When the power cord is plugged in, the standby LED flashes once and goes out. The set does not power up. This model uses power board BN96-03775A. To provide a search reference for others with similar problems, this power board is also listed for models LNS3251D, LNS3251DX, LN32B530FXZA, LN40B530FXZA, LN3241D, LN3241DC, LN3241DX, LNS3238DX, LE32S73BDX, LES3251D, LES3251DA, LES3251DX, LES3251D, LES3251DX. There is an “XXA” suffix after many of these models on a second tag on the back of the set.
The power board appears to be the problem. With the main board disconnected, the only output voltage is 6.02 VDC at what appears to be one of the power-on pins. There is no 5.4, 12 or 13 volt output. On the inverter side, there is no 24 volt output. There is no voltage to any of the “cold” side components except for the single pin noted above. This power source comes directly from the “hot” side and is not associated with the transformer that feeds the other components. There was one swollen capacitor which I replaced, but did not fix the problem. Close examination with a magnifying glass showed no signs of excess heat or other damage. I could not find any cracked solder joints on the back side of the board. There is AC power to the board and voltage to all components on the “Hot” side. Jumpers and most components have an input voltage of ~78.5 VDC. A few pins that appear to feed the power-on circuit have “hot” side voltages in the 40-60 range and outputs to the “cold” side of 4 to 6.02 VDC.
I could use a schematic, parts list, and some ideas of where to look next. Possibly the 5.4 VDC standby circuit might be out so the board won't start. I doubt the absence of the standby light has much meaning because the set could have died while powered up and the mainboard thinks it's powered on. Could be a bad transformer, but am hoping it's a fuse or diode-something easy to purchase locally. A few pictures are attached. Thanks for any help you can provide.
The power board appears to be the problem. With the main board disconnected, the only output voltage is 6.02 VDC at what appears to be one of the power-on pins. There is no 5.4, 12 or 13 volt output. On the inverter side, there is no 24 volt output. There is no voltage to any of the “cold” side components except for the single pin noted above. This power source comes directly from the “hot” side and is not associated with the transformer that feeds the other components. There was one swollen capacitor which I replaced, but did not fix the problem. Close examination with a magnifying glass showed no signs of excess heat or other damage. I could not find any cracked solder joints on the back side of the board. There is AC power to the board and voltage to all components on the “Hot” side. Jumpers and most components have an input voltage of ~78.5 VDC. A few pins that appear to feed the power-on circuit have “hot” side voltages in the 40-60 range and outputs to the “cold” side of 4 to 6.02 VDC.
I could use a schematic, parts list, and some ideas of where to look next. Possibly the 5.4 VDC standby circuit might be out so the board won't start. I doubt the absence of the standby light has much meaning because the set could have died while powered up and the mainboard thinks it's powered on. Could be a bad transformer, but am hoping it's a fuse or diode-something easy to purchase locally. A few pictures are attached. Thanks for any help you can provide.
Attached Files
Comment