Tobishi dead CRT TV repaired
Tobishi is China made CRT TV and in my country not many people own CRT TV any more. This customer insisted that I repair this one because he wanted to give it to his friend as a gift. It was a dead CRT TV.
It was a dirty one but after cleaning I was able to see what inside this TV set. The main fuse was intact and the 400 volts was reaching the main capacitor. I checked for any voltage reading on the secondary side of the power supply. All the readings were very low. It seems like we have a problem either in the primary or the secondary sections of the power supply.
After checking all the primary suspected component and found all of them are function within factory specification. I moved my search to the secondary section of the power supply and I was not shocked to see that almost all the capacitors in that section were giving me a very high ESR reading.
I am sure you can tell which one I replaced because they all look shinning and nice. To my surprise, that did not bring this CRT TV to life.
All the voltage readings at the secondary section of the power supply are back to being steady and normal. That was the result of the replacement of these bad capacitors. I was reading, 145 volts which goes directly to the horizontal output transistor. I could read the 12, 42 and 5 volts there but that did not bring this TV back to life for some reason. According to these reading, the TV should be on but it was not.
I did more checking at the fly back area but all of them checked ok. All the capacitors checked ok as well. What was causing this TV not to come on? I asked myself that question so many times. I decided to leave it for a while, take a break then come back to work on it.
I have seen this kind of problem before and I think I have solved this problem by trying to power up this TV with a remote control. I pushed the power button on the remote control and wow, the TV came on displaying a very nice picture with nice colors.
Mission accomplished.
This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment. Please give a support by clicking on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.
By the way if you have any good repair article that you want me to publish in this blog please do contact me HERE.
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ZED
September 4, 2013 at 9:37 pm
I would like to ask is the led lighting in the tv when you push the power in the remote control.because you did not mention it i am only curious and it should be the led on the tv should be on. thanks for sharing this article.
Waleed Rishmawi
September 5, 2013 at 3:39 pm
yes, the LED of the stand by light was on. and you could feel the high tension on the screen by putting your arm and the the hair on your arm get up..funny but effective.
Naseem
September 5, 2013 at 7:11 pm
Thanks for the good report!!
keep going...I would like you to write more about problems of CRT and LCD TVs as well.
Regards,
Mohammed Kasim CM
September 6, 2013 at 2:32 pm
thank you so much for the nice article. I have a TV which powers on and the main IC is not sending power on signal to +5v regulator OOBCOW. It is a panasonic 21" model. Main IC is TDA12166. No high voltage. All secondary voltages are OK. Can you help me to solve it?
Waleed Rishmawi
September 6, 2013 at 4:19 pm
what voltage reading are you getting at the secondary diodes? are you getting any voltages on the HOT (horizantal output transistor). are you getting any voltages on the ic input? if you can give me the model number of the tv, I will down load the schematic and help you better. let me know
Mohammed Kasim
September 6, 2013 at 10:54 pm
Yes Hot is geting around 140V and main IC getting 5v stby .The model number is panasonic 21FX32.. When I power on GREEn light come ON after 30 to 60 second RED light came on and the set goes to standby mode.....
Waleed Rishmawi
September 7, 2013 at 4:16 pm
is that a crt 21 inches tv set? if yes, then the 140 is too high for such a small tv set. try to adjust the B voltage in the power supply and see what happens. seems like the tv is shutting it self off due to his high voltage. in this size tv, it should be between 85-100 not more than that. i will try to get the schematic for this tv. let me know if you have an changes.
Mohammed Kasim C M
September 7, 2013 at 7:06 pm
That voltage is correct. I had checked it when it is working The error amplifier IC SE144 is connected to that B+ line........
Waleed Rishmawi
September 10, 2013 at 5:11 pm
have you checked the capacitors in the power supply primary and secondary?
PRUDENCIO G. PERITOS JR.
January 9, 2014 at 1:32 pm
i have the problem about this,,,my nieghbor told me that her tv is dead,,,and she asking me ma favor to fix her tv,,,and i decided to try,hoping that i can fix it but im not sure.
Bon
September 10, 2016 at 8:42 pm
I have a problem of a devant flat screen tv .if you switch on it appear only a blue indicator .what was the possible promblem on it pls help me sir thanks
thabani mbengo
January 17, 2017 at 9:59 pm
Hie sir l' m facing a challenge I'm repairing a Chinese model 21inch Tv power LEDs OK but no 8volts all secondary diodes OK 11volts up to transitor c2655. Not switching? Pliz help
aswin
December 16, 2017 at 1:44 am
I Have a China CRT TV ...it is in standby mode ...the problem i found is the 25v is not reaching on