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Sonodyne SCR2065 brought back to life

By on February 2, 2016
amplifier repair
Two Sonodyne SCR2065 Amplidecks were brought to me with a request that at-least one be restored.   These were very popular in India once upon a time, when Cassette Tape Recorders were a fancy!
 amplifier repairing
The sets were in very bad shape, with a lot of dust and dirt collection all over. After thorough cleaning of both the sets, I picked up the one, which had no visible damage to the mechanism. The set was coming on. My first attention was on the tape deck. If it does not work, there is no point in servicing this. So, I removed it. On visual inspection, I noticed that three belts have to be replaced.   Replaced the three belts from my stock. Lubricated the mechanism and run the motor giving 12V external supply.
It was working well. Cleaned the heads and pinch roller. The next attention was on the board.   Since this set has been kept idle for a very long time, it actually requires replacement of all the electrolytic capacitors. But customer was not having enough budget. So, I started removing only the main filter capacitors, which I found were out of safe ESR reading. Look at the condition of the main filter capacitors and the board:
 capacitor leaked
capacitor leak
One point to be born in mind is that such large filter capacitors should necessarily be removed whether good or bad, to inspect the bottom, to see any leakage or traces of wearing out. From the above picture, it is clear that the capacitors have leaked and the electrolyte has become powder!   Cleaned the board and replaced both 4700mfd with 50 V Rating. Same was the condition of another 1000/35V and 220/50V. I replaced both of them. The .1mfd ceramic capacitors across the rectifier diodes were cracked:
 rectifier diode crack
These were also replaced. Then I touched a few places, where there were track cuts and bad solders.  (I could make out that this set has undergone many repairs earlier). Cleaned and lubricated the record/play switch, all controls, pots and input sockets with WD40. Then fit the tape deck back, and played a cassette. Only one channel was working and there were distortions. So removed the amplifier board and noticed that it was in a bad shape. Therefore, I removed the amplifier board from the other set, which looked in a much better condition. Since on one side, two 22 Ohm carbon resistors were seen connected in series, in place of 500 Ohm wire wound, I removed both the resistors. These are suppressor resistors used in the positive and negative rails. I used two 5W 1K resistors in parallel as replacement. I connected one on top and one at bottom.
 repair amplifier
stk461 amplifier
Connected the amplifier board externally and played. It was working very well. Fit the amplifier board back. Fit back the front panel, knobs and cover. These are the components replaced:
 replaced capacitor
The set worked perfectly well, in aux input, phone input (2), and tape. I recorded one song in a cassette, and was wonder struck at the amazing quality of recording! Another job done satisfactorily. I have advised the customer to preserve the other set as a standby for removal of any vital parts, in case of failure of this set again (which is very likely, as I could not do the essential maintenance).
amplifier repaired
This article was prepared for you by Parasuraman Subramanian from India. He is 66 years old and has more than 30 years’ experience in handling antiques equipment Valve Radio, Amps, Reel Tape Recorders and currently studying latest techs classes conduct by Kerala State Electronics Technicians’ Association. He was a BBA graduate, retired as MD of a USA company.

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You may check on his previous repair article below:



  1. Albert van Bemmelen

    February 2, 2016 at 5:47 pm

    You again did a marvelous repair that not many engineers would have taken the time for! And the customer will be pleased that it still could be fixed cause else it probably would have been thrown away easily. The WD40 spray can you used reminds me of something that I recently noticed with my Contactspray C60, C61 washing/cleaning lubricant cans. They all leak even when the metal cans are not corroding at all! The blu-ish content almost invisible leaked all over the surface of my Instruments Cabinet. And it is hardly removable, not even with Alcohol or Paint remover. It smells but not very noticeable. And the Blue color stays noticeable afterwards. So you are not aware of the leakage before it happend. So I warn everyone to better place the Kontakt spray/ Contact Spray cans in a safe plastified box of some sort or in a closed bag. Strangely most metal Contact spay cans also do oxidize although the content should be used to prevent electrical contacts from oxidizing. And for contact cleaning purposes. So better take care of this before they contaminated the working area at your home!

  2. Albert Hoekman

    February 2, 2016 at 5:53 pm

    Nice Job! Thanks for sharing the article.

  3. Robert Calk

    February 2, 2016 at 9:15 pm

    Nice job, Parasuraman. I'm glad you managed to save one of them.

    • Shishir ganguli

      June 3, 2021 at 10:40 pm

      Dear sir I have one scr 2065 where both the volume controls need change please me how are knobs fixed no grub screws seen they do come out by pulling either pl advice.

  4. Yogesh Panchal

    February 2, 2016 at 10:09 pm

    Good job! sir.please keep sharing.

  5. Riaan

    February 3, 2016 at 12:29 am

    Hi. Nice article! Tell me, do you use WD-40 on pots and faders? How does it work/ last on these? Is it better than Kontact cleaner?

    • Parasuraman S

      February 3, 2016 at 10:52 pm

      Yes, I do. Since it contains a mild lubricant, it lasts for some time. It has a capacity to clear off fine dust. Moreover, the powerful spraying action will clear dirt and dust. I have no idea about Kontact Cleaner and what it contains!

      • Rohan

        June 17, 2018 at 6:13 pm

        Sir i tried to restor two 2065 amps but unfortunately missing transistor in both in same position. So how do i identify them. Position in board marked t101c. Npn type. Which will work here.

      • Pravin

        October 5, 2020 at 1:09 pm

        i want red mercury valve
        Ech 81 ef89 el 84 and what prise

  6. Mark

    February 3, 2016 at 7:09 am

    Hey Parasuraman,

    Once again, thanks for your patience on what would seem an item to be thrown out. It gives a good sense of satisfaction to see something that looks so bad once again come back into service.
    Keep up the good work!

  7. Suranga Electronics

    February 3, 2016 at 4:07 pm

    Nice Repair.. I am Lazy to repair old model equipment. But You are clever..

    • Parasuraman S

      February 3, 2016 at 10:55 pm

      When I see an old equipment brought me in a bad condition, I look at it like a Doctor, who gets an old granny as an inpatient. While in the case of granny, many other factors come into consideration, old equipment can be brought to some good shape, if we work on it sincerely and earnestly. I love to see it working again and it is a thrill that one should experience to enjoy!


        July 1, 2020 at 12:22 pm

        I have a sonodyne equalizer of Uranus brand and it was so perfectly working till a couple of days ago..

        But recently, one channel is developing humming after 15 minutes of operation...

        Inspected inside, at power supply area, two condensers are heating at the base...may be for ripple of voltage..!

        One capacitor at output stage is giving sound like generator when touched...

        What could be the reason..?

        Kindly help me...


    August 19, 2016 at 2:30 am

    Respected Sir,
    I am from Kolkata ... in search for a fully restored high quality valve radio set ..... Can you help me in this regards .... Waiting for a favourable reply...
    Faithfully Yours,
    S. GHOSH

  9. Mark Eric Rebeiro

    August 25, 2017 at 2:51 pm

    I have a Sonodyne scr2065 ONE OF THE CHANNEL NOT WORKING. What should I do. I need it to be brought back into running condition. Please help.

  10. Anirban Naskar

    January 7, 2018 at 8:24 pm

    I bought this unit and upon inspection found out that the play button of the cassette deck is not functioning at all. The button is getting clicked but the pinch roller and head assembly is not engaging at all. Can you provide some assistance?

  11. Mark ERIC Rebeiro

    May 5, 2018 at 7:16 pm

    I have a sonodyne scr 2065..only one channel working. Need urgent repairing

  12. Rohan

    June 17, 2018 at 6:16 pm

    What transistor i use in scr2065 near to power section. Which is missing on board. Position marked t101c. Give me advice for restoration.

  13. Subhas Nag

    April 12, 2019 at 4:36 pm

    I want to purchase the SCR2065A circute Boar & how can i purchase it.


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