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My TV died

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Roff

Well-Known Member
My wife just called and told me that when she turned on our 15 year old 31 inch Mitsubishi TV, it made a loud pop, flatlined (no vertical deflection), and started stinking. Where should I start looking if I decide to try to fix it?
 

Papabravo

Well-Known Member
High voltage power supply. It generates the voltage applied to the vertical deflection plates. Good luck finding the components to substitute.
 

audioguru

Well-Known Member
Most Helpful Member
Papabravo said:
High voltage power supply. It generates the voltage applied to the vertical deflection plates.
No way, man.
The high voltage power supply in a CRT TV is made by the horizontal deflection driver.
The vertical deflection driver stopped but the screen was still lighted so the high voltage supply and the horizontal deflection must still work.

No way, man.
A CRT TV doesn't have deflection plates. It has deflection coils around the neck of the tube.

Hi Ron,
My 8 years old 32" Sony TV suddenly stopped. I keyed its part number into Google and got its schematics for free and many people talking about the same problem. Some said to change many capacitors, some said to re-solder many joints.
I spotted two black rubber wedgies that fell from the deflection coils and thought that maybe they shorted something so I replaced three transistors and a fuse-resistor (Sony parts from Sony) and the TV worked perfectly for a week.
Then the same parts failed again.

I bought a new TV for 1/4 the cost of my old one. They are disposable.
 

Papabravo

Well-Known Member
OK - so maybe I was thinking of scopes and yes, I understand that the horizontal sweep is used to generate the high voltage because it is a higher frequency, but you're not suggesting that a low voltage is used for vertical deflection - are you? Maybe you are -- would 60V be a practical value for the vertical deflection Vs? It is typical of a vertical deflection IC from ST Microelectronics.

I definitely agree that repairing a TV is not worth the effort, especially since the LCD flatscreen and plasma prices are coming down.
 
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audioguru

Well-Known Member
Most Helpful Member
The vertical deflection IC in my Sony 32" TV is powered by +12V and -15V. It has a voltage-boosting diode and capacitor connected to it. Its output to the vertical deflection coil is 57V p-p.
 

Optikon

New Member
Ron H said:
My wife just called and told me that when she turned on our 15 year old 31 inch Mitsubishi TV, it made a loud pop, flatlined (no vertical deflection), and started stinking. Where should I start looking if I decide to try to fix it?
I suppose its worth a try to fix for a spare. But if it were me, I'd look at this as an opportunity to upgrade my set. Especially now with the HDTV craze going on. If you replace something obviously broken and it keeps having trouble, will it be worth your time to chase the issues down?
 

Papabravo

Well-Known Member
audioguru said:
The vertical deflection IC in my Sony 32" TV is powered by +12V and -15V. It has a voltage-boosting diode and capacitor connected to it. Its output to the vertical deflection coil is 57V p-p.
That works for me. So I would guess you could start there and work backwards.
 

Roff

Well-Known Member
Optikon said:
I suppose its worth a try to fix for a spare. But if it were me, I'd look at this as an opportunity to upgrade my set. Especially now with the HDTV craze going on. If you replace something obviously broken and it keeps having trouble, will it be worth your time to chase the issues down?
My understanding HDTV screens can display 4:3 NTSC video, but the sides will be gray, or the picture will be stretched horizontally. I'm not sure I want to deal with that, but on the other hand, I guess a new NTSC TV will be obsolete in a couple of years.
 

Roff

Well-Known Member
audioguru said:
They said that years ago. It didn't happen.
In the US, analog TV will be switched off by Feb. 17, 2009. All broadcast TV after that date will be HDTV with a 16:9 aspect ratio, which will have to be stretched or letterboxed when displayed on a 4:3 screen. That's what I mean by obsolete.
 

Papabravo

Well-Known Member
Ron H said:
In the US, analog TV will be switched off by Feb. 17, 2009. All broadcast TV after that date will be HDTV with a 16:9 aspect ratio, which will have to be stretched or letterboxed when displayed on a 4:3 screen. That's what I mean by obsolete.
Since they're going to auction the spectrum for billions and billions, maybe enough to make a dent in the war debt, the winners will be understandably cross if the government renegs.

My Sony has 5 display modes for different aspect ratios as the nature of the signal changes. I like NTSC broadcasts in "Wide Zoom". Go down to a "wall 'o screens" store and ask the clerk for a remote and tell him to leave you alone for a while so you can futz with it.
 
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Roff

Well-Known Member
Papabravo said:
Since they're going to auction the spectrum for billions and billions, maybe enough to make a dent in the war debt, the winners will be understandably cross if the government renegs.

My Sony has 5 display modes for different aspect ratios as the nature of the signal changes. I like NTSC broadcasts in "Wide Zoom". Go down to a "wall 'o screens" store and ask the clerk for a remote and tell him to leave you alone for a while so you can futz with it.
:D Good idea! :D

And then check out Costco before I buy anything.
 

zevon8

New Member
OT, but I keep meaning to mention... RonH love the Tek 454 "wizard", good one. My favorite was the "pin-up girl" drawn in the pulse amplifier sections.

Back on topic, I seem to remember that TV eating OSD chips, as well as eating many 1uF and 10uF filter caps, bringing early demise to many IC's
 

RODALCO

Well-Known Member
If it is not the HT supply, start replacing electrolytic capacitors. Especially the mains voltage ones near the power supply.

Sometimes a bulge may be visible at the side of the can, or gunge oozing out.
Ensure that the replacements are 105°C rated. ( a bit dearer but better quality then 85°C caps ).

Check for dry joints and obvious discolouration in components which may have been heat stressed.

Good luck ! I still have an old Philips 26" which is from 1982 ( 25 y.o. ) It is under repair at the moment, code E 3 appeared, late last year, haven't had enough time to fix all problem parts.
 

mvs sarma

Well-Known Member
Generally the vertical output is fed to the v def coils thro' an electrolytic. some times this cap (10uF approx)gives way due to aging. try replace it. mean time try checke if any power transistors are there in the Vertical output stage-judt before the cap under concern.

the damaged cap can be identified easily.
 

HiTech

Well-Known Member
RonH
If you have a white horizontal line on the CRT, then you still have high voltage circuitry operating properly and it's the vertical deflection chip that's likely the culprit. I have serviced many a vertical collapsed Mitsubishi big CRT set. Easy to locate chip, often attached to a heat sink and they are pretty good that outling the vertical section on the pcb with a label. It's typically an LA3xxx or similar chip that sells for just a few dollars. You may ned to get into the service menu after its replacement to adjust vertical linearity/size. Some of those vertical chips actually blow a hole in them and emit a slight burn odor.

ps: discharge that anode connection to ground on the crt before you go probing around in the chassis!
 

Roff

Well-Known Member
HiTech said:
RonH
If you have a white horizontal line on the CRT, then you still have high voltage circuitry operating properly and it's the vertical deflection chip that's likely the culprit. I have serviced many a vertical collapsed Mitsubishi big CRT set. Easy to locate chip, often attached to a heat sink and they are pretty good that outling the vertical section on the pcb with a label. It's typically an LA3xxx or similar chip that sells for just a few dollars. You may ned to get into the service menu after its replacement to adjust vertical linearity/size. Some of those vertical chips actually blow a hole in them and emit a slight burn odor.

ps: discharge that anode connection to ground on the crt before you go probing around in the chassis!
Good stuff, HiTech. If the vertical deflection chip failed,I'm worried about what caused it. What else should I be looking for?
And how do I move the damned TV? It must weigh a hundred pounds. I know two men (I'm old and feeble), but I'm not sure where I'm going to get the small boy. :D
I'm thinking of just setting fire to the house. ;)
 

mvs sarma

Well-Known Member
Hi RonH,
i am sure you are psycologically VERY STRONG- as we see you practicing electronics and participating in a forum while declaring yourself as old and feeble. pehaps an advance reminder of what we could be-- as age advances.

i am sure that weight has nothing to do and you can still be able to procure and replace a chip, and asssume that no ther chip might have gone faulty. awaiting a positive post soon that you succeeded in restoring the TV--ofcourse unlessyou feel that there is overall deterioration due to aging of the TV picture tube??? i don't expect any other failures!!
 

ljcox

Well-Known Member
Ron,
I've fixed a few TVs in my time.

The first step is to find a circuit, someone said to use Google.

Then open it up, discharge the tube as someone said above and look for any obvious problems such as burnt resistors, dry joints, etc. You said it "started stinking" so there should be something obviously burnt that will give you a starting point.

Electroyltic caps are often the problem.

Also check the Vert output transistor with a multimeter.

You could also measure the resistance of the vertical deflection coils.

If you can't find anything by the above, then you will have to turn it on and measure the voltage rails, often you will find one low or zero.

If you have a scope look at the output from the vert oscillator.

It may be advisable to wear eye protection if it is an old set as the older electros did not have the explosion protection of the newer ones.

It is often not difficult to find faults. If you have a problem, post the circuit so we can help.
 
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Roff

Well-Known Member
I have apparently painted a picture of myself as an inept, doddering old fool.
I have a tendency to exaggerate sometimes, hoping to inject a little humor.:rolleyes: Usually I fail miserably.
I'm actually not exactly feeble (except maybe feeble-minded), but I am 66, and I have lost probably half the strength I had 20 years ago. I also have had back surgery, whilch turned out very well, but I plan to keep it that way, so I don't attempt to lift 100 lb TVs.
OK, on to the technical part. I have repaired one or two TVs in my lifetime, I know a lot about video, (I'm an old video circuit design engineer) and I'm really good at troubleshooting. I just don't like working on TVs.
I'll let you guys know what I find if and when I open it up.
Oh yeah - thanks for all the advice, guys. I mean this sincerely . I'm not exaggerating.:)
 
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