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  #1  
Old 04-04-2011, 08:47 AM
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Unhappy mitsubishi tv problem.. cs-35301

hello my mitsubishi cs-35301 stoped working like normal.
there is a thin line spanning the screen horisontally when its on a working channel..

audio works fine..
i took the back off of it and looked around for the obvious.. cracked solder connections, and buldging caps..

i found a few cold solder connections or atleast they looked like them. and i reflowed them.
in the powersupply area i found 1 cap that looked as if it might of have been leaking out the top of it. so i replaced that cap.

i cant find the vertical IC on this board. i dont know what it looks like.
so i dont know what to do.. it would be a shame to toss this huge guy away. at 167lbs just getting rid of it is a challenge.

any assistance or wisdom would be a blessing.
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Old 04-04-2011, 09:13 AM
JCFitz JCFitz is offline
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The vertical ic on that should be mounted to a heatsink.It will be a flat ic with all the pins in line and a screw holding it to the heatsink and near the flyback.The no. on it would start with LA something as it was made by Sanyo.Probably 95% of 80s and 90s tvs use Sanyo made vertical ics.You probably have some bad electrolytics near the ic which caused it's demise.Also a resistor may have burned open from from the shorted ic.It will be in series with the rectifier feeding the the B+ to the vertical ic from the flyback transformer.

Those 35" Mitsubishis are great sets other than the electrolytic cap leaking problems.The crts were strong and lasted.Only seen one with a weak jug. Belonged to a retired guy and he said it was never turned off.
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Old 04-04-2011, 09:18 AM
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thank you.
i also found a big green resistor that has a very small crack running up the side of it in the main powersupply section its R9610
in the schmatic's parts list it says its a R-metal 3w 1.2 ohm-J

so i should probably replace that resistor also..
does it matter that the resistor is R-metal (whatever that means) or can i just slap any 3+w 1.2ohm in its place?
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Old 04-04-2011, 09:49 AM
JCFitz JCFitz is offline
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It is probably metal film. You could get away with carbon film for this but I personally would buy another metal film resistor. I've seen those carbon films burst into flames when they were overloaded.

The metal film ones usually say flameproof on the package.
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Old 04-04-2011, 09:56 AM
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thanks. guess this project will have to wait on hold for a week or so while i get the parts. meanwhile i will start checking and replacing caps on the main board.. is it possible that this one resistor is the main issue and the Vertical Ic is still ok or does it sound more likley that it was a chain reaction.. and one thing after another went wrong?
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Old 04-04-2011, 10:08 AM
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the resistor is reading open.

is it safe for me to "try" a 1.2ohm 3+w resistor for a moment to see if it is the issue?
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Old 04-04-2011, 11:15 AM
JCFitz JCFitz is offline
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You probably had a capacitor that developed high esr( usually the pump up cap. It's in series between a diode and 2 pins of the ic)which caused the ic to fail and short and took out a resistor.Usually the ic is shorted and will take out a resistor in short order.The capacitor needs to be replaced(probably a 100uf or 220uf) before replacing the ic or it will fail quickly.
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Old 04-04-2011, 12:08 PM
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thank you very much. i guess i will lable all the wires and take note of where they go, then take the boards out being sure to discharge everything..

im willing to recap the entire television.. but if i was to do that, would the tv need some kind of adjusting or calabration? because i dont have anything other than a nice multimeter and a soldering station.

one other thing i am noticing.. the huge red wire that runs from the screen to the board doesent seem to be discharging.. i touch it to the exposed metal wire that runs across and around the back of the television and dont get any spark or sound.. even after it was just turned off.. does that mean something else is wrong too?

if its safe for me to replace the caps i will go ahead and order them.
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Old 04-04-2011, 12:55 PM
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ok im having a hard time finding the parts that you mentioned, the resistor and cap. can you please point out which lead or part i should check out in this image?

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Old 04-04-2011, 08:07 PM
JCFitz JCFitz is offline
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Can't quite make out the designation but looks like C458. The 100ufconnected between pins 9 and 13 is the usual culprit that causes vertical
output ics to fail.The resistor that would have opened if ic401 shorted is not in the picture.
If you trace back from the anode of d401 and positive side of c460 you should find another diode. between the anode of that diode and the flyback transformer in the circuit will be a low ohm value resistor. Check and see if it's open.Most sets run the vertical ic off the flyback. There was 1 Mitsubishi projection that ran it off the power supply but I don't recall a direct view Mitsubishi doing that.

You don't need to recap the set.I would check for signs of others leaking and replace the leakers as a preventative measure. you might have to take the power supply caps out to see if they are leaking to catch hidden leakers. Most of the smaller electrolytics are spaced enough off the board you can see underneath them. If you see a blackish wet looking corrosion on the lead it's a leaker and will cause future troubles.If it's clean the cap is probably good . Mitsubishi was known for this cap leakage problem in the late 80s-mid 90s sets.I've found as many as 80 in 1 set but electrolytics are pretty cheap.Won't affect alignment.
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Old 04-04-2011, 08:21 PM
JCFitz JCFitz is offline
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Quote:
Originally Posted by aidynphoenix View Post
thank you very much. i guess i will lable all the wires and take note of where they go, then take the boards out being sure to discharge everything..

im willing to recap the entire television.. but if i was to do that, would the tv need some kind of adjusting or calabration? because i dont have anything other than a nice multimeter and a soldering station.

one other thing i am noticing.. the huge red wire that runs from the screen to the board doesent seem to be discharging.. i touch it to the exposed metal wire that runs across and around the back of the television and dont get any spark or sound.. even after it was just turned off.. does that mean something else is wrong too?

if its safe for me to replace the caps i will go ahead and order them.
To discharge the hv you need to get a screwdriver or something under the anode cap connected to that wire and ground it to the dag of the tube. There is usually a braided wire running across the back of the tube hugging the dag of the tube to connect a clip lead to and the other end to the screwdriver. If it doesn't spark it doesn't mean anything. It probably has a built in bleeder or discharged when you turned the set off. The fact that you had a line means the hv was working normally.Otherwise nothing would have been on the screen.
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Old 04-04-2011, 09:51 PM
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wow manny thanks!! you really know your stuff! il follow the traces from the ic to find a blown resistor. im hoping that the blown metal film resistor 1.2ohm that i found in the powersupply is the one. but il look untill i find it...
did i mention thanks?
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  #13  
Old 04-11-2011, 02:12 PM
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Quote:
Originally Posted by JCFitz View Post
It is probably metal film. You could get away with carbon film for this but I personally would buy another metal film resistor. I've seen those carbon films burst into flames when they were overloaded.

The metal film ones usually say flameproof on the package.
looks like i can get a wirewound resistor 1.2ohm 3w for a fraction of the price of the metal ones.. would a wirewound resistor work in its place?

EDIT: oh never mind i found a metal film one for cheap..

Last edited by aidynphoenix; 04-11-2011 at 02:19 PM.
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Old 05-02-2011, 12:33 AM
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i got all the parts.. it took me awhile.. the ic was out of stock for a few weeks..

i think i will have some playtime tomorrow.
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  #15  
Old 05-16-2011, 04:48 PM
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ok so i put in the new vertical ic. replaced the 1.2ohm metal film resistor and the blown capaciator. (atleast i think i found the right cap) it was buldged and leaking stuff. the cap and resistor that i replaced were both in the psu section.

i put it all back together and hit the power button. the middle area of the screen lit up a purpleish green flash for a moment. and i heard a noise.. not quite a pop, could of been a loud relay or something. then nothing on the screen... now when i turn it on a hear a high pitched squeel, then there is a purple bar across the screen instead of two green bars.. i quickly turned it back off.

i guess i missed the bad components stil.. looks like might need to order another ic if i destroyed this one.. on the original i found a hole in the ic.. so it was easy to tell that it was blown. im going to try again.
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