Sabotage Done By A Jealous Technician Solved In CRT TV
Model and make: Panasonic CRT Colour TV, TC-21FJ20C
Problem reported: Dead. Futile attempts made by another technician. (Tampered set)
History of complaint: Set was going off by its own while working, but came on after hammering on the cabinet. Became dead subsequently. As on-site troubleshooting done by a technician could not solve, he removed the board and took it home. This customer first brought the TV to my home, but found gates locked, as I was out of station. That’s when a technician who happened to be around the auto stand, offered to look into it. But he was not able to resolve the complaint even after a few days. By the time, when the customer came to know that I was back, he asked the technician to return the board, but made a mistake of informing him that it was being taken to me for resolving! (You will come to know what it cost the customer, later in the article!)
Preliminary Action done: Looked for any bulgy capacitors, strained or burnt components. Could not find any.
Trouble shooting done: Found B+ missing. SMPS transformer was checked with Ring Tester, which showed short either on primary or secondary. Checked for any shorts or change of value in active and passive components. Found resistor open, opto-coupler short and value of a few resistors changed. Replaced all these including a couple of diodes. Replacedalso the filter capacitors including the fixed filter capacitors across the diodes. Opto-coupler failed on switch on test. Traced leaky capacitors and diode in feedback circuit. Replaced these along with opto-coupler. B+ was found ok on switch on. Replaced all other electrolytic capacitors on the board as a preventive maintenance including the fixed capacitors in the horizontal section, as the values were found to be out of range.
Tampering and sabotage noticed on the board, most presumably done by the previous technician due to jealousy. It is unfortunate that some technicians resort to this very cheap and mean attitude, when they fail and are forced to pass on the case to another! Got the circuit diagram of the TV from my techie friends and replaced the missing capacitor and resistor and removed the purposeful short done in another place.
After having done thorough dry solder patch-up and inspection of the board, I tested it on a spare CRT Tube that I keep for testing boards. Found it to be ok. So asked the customer to bring the TV to my home. Fit the board in the TV and ran it for hours together to ensure proper working. Provided a new Remote, as the customer had lost it.
Conclusion: Satisfaction ‘leaped’ into the Bag!
This article was prepared for you by Parasuraman Subramanian from India. He is 69 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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