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Re: Convergence problem with JVC AV-48WP74 tv

coldfriction Posted Oct 09, 2005, in response to:Kah

This might help. I had a problem similar to yours. Basically the red went out of alignment. It is pinched or bowed at the top of the screen and will not converge with the other colors. This website was also helpful to learn about the problem and what worked for other people. http://www.network54.com/Forum/185128 http://archive.avsforum.com/avs-vb/history/forum/63-65.html I found that the problem is very common with projection TV's and the STK are the problem chips. A guy from the web helped me out with the problem and here is his response. =-=- =- =-= -= -= - chances are that IC804 has failed. You have two ICs that allow you to converge the three colors. IC804 is used for Red Horizontal and Vertical Convergence and also for Green Vertical Convergence. IC805 is used for Blue Horizontal and Vertical Convergence and also for Green Horizontal Convergence. These ICs run very hot and have a very high failure rate which sometimes will cause damage to resistors in their associated circuits. They are both STK-110 and it's best to replace them both at the same time. It's also a good idea to upgrade them to either STK-150 or STK-180. These will run a lot cooler than the STK-110. =- =- =- =- =- =- =-= -= - Before replacement do inspect for any open or overheated resistors as I stated earlier. Being you only have problems with Red Convergence the plus and minus power supplies should be okay since they are common to both ICs. Try www.tritronicsinc.com. They have the Hitachi CZ00433 (STK392-150) in stock for $20.11 ($32.43 retail). These are Hitachi OEMs. I've had very good results replacing STK392-110s with these chips. Do check for open or overheated resistors before replacing these chips. Good Luck, Eric =- =- = -= -= -= -= - =- =- =- =- =- =- =- I replaced the STK392-110 with STK392-150 and it worked. Basically here's how I did it. First, I removed the board which the STK chips are attached to. The board which the STK chips are attached to are at the very inside of the TV. You will see two black heat sinks where the ships are located. There are 3 tabs/clips to push and to be able to remove the board. Mark the cable that you will remove out of the board so you know how to put them back. I just scribe color code to the plastics. To remove the solder, use a wick and a 45watt soldering iron. Place the wick on top of the solder and heat it up with the soldering iron. The solder will be absorbed by the wick. It's a clean process. Install the NEW chip on the board. Screw the chip then solder the terminals. T The process took 15mins.

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    Ok just an update: I fixed the black menu screen problem. Apparently it must have just been a loose wire or something because I went back into the board area and just wiggled all the wiring connections and harnesses and started the tv back up and it worked! All back to normal. So just FYI in case this info helps anyone else.

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    Your post helped me a lot. I have almost the same model TV with the same problem. I replaced the two IC's and started the TV up. The picture was back to normal and looked great but now when I go into the tv's own setup menu, the menu is just a black box with nothing inside of it. It used to have settings and all that. Anyone have any ideas? Please?! I am good with electronics but this is my first time working on a projection TV such as this. Thanks again for any help or ideas!

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    "I replaced the STK392-110 with STK392-150 and it worked. Basically here's how I did it. First, I removed the board which the STK chips are attached to. The board which the STK chips are attached to are at the very inside of the TV. You will see two black heat sinks where the ships are located. There are 3 tabs/clips to push and to be able to remove the board. Mark the cable that you will remove out of the board so you know how to put them back. I just scribe color code to the plastics. To remove the solder, use a wick and a 45watt soldering iron. Place the wick on top of the solder and heat it up with the soldering iron. The solder will be absorbed by the wick. It's a clean process. Install the NEW chip on the board. Screw the chip then solder the terminals. T The process took 15mins." this guy is so full of crap i have been trying to unhook one of the wire connecrior and it is taking well over 15 mins. Also what would be the best way to solder the new chip in with out haveing the solder run together?

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    Awsome ! A good friend gave me this TV and told me it had a conv. problem.You gave me the answers to solve the problem,{and cheap}. I'm now a very happy camper! Thank you!

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    I tried re-soldering the board, but I believe I screwed it up in the process. I overheated some of the contacts, and some of the pads (the small metal contacts around the holes in the board) fell off. I just got off the phone with a JVC parts distributor in my area, and they quoted me $151.20 CAD incl. shipping for a whole new convergence assembly. A lesson for people who are attempting this repair: DO NOT OVERHEAT THE CONTACTS WHEN DESOLDERING. I learned that lesson the hard way. If you've never soldered before or are an amateur (like myself), read up on soldering/desoldering technique or pick up a book. Google is a great resource. I'm not sure if I'm going to go ahead and purchase the new assembly and repair the TV, or just buy a whole new one, but I will post updates if I decide to repair.

    Comment 1, Last comment by Matthew Boyd Nov 27, 2007

    Things did not go so well with my install. The red gun went out of convergence on my TV, and I went to my local retailer, and they did not have the 150 chips, only the 110s. I went ahead and installed the 110 chips. When I powered up the TV, all I heard was a thumping sound, and a click like a relay going off and on. I turned it off, and removed the convergence board. It was then I noticed the smoked resistor. One of the 2.2 resistors what discolored, but I did not notice it because it was discolored on the bottom of the resistor. Sure enough, it tested open. So tomorrow I am going to pick up the 2.2 resistor I need to replace (I did test the rest, they were ok), but I would like to know if yall think I fried my 110 chips by running it with one open resistor? Also, I marked all my connections when I took the board out, but I noticed one extra plug-in one the large silver compontent that is to the left of the 100 chip assemblies when facing the TV. It is a 6 pin connection in the side of the silver box (im not sure what it is..) Is there supposed to be a plug in this connection? Thanks, C. Alan

    Comment 1, Last comment by Alan Jul 11, 2007

    hey any help would be really appretiated..... I replaced the stk,s w/ 150s, I didnt see any bad resistors so I tryied it out, still the red doesnt contol left to right only up and down so then I replaced two resitors to be safe but still no good ...did i ruin the stk,s by not replasing the resistors first ? any ideas ? Help...Greg

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    I performed this repair, and like Alan, also got this thumping noise when I turned on the set. I searched on Google and found that this is called "Power Supply Overcurrent Shutdown." Quoted from the site: "Power Supply Overcurrent Shutdown means the set has found a problem in one of the circuits in the tv and shuts the tv off and keeps it off. the most common circuit in your model to do this is the convergence circuit." Perhaps there's a loose connection somewhere, Alan? I'm going to try re-soldering in the morning, hopefully this will fix the problem.

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    I rechecked my work on the board and it appears that one of the prongs for the IC 805 chip was not soldered well and didn't have a connection. Resolder ensuring a good connection and it solved the problem. Which would explain why the lines would not respond to any movement. I would like to thank the message board for all the help.

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    I replaced both convergance ic and one resistor that looked a little brown with the power resistor that was recommended in these posts. I fixed the initial problem of the red being off. But now the blue is a off, but only in the top right quadrant of the screen. I have gone into the initial setup up mode and attempted to adjust it manually, but the lines in the affected area will not move. The blue lines will move in other sections of the screen but not in the affected area. Help

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