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Degausser Jerry, do you have a circuit diagram showingthe degausser on a Sony KV27S42??

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  • BrianMcL Jul 06, 2008

    Thanks for that. I took the THP601 right off the board and re-installed it. It has 2 pins. Didn't solve the problem though. Still got the weird colors on the sides of the screen. Strangely, there are small area right up against the outside ofthe screen that seem to be unaffected. Very thin area of normal color. Centre of the screen is fine...normal. May not be a degaussing issue. Took the THP601 appart and it is pretty simple...just a PTC with contacts....nothing to break. Does the PTC loose is resistance? Just a ceramic disc.

  • BrianMcL Jul 06, 2008

    Thanks again Jerry. The degausser does seem to come on and "try" to eliminate the color distortion. Starts to wave in and out.....but it stays, partially.

    Oh well, thanks for the very excellent help.

    Looks like a LCD is in my future.

  • BrianMcL Jul 06, 2008

    one other quick note.......if I move a magnet near the sides the picture returns to normal. So I will order the THP601 and possibly the relay as well......worth a shot. Everybody talks aboutthe THP being 3 legged...as I said mine is 2 legged. Will the supplier know the correct one for the model. There is no part number on it.

  • BrianMcL Jul 07, 2008

    Thanks again Jerry. I have tried to order the part THP601 from a couple of supply jouses and they both said it is no longer available. BooHoo..... : (

  • BrianMcL Jul 07, 2008

    Do you know how I can get the correct Sony part number for this posistor for the KV27S42. I want to be sure to get the 2 leg one not the 3 leg one which is much more common.

  • BrianMcL Jul 07, 2008

    I got the correct number...it has changed a couple of times. I'll let you know if that was the problem. Here's hop'n....Thanks for ALL the help.

  • BrianMcL Aug 01, 2008

    Jerry...do you know what the resistance should be on that thermistor...THP601 ( original part # 180358611 changed upto 180354111) on the KV-27S42. I did order the part but they send me a 3 legged part, original was 2 legged. They said this was the replacement. It has 2 pieces of ceramic disc inside with a resistance on each of 9 ohms....total if I just connect the two pins of 18 ohms. Does that sound like the correct value? The old one was tested at less than 1 ohm....but it could be bad. Need to get a schematic to see what the value should be. Any idea where I can get that info? Thanks

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  • Master
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I don't have the service manual copy. I was servicing these sets more than 6 years ago when I was working with a service contractor for warranty repairs.

The degausser is very simple. The AC is switched on with the relay. The relay feeds the degausser in series with the thermisistor. There is not very much involved to trace this out by following the traces on the circuit board.

The common fault is that the thermistor goes bad. You can order this part from any of the parts distributors for Sony parts. I cannot remember the cost of the thermosistor, but I think that from Sony it was in the area of about ten dollars at the time.

It is very rare that the coil or the relay goes bad. On some rare occasions I have seen cold solder connections cause the degausser to not function.

Your set will work with no degausser working. You can order from any place that sells parts for TV service, a manual degaussing coil that plugs in to the AC. You can manualy degausse the CRT face several times per week. This should work out well.

Manual CRT degausser coil:
http://www.datadev.com/degausser-small-office-monitor-tv-television-dc13.html


My preference is original parts. But, if you want to chance an after market part check the link below.

Donberg Electronics sells some types of thermistors:
http://www.donberg.ie/warehs/grouptp.htm



In the service shop we used a manual degausser when were changing picture tubes. We needed to have the screen degaused very fast so that we can do the purity and convergence set-up.


Jerry G.



Posted on Jul 06, 2008

  • 2 more comments 
  • Jerry Greenberg
    Jerry Greenberg Jul 06, 2008

    These parts can fail. Very often the failure is not visual. This type of part is not able to be simply tested with an ohm meter. It is very current and voltage dependent to operate.



    When you turn on the set, you should hear the degausser work. It makes a thud type of sound coming from around the metal shielding that is housing the CRT. If you look carefuly you can see the degausser coil sitting sort of below it. This coil is wrapped in high temperature type plastic tape. It should be connected through a pair of black and white wires to the power supply area where the thermosistor is located.



    The replacement part is not difficult to order from any place that sells Sony service parts. As I said, it is not expensive.



    If the degausser is working and there is discoloration in the picture, providing that the yoke and purity set-up was never disturbed, the mask inside of the tube, properly called an "apature grill" for the Trinitron tube may be warped or not sitting properly. In the regular CRT, this part is called the "shadow mask". This defect can happen if the set has been dropped or hit sort of hard. This part can easily be damaged. I have seen the apature grill be damaged while the set was being moved by movers, or simply moving it between rooms. It does not take much.



    Also, if someone goes near the face of the CRT with a very strong magnet, they can pull it hard enough to do some damage.



    Damage to the grill is not able to be repaired. This means a new CRT. Considering CRT's these days, new or rebuilt ones are very scarce to find. Their cost is also not worth it anyways.





    Jerry G.





  • Jerry Greenberg
    Jerry Greenberg Jul 07, 2008

    If you call an authorized Sony parts dealer, they can find out the correct part number from the model and serial number of the set. If you buy a 2 leg type and specify it for the Sony, I believe that all the Sony ones are very much the same, especialy in the same size range of set. Your set was a very common size.



    As for putting a magnet near to the edge of the screen and making the fault look less, this tells me that the screen may be badly magetized and you are introducing a nutralizing effect. If you can have a gratting pattern to check the convergence, you may find that when you make the problem go away with the magnet, the convergence is getting offset.



    What would be nice is if you can get your hands on a manual TV CRT degausser and see what happens. Maybe there is a local TV shop near to you where you can leave a deposit on one, and sort of make the man a rental deal, or simply pay him a service call to look at the set for you and degausse it while he is there. He may also be able to order the part for you and change it right in house. If he has a lot of experience he should be able to recognize if the mask in the CRT is bad, or it is simply a magnetism problem.



    If the set was good before, then I would not say that it is a purity adjustment problem. It is either a magentism problem, or the mask is damaged.



    Jerry G.







  • Jerry Greenberg
    Jerry Greenberg Jul 07, 2008

    I have a supplier called Global Electronics Supplies. They are one of the biggest for TV service parts.



    http://www.globalsemi.com/aboutus.aspx



    Tel: 1-800-668-8776



    If they cannot have the part, order yourself a hand held TV degaussing coil. You can manualy degausse the CRT a few times per week.



    The other solution is to find a scrapper TV set with a good part in it. Most of these thermosistors are very much the same. If you took one from another manufacture in the 25 to 32 inch size it should also work for you. This is a very simple operation type thing.





    Jerry G.





  • Jerry Greenberg
    Jerry Greenberg Jul 07, 2008

    Getting back to this part, I do not have the service manual to know the part number. But, any authorized Sony parts dealer should be able to locate it through their system.





    Jerry G.

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Magnetized needs degaussing


proceed with this steps and fix it. God bless you
Instructions
    • 1 Turn on your Sony Trinitron television.
    • 2 Flip the power switch on your degausser.

    • 3 Maneuver the degausser's coil so that it is a few inches away from the face of the screen. Draw the center of the degausser coil around the entire perimeter of the screen, and then return the degausser to the middle of the screen.
    • 4 Slowly back away from the Trintron's screen. This serves to decrease the degausser's impact on the CRT's magnetic field to zero. Continue backing away until you are about five feet away from the screen
    • 5 Flip the power switch on your degausser to turn it off. The CRT's magnetic field should return to its normal state and the picture quality of your Sony Trinitron should improve.




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Oct 15, 2012 | Sony KP-53HS10 TV

1 Answer

I have a sony kv27s42 tv. it shut itself off last night and the red light on front of the tv is blinking. is there anything i can do?


Hi there stuibel,
is there any ticking sound that's coming from the inside? if there is than could be the relay (posistor)
that's causing your tv to shut down. need to replace that.

thanks,

George.

May 29, 2011 | Sony Televison & Video

2 Answers

Can't trun off closed caption


Here is a link to the operating instruction manual:
http://www.docs.sony.com/release/KV27S42.pdf

Look at page 23 for help with the closed captioning.

If this has helped, please give me the appropriate thumbs up! Thanks, and good luck!

Aug 16, 2010 | Sony KV-27S42 27" TV

1 Answer

The problem is that it is not Degaussing


1. You may be able to obtain a schematic at this site if you do a Google search. ESI
Troubleshooting a degaussing circuit is very tedious but good luck!
I hope this helps.

Apr 22, 2010 | NEC AccuSync AS120-BK (Black) Monitor

1 Answer

Recently the picture my Sony flat screen TV has started looking quite green - does not matter if we are viewing TV or DVD - everything has a greenish hue now. Its about 5 years old and out of warrenty. Is...


The set is probably magnetized and needs degaussing (demagnetizing).
All CRT type TV's have an internal demagnetizing circuit that is engaged when the set is first turned on after being off for the day.
If this circuit is working then you sometimes hear a "bonk" sound (about 1/2 a second long) when the set is first turned on. If this circuit isn't working the set will become magnetized over time and will have to be degaussed using a degauss coil available at a TV repair shop (cost aprox. $35.00) and you should have the circuit checked at the same time. A set will also become magnetized if a large speaker (magnet) or motor is close to the TV. Be sure to vote/rate me if this helped Thanks!

Oct 19, 2009 | Sony KV-35V35 TV

1 Answer

GREEN GLOW IN THE LEFT UPPER CORNER AND RIGHT LOWER CORNER


Magnetized The set is probably magnetized and needs degaussing (demagnetizing).
All CRT type TV's have an internal demagnetizing circuit that is engaged when the set is first turned on after being off for the day.
If this circuit is working then you sometimes hear a "bonk" sound (about 1/2 a second long when the set is first turned on. If this circuit isn't working the set will become magnetized over time and will have to be degaussed using a degauss coil available at a TV repair shop (cost aprox. $35.00) and you should have the circuit checked at the same time. A set will also become magnetized if a large speaker (magnet) or motor is close to the TV.

Oct 02, 2009 | Sony KV-32V42 32" TV

1 Answer

Sony KV-27S42 27" TV Problem


Hello BrianMcL
You are 100% correct, you will need a degaussing coil to take care of this problem. The instructions on how to use it will be included with the degaussing coil.
I hope this helps,
Thank you,
Shuttle83

Jul 06, 2008 | Sony KV-27S42 27" TV

1 Answer

KV-28CL10U colour circles


There are two things that commonly cause the fault that you are describing. Below is the main one.

It is very possible that the degaussing circuit or the degaussing coil is no longer working. A common fault is that the degaussing thermosistor has gone defective and the CRT has become magnetized. The earth's magnetic field along with other environmental things cause the CRT's internal mask to become magnetized over time.

The thermosistor in most Sony TV sets is located in the power supply area. It looks like a little black square box with 3 solder posts on it. In some models it has 2 solder posts. After a number of years this part may fail.

When the power is first turned on, the thermosistor is very conductive. After it heats up, it goes very high in resistance. It drives a high decaying AC mains current through the degausing coil (located around the shroud of the CRT assy) for about 50 to 60 ms. It then allows the current to decay to zero over the next 50 ms. When you turn on the TV set, you normaly hear a kind of a loud thump noise. This is the degaussing action.

Once the degausser is serviced and is working properly, it may take a number of power cycles to eventualy demagnetize the CRT. After shutting off the TV, it takes about 20 minutes before the degausser can work again. The thremosistor needs some time to cool down.

If you are not experience and trained for doing TV service, I would suggest you give the set out to an experienced TV service tech to change this part. There are serious safety issues when working inside of TV sets.

It is possible to purchase a manual hand held degaussing coil. There is a proper procedure for using this type of coil. If you were to manualy degausse your CRT, you would have to do it on an almost daily basis. The manual degaussing coil is fairly expensive to purchase. It would be better to service the set.

--

The second thing that causes the CRT to show colour purity problems (color splotches, or circles, or patches), is that the mask inside on the face of the tube has become dislodged off its supports or became warped. This can happen if the set has been dropped, or hit hard enough to do some damage to the mask. I have seen this where TV sets were roughly handled during moving them.

The only fix for a damaged CRT mask is to replace the CRT. The cost would be as much or more than the set is worth. This is if you can even find a replacement CRT. Most all of the manufactures no longer manufacture replacement CRT's for consumer products.

Only specialized CRT's are still being produced on a limited bases for specific industrial and military equipment that must still be kept in service. These are for some types of radar, medical, aerospace, and other related industries.


Jerry G.




Apr 15, 2008 | Televison & Video

1 Answer

Colour


The CRT shadow-mask may no longer be degaussing, or the shadow-mask in the CRT is defective.

In or near to the power supply there is a thermoresistor that controls the degausser coils. When the set is turned on this thermoresistor gives a momentary high AC current to the degausser coil with a rapid decay for slightly over a period of about 200 ms or 1/5th of a second.

If this thermoresitor is defective, it will have to be changed to resore the degausser coil to work again.

On rare occasions I have had a bad degausser coil that had to be changed. I have also had the shadow-mask in the CRT become defective. The fix for a bad shadow-mask is to change the CRT. This is not feasible for this TV set!

You should get an experienced TV service tech to fix this for you.


Jerry G.

Nov 05, 2007 | Sanyo DS32224 TV

1 Answer

Weird colours all of a sudden


These sets sometime have a fault with the auto degaussing circuit. It will start to work and because of a bad solder connection, the unit shuts off the degaussing right in the middle of it cycle and cause a rainbow effect of color. Your gonna have to go in and trouble shoot the degaussing circuit my freind, BUT if your not a tech I highly advise against this as theres alot of high voltage inside these sets. Have it checked out by a service person. It really depense on you if its worth it. Personally, myself, I wouldnt invest a dime in a 15 year old set. Good Luck

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