Hi guys, Need help to repair Mitsubishi console TV model CK35304. (36-inch, manuf. date 1994).
Approx a month ago, when you would turn on the TV each day for the first time, the top of the screen would be shrunk down a few inches. As TV warmed up, the screen would return to normal. Color and clarity of picture has been excellent throughout.
The other day, turned it on, just get a line thru the middle of the tube. So, whatever was going bad, has definitely gone bad. I do not have TV repair experience, but I have experience repairing other high-voltage items, such as many Tube Guitar Amps, antique radios, PC's, and even rebuilt a Video Game monitor once (installed a capacitor kit). So I am familiar with the voltages involved.
I talked with a friend of mine who repairs TV (lives several hours away from me...), and while he is hesitate to tell me a lot (he never tells the secrets of the trade, so to speak...), he said that this a typical problem with Mitsubishi TVs, and that the problem is probably in the Vertical output circuit, then said 'maybe 5 capacitors, probably a chip, and maybe a fuse'.
Here are some photos of the boards inside the set:
(mainboard)
(closeup of area that may be the problem...)
(power supply board)
You guys can tell me whether my friends general advice is accurate or not. For starters, I have proceeded assuming his advice was good, and did some searches to try to narrow down what I am looking for.
Doing some Google searches based upon part numbers on the transistors that I see on the mainboard (picture "tv2.jpg" above) , I found that TA8427K is apparently my Vertical Deflector chip, that C2073 is apparently my Vertical Output chip. In this circuit, I see the following components (and checked them in-circuit, where noted:
- fuse (checks good)
- 15K ohm 3 watt resis. - checks good, approx 14K ohms in circuit
- 4700uF at 10V cap - did not test
- 2.7 ohm resistor - good
- 2700 ohm resis - good
- red capacitor approx 1 inch size with numbers (2A : 335K S) - value unknown, not tested
- resistor with bands of "yellow - purple - gold - gold" - tests approx
4 ohms.My photo tv1.jpg above highlights this area of the board. I do not see any visibly burned components or exploded/leaking caps.
Assistance is MUCH appreciated. I really need to fix this myself, as cash is very tight. I do not mind installing a few "extra" parts, shotgun approach is fine. Also, advice as to where is best to buy the parts (the IC's, as I probably have the caps & resistors) will be appreciated. THANKS. BJ