Saved Yet Another Wasp Infested 2-IN-1 Of NATIONAL Make, Model RX-CW54F
This was one among the two sets brought by a new customer from a faraway distance. He wanted me to check whether it could be restored to working condition. The third picture above would show you the mud and wasp worms that fell out while cleaning the screw holes. I had to chisel out a couple of screw holds as the heads had lost the groves. I had already cautioned the customer about damages that might take place due to the wasp nesting. Cleaned the inside thoroughly using various brushes and brought the boards to the working table.
Applied PCB cleaning sprays and once again cleaned both sides of the boards until they were free of rust and dust. As the E-Caps were found corroded, replaced all of them on main board and graphic equalizer board. The PCB tracks were very thin and flimsy making removal of components difficult without damages. Then retouched every point on both the boards:
Look how shining the contact points are after the laborious and tedious retouch work! As a few of the zig zag legged ICs had collected rust in the pins, I had to use my automatic desoldering gun and pluck them out to clean. Just see the kind of rust formations between the dense pins and how it became clean after repeated rubbing with metal brush:
The headphone socket was found broken and on removing it from the board, it fell out smithereens! As a replacement socket with 7 pins were not available, I had to short the pins and provide the resistor connected outputs for HP directly, which meant that speakers would not get isolated when HP is inserted.
I fixed an HP socket on the front cabinet and wired it to the PCB to the holes you can see next to the R & L markings and I informed the customer too about this modification.
The circuit what you see above is that of RX-CW55F which I could download as the other was not available. The difference was in the timer and display circuits added to the latest version. All other circuits including the reference numbers of components were one and the same, which helped me a lot in carrying out stage by stage checking and troubleshooting. Then connected the boards to the PS and played the radio. All functions including Line In worked very well and radio stations were also picked up even without an external antenna! The output was superb and I shared the video with the customer.
Next step was to overhaul the mechanism as it had corrosion and settled dust all over and the belts were broken. The double cassette mechanism fit together to work on a single motor which also had high speed connections too (four pins instead of the usual two pins) was so complicated that I had to spend hours together in dismantling one after the other, disassembling the gear wheels, cleaning and lubricating them with silicone grease. Just have a look at the following pictures that would show you how complex and complicated this mechanism is:
I provided a socket and pin for the motor connection from the board instead of direct solder to it as removal of the mechanism for testing or adjusting would then be easier. You can see that in the first picture above, which I have marked with an arrow. I had to dismantle the capstan holder plate a few times to replace the belt of suitable size. If both the belts are not of even tension with matched hold on the motor, the running might not be soft and smooth, which might strain the motor and cause failure. The mechanism worked satisfactorily after doing the overhauling, but the motor was getting hot after a prolonged use, which I have cautioned the customer. I also told him not to use the dubbing or high speed dubbing as the mechanism had developed natural wear and tear. Anyhow, the tapes played very well after cleaning the heads and pinch rollers and I aligned them to get a peak output without any distortion or noise.
The performance was really superb. Mission accomplished with great vigor and enthusiasm that escalated the satisfaction’s eligibility to get entry 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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Albert van Bemmelen
June 13, 2026 at 2:27 pm
Your professional repairs quite often turn from complex electronic repairs frequently also into advanced mechanicle engineering. Like in this multi-issue National radio cassette recorder repair.
I think that if you also were able to print defect or missing parts with a 3D printer at home it would greatly help you to even fix the things you as supermotivated fixer otherwise now still would have to pass on.
Parasuraman S
June 13, 2026 at 3:02 pm
Many thanks for your wonderful encouraging comments, dear Albert! I value it very much! Yes, I shall try 3D printing one of these days. Thanks again!
Mark J
June 14, 2026 at 3:10 am
Another great repair and restore Parasuraman. What is your technique for dealing with stripped screws or screws with missing groves?
Philip
June 14, 2026 at 10:54 pm
In as much as I try to make my repaired board have a professional repair outlook, the thin conductive copper tracks, as if they hold a grudge against me, will always defy my average competence. A messy job is what is portrayed, successful or not successful.