metal tips. Then the needle was moving left and right very well.

After trying it a few times, applied Fevibond (a rubber compound) so that it does not slip out. Also cut extra length of the tips so that it does not cause any obstruction.

fixing radio tuner

Put back the Tuner PCB and its connectors to the main board. Tried the tuner and it was working very well. Even the tape was working very well. Assembled the set back and allowed it to run for several hours before calling the customer to come and collect it! (That was a lot of ‘C’ in sequence (LOL)) Satisfaction was only happy to jump to its collection bag! Here is the proof for final working; look at the red LED Sound Level Indicator in the middle, above cassette door!


This article was prepared for you by Parasuraman Subramanian from India. He is 70 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.

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You may check on his previous repair article below:




  1. Albert van Bemmelen

    November 10, 2020 at 8:50 pm

    Nice solution to a repair that almost couldn't be fixed. At least not without getting new spare parts. But you still managed to give it a second life by fixing the original wheel in an original way! And in case this failed and original parts were not available either, only printing new parts with a 3D printer could have been another, but timeconsuming, option.

    • Parasuraman S

      November 10, 2020 at 9:44 pm

      Very true! Many thanks!

  2. Waleed Rishmawi

    November 11, 2020 at 2:45 pm

    wow, a surgical repair paying attention to the finest details, that is what I call mission accomplished. have a blessed day

    • Parasuraman S

      November 13, 2020 at 7:39 am

      Many thanks!

  3. Gabriel Sand

    November 13, 2020 at 2:11 pm

    JB Weld epoxy works very well. I've used it to repair many a broken item successfully.

    • Parasuraman S

      November 15, 2020 at 5:49 pm

      Many thanks for your suggestion.

  4. Yogesh Panchal

    November 13, 2020 at 11:11 pm

    Good job! Sir,
    Really threading the Radio needle required expertise i know i had wasted almost 3-Days to get the work done.

    • Parasuraman S

      November 15, 2020 at 5:52 pm

      Yes, it is a tricky affair and keeps one bogged down for hours or even days! Many thanks for your valuable comments!

  5. edgar

    December 6, 2022 at 8:29 am

    saludos desde peru
    quisira q mediga cuantas vueltas avan por cada polea
    Greetings from Peru
    I would like you to measure how many turns are made by each pulley

  6. pascal

    May 7, 2023 at 2:53 pm

    Hello, I am looking for the Panasonic RX 5100F service manual to put the tuner cord back, Dial threading.

    Than you very much


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