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

5 Answers

Repeatedly blowing R842

I have replaced the amplifier IC's and the one resistor (R842 - 1.8 ohm) that was open. When I hooked everything back up, the picture was fine for about 10 seconds and the same resistor blew again and the picture was back to being bowed in at the top and bottom in the green. I replaced the resistor again and the same thing happened. Where should I check further for the source of the problem. Obviously, something is wrong elsewhere to keep blowing the same resistor. Any help will be greatly appreciated. If you want to email me, I am charles dot vance at westknox dot net. Thank you for your time and expertise.

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  • CVance Jul 30, 2008

    I checked the capacitors on the convergence board and cannot find any that look like they may be leaking or swelled up or anything else out of the ordinary. I was mistaken in the resistor number, it is R862. In tracing the lines on the circuit board, it appears to go from the amplifier IC to the green output plug.



    Thanks,

    Charles Vance

  • CVance Jul 30, 2008

    I checked the capacitors on the convergence board and cannot find any that look like they may be leaking or swelled up or anything else out of the ordinary. I was mistaken in the resistor number, it is R862. In tracing the lines on the circuit board, it appears to go from the amplifier IC to the green output plug.

    Thanks,
    Charles Vance

  • CVance Jul 30, 2008

    I will order a manual. Meanwhile, any other ideas I can check into?

  • CVance Jul 30, 2008

    Is the amplifier itself the large square metal plug in box on the convergence board?

  • CVance Jul 30, 2008

    I have a service manual on order.
    Is the amplifier the standup silver enclosed "module" that is not soldered onto the board but plugs in as a computer card would? If so, is this serviceable, as in checking resistors, etc?
    Also, since the resistor that is in question appears to go to the small cable for the green projector, could there be something in the green projector that is causing this?
    I am going crosseyed watching the messed up picture, so I am desperate to get this tv fixed.

  • CVance Jul 30, 2008

    The resistor I replaced the bad one with was a 2 watt resistor, the original was a 1 watt.

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  • 1,011 Answers

Dear,
is the resistance value is ok. if its exatly the same then check the wattage of the resistance. may be you are using the low wattagel resistance. resistance blows only if the heavy current (more than it rating) flow through it. check by using a high wattage resistor of the same value.

regards,

Posted on Jul 30, 2008

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  • Master
  • 2,267 Answers

I can send you the service manual.
Double check the solder as well and make sure they are not shorting out.
I would suggest to desolder pin # 7 and 9 from IC804. Also try to remove the wire that is connecting to the green convergence yoke.

Posted on Jul 30, 2008

  • Jaime Hernandez Jul 30, 2008

    Do not touch that silver square box, the failure is not there.

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  • Master
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Quit replacing the resistors, this can make it worse. What ever the fuse relays to must be replaced. Seems like it is the Amplifier since you replaced the ICs for it. Let me know if you have any further questions and good luck

Posted on Jul 30, 2008

  • Benjamin Patri
    Benjamin Patri Jul 31, 2008

    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.

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  • 2,035 Answers

This could the problem with short in the board you need have service manual to verify the problem you get one from this website:


http://servicemanuals.vstore.ca/


Good luck....

Posted on Jul 30, 2008

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  • 2,071 Answers

It is the capacitor caused that's the resistors blows,because the the capacitor cannot hold the storage voltage that why he passed it to resistor then the resistor can't also that why it's blow.Look for the capacitor associated to that resistor trace the line,for dryed up and leak capacitor...

Hope this may help;

Regards,
VOTIT

Posted on Jul 30, 2008

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1 Answer

How do you fix the color to a model 43fdx11b hitachi


Hello!you mean: colors out of convergence? nothing you can do about that, unless you replace 2 convergence amplifiers I.C. chips, plus all those burned 1 watt low ohms resistors with exact values, which only could be obtained via service manual or schematics. After resistor is burned, there is no way to read color code properly, due to partial evaporation of pigments. this is a "pro" job. If you try or tried, already to converge those "stubborn" crosses, there is more to do, even after you removed and replaced two 20 pin I.C. chips, soldered dead into sweep module, plus located and replaced resistors with precise values, you need to get your settings back to normal, by going into "factory service mode' or, at least into "convergence alignment" menu and fight with those crosses!Don't forget the white "****"! Otherwise, you will be re-servicing your set all over after 30 days of usage.good luck,Alex.

Feb 01, 2012 | Hitachi Projection Televisions

1 Answer

2.2 ohm resistor blowing after convergence repair


It might be the issue on the board. I would recommend you to show it to a repairman

Sep 07, 2008 | Panasonic PT-47WX49 47" Rear Projection...

Tip

Convergence - diagnosing a convergence problem - bowed picture/rainbow...


Convergence = the joining together of the 3 colors making up the picture cd3c9b5.jpg
Here is a picture of a Convergence mis-alignment

Typical repair:
Replace both convergence ICs + any burnt up resistors + any blown fuses = repair cost $250-350 or repair it yourself for about $30 and a few hours of time. Repairing requires tools, soldering and disassembly skills.

Overview:
All CRT rear projections have 3 picture tubes - red, green, and blue.
Each picture tube has an electromagnet (yoke) that pulls the beams horizontally or vertically. Therefore, there are 6 convergence amplifiers. One for each color, vertical and horizontal. Any one of these amps can fail independently, or whole sections can fail. Depending on the design of the TV, almost all use an IC (integrated circuit or "chip"). These have a part number beginning with STK (ie stk392-110 most common *see pic below) and run very hot, and fail regularly (5-8 years). Most STK designs have 3 amps per IC, giving you 2 ICs to run the convergence. Many manufacturers will have all 3 vertical amps on one, horizontal on the other. Others will have both the red amps on one, the blue on the other, and the green will be split between the two ICs.

Diagnosing:
The best way to diagnose is to enter the convergence alignment for your TV. Some TV's will have an auto alignment, others will let you adjust the colors yourself. The auto align is hard to troubleshoot because you cannot tell which will not move. If auto align does not work, you have some sort of failure or malfunction. In a manual alignment, you can see which colors will move and in which directions (vertical or horizontal). Using this deduction, you can see which amps have failed and replace accordingly. Red and Blue are typically adjustable, while green is left to factory alignment and not user adjustable. Try looking at the picture with something familiar on the screen. Try to have words or letters around the edges. You can usually see which colors are straight and where they belong, and which colors are out of place. If every color is off in both directions, this is a good indication that there is no power at all. The amps run off + and - 24 volts, and usually have 2 fuses for each power supply line. If everything is off, these fuses probably blew when one or both of the ICs shorted out. *RCA customers see below* Each convergence amp has some resistors that set up the amplifiers gain. Typically and input resistor (small like 1.5 ohm 1 watt) and a feedback resistor (larger like 150 ohm). Its quite common for the smaller value input resistors to blow out, so check them before you replace everything. They are typically right by the ICs (largest heatsinks in the tv) and most of them you can see if they're burnt up. Unhook the yokes (mark them if unmarked) and then you can OHM out the resistors to see if they are opened up. Replace any possibly bad resistors, sometimes they check good but look damaged = replace them! Some TVs will just be dead or go into shutdown. If the + or - 24volt fuses are blown, suspect the ICs and replace them both.

Repairing:
This is kind of tricky, as these ICs usually have 18 pins on each of them. Find all your bad parts, remove them and replace with good ones. The fuses and resistors are pretty straight forward. The ICs are harder. They are mounted to the heatsinks and depending on the make and model, they can be hard to get out. They are thermally bonded to the heatsink with heat sink compound or paste. If it is dry, replace the paste with new stuff. Make sure to get a nice, even, and thin layer on there to give a good heat transfer. The trick to the ICs is to make sure all your pins are straight before you install them. Start at one end and slowly work the IC and get each pin to pop into the hole. Once you solder in all the bad parts, the TV should be able to kick back on and run. At this point, its good to center the colors up in the customer mode. If you want to take it further, get the service manual for that TV and go into service mode and do the full re-alignment. This can backfire so get the manual or make sure you know what your doing as you might accidentally erase all the data.

cb47ab9.jpg
*stk392-110 = the most common IC. Almost all look just like this

Convergence is a very common failure and can be repaired by someone with a little soldering know how and some time to dedicate. Its quite complex, and every make and model are different. Let me know if you have any specific questions for your product and I can help you get the job done. Remember to have patience, good luck!

*RCA typically uses no ICs, and the convergence power board blows out (older models - wood cabinet) OR a small fuse blows out because of solder connections on the flyback transformer (newer models - plastic cabinet) and just needs resoldering and a new fuse.

on Jun 01, 2010 | Projection Televisions

2 Answers

Color convergence


find the change value capacitors and resistors in the convergence section!

Oct 08, 2007 | Toshiba TP50G60 50" Rear Projection...

1 Answer

I just replaced the convergence board on my JVC AV-56WP74, but the red still won't line up. Are there other parts that should be changed?


you also need to check and replace low value resistors in that circiut.they are all 1 watt,usually they get discolored when stressed.R842 2.2 ohm,R854 and R846 1.5 ohm,R850 2.2 ohm,R858 3.3 ohm,R862 1.8 ohm.they must be the exact value available in MD from surburban electronics.please note stk392-110 upgrade to stk392-150 for future referance.ONCE AGAIN CHECK ALL LOW VALUE RESISTORS

Sep 18, 2009 | JVC AV-56WP74 56" Rear Projection...

1 Answer

Samsung SP42W4PHX convergance problem


Hi
The resistors are 39 ohms, metal oxide.
Usually both the stk392-010 ic`s (on heatsinks )
want swapping. You can get them off ebay..

Dave H.

Jan 17, 2009 | Toshiba 53H71 53 in. Rear Projection...

1 Answer

Just a resistor?


R842 is off of pin 18 of IC804 which controls the red convrgence yoke. I would recomend changing both STK392-110 Ics as well as checking the other resistors R842 is a 2.2 ohm 1 watt metal film resistor. let me know if you need more assistance.

May 30, 2008 | JVC AV-56WP74 56" Rear Projection...

1 Answer

Phillips 60pw9363 Which IC is red and which is blue


Thats the DPTV 335 series chassis when the IC blows it will usually take out 1 or 2 6.8 ohm resistors along with it. Look at the resistors right next to the ICs you will notice 1 or 2 with a little discoloration in the middle replace those and your set should be back to working just fine. Let me know if you need more help. These resistors are easy to spoy they all look alike and shouldnt have any bands on them they will be stamped 6R8 ohm 1W J

Apr 12, 2008 | Projection Televisions

1 Answer

RESISTORS


the baby blue ones with the lines Blue,Gray, Gold ,and gold are the 6.8 ohm resistors the other resistors with the lines blue,orange,brown and gold are 630 ohm , Yes if those resistors are open even one of them the set will not converge. A digital ohm meter is more accurate, but you have to remove one side of the resistor to check them and if theyre open they wont read anything. If you leave them in circuit even a open resistor can measure good due to the resistance in the circuit. Removing 1 leg out of circuit then checking will spot an open resistor quickly.

Apr 04, 2008 | Philips 55PP9352 55" Projection Television

1 Answer

Replaced ic on philips you told me about which resitors are 6.8 ohm ....


your model is 55PP9352/17 correct? If so all the resistors from R3149 - R3160 are all 6.8Ohm 1watt 5% tolerance. metal film resistors. The resistors in your upper pic 3157 and 3158 appear to be open by looking at the pic I cant actually make out the banding colors to determine what rating they are. But if your set is a 55PP9352/17 they should be 6.8 ohm. let me know the actual color of the bands in order and I will post the ratings of 3157 &3158

Apr 04, 2008 | Philips 55PP9352 55" Projection Television

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