I have a 56 inch JVC AV-56WP74 manufactured in 2003. All of a sudden the green has a sag on the upper left corner of the screen. After reading the blogs like so many others it seems the convergence ICs are in need of replacement. I removed the board and the originals are STK392-110.
My plans are to replace the STK392-110s with STK392-120s. I will order a service manual and supplies for removing and replacing the old chips.
My questions are:
1. Do I need to replace all the resistors around the ICs also? None of them look physically damaged. Is it possible that they are all OK? I have not tested them yet with a meter. Are they replaced to maintain tolerances that may have drifted over time or just if damaged? I noticed many of the kits include a handful.
2. Are the STK392-120 ICs the proper upgrade?
3. Does the service manual contain enough documentation to reset the convergence if needed or do I need to look else where for additional information.
4. I have seen some posts about a light sensor that wipes ROM if the set is powered with covers removed. Any truth to this and if so where is the sensor located.
Any thoughts or information about the project are appreciated. Thanks.
When it comes to the resistors i only replace them if they need to be replaced. Your meter ( if it is really accurate ) will find the defective ones that are bad that need replaced or if the tolorance has changed too high in value . I generally use the exact replacements of the STK's just don't buy cheap ones as they do not last long . Average cost of better ones are $18.00 to 29.00 . Yes a service manuel will help you with the convergence setup if touch up is needed beyond what the menu gives you to align the colors . But if you install these parts and after going thru menu setup of the convergence and the colors are still way out of alignment check those resistors again or a pico fuse may have opened up as well . Not sure what there talking about as a light sensor ? I've been servicing sets for quite a while and have not heard of a light sensor for the convergence . Also when replacing the STK's make sure you put new Heat sink compound between the IC's and bracket these mount on . Failure to do so will result in overheating and cause these to go bad sooner than normal . Good luck on your repair , James
The light sensor is not directly related to any convergence issue. It is in reference to powering the unit with covers removed and damage to ROM. With all the vents around the circuit boards it seems far fetched to me but I wanted a second opinion. Take a look at http://www.iwaynet.net/~nesda/Jan04/Jan0413.html
WOW , i'm not sure about that as my service manuel does not state this. I guess just make sure you have it unplugged before you take the back off . It also looks like it only affects the DVI module as what i read. Just if you test it unplug the cables going to it with the back off . Also i don't know of too many people who still use this as there high def picture any more . I will check into this and of i hear more i'll let you know . Thanks for the info , James
When it comes to the resistors i only replace them if they need to be replaced. Your meter ( if it is really accurate ) will find the defective ones that are bad that need replaced or if the tolorance has changed too high in value . I generally use the exact replacements of the STK's just don't buy cheap ones as they do not last long . Average cost of better ones are $18.00 to 29.00 . Yes a service manuel will help you with the convergence setup if touch up is needed beyond what the menu gives you to align the colors . But if you install these parts and after going thru menu setup of the convergence and the colors are still way out of alignment check those resistors again or a pico fuse may have opened up as well . Not sure what there talking about as a light sensor ? I've been servicing sets for quite a while and have not heard of a light sensor for the convergence . Also when replacing the STK's make sure you put new Heat sink compound between the IC's and bracket these mount on . Failure to do so will result in overheating and cause these to go bad sooner than normal . Good luck on your repair , James
The light sensor is not directly related to any convergence issue. It is in reference to powering the unit with covers removed and damage to ROM. With all the vents around the circuit boards it seems far fetched to me but I wanted a second opinion. Take a look at http://www.iwaynet.net/~nesda/Jan04/Jan0413.html
WOW , i'm not sure about that as my service manuel does not state this. I guess just make sure you have it unplugged before you take the back off . It also looks like it only affects the DVI module as what i read. Just if you test it unplug the cables going to it with the back off . Also i don't know of too many people who still use this as there high def picture any more . I will check into this and of i hear more i'll let you know . Thanks for the info , James
what the size of the resisters on this ex. 1/2watts 5%tolerance
Most of the resistors wattages are 1/2 to 1 watts . Even if you use a 1 watt and it calls for a 1/2watt it is OK as you do not want to go from a 1watt to a 1/2watt. The tolerance the lower the better 5% is OK . Just don't go higher .
I purchased all 2 Watt resistors. The manual shows 1 and 2 watt 5% tolerance around the convergence ICs.
Things I learned. Use a temperature controlled soldering iron. I purchased a Xytronic 379 Soldering Station. I tried several different solder vacuums but none worked as well as flux coated copper braid. The braid pulled all the solder from the ICs. I purchased several rolls but my favorite was the .080. I used heat sink clips to help protect the components while soldering them into place. Be cautious when buying the ICs as there are inferior ones on the market. I replaced STK392-110s with STK392-120s. I marked the cables and removed the board from the TV. It did require removing front and rear access panels. The temperature controled soldering iron was a key part of my success.
I put a small muffin fan in front of the IC heat sinks. It is controlled by a normally open contact round thermostat disk attached to the heat sink. It closes at 107 degrees Fahrenheit and opens at 93 degrees. That way it is automatically controlled. I did resist the urge to bring in outside are for fear of the dust that could be introduced and possibly cover the lenses.
I was not going to spend 300-500 to fix a TV that was 5 years old. I got it second hand and did not spend that much.
I have pictures and manuals for JVC AV-56WP74 and similar models if anyone is interested.
ok fellas I replace all the reisitor that where bad I plug all the wires to the convergence board, I plug in the tv and hear like thumping noise off on off on, but when I unplug the convergence board and plug in the tv set again the tv comes on fine exept the 3d problem occurs, what can be causing this problem model 48wp74 convergence board ssb-5051a-m2
When preparing to do my repairs I read that the noise was possibly an overload or bad connection. Check all the solder joints. Look for bridging, cold joints or solder pads that may have been damaged. Re-check resistors. Also when reconnecting board make sure all cables are firmly seated.
Hello Ray,
I was wondering when you changed the IC's and went into the convergence menu from the remote, did you go to manual and then were you able to move around the cursor and use the volume and channel buttons on the remote to align everything back up ? I just replaced my IC's 2 days ago on the same JVC you have and when i put it on the color looked better (not a horrible red anymore) but it was out of focus , so when i go to the convergence menu and do manual , i can move the cursor around with the number buttons, but when i try to use the volume and channel buttons nothng moves, so i can't align it up. I am thinking maybe i should go buy the tool to test the resistors but not sure . Could the resistors cause it from not aligning , anyone ?
Thanks
Ed
I replaced the STK's on an AV-48SP30 and a 48WP74. Both had convergence problems. The 74 had a burned resistor, which I replaced. The 30 set came out perfect and the convergence lined up perfectly from the get go. The 74 came out better, as I could move the blue around, but it was difficult to manually converge the edges and corners. They didn't want to move into perfect convergence without moving two or three grids to the left or right. I finally got it very close, and am happy with the picture. Should I double check my solder connections on the 74, or is there some other component that might be damaged? BTW, the job was relatively easy once I figured out how to get the braid working like it should.
i have a jvc and i found a convergence board but it is not the same serial number as mine but has all the same plugs can i still use it ????????