Shorted Diode and Bulged Capacitor in Philips CRT TV Repaired
This CRT TV was brought to me by my relative stating that after a lightning strike, it became dead. Expecting an almost impossible task of large damages that could have happened, I opened the set and cleaned it up and looked for any damages. Could not find any. So, discharged the anode , dismantled the PCB and brought it to my workshop table for investigation. Saw one 100uF/160V bulgy in the B+ section. On checking the secondary area, found one diode short. Replaced these along with a filter cap of the Diode. Looked for any other shorted components in the primary and secondary of SMPS and did not find any. Same was the case in the Horizontal and Vertical sections too.
Having done that disconnected the jumper that goes to the Horizontal Output Transistor through the FBT primary. Connected a 100W Bulb as a load and applied power to the SMPS through a 200W Bulb. The output showed 110V DC correctly and the Red Led was bright indicating that all was well. Having satisfied that the power supply and uController was ok, rejoined the jumper wire and loaded the PCB to the CRT Tube. Applied power and saw a normal Blue Raster.
So, gave video input and found the picture to be excellent. I allowed the set to remain on for several hours, before disconnecting and fixing the back cover. A job done so briskly that I could not believe myself! Another satisfaction ‘grain’ got added to the bag, leaving a ‘grin’ on me!
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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