Leaky Capacitor Caused Onida CRT TV To Become Dead
MAKE AND MODEL: ONIDA CO21SJG350BR CRT TV
COMPLAINT REPORTED: Dead
TROUBLESHOOTING AND RECTIFICATION DONE: Opened and cleaned the set thoroughly. Discharged the anode, disconnected the yoke, CRT Earth Wire, Speakers and Degaussing Coil. Removed the CRT Board from the neck of the CRT by slightly shaking and slowly pulling it out without causing strain to the pins or neck. Some CRT PCBs, if not opened before, might be stuck with some glue to the neck. We have to carefully see and then remove. Otherwise we are likely to damage the CRT neck, especially if we use force. Cleaned the board also thoroughly and brought it to work table for visual examination. Found a lot of dry solders. ESR of caps were out of range in most. Ring testing on the SMPS transformer and FBT (LOT) was ok. Could not find any burnt fuse or other components in the SMPS primary. Disconnected the jumper wire that goes to primary of the FBT to the collector of Horizontal Output Transistor.
Then connected a 100W bulb and powered on the set. Found B+ missing. So, the SMPS was not switching on. Disconnected the power and checked for 300V DC in the tank capacitor. Did not find it. Either there is a quick discharge or the cap itself is bad. The ESR of this cap was already tested to be very poor. So removed it and was not surprised to see that it had leaked underneath though we cannot see anything from the top. So, to begin with, I replaced all the electrolytic capacitors in the power supply section including the B+ 110V line. Then applied power and found that the 110V DV was perfect and the loaded bulb lit indicating that the power supply section was ok. Then reconnected the jumper wire, and connected it to CRT, by putting back all the connectors, before which I applied drop of lubricant cleaning oil in every sockets of connectors, including the CRT Socket. Found that the raster was ok. The picture was not good enough when connected to a Video input. So, once again removed the board after discharging anode and replaced all the electrolytic capacitors on the board and did a thorough dry solder patch up from one end to the other. Cleaned the board thoroughly and allowed it to dry up before connecting it back to the CRT. When the set was powered up, it was found working very well. After allowing it to run for several hours, informed the customer to come and pick it up. Mission accomplished and satisfaction got added!
HERE ARE A FEW PICTURES:
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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https://jestineyong.com/bad-capacitors-and-eye-unit-found-in-onida-dvd-player/
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Albert van Bemmelen
August 15, 2020 at 7:13 pm
I still wonder if you are always satisfactory compensated by any customer after replacing all those bad or almost bad e-caps and the extra work you needed to carry out, including the solder patching and cleaning up task? Or maybe you now are finally sponsored by those capacitor manufacturers to make ends meet? (LOL).
Parasuraman S
August 15, 2020 at 10:56 pm
"Or maybe you now are finally sponsored by those capacitor manufacturers to make ends meet? (LOL). Ha! Ha! Ha! How I wish they do! Well, anyhow, the customers do pay me gladly for the expenses incurred, because they get a set back in almost original condition! That's the kind of feedback I have been getting! Moreover, many of us do things for our own satisfaction rather than for money!
Yogesh Panchal
August 15, 2020 at 10:31 pm
Good Job! Sir,
Parasuraman S
August 16, 2020 at 4:29 pm
Many thanks!
Henrique J. G. Ulbrich
August 16, 2020 at 3:15 am
Albert, I agree with your comments. As a matter of fact, the actual problem is the poor quality of the Chinese e-caps, that forces the technician to change them all. Pointing out that some of them, if still good now, will be bad in a few time. I have enough age to remember the tube devices I´ve maintained since my youth, and even the first transistorized radios (remember the Spika). Many of these devices, still functioning, have the original e-caps, and in good condition (without ESR problems). At that time, one saying that there is a need to change all the e-caps of a device could sound like a non-sense.
Concerning the extra work for solder patching and cleaning the device under maintenance, I understand that this is the normal behavior of a competent technician. OK, it is extra work, but necessary. A quality of a competent and honest professional.
Parasuraman S
August 16, 2020 at 4:31 pm
Many thanks for your sharing the experience, detailed observation and comments! It is very valuable!
Albert van Bemmelen
August 16, 2020 at 1:03 pm
indeed Henrique, no doubt that Parasuraman is taking the cleaning and e-cap replacing to a whole new level of professionalism! About the todays bad e-caps problem... I wonder if data exists that lists all those manufacturers on what capacitor brands to avoid if that is possible at all?
Parasuraman S
August 16, 2020 at 4:34 pm
Many thanks for your comments! The manufacturers, as I have noticed are mostly different. I feel even the design of a circuit and choice of components/ values and rating used has to be blamed for such failures! Though this is very low!
Imoudu ONWUMAH
August 17, 2020 at 1:43 am
Another wonderful repair work,counting caps changed,about 48caps,that would have taken ur time.Time taken to satisfy client,is a well spent time.To do this you must have hundreds of caps in stock.l am learning from you.Thanks
Parasuraman S
August 17, 2020 at 11:22 pm
Yes, I am always keeping sufficient stock of e.caps, ics, transistors, diodes, fixed caps, zener diodes, all resistors from 1/4 watt to 20W including fusable, fuses, pots, switches, jacks, sockets etc. As I normally work from very early in the morning, sometimes as early as 2 AM, finding the component that you want in our stock is very important! I also store transformers, coils and may other things. In fact, my service room is a mini electronic shop! (LOL)
Humberto
August 19, 2020 at 11:47 am
Wow! There are still many CRT devices working yet around the World.
Parasuraman S
August 19, 2020 at 11:40 pm
Yes, people around here still prefer to watch CRT TVs.
Imoudu Onwumah
August 20, 2020 at 2:04 am
As Humberto exclaimed,t's Wow!
Do I say sales outlets in the making.