The Labour Pain Of Reviving A Neglected SONY Two-In-One Model CFS-KDW40S
This set was brought by a recently added regular customer with a request that it be revived, as he got interest in getting such sets lying unused in his attic revived after seeing my missions in the home during his first visit for repairing his TV.
Perhaps you can see from the second picture above that the screw holes were all blocked by mud wasps. I got a confirmation from the customer that I could force and even break the screw legs, if necessary in order to open the set for repair. In the present condition, the set was getting on, but with crackling noises and no functions worked! You can imagine how much trouble I would have taken to clean the screw holes and the screw heads.
Unfortunately four of the screws had formed rust and the screw driver had no holding slots on these. So, I resorted to breaking the joints all around the screws using a long flat tipped screwdriver, sharpened and bent for such purposes and finally opened the back cover. Following two pictures would show you the kind of dust I had to clean up:
What the second picture show are the remnants of mud, lizard egg-shells and broken plastic parts! I accepted the work only because the customer showed a lot of enthusiasm in getting it repaired and working. Otherwise, the time spent on such sets might not commensurate with the maximum charges that could be billed!
After spending almost an hour or more in cleaning, in the process of which I had to dismantle everything fit inside the cabinet, I brought the (‘viscera’ to use a hospital word! Ha! Ha!) boards to my table to deal with it individually.
I did not venture to change all electrolytic caps, as the customer was not capable of settling a large bill; because even the rough estimate that I gave before taking up the work was accepted on condition that I take the settlement in a couple of instalments! The charge within me to set right the set overcame the pull to decline, though I was going through a financially tight period! Sometimes it is like that; we cannot be rigid, though many would take advantage of such an attitude in a technician! I have warned the customer that the set might return back soon, which he accepted.
As a first step, I retouched all the points on the AC-in, DC-out board in which the transformer was fit and bypassed the selection for 110V and battery connection. The contacts within the AC in socket and voltage selector switch might have collected fungi and are generally found to be trouble makers. After ensuring that the primary power supply was intact, I checked the amplifier board. It had a lot of dry solders, which I patched up. The volume control was fit on a small PCB with inserting pins for attaching to the Amp board and I found these to be very loose. I retouched the points and made it strong enough to hold in place. All switches and controls were well lubricated and activated several times in quick succession, for self-cleaning of contacts within. I used CRC 2-26 for such purposes and also used PCB Cleaning IPA spray.
The radio board was also retouched and lubricated similarly. After completing these exercises, I assembled the PCBs together by interconnecting the pins and sockets and applied power using crocodile clipped wires. The set was working very well in Radio Mode and picked all stations in FM and AM, when an external antenna was given. Incidentally, the telescopic ROD antenna (TRA) was missing in the set. The tape mechanism was not taken up at this stage.
Caution: Following portion of this article can be grasped only by those who have exposure to tape mechanism and have hands on experience in rectifying the defects. Those who are interested still may please help yourselves by studying the tutorial in the following link: https://www.instructables.com/Intro-to-Cassette-Recorder-OperationMaintenance-a/ They have covered all mechanical moving parts and we can become familiar with it well.
After allowing the radio to work for sufficient time, I took up the mechanism and changed the two belts in it as it had become rigidly deformed. Provided another two belts that were found missing. Then lubricated the gear wheels and moving parts with silicone grease, after cleaning all the reachable parts thoroughly. I applied a 9V DC to the motor and checked the functioning of the mechanism and noticed that the take up wheels were not running on both the decks. I had to remove the covering assembly a few times already to change the belt to a suitable one. Then dismantled the mechanism again to trace the cause for malfunctioning of take up wheel. The gear wheels of both the mechanisms had cracked at the place where it fits in tightly holding the centre rod that rotates the assembly. This assembly engages when FF or REW buttons are pressed. When play is activated, there was yet another wheel on both, with rubber rings.
These wheels were also worn out. I requested for replacement wheels in two Antique Audio groups and got response from a person located very far off. I placed order paying a very high price, as there was no other go! Got the exact replacement a couple of days later, which I fixed, upon which the play mode was ok. Then I did a crude modification to hold the cracked wheels intact. Time for picture back up to enable following the narration:
The FF and REW functions worked satisfactorily after this crude patch up. Then I assembled the mechanism back and fixed it connected to the main board and played a few cassettes, after cleaning the pinch roller and head using IPA. The tape section got restored without flutter only after I played A & B sides of several cassettes one by one in both the mechanisms. You may ask why? The mechanism was left unused for a very long time. After the moving parts rubbed each other while playing, it got smooth assisted by the grease applied and any residual stubborn dirt clearing away.
Moreover, the new rubber wheel that I fixed became smooth enough by continuous running. This is called another ageing process for mechanically moving items. In this type of mechanism, the electrical energy is converted to mechanical energy and made use of for various functions. The following picture is an extract from the video that I took to share with the customer, just to show you all how I kept the tape in place for testing the mechanism:
The next step was to provide a rod antenna to the stub, in which a rusted screw was stuck. Moreover, the place where it was fit was found cracked. I removed the stub, applied CRC2-26 and waited for it to sink in. Kept the stub on a small winch and tried to remove the screw with a lot of force. It did not budge. So, filed all the four sides of the screw and made it look like a nut. Then used my small player to turn it and take it out. Then cleaned and made the fixing area even and smooth. Took a long screw with washer and fixed the antenna stub in place and inserted a new TRA and screwed it on to the stub. Unfortunately, I did not click any snaps of these which I remembered only while writing this article! I just took a screen shot from a video, which shows the new antenna fixed and I am sharing it here just for the sake of support:
The next step was to provide new screws and build up holding rings for the screw-heads. Luckily the broken piece could be fixed back in one screw slot and I had to rebuild the hold only for three legs. On combing my washer collections, I got exactly three pieces of fiber rings with small holes in the middle which were strong enough to hold the screw head. First I used a file and ground the broken legs to make the surface even and smooth. Then fixed these fiber washers on top with Superglue. Allowed it to cure and strengthened it further by inserting cut leads of components using the soldering iron. I inserted such metal wire support on three sides of each leg. Let us have a look at the pictures to understand the work better:
The next step was to measure the length which was lost in the breaking so as to fetch suitable screws that will compensate. That could be achieved only by using long screws of various lengths, putting it inside and finding out whether it was reaching the threaded hole. After a few trials by putting the back cover and removing it, I got the correct length and then fixed the back cover properly. Why did I take so much trouble? Two of the screws were serving as the hold for the speakers which had only three screws fit within and one each was from the outer cabinet.
Secondly if we do not fix the back cover tightly, there will be vibration and noise generated due to that. That is the disadvantage whenever the speakers are fit inside the main cabinet. All screws should be fit tightly. Anyhow, finally the set was fit and tested for hours together on Radio and tapes, except for high speed dubbing. The high speed dubbing causes a lot of strain on the gear wheels, and as these are all patched up to make it work, it might not stand. I made it clear to the customer too. I heaved a euphoric sigh of relief and informed the customer to come and pickup, which he did on the next day morning. Mission accomplished after a lot of strainful efforts put in, but the end result culminating in happiness, which cannot be equaled by any monetary benefits! Intense satisfaction entered into the collection bag!
This article was prepared for you by Parasuraman Subramanian from India. He is 76 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 article on Multiple Problems Solved In National Two In One Model RXF9F
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Albert van Bemmelen
January 24, 2026 at 10:29 pm
Beside your dedicated care you now also included a photo snapshot from a videoclip to this article which also adds to the methodically done work!
And the link to the instructable may be of great help to many readers too!
Parasuraman S
January 24, 2026 at 10:45 pm
Many thanks for your expert comments, dear Albert!
Mark J
January 25, 2026 at 4:09 am
Parasuraman great repair and restoration. Thank you for sharing.
Parasuraman S
January 25, 2026 at 7:54 am
Many thanks, dear Mark!
Waleed Rishmawi
January 26, 2026 at 2:51 pm
you are a pioneer in fixing old dead stuff..LOL. no capacitor replacment at this time...love your artiles. thanks for sharing...be blessed my friend.
Parasuraman S
January 26, 2026 at 8:25 pm
Many thanks for your comments, dear friend! I value it very much!
Yogesh Panchal
January 26, 2026 at 6:10 pm
Good Job! Sir
A very laborious and time consuming task, this behavior of yours acts as a powerbank for us.
Parasuraman S
January 27, 2026 at 2:56 pm
Many thanks for your encouragement, which is the fuel for my propulsion forward.