Question about JVC AV-56WP74 56" Rear Projection HDTV-Ready Television

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Amplifier Is the amplifier the silver, enclosed plugin module device on the convergence board? It appears that the 3 small cables that plug into the board go to the 3 different color projectors. Could something be wrong in the green projector that is causing this also? I can order the amplifier (if this is what the silver enclosed "module" is and try replacing it along with the resistor (which is again bad). Also, is the amplifier itself serviceable, ie resistors, etc? I have a service manual on order, by the way. I have some electronic experience, just not tv specific experience. I do think I am going crosseyed watching the messed up picture on this tv, so I am desperate to get it working properly again.

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I just reread your first post, Is the green the only one out of alignment? If so then the amplifier is not the problem. ICs that generally are at fault are on the digital convergence board but since you replaced them, then I would actually turn to the green projector like you said and try replacing that. There must be a short in it or in the cable going to it.

Posted on Jul 31, 2008

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Convergance chip


devices: Any Projection TV with a Convergence Amp board

If I knew which Mitsubishi Projection TV you're looking at, I could help quite a bit more. In general, the "convergence chips" on a typical Convergence Amplifier board are actually two STK's mounted to large heat sinks. "STK" is electrical engineering slang for "Convergence Amplifier Integrated Circuit".

Here's a helpful Solution archived at FixYa:
http://www.fixya.com/support/t4337218-image_bowed_line

You'll see in the photo that the STK on the PC board actually have part numbers on them that begin with "STK".

Dec 09, 2011 | Mitsubishi Projection Televisions

1 Answer

I was looking at a RCA D52W20 52 in. Rear Projection HDTV-Ready Television but they said that the colors went out of alignment...do you know what could cause that on this tv or what a possible fix could...


If one or more of the colors is displayed in a bow-tie rather than a full-screen rectangle, the STK392-nnn convergence amplifiers have probably gone bad (nnn is a three-digit type variant number). This is a common failure in CRT-type rear-projection TVs. There are two of these amplifier modules mounted on a metal plate or finned radiator. I recommend replacing both (one of the colors is shared between the two modules, or each color uses one amplifier from each module so both amplifiers could be damaged).

The STK392 has three power amplifiers inside. Each color needs two amplifiers for its convergence correction coils, so two modules are used. There are at least two different connection configurations among the different variants. Some variant numbers are merely higher-power versions of others, so they can be substituted (never sub a lower-power version for what is in your set - it will die rapidly and possibly with destructive fireworks). If you don't understand the datasheet for the part, don't try to substitute a different variant unless the dealer guarantees it is a suitable replacement.

The photos below show two typical package types close to actual size (the pin-to-pin spacing is 0.100 inches). It is best to get name-brand parts (e. g., Sanyo, Hitachi or Toshiba); some of the Chinese off-brand replacements don't last very long. When I had a string of these jobs several years ago, I paid about $23-$35 each, but I saw some overpriced as high as $75 and some off-brand or no-name units as low as $12.
kato_tech_20.jpg
(Photo from MCM Electronics)
kato_tech_19.jpg
(photo from electronic-spare-parts.com)

Often when the amplifier fails, some of the resistors connected to it are burned out. If all three colors are in the bow-tie shape, look for a small green fuse near the amplifiers and check whether is also needs replacing (don't change a blown fuse without also replacing the amplifiers or you'll waste a fuse).

It is essential to clean off the old heat-transfer grease from the heat sink surface and replace it. Apply a very thin, even layer of new heat-transfer grease to the metal plate on the back of the new amplifier so the entire surface is covered. Do not use too much; this will actually reduce the effectiveness of the thermal transfer. You want just enough to wet the contact between the module and its heat sink so any microscopic irregularities in the surfaces are filled in. Replacement should be performed by someone reasonably skilled at replacing soldered parts on a printed circuit board.

If nobody tried to adjust the convergence (see next paragraph) before the failed amplifiers were changed, very little if any adjustment should be needed unless there were burned-out resistors. If you still have a major misalignment, check the resistors around the module again to see if you missed a bad one.

STK392 failure is the most common electrical cause of mis-convergence. The most common mechanical cause is a shift in the optics due to a mechanical shock or twisting force on the TV. A stray magnetic field could also affect convergence. Minor convergence problems can be corrected by using the remote control to go into Service mode, selecting the Convergence function to bring up a pattern of dots on a square grid, and tweaking the offending colors back into place a little bit at a time all over the screen (there is some interaction; moving the convergence pattern dots in one place causes them to shift elsewhere). Be careful to keep the dots square in the grid or the picture proportions will be distorted, and be patient - it can take a while to get it right. Complete instructions are available in a downloadable service manual located at a number of places on the Internet (sorry, it's probably not free, but it's still a lot cheaper than calling in a tech who may have little more experience at RPTV convergence than you do).

Sep 10, 2011 | RCA D52W20 52" Rear Projection HDTV-Ready...

1 Answer

Color is off and can't adjust the blue convergence on my 55 inch philips rear projection


If the blue component of the picture is bow-tie shaped, you probably have a fried convergence amplifier (CRT type sets only). They are inside two modules in the typical CRT type RPTV. Each one has three amplifiers inside, so you have two for each color. If the blue CRT shares an amplifier from each module, you will need to replace both. I recommend replacing both anyway because they are notorious for having a high failure rate and you won't have to guess which one has the blue amplifiers. Check the resistors connected to the middle pins of the amplifiers - sometimes they get burned out when the amplifier fails.

The part number on the convergence module is STK392-nnn, where nnn is a three digit number indicating the variant specifically used in your set. Some of the variants are rated for a higher current than others, and some have different pin arrangements. Make sure you get a name-brand such as Sanyo or Samsung; there are some unbranded Chinese copies out there with poor reliability. The typical price is $12-$25.

The modules are black plastic slabs about 3" wide by 1 3/4" high, with the bottom corners trimmed off at a 45 degree angle. A row of pins comes out of the bottom edge and go into the circuit board. They are mounted on some sort of metal plate or radiator to dissipate heat (heat sink). When you replace them, apply a very thin even coating of thermal transfer grease to the metal plate on the backside of the module, and clean off the old grease on the heat sink. You want only enough grease to ensure a "wet contact" between the parts; more than that will actually reduce heat transfer. While replacement is straightforward, it does require skill at reworking soldered connections on circuit boards.

The hardest part will be restoring convergence since you tried to adjust it. Be patient, and try to get the convergence points square to each other so the picture isn't distorted. Adjust each one a little bit at a time. There is some interaction between the adjustments, so what you do on one part of the picture affects other areas.

Mar 14, 2011 | Philips Projection Televisions

1 Answer

Fuse blew out in our 52" rca projection tv. replaced it...now the three colors don't line up. what could be the problem?


If one or more of the color components of the picture is also distorted in a bow-tie shape, you have a blown convergence amplifier module - the fuse went when the amplifier melted down. This is a common failure in CRT-type rear projection TVs. The modules are black plastic slabs about 3" wide by 1 11/16" high by 5/16" thick with 22 pins on the bottom edge (more or less, depending on version). They are marked STK392-nnn, where nnn is a three-digit number denoting the specific version. There are two of them, and they will be bolted to one or two flat or finned metal plates to dissipate the heat they generate. Sometimes when they go out, they also burn out some resistors in the convergence circuitry nearby on the circuit board.

If you don't have to replace any resistors, you may not need to readjust the convergence on the set after repairs, provided you don't try to adjust the convergence beforehand.

The part price is generally between $12-$35. Avoid the cheap Chinese no-name knockoffs - they don't last. The major brand supplier of this parts family is Sanyo.

On the other hand, if you just have a minor misalignment, this could have been caused by a mechanical shift in the optics when you dragged the set away from the wall to get at the fuse (if you went "bump" - "oops!"). The problem can be corrected electrically using your remote control - see your owner's manual for the front panel and remote control combination code to get into convergence adjustment mode. Be careful to keep the convergence dot spacing uniform across the screen or your picture will be misshapen, work in small increments, and keep in mind that adjustments in one part of the picture affect convergence elsewhere. If an attempt to adjust the convergence results in no adjustment (you can't move the dots of one or two of the colors) stop - you do have a bad part. Attempting to adjust convergence with a bad part will make a lot of extra convergence adjustment work after repairs.

Nov 28, 2010 | RCA HD52W56 52" Rear Projection HDTV

1 Answer

Color is off with double image?


Is the image bow-tie shaped, with red, green or blue fringing effects? If so, one of your convergence amplifiers has gone bad. (Bow-tie: at least one of the three primary colors in the picture goes out to the corners, but the top, bottom and sides are bowed in at the center.)

If it is simple color fringing, with no color grossly misplaced, something has messed up the convergence. This may be caused by a strong magnet near the set (for example, a poorly shielded audio speaker), moving the set so its orientation in the geomagnetic field is altered or its components mechanically shifted (rough handling).

If a convergence amplifier is bad, replace it before doing anything else. If you just have minor fringing, see your owner's manual for instructions on using the remote control to adjust convergence. If it isn't in the owner's manual, you'll need the service manual. Caution: if you try to adjust convergence with a failed convergence amplifier, not only will it not help, but you will have a lot of extra work trying to get it back to normal after you replace the amplifier. Try a small adjustment along one edge of the picture. If one or more of the selected color dots in the convergence pattern won't move, and you are sure you are following adjustment directions, stop immediately and proceed with hardware repair.

Convergence amplifiers are usually marked STK392-nnn where nnn is a specific variant number. Two are used; I usually change both because quite a few people have changed one and had the other die not long afterwards. Sometimes there is a fuse in the power feed to these modules that is also blown. If you change the fuse without replacing the amplifiers, you'll probably waste a new fuse.

Oct 06, 2010 | Panasonic PT-53WX53 53" Rear Projection...

1 Answer

Picture shaped like a bowtie, (shrinking)


Hello, This is your classic convergence Amplifier IC problem. Here is a way to deal with it. These are generic instrustions: 1) Get the schematic/service manual for this TV (You will need it because it contains the part numbers and component values you will need for replacement) 2) On the schematic/service manual locate the convergence amplifiers (STK392-110, 120, 150) and the biasing resistors (Write the resistor values down from the schematic) 3) Unplug the TV and remove the rear cover to expose the electronic circuitry. 4) Using the schematic/service manual find the physical location of the two convergence amplifiers (Usually attached to a big metal silver in color heat sink) (Basically it will look like two big black six sided flat modules with a lot of pins on the bottom (18-22 to be exact)). 5) After finding the heat sink and amplifiers remove the screws or the tension bar holding the amplifiers in place. 6) Using a soldering iron and a de-soldering device (either a de-soldering pump or de-soldering wick) remove the solder from the pins of the amplifiers and biasing resistors that protrude from the solder side of the circuit board. (Take into mind that you may have to remove the board in order to do this, use the instructions in the schematic/service manual to do this, and make sure you mark everything you remove to make sure you have a guide as to how to put it back) 7) After removing the solder from the pins off the amplifiers and the biasing resistors, remove the resistors making a list of the value, part number, and location on the board (all of this should be in the schematic/service manual). Then remove the two convergence amplifier modules taking care so as not to damage the circuit board. NOTE: The heat sink compound (the white goopy stuff) may have hardened and caused the module to stick to the heat sink, you will have to gently pry the module away from the heat sink, I have used a light application of isopropyl alcohol to dissolve the heat sink paste. 8) Once the modules are loose from the heat sink, you can gradually remove them from the circuit board. 9) Clean the heat sink off by using the alcohol and a heavy paper towel (remove all of the heat sink paste, and yes this is messy) At this point you have removed the two convergence amplifier modules and the biasing resistors and cleaned the heat sink. Now you will have to use your schematic/service manual to find the part locations, values and numbers you will need to replace the old parts I suggest replacing the biasing resistors first. 1) Sort out the resistors you will need and as stated in the schematic/service manual and replace them according to the schematic/service manual locations and part numbers. 2) Solder the components (resistors) in place making sure not to short out anything in the process. 3) Apply heat sink paste to the metal side of the modules one at a time and the put the modules into the circuit board lining up the screw holes of the modules with the screw holes in the heat sink, use the removed screws or tension bar to hold the modules down once in place in the circuit board and on the heat sink. 4) Solder the pins of both amplifier modules to the circuit board, taking care not to short out anything. 5) Reinstall the board to the TV, reconnect all cables removed (DOUBLE CHECK EVERYTHING) If all went well the convergence amps should be working, and you will need to realign the convergence of your TV, I suggest using the AUTO Convergence feature of your TV (Use the instructions in the schematic/service manual). All should be good now. Now these instructions are generic in nature but can be use for a number of Models of Projection TVs. In addition to this also make sure your Yoke transformers on your CRTs are functioning as they should, check the voltages applied to them. I hope this helps, Thank you, Shuttle83 http://www.electron-age-technologies-llc.com

Jun 10, 2009 | JVC AV-56WP30 56" Rear Projection...

2 Answers

Need of a Convergence Board for an RCA PROSCAN Model 80690WW1


You can order a replacement Convergence Board or Convergence Amplifier Board for this model (PS8069) from a major RCA parts distributor at the link below:

RCA PS80690 Replacement Part Convergence Board

RCA PS80690 Replacement Part Convergence Amplifier Board (2F27039-502)


Please note, these boards are no longer available from the original manufacturer (RCA) and only appear to be available from PTS.

Apr 08, 2009 | RCA Projection Televisions

1 Answer

50HX70 picture


Hello jcside,

its not a costly repair the parts cost about $13.99 each (Convergence Amplifier ICs) Just remember you will need to change both of them. Also you will spend about $10 - $15 on the bias resistors.

Here is some advice I posted sometime ago, it applies in your case:
This denotes a convergence problem as you surmised. Believe it or not it would be cheaper for you to replace the two convergence amplifiers and the biasing resistors. You would not actually be replacing the convergence board since these devices are usually located on the deflection board in most cases. However in answer to your question, the boards are easily removed, depending on your level of patience (lots of cables to move around), I would also advise you to either mark down all of the connection you will remove, or take pictures of the board and its connectors. If you choose to just replace the Amplifiers and the biasing resistors there is a lot of information on this site on how to do so: This will get you started:

1) Unplug the TV and then get a schematic of the TV I use http://www.servicemanuals.net or http://www.manualsparadise.com
2) On the schematic locate the STK392-xxx series IC packs (usually attached to a large heat sink)
3) determine if the STK392s are 110, 120 or 150.
4) if the STK392-xxx's are 110s replace with 110s (forget that upgrade stuff it is a hit or miss game that I don't believe you want to get into), if they are 120s replace with 120s and so on.
5)Now to replace the STKs: remove the module from the TV and unsolder theold STKs along with the bias resistors, and replace them with the newones (be sure to apply heat sink paste to the STKs when attaching themto the heatsink)
6) make sure there are no short circuits form your soldering job.
7) Reinstall the module and then turn on the TV.
8) do manual adjustment and the auto-convergence test and then things should be back to normal.


I hope this helps

Shuttle83

http://www.electron-age-technologies-llc.com

Now if you think you can do this have at it, if not I would suggest that you have it done by a qualified TV technician.

Feb 14, 2009 | Toshiba 50HX70 50" Rear Projection...

2 Answers

Convergence problem


Hello nursecmp,

You have a convergence amplifier problem. Now you have two choices: 1) fix it yourself or 2) Get it fix by a qualified TV repair person. Granted if you choose the latter, you will spend about $200-$500 depending on the shop. So as you stated you would want to do this yourself. OK, I will not get into the problems with this, rather I'll give you the basic procedure and the you can search fixya for a more in depth solution (I'll show you how to do this after the basic instruction on how to replace the Convergence Amplifiers (I rarely give these instructions) Here goes:

1) Get the schematic/service manual for this TV (You will need it because it contains the part numbers and component values you will need for replacement)

2) On the schematic/service manual locate the convergence amplifiers (STK392-110, 120, 150) and the biasing resistors (Write the resistor values down from the schematic)

3) Unplug the TV and remove the rear cover to expose the electronic circuitry.

4) Using the schematic/service manual find the physical location of the two convergence amplifiers (Usually attached to a big metal silver in color heat sink) (Basically it will look like two big black six sided flat modules with a lot of pins on the bottom (18-22 to be exact)).

5) After finding the heat sink and amplifiers remove the screws or the tension bar holding the amplifiers in place.

6) Using a soldering iron and a de-soldering device (either a de-soldering pump or de-soldering wick) remove the solder from the pins of the amplifiers and biasing resistors that protrude from the solder side of the circuit board. (Take into mind that you may have to remove the board in order to do this, use the instructions in the schematic/service manual to do this, and make sure you mark everything you remove to make sure you have a guide as to how to put it back)

7) After removing the solder from the pins off the amplifiers and the biasing resistors, remove the resistors making a list of the value, part number, and location on the board (all of this should be in the schematic/service manual). Then remove the two convergence amplifier modules taking care so as not to damage the circuit board. NOTE: The heat sink compound (the white goopy stuff) may have hardened and caused the module to stick to the heat sink, you will have to gently pry the module away from the heat sink, I have used a light application of isopropyl alcohol to dissolve the heat sink paste.

8) Once the modules are loose from the heat sink, you can gradually remove them from the circuit board.

9) Clean the heat sink off by using the alcohol and a heavy paper towel (remove all of the heat sink paste, and yes this is messy)

At this point you have removed the two convergence amplifier modules and the biasing resistors and cleaned the heat sink.

Now you will have to use your schematic/service manual to find the part locations, values and numbers you will need to replace the old parts I suggest replacing the biasing resistors first.

1) Sort out the resistors you will need and as stated in the schematic/service manual and replace them according to the schematic/service manual locations and part numbers.

2) Solder the components (resistors) in place making sure not to short out anything in the process.

3) Apply heat sink paste to the metal side of the modules one at a time and the put the modules into the circuit board lining up the screw holes of the modules with the screw holes in the heat sink, use the removed screws or tension bar to hold the modules down once in place in the circuit board and on the heat sink.

4) Solder the pins of both amplifier modules to the circuit board, taking care not to short out anything.

5) Reinstall the board to the TV, reconnect all cables removed (DOUBLE CHECK EVERYTHING)


If all went well the convergence amps should be working, and you will need to realign the convergence of your TV, I suggest using the AUTO Convergence feature of your TV (Use the instructions in the schematic/service manual).

All should be good now.

Now these instructions are generic in nature but can be use for a number of Models of Projection TVs.

Jul 18, 2008 | Philips Magnavox 51MP392H Rear Projection...

2 Answers

Projection TV Convergence


they have inherent problems with the glycol oil used to cool the tube leaking past the bladders & onto the boards.... & it's conductive :p

Sep 30, 2007 | Projection Televisions

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