Question about Mitsubishi WS-55807 TV
I have a WS-55807 that will not power up. When the power button is pressed I hear a click from the back of the set, the timer light comes on and 3 seconds later I hear a click from the back of the set, and the timer light goes off. I started checking power to the unit with a voltmeter. For those intersted I have attached scematics: I verified that the PCB main fuse is good and there is 120V at point PT.
From what I can tell is happening, the power button is pressed and the P-ON transistor is given a signal to conduct which causes K9A50 to close. K9A50 opens after about 3 seconds.
I am looking for other troubleshootinng steps. I have checked fuses F9A01 and F9A06, both are good. What are some other things to check for? Where does the P-ON signal come from?
In the switched supplies regulator circuitry I found fuses F9A04 and F9A05 blown (denoted by red lines thru components). I jumpered around F9A04 and F9A05 with good 5A fuses and the TV powered on. However when the set was plugged into an outlet there was a huge power draw (sparks from the outlet).
After jumpering around the blown fuses, the TV stayed powered on for about 30 sec and then powered down. I pressed the power button a few more times and the same result. The TV stayed on for only 30 sec.
I pulled the middle PCB whichs holds these circuits and I found the
D9A60 diode open and IC8C02, one of the convergence IC's fried. I don't know if these were like this before or after jumpering.
I replaced all bad components and I am back to square one. The K9A50 relay stays closed for 3 sec and the set does not power on any further.
First off you should replace both convergance IC and check the resisters coming off the output if any of the resisters are bad it will trash the ic on trying to power up.
i would also replace the caps in the DM section
Posted on Dec 19, 2007
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Posted on Jan 02, 2017
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