Burst Capacitor And Cracked Dry Solder Found In Philips CRT TV
This CRT TV belongs to my classmate, who stays nearby my house. When he called me up and told that his TV was dead, I visited his house and checked. Removed the cover and found that the Fuse was blown and there was a bulgy capacitor.
I removed the PCB after observing precautions by discharging the anode to ground. Did a general cleaning and brought the board home for further check up.
Found many of the capacitors had overshot ESR range and become quite old. Looks like this TV belongs to the fag end of 1990s! There were a lot of dry solders and cracked connections.
Got myself involved my extremely enjoying work of replacing all the electrolytic capacitors on this TV and retouching the board from one end to the other. It took several hours of sitting, with healthy breaks not to break my back! Look at the condition of one capacitor and the value of another, which I matched by connecting two capacitors. Since these were in the horizontal section, I did not want to put a 10uF in its place.
Cleaned the board thoroughly and rechecked for any man made mistakes of overlapping solder, causing shorts. Found three of them on minute examination of the PCB under a lens. Rectified these and looked for the jumper wire that goes to the primary of the FBT. The design of this TV was in such a way that when we remove the Horizontal coil connector, it also disconnects the supply to the primary section of the FBT. The Vertical coil connector was separate and that goes to a different socket on the board near the Vertical IC. Just see the pictures below, along with the pictures of the boards after cleaning. This is a very thoughtful and useful design, for making servicing easy. I remembered that in the earlier times, manufacturers provided facilities for board level servicing, but now-a-days, the board replacement servicing methods are employed, increasing the e-waste!
By the way, this TV was having separate modules for SMPS switching and Audio. Just have a look:
The TV was using a very old uController :
Connected a 100W Bulb at the output of B+, which was 95V in this TV and switched on and found the PS working fine.
I had removed and cleaned the voltage adjusting pot from the SMPS switching module. Adjusted it to make it exact 95V.
As the TV was not having a Remote Control, bought a new one from the market and tested. It was not working, though the RC was checked to be working. Checked the IR and found it to be defective and replaced it.
Brought the TV to my home and connected the Board and checked and found it to be working fine!
Here are the parts replaced in this CTV:
Thus added this too to my satisfaction list, with an additional boost when we do something to our own classmate!
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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