Basically, I replaced the convergence chips on this TV myself about 6 months ago because I had experienced the "bowtie effect". The TV does not experience that anymore, but it does experience some weird convergence problems. First of all, I should say that red convergence is fully adjustable in both normal and advanced modes. Blue convergence can only be adjusted vertically in normal mode. HOWEVER, in advanced mode, blue convergence can be adjusted BOTH vertically and horizontally, but only on the left and right thirds of the screen. The middle only allows for vertical adjustment. I'm stumped. I am told to check the pico-fuses and the resistors on the convergence board as well as the white connectors between the convergence board and the other boards. Are there any other suggestions??
Info on my IC replacement job can be found here:
http://www.hometheaterspot.com/fusionbb/showtopic.php?tid/140550/fromsearch/1/hl/55857/tp/3/Sep 17, 2009
- I checked continuity between each contact on each of the convergence chips and its corresponding trace on the board. They're all good. I also checked all of the 3.9 ohm resistors. They read 2 ohms, but they're still connected, so there may be some other paths connecting them.
I bought my convergence chips from Blue Star International and am currently inquiring about the brand of STK chip I bought. I am beginning to think they weren't authentic Mitsubishi parts or Sanyo parts.
I checked the pico fuses too and they're fine. In my experience, I blow them when there is a bad connection between an STK chip and the rest of the board, so i think that's all good.
I also went ahead and traced all of the lines attached to the BH line and everything checks out value-wise on the board all the way to the convergence generator board.
Could one of the chips on the generator board itself be causing this issue?? i.e. IC8D03, IC8D04, or IC8D08??
If not, my guess is that it's a poorly manufactured "new" convergence amp chip...Sep 17, 2009
- If I had bad grounds, wouldn't I be blowing the pico fuses??
I haven't checked the caps yet. I suppose I'd have to desolder them and check them on a multimeter, right??Sep 17, 2009
- Hehe. The ones I got were $6 each... I don't know if that speaks to the quality...
What if I just switched out the horizontal convergence amp?? That would be one less thermally damaging process to the vertical circuit since I'd have to desolder all the pins and solder a new horizontal chip in...
I'll try your source and we'll see what happens I guess...Sep 17, 2009
- I'm still going to double check the existing IC's to make sure the signals aren't intermittent or loose. I am also going to lift one leg of each 3.9 ohm resistor and re-check the resistance since they came out to 2 ohms.Sep 18, 2009
- Well, I checked the resistors out of circuit and they all read 4 ohms.
I double checked IC8C01 and I noticed that the big brown ground wire was not screwed to the heatsink... Would that give me issues???
I checked all the connections to and from the convergence IC's and they're all connected where they're supposed to and not shorted.
I dunno what the deal is...Sep 19, 2009
- Well, I reconnected it and nothing changed... I do have some spare IC's, so I guess popping one of those on there is the next thing to try...
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