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!
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:
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:
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.
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:
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).
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.
Please give a support by clicking on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.
P.S-If you enjoyed reading this, click here to subscribe to my blog (free subscription). That way, you’ll never miss a post. You can also forward this website link to your friends and colleagues-thanks!
You may check on his previous repair article below: