Question about Emerson EWF2704 TV

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No sound No picture slight but audible buzzing in flyback. That says it all. Fuse is OK Brown on circuit board around Large heat sinked transisters. "assumption these may be regulators" Can not read part numbers. Had slight smell before it died. Suggesting overheating. No blackened components. Solder is not bright in these areas, but not exactly frosted either. This may be designed to run hot. Very near specification limits of PCB material it looks like. Died suddenly after very slight smell for a few days.

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Re: No sound No picture slight but audible buzzing in...

Some small electrolytics died. That was the problem.

Thanks for trying.=

Posted on Dec 08, 2007

Re: No sound No picture slight but audible buzzing in...

Take it apart and check the low ohm resistors around the flyback
and see if your horizonal Transistor is short,Do a diode test on the juntion of the Horiz-transistor does it read low ohms from collector to ground,with set unplug.Let us know

Posted on Dec 08, 2007

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Has sound but no picture.but if ,i should slightly adjust the screen volt on flyback transformer ,some even lines can be seen

Video processor section circuit fault. It is at the main board. Contact any service technician.

Apr 17, 2015 | Standard (CRT) Televisions


Diagnosing and repair of TV High Voltage problems.

Your TV is dead or perhaps the turn on relay clicks and immediately clicks again, followed by your standby light blinking a specific code. For each TV the code is different. To find out your code google "(your brand name) error codes". This should return the listing of codes for your unit. Check the code to see if it is the high voltage section with the problem.

The hardest working section of any TV is the high voltage section. This does not apply to flat screens and DLPs only CRT projection units and conventional direct view units. The flyback get hot and is made of many windings of very thin wire which is only shellaced to insulate it. Over time the windings coating breaks down and the windings short together. This can happen in as little as several years. Once shorted there is less resistance and the current being pushed through the flyback increases. This overloads the Horizontal Output Transistor which gets hot and fails. This in turn causes the low voltage power supply to detect the overload and not allow the unit to start up, giving you the error code blinks.

The flyback is generally near the rear of the unit and is cylindrical with large rubber wire or wires if projection coming out of it and going to a rubber cup on the CRT or CRTs. Near the flyback will be a large heat sink with a large transistor mounted to it. With the set unplugged check the HOT with a DMM on diode scale for resistance. The leads of the HOT should be marked on the circuit board (C= collector, B=base,E=emittter). If the HOT has 0 resistance between all the leads it is shorted and you need to replace both it and the flyback.

You should be able to obtain both parts at or . Unsolder both parts and remove from the board. When installing the new HOT be sure to clean off the heat sink and apply new heat sink compound available from the parts supplier. The flyback also will have two additional wires to remove and replace. One goes to the CRT board and may plug into a plastic box on the CRT jack or be soldered into the board depending on the model. This process should be self explanatory if you study it a while.

Depending on whether you have a projection TV or a Direct View TV the procedure is a little different. I will describe the procedure for a direct view TV first.

The 2nd anode lead (large red rubber wire going to the CRT) is plugged into the CRT and may have 48 kilo volts on it! Discharge the potential to the ground strap (bare wire going around the CRT) using an insulated screwdriver and a wire with gator clips on each end. If the CRT was storing power there will be a spark and loud snap when you make contact. Once discharged the tube is safe. Pull back the rubber boot and remove the wire from the hole in the tube. Install the new flyback wire. Solder the new flyback to the board reassemble everything and turn on. If you were successful the unit will start. You will need to set the focus and screen drive using the two potentiometers on the back of the flyback. Top is focus, bottom screen drive. Turn up the screen drive to get a picture. Tune to a channel with text. Turn focus to get the sharpest image. Tune to a channel which has both black and white in large amounts. Turn up screen drive until the black just begins to light up or starts looking gray then back it off slightly and you should be done with the unit. Be careful while adjusting the flyback as the set will have lethal voltages in it.

Now for the flyback on a projection TV. It will have 4 large rubber wires coming out of it. If the new one came with wires they should be removed at the HV divider block (located at the front of the set normally, just follow the wires to their end) if not they should be removed at the flyback. To remove at the flyback, which is the most common hookup, slide the rubber boot off the post and using needle nose pliers pry the cable out. It should have a bare end which connects to a clip at the bottom of the new unit. Do them one at a time to avoid getting them wrong. When done you may have to adjust the focus and screen drive but it will be on a separate box called the HV divider block usually near the front of the unit behind the grill. Same process as listed above for the direct view set. If your unit still does not run you may also have to replace the HV divider block. All safety rules apply here also.

That should conclude the repair and if successful your set will work. If the unit still does not work go to my tip on troubleshooting at which explains the basic troubleshooting method to find any problems in standard televisions.

Thanks for using FixYa.


on May 23, 2010 | Standard (CRT) Televisions

2 Answers

Won't turn on and stay on but makes a high pitched buzzing noise

I have found the horizontal output transistor (HOT) to fail and then causing the flyback transformer to fail. Both parts are under $30 total, but the danger is in replacing them. Make sure you discharge the flyback to the ground strap.

Oct 02, 2009 | RCA F36650 36" TV

2 Answers

My tv has a line threw the middle of it...the picture will come on but only if you move the tv.

Sounds like you may have a bad solder connection on the vertical ic, it is a small ic connected to a heat sink near the flyback. Usually a 5 pin ic, look on the solder side of the board for a solder connection with what looks like a ring around the pin.

Sep 02, 2009 | Sharp Standard (CRT) Televisions

1 Answer

Tv has picture but no sound !

Tihs would be do to a faulty flyback , A fly back is a circuit board that is on the back of the tube this being replaced will have much better results.

Jun 19, 2009 | RCA F27664 27" TV

1 Answer

Sound is one but very often picture goes to just a line across the screen, mid-screen

sounds like cold solder joint in the vertical circuit. May be schematic inside case, or look on main board for silkscreen labels, ones starting with V are for vertical circuit. look at solder side with magnifier and you will most likely fine one or more "cold" broken joints, especially where large wattage resistors or IC's with large heat sinks are attached to the main board. Just reheat them and flow new solder on them and send me 5 bucks (only kidding) should be a good fix.

Jun 12, 2009 | Insignia NS- 27" TV27 TV

1 Answer

TV Making a Loud Noise

this can happen with the flyback transformer's brightness which can be adjusted , also the power transformer can make humming or buzzing sounds which can't be adjusted , also this can happen with the picture tube or the CRT board failing , and sometimes chips with heat sinks or the IC's themselfs

Oct 07, 2008 | Symphonic ST420FF 20" TV

1 Answer

My Mitsubishi WS 55511 died.

If you are lucky, it's only a blown fuse. Some tv's this large have more than one fuse, so look real hard and find all fuses. If fuses are good, then about 95% of the time, when you have no picture/no sound, the problem is a bad H.O.T. This is a large transistor with three pins soldered into the main board and is very easy to find because it is connected to a metal "heat sink". Look for a large red or black wire coming from the pic tube down to the main circuit board (sometimes it's blue, but it's the only wire coming from the GLASS part of the tube to the board. This wire goes to about the largest component on the board called the "flyback transformer". It is usually black and is about 3 or 4 inches tall, 2 inches wide, and 2 inches thick. The h.o.t. will usually be located in the area of the "flyback". The h.o.t. will be screwed with one screw or clamped onto a large piece of metal (usually silver). This piece of metal is usually about 2 inces square and is about 1/8 of an inch thick and is mounted perpendicular to the main board. Imagine a slice of bread standing on one side rather than lying flat and this is what the heat sink looks like. Sometimes you will see several heat sinks with transistors screwed into them, but the one you are looking for will always be the largest transistor with three pins. Don't forget to unplug the tv before you begin and stay away from the large wire coming out of the tube going to the "flyback". Do NOT unplug this wire from the tube. It can shock you very badly EVEN WITH THE TV OFF FOR SEVERAL DAYS. Just be careful and go ahead and give this a try. You can do it, and this is probably going to fix your set. If not, then replace the flyback transformer. The H.O.T. is about $10 or $15 and the flyback can be from $30 to $80. It is possible that none of this will fix your set, but you have about a 95% chance that it will and with such a big and nice and relatively new set, I would give it a shot. Keever

Mar 03, 2008 | Mitsubishi WS-55807 TV

1 Answer

Power went out, tv won't come on

If you are lucky, it's only a blown fuse, but with a blinking light on the front, this is doubtful. I would pull the back cover anyway and check the fuse. If fuse is ok, then normally if you have no sound and no picture, you have a blown "horizontal output transistor". Look for the big wire (usually red) coming from the picture tube to the circuit board. The red wire goes to a large object on the circuit board called the "flyback" transformer". Usually very near this transformer you will find the h.o.t. (horizontal output transistor). It will normally be mounted on a silver piece of metal (a heat sink), about 2 or 3 inches square or possibly rectangular. The transistor has three pins coming out of it and is probably the largest transistor you will see that has only 3 pins. The upper portion of the transistor will be clamped (or screwed) into the metal heat sink. You have to desolder the h.o.t. and replace it with a new one. The h.o.t. usually costs only about $10.00. If the fuse and h.o.t. are good, then the "flyback" is probably bad and they run from $25 to $100. If the TV is worth only about $200, then replacing the flyback is not recommended, because there is no guarantee that this will solve the problem. Keever.

Mar 02, 2008 | Mitsubishi WS-65908 TV

3 Answers

Only see a slice of picture + bright horizontal band

you could do three of these change flyback change yoke change cap that couple the horizontal transistor.good luck

Apr 27, 2007 | Toshiba 27A33 27" TV

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