Question about RCA P52960 52" Rear Projection Television

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SCR mounted on heat sink on board marked 15888430 blown, fuse blown

I can't find this part number on any parts web sites SCR marked 019701 on the board next to the component. Any suggestions about board or component availability or potential cause of failure?

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  • pksent Aug 22, 2008

    Unfortunatly, the face of the diode cracked when it blew and destroyed the face. Also after closer examination the part number on the board apears to be Q19701. I have a possible part # for the board RCA 250686. Any body know a source? Thanks!

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  • RCA Master
  • 1,550 Answers

The real number are on the front of the scr body check it

Posted on Aug 22, 2008

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Power tv on and then it clicks and turns off


Most of the time there are one or more 5 amp pico fuses open on the power supply. The cause of them opening is the +/- 30 volt line shorting from the convergence circuit. If you take this repair on yourself and are familiar with a ohm meter, you can check the small green pico fuses in the power supply. Remove the power from the set, take the back off. The board in the center is the power supply and convergence circuit. In the center of the you will a transformer. Just to the left of the transformer you will small green fuses that look like resisters. They are marked on the board but are sometimes hard to see. If one is open for the 30 volt line, the convergence IC's need to be replaced. They are mounted on the back of the large heat sink and the board must be removed to replace them. When you remove the board, be sure to remove all the screws not only around the edges of the board but also in the center too. There are also screws on each end of the heat sink and on the blind side center foot securing a ground wire. On each side of the board there are plug clips that must be lifted. At the front of the board there are plug connectors that need to be unplugged. Once the board is removed the IC's are easy to replace. Remove them from the heat sink, Unsolder them from the board using solderwik. The Convergence IC's should be STK392-570. If there is only one, it is a STK393-110. When replacing them, I recommend using heat sink compound on the back of the IC's where they contact the heat sink. solder in the new IC's then attach the heat sink to them.
Replace the small pico fuse or fuses, they should be rated at 5 amps. Once all the parts are replaced, remount the board making sure the heat sink holes align with the board holes. Reconnect the plug connectors, Plug clips, and reinstall all the board screws.

I hope this helps,
Skyassoc

Dec 12, 2010 | Mitsubishi WS-55809 55" Rear Projection...

Tip

How to find and replace a defective vertical IC.


When your TV works, has sound, good indicator light but all you have for a picture is a horizontal line across the screen, you have no vertical drive. This can be caused by the IC overheating or a power spike. In addition if you have a newer TV (projector) it may not turn on and will only blink an error code.

This is not a difficult fix but requires patience, good soldering skills and dilligence. Begin by unplugging the set and removing the rear lower area. Around the perimeter of the section you will see screws. Some will have arrows pointing at them. Remove all these screws and remove the rear cover.

Now you should be able to see the entire chassis. It will be mounted on a plastic frame and will consist of two or more circuit boards. The one, usually on the left, will be a small signal board. The one on the right will be the low voltage power supply, high voltage power supply and you guessed it, the vertical drive section.

The vertical IC is located near where the wires from the yoke which are red,green,yellow and blue terminate on the main board. The yoke is a large coil on the rear of the CRT which spreads the beam. It is slid over the glass CRT. Follow the wires (which should be green, yellow, blue and red to the circuit board. This will be the vacinity of the vertical IC. It will be mounted to a large heat sink and generally the designation begins with "LA" followed by 4 numbers. Panasonics generally begin with TDA.

Once located, remove and replace the unit. Removing the unit will probably require removing the circuit board. This involves removing all the screws around the perimeter of the board and any which you find in the center of the board. Do not force it, if it will not move easily look for and remove more screws.

You can get the replacement parts at http://www.encompass.com . Make sure you clean off the old heat sink compond and reinstall new heat sink silicone also available at the same web site. The heat sink compound facilitates heat transfer to the heat sink and keeps the IC cool. Generally the ICs are run at a high output and get very hot.

After replacement of the IC check all the safety resisters near it for continuity and also any and all diodes for integrity. These parts would be in the vicinity of the heat sink. Removing the IC may require prying it off the heat sink as many times the heat sink compound acts like a glue.

If everything checks ok you should have a working set.

If you do not have vertical drive, you will need a schematic to find the power source for the IC and test the circuit to see if it has the proper voltages.

You can sometimes get schematics from http://www.encompass.com but they do not have all of them. If you do not mind paying about $16.00 US you can get any service manual from http://www.servicemanuals.net .

Once the proper power is supplied to the IC you should have a working set.

Remember to use an isolation transformer anytime you are going to check voltages in the set. Modern TVs have the chassis attached to neutral making a 60 volt difference between the chassis and hot side. This means that if you do not use an isolation transformer and apply a DVM with a low path of resistance you will cause a direct short and blow the fuse, if you are lucky. Also remember to be careful when measuring voltages as there are lethal voltages in a TV when plugged in and running.

Thanks for using FixYa and for the great rating.

hardrocko

on May 11, 2010 | Televison & Video

1 Answer

How many convergence boards are on the sony model kp53hs30? and is there a step by step insturctions on how to change them? or how do you tell which one is bad? or just change both.


See attached photos of typical Sony---set uses two chips mounted to heat sinks with fins side by side.

This is a older set--chips will have number marked on front of them: STK-392-150, -110 OR -560.

The chips are usually located on the sweep board; you will have to get that board up to unsolder/replace them.

Depending on where you find them I can step thru the repair for you.

Total parts cost on EBAY for a pair of the chips etc will be under 25 dollars.

See also typical convergence chip--you need to id ones in your set for correct number.

If the information or photos helped you rate this solution as very helpful as I do this here for free.

If you need help,l am willing---have fixed hundreds of sets with this problem.

SD TECH



580ca06.jpg




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Chips will look like this but have different STK number on the front of them.




07dfa62.jpg


Typical Sony heat sinks with fins--chips will be mounted on other side.

Let me know if you have questions as I am here to help.

Aug 18, 2010 | Sony KP-53HS30 53" Rear Projection...

2 Answers

Tv turned itself off. turn power back on, picture


Your TV is experiencing a convergence issue as indicated by the 3 blinks. The only way to fix this is replacing the convergence ICs. It is not a hard task to replace these ICs. You just need to know how to solder and work on printed circuit boards.

The convergence ICs are mounted on a large heat sink and are marked with codes starting with the letters STK and there are two of them. You need to replace both.

Look for the heat sink with two ICs mounted on it and check the markings.

Once found, cut the IC legs with a small side cutter and unscrew it from the heat sink. Remove the legs left soldered on the board.

Take note of the IC markings for ordering the right part and how it was installed. Don't forget to buy along with the IC a thermal compound.

Check the pico fuses on the same board. Most likely you will find a blown one. These fuses look very much like a resistor, not like the usual transparent fuse, and usually yellow.

Once you have the replacement ICs, put it on the board in the same way as it was installed before. Make sure the screw holes are aligned before soldering the legs into the board.

Put a reasonable amount of thermal grease/compound between the ICs and the heat sink and fix them with the screws.

Double check the board for any splash of solders that might cause a short circuit and damage the board.


Dec 07, 2009 | Panasonic PT-47WX53 47" Rear Projection...

1 Answer

Hi. i have a 54 inch samsung rear projection tv. 2 years ago something happend within the tv and the picture was doubled. and there were red lines going through the tv. i had sears come out today and look...


Hi,
This sounds like the most common thing that fails on projection TV's, regardless of the brand. The convergence circuit has two, or sometimes three STK IC chips mounted on heat sinks to drive the convergence yokes. They typically last anywhere from 5-10 years, then they fail.

It sounds like in your case, the solder joints on the bottom of one of these chips may be failing and some fresh solder will make it go for a while. I would recommend you to replace both the STK chips.
These ICs are used to align and keep aligned the three colors on the screen...

INSTRUCTION TO REPLACE CONVERGENCE ICs:

The parts you will need are two ic's that are referred to as STK ic's. This is in reference to the first three letters of the part number. You will also need some pico fuses. The pico fuses are little yellow fuses that look like resistors. When they blow, they will show no physical sign of failure. The amperage rating will be printed on the fuse. For example a 5 amp fuse will have the number 5000 on it. A 3.15 amp fuse will have the number 3150 on it. You will need to use an ohm meter to test these fuses

The stk ic's are on the "D" board, attached to large heat sinks, When looking from the back you can see the heat sinks but the part's themselves will be pointing away from you and hard to see without removing the board, or using a mirror to look at the part numbers. The fuses are generally located under the fins of the heat sinks. There are several of them and vary by model. On the "G" board there will be two yellow pico fuses near the connector going to "D" board. These fuses provide power to the stk ic's you must check these as well.

When replacing the STKs make sure you use heat sink compound on the back of the ic's before installing them. Also as a rule of thumb, screw or clamp the ic's down to their heat sinks before you solder the pins. Replace any blown pico fuses and re- install your boards. When you turn your set on it may still be out of convergence due to many factors. Try pressing the auto focus button on front of your set.

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Rnj VINODKUMAR

Nov 11, 2009 | Samsung Televison & Video

1 Answer

Hi i have a RCA P52937SG with the bowing of the screen


The problem may still be on the power supply board (one of the supplies may be missing and) when you unplug the supply both supplies go missing check the supply voltages and repost

Oct 14, 2009 | RCA P52937 52" Rear Projection Television

1 Answer

Where to buy F9A04 and F9A05 fuses (Mitsubishi)


Those are called "pico fuses" and marked value is on the board, probably 5 amp. You will want to replace the STK IC's mounted to the large heat sink also. Any TV repair shop should be able to help or supply the parts you need (policy permitting).

Dec 21, 2008 | Mitsubishi WS-55809 55" Rear Projection...

1 Answer

MITSUBISHI WT46809 WON'T TURN ON


might say like f203 ... just look at all fuses on cov. board and see if wire inside fuses is blown apart .

Sep 09, 2008 | Mitsubishi WT-46809 46" Rear Projection...

1 Answer

Rear projection convergence out. replaced boards, blowing fuses


99% of these problems are due to either shorted pins or a missed pico fuse. The stk ic's are on the "D" board, attached to large heat sinks, When looking from the back you can see the heat sinks but the part's themselves will be pointing away from you and hard to see without removing the board, or using a mirror to look at the part numbers. The fuses are generally located under the fins of the heat sinks. There are several of them and vary by model. On the "G" board there will be two yellow pico fuses near the connector going to "D" board. These fuses provide power to the stk ic's you must check these as well.

Dec 16, 2007 | Sony KP-51WS500 51" Rear Projection...

1 Answer

Need detailed instruction


No. Usual procedure== Check the IC's that are mounted to
the large heat sink on center circuit board.Part # Stk392-570 X 2.
Check fuses FA904 & FA905 in power supply-replace,if open.
If either fuse is bad, replace both convergence IC's.
If both fuses check good and both IC's check good with your
meter,then check all the other fuse devices in power supply.
After that, advanced diagnosis by an experienced TV tech might be needed.

Oct 20, 2007 | Mitsubishi WS-55908 55" Rear Projection...

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