Question about Emerson EWF2704 TV

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No hi voltage

One open diode fuse not shure how to test horizonal output tranister tks

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Re: no hi voltage

Using an ohmmeter' the B to C junction will test as a diode, but E to B junction will show low resistance, approximately 50 ohms in both directions. now, E to C ohmmeter test will test as a diode. the foregoing results indicate a good transistor. reading other than this indicate a bad H-output transistor. good luck!

Posted on Mar 01, 2007

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110 voltage is missing

Check and replace damaged component/s at its horizontal scan output section circuit. Check the LOT (Line Output Transformer) too for damage. Replace the horizontal scan output transistor. Check the input voltage to LOT. If the voltage is absent check the feeder resistor; if any. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
Type in this key phrase " my service table today " in the search box at the top right of the display window of the home page, to get gathered some pages which has the details of practical experiences to the author of that site.

Dec 04, 2015 | Standard (CRT) Televisions

1 Answer

No power fuse is not blown

Check and replace damaged component/s at its horizontal scan output section circuit. Check the LOT (Line Output Transformer) too for damage. Replace the horizontal scan output transistor. Check the input voltage to LOT. If the voltage is absent check the feeder resistor; if any. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
Type in the brand name of your device, in the search box [at the top right] of the display window and the Search will start at once as you type in, and will show you all the related posts. It will make surf easy.

Apr 24, 2015 | Standard (CRT) Televisions

1 Answer

Fault finding

If your tv does not turn on at all Look for the voltage rectifier, voltage regulator. Diodes and resisters in the power circuit. Burnt solder traces, the flyback transformer, the horizontal and vertical output transistors. and especially bulging or dry electrolytic capacitors (which is what caused all of the others to fail) The symptoms that the electrolytic capacitors need replacing are lines on the screen, and later black bars on the top and bottom of the screen. To test any semiconductor use a solder ****** and a solder gun to remove the solder gently until you can remove each part test using a multimeter on diode setting. test the legs in any order for open circuit or short circuit if you have a high reading one way and a small reading the other way then the component is good. Any component that gets hot enough to need an aluminum heat-sink is suspect.

Oct 20, 2013 | Panasonic Standard (CRT) Televisions

1 Answer

Tv model #46h84 wont turn on no picture or sound

Assuming thar you can open the tv case and deal with electronic parts, you should first check the main fuse. If it is OK, check the anti-surge resistor (generally 3,3 Ohms/5W). One of these components may be bad. Before replacing the bad one, check for short in MOSFET power switching transistor, fast output rectifier diode (+ or - 90V line voltage). After findind out the culprit replace the bad components a afterwards plug in the tv and test.

Good luck. I hope this will help you.


Sep 25, 2013 | JVC AV-A21M3U 21" TV

1 Answer

My sony 21 kv21da55 is not working it is totally dead i pulled out the system ic how was that?

Please do not dessolder anything before a thorough test. You should first check the main fuse. If it is blackened the MOSFET switchinhg transistor is probably bad and need to be replaced. The test should then go on thorugh the output line voltage in search of shorted components.
Only when the fuse is clean but open (interrupted) you can replace it and plug in the tv set and test.
Be careful and follow safety instructions on dealing with high voltage section of tv set. High voltage is letal.

I hope this will help you,


Sep 22, 2013 | Sony FD Trinitron WEGA KV-21CL10 21" TV

1 Answer

The picture wont come on, power is on but screen is black

this a lack of RASTER, TEST AND measure a) , fuse, c. breaker, transformer, filter, diode, rectifier, IC voltage regulator +horizonta output transistor, HV rectifier, and Flyback HV.
God bless you

Oct 11, 2012 | Mitsubishi WS-73907 TV

1 Answer



I'm assuming that your outlet is live, your problem has some diy steps as follows :

1. Check the power cord for internal open, this is due to frequent bending and pulling. Wiggle the plug while the tv is power on.

2. Check the power switch for dry joints, open contact.

3. Check the internal fuse, it might be open due to voltage surge. Replaced with same ratings.

4. If the new fuse blew again, this is an indication of short in the power supply, most common caused is the rectifier diode, main filter capacitor, voltage regulator.

Some steps above need a tools and test instrument. If that is not available you may look to qualified technician to isolate the problem.

Hope it may help you.

Have a nice day!

Feb 08, 2011 | Sansui DTV1300 TV

1 Answer

While testing vdc at the base board for the cathode wires found that the red and blue were at 4 VDC and green was at 8. Picture has mainly blue and green tints.No loose soldier joints found.

Have you measured the voltages at the collectors of the three video output transistors?. There must be a voltage over 124 to140VDC at least. All voltages at the base of that transistors should be between 2.5 to 3.75VDC according to the level of chroma signal from the chroma Ic.
You must check these voltages with a good quality digital or analogue multimeters, otherwise you will get only false values instead of the real. You just check the main voltage that goes to the video output stage, that is the high voltage comes to the crt base, from the main board. It should be more than 260VDC. Normally in all tvs this voltage is derived from the LOT. After rectifying it and filtered with a 10Mfd 350V capacitor, and given to the baseboard as the main supply to video output stage. If the smoothing capacitor [10Mfd] gets value changed, that is if it gets a low value due to age, otherwise whether it has an internal short, you won't get the above said 260VDC at the CRT base boad. At first locate this capacitor and replace it with a new one with same capacity and voltage ratings. and check all video output [ 3 of them] transitors too. Check the transistors for collector to emitter leak, not on circuit, but after take it out desoldered. Then only you will get the proper measurement of leak. Set the multimeter in MegOhms rage, and don't held the transistor by hand too. If you do so you will see some deflection in the meter due to your body resistance.
Check the capacitor first. Replace it. It is best. Check the rectifying diode that rectifies this voltage from the LOT winding. If it has a leak, you will get a low voltage at this rail.
Remember, LOT works at high frequecy. So the diode used there as retifier is a special type, fast recovery diode, and should be repaced with the same number. Never use ordinary diodes that we uses for line rectification purpose.
Remember, colector voltages at the video output transistors must be above 140VDC. Again recomends to use a good quality multimeter, as cheaper one cannot measure this voltage accurately.
Ok. Wish you all sucess.

Oct 23, 2010 | Proscan PS36125 36" TV

1 Answer

Se calienta demasiado y no se si sea el flyback

Change the Hi Voltage Output and the Fuse make shure it the same fuse ....

Sep 21, 2010 | RCA F31672ET TV

5 Answers

Tv does not power up

I have seen the schematic, d982 is a 13v 1/2w zener

Jun 28, 2006 | Mitsubishi CS-35503 TV

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