I just want to share the fix on my Sony KDL-52V4100 LCD TV set with a bad T-Con board.
The problem was an almost white image, typical of a bad chroma chip. After verification, I effectively found on the T-Con board that the chroma chip was outputting only half of the 18 chroma reference voltages. Under the FPC_LEFT ribbon connector, VGMA1-VGMA8 test points were fine producing different voltages in descendant values from about 20 volts to about 7 volts, but VGMA9-VGMA18 were all at zero volt.
Since the service manual for this board is not available, I found that the chroma chip was IC321. It is a ISL240007IRZ made by Intersil (now Renesas). It is a programmable 14-Channel x 2 Bank, 8-bit TFT-LCD VREF Generator. Each bank has its own I2C serial interface. Sadly, the detailed spec sheet for this chip is not available. So no pinout.
I was about to order a replacement chip when I remarked 4 test points labeled VREFL_L, VREFL_H, VREF_U_L and VREFU_H. I figured out that they were the two I2C serial interface to program each bank of the chroma chip. Now, if one of the two I2C serial interface was missing the programming signal, it would explain why half of the reference voltages were missing.
Bingo! I found RG18 connected to REFU_L that was open. It was a 0603 resistor of 6.8K ohm (marked 682). I didn't have a replacement resistor on hand, but in my scrap pile of boards I found a 0804 6.8K ohm resistor that was an almost perfect replacement. After soldering it in place, connecting back the T-Con board and powering up the TV set it was fixed. Perfect image.
The fix is applicable to the following Sony models that share the same TCON board :
KDL-52S4100
KDL-52S5100
KDL-52V4100
KDL-52V5100
It should also apply to a similar T-Con board having the same THF9301 main chip, like the FHD60C4LV1.1 and the 320HAC2LV0.0.
I hope it will help someone.
The problem was an almost white image, typical of a bad chroma chip. After verification, I effectively found on the T-Con board that the chroma chip was outputting only half of the 18 chroma reference voltages. Under the FPC_LEFT ribbon connector, VGMA1-VGMA8 test points were fine producing different voltages in descendant values from about 20 volts to about 7 volts, but VGMA9-VGMA18 were all at zero volt.
Since the service manual for this board is not available, I found that the chroma chip was IC321. It is a ISL240007IRZ made by Intersil (now Renesas). It is a programmable 14-Channel x 2 Bank, 8-bit TFT-LCD VREF Generator. Each bank has its own I2C serial interface. Sadly, the detailed spec sheet for this chip is not available. So no pinout.
I was about to order a replacement chip when I remarked 4 test points labeled VREFL_L, VREFL_H, VREF_U_L and VREFU_H. I figured out that they were the two I2C serial interface to program each bank of the chroma chip. Now, if one of the two I2C serial interface was missing the programming signal, it would explain why half of the reference voltages were missing.
Bingo! I found RG18 connected to REFU_L that was open. It was a 0603 resistor of 6.8K ohm (marked 682). I didn't have a replacement resistor on hand, but in my scrap pile of boards I found a 0804 6.8K ohm resistor that was an almost perfect replacement. After soldering it in place, connecting back the T-Con board and powering up the TV set it was fixed. Perfect image.
The fix is applicable to the following Sony models that share the same TCON board :
KDL-52S4100
KDL-52S5100
KDL-52V4100
KDL-52V5100
It should also apply to a similar T-Con board having the same THF9301 main chip, like the FHD60C4LV1.1 and the 320HAC2LV0.0.
I hope it will help someone.
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