Resolved Two Issues In Grundig K-RR125 Two-In-One
This set belongs to my school classmate, who lives close by. The complaint was that it was working intermittently and sometimes only some noise came in the speaker, but it was not picking up radio. This has visited me a couple of times before, and once, after a lot of persuasion, I changed all the electrolytic capacitors in the set. The Tape section was disconnected as they no longer used it and the mechanism had irreparable wear outs. This visit of the set was after a gap of almost three years. Last repair was to replace the worn out volume control, which I had to wire it on to PCB and fix it on the outer cover.
I opened the set and subjected it to a thorough cleaning. Then dismantled the boards.
Checked the primary of the transformer and found it to be ok. When I checked the mains cord, it showed high resistance on one wire and when I shook it, it was intermittently getting open. So, replaced the mains cord. Then externally connected the boards to the power supply and switched it on. Though now, the amplifier section was working, the tuner section was not working. I cleaned and lubricated all the switches and controls. But still it did not work in any band.
So, checked the connecting wires and found these were rusted and some wires were just holding on in one strand. So, chopped off all the wires, removed the cut pieces from the Main board, scraped the wires and cleaned the strands with tweezers and re-soldered these back to the main board ensuring the order it was before. When I powered on the set again, it worked very well.
Here is the picture of the trouble-maker:
Allowed the set to work for several hours, before I called my friend to come and collect. Mission accomplished and satisfaction got added to its bag.
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:
https://jestineyong.com/smps-of-running-display-failed-due-to-defective-pwm-3842-ic/
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Lynn Blakely
October 30, 2020 at 9:45 am
Sir Parasuraman: It does give a nice feeling of satisfaction jumping into the bag. One of the best feelings a repairman like yourself can have. A good job as usual, thanks for the pictures.
Parasuraman S
October 31, 2020 at 12:29 am
Many thanks for your encouraging comments!
Albert van Bemmelen
October 30, 2020 at 2:40 pm
Lynn already said it, couldn't have said it any better!
Parasuraman S
October 31, 2020 at 12:30 am
Many thanks!
Yogesh Panchal
October 30, 2020 at 4:26 pm
Good Job!Sir
Parasuraman S
October 31, 2020 at 12:30 am
Many thanks!
Humberto
October 31, 2020 at 10:16 am
Good repair. Congratulations
Parasuraman S
October 31, 2020 at 2:17 pm
Many thanks!
Waleed Rishmawi
October 31, 2020 at 6:21 pm
very good repair job as usual. you gave a new breath to a dying device. have a blessed day my friend.
Parasuraman S
November 3, 2020 at 8:36 am
Many thanks, my dear friend! Very encouraging as usual!