Akai LCT2060 LCD TV (Again) - Safe to install new inverter board?
This is my second post on this TV and I'm sorry it has taken a while to get back here with what I hope is useful information.
LCD TV has no picture or sound. DMM indicates an output of 12.5 vdc with no load on the 120vac to 12vdc 4A adapter. When adapter is connected to the mainboard the red (standby/off) LED is lit. Pressing the power on switch (control board) kills the red LED. The voltage measured at power jack and F1 & F2 drops when powered on and it actually starts out at about 9.5v or so and creeps up slowly to settle at a pretty stable 10.1 after a good 3-5 minute warm up. Never gets closer to 12v or over 10.2v even after an hour.
I suspected a bad inverter board on this TV and I do have a replacement inverter board. I don't want to bork the new board when I install it if something on the mainboard can hurt it. Is there something to look for that might help insure a successful inverter install.
Visual inspection gives no apparent indication of bad electrolytic caps. None are bulged or exploded. Electrolytic caps are G-Luxon (China o'course) 5X10mm, 1000uf, 16v, 85c.
The below values seem to be within spec for the mainboard regulators (pic 5 red line) and I've listed the values for the inverter board cn1 vis (J3) with a.DMM set @20vdc:
Reg4 is an 1117-18
A 0v
Vout 1.77v
Vin 4.99v
Reg7 is an 1117-18
A 0v
Vout 1.77v
Vin 4.99v
Reg1 is an 1117-50
A 0v
Vout 4.98v
Vin 10.1xv
Reg2 is an 1117-33
A 0v
Vin 4.99v
Vout 3.29v
Reg5 is a SI8050SD:
Pin 1-Vin 10.1xv
Pin 2-sw 5.09v
Pin 3- pgnd 0v
Pin 4- FB 5.00v
Pin5- shdn 2.38v
Reg3 is a SI8050SD:
Pin 1-Vin 10.1xv
Pin 2-sw 5.04v
Pin 3- pgnd 0v
Pin 4- FB 5.00v
Pin5- shdn 2.38v
Reg6 (audio) is an UTC78D08:
A 0v
Vout 7.99v
Vin 10.1v
J3 on the mainboard (lower right in pic2) goes to cn1 on the inverter board:
The inverter board is a PCBINV043-06L Rev. 1. Cn1 where the mainboard J3 connects on the inverter board (pic 3) has no legend or pin out label.
P1, P2, and P3 at J3 on mainboard are all 10.1v with the DMM and are connected to F1
P4, P5, and P6 are all 0v on mainboard as they trace back to gnd but are coupled to P1,2,&3 through a pair of caps.
P7 gives a DMM of .89v (Dimming/brightness?)
P8 is 4.26v (Inverter control?)
LCD TV has no picture or sound. DMM indicates an output of 12.5 vdc with no load on the 120vac to 12vdc 4A adapter. When adapter is connected to the mainboard the red (standby/off) LED is lit. Pressing the power on switch (control board) kills the red LED. The voltage measured at power jack and F1 & F2 drops when powered on and it actually starts out at about 9.5v or so and creeps up slowly to settle at a pretty stable 10.1 after a good 3-5 minute warm up. Never gets closer to 12v or over 10.2v even after an hour.
I suspected a bad inverter board on this TV and I do have a replacement inverter board. I don't want to bork the new board when I install it if something on the mainboard can hurt it. Is there something to look for that might help insure a successful inverter install.
Visual inspection gives no apparent indication of bad electrolytic caps. None are bulged or exploded. Electrolytic caps are G-Luxon (China o'course) 5X10mm, 1000uf, 16v, 85c.
The below values seem to be within spec for the mainboard regulators (pic 5 red line) and I've listed the values for the inverter board cn1 vis (J3) with a.DMM set @20vdc:
Reg4 is an 1117-18
A 0v
Vout 1.77v
Vin 4.99v
Reg7 is an 1117-18
A 0v
Vout 1.77v
Vin 4.99v
Reg1 is an 1117-50
A 0v
Vout 4.98v
Vin 10.1xv
Reg2 is an 1117-33
A 0v
Vin 4.99v
Vout 3.29v
Reg5 is a SI8050SD:
Pin 1-Vin 10.1xv
Pin 2-sw 5.09v
Pin 3- pgnd 0v
Pin 4- FB 5.00v
Pin5- shdn 2.38v
Reg3 is a SI8050SD:
Pin 1-Vin 10.1xv
Pin 2-sw 5.04v
Pin 3- pgnd 0v
Pin 4- FB 5.00v
Pin5- shdn 2.38v
Reg6 (audio) is an UTC78D08:
A 0v
Vout 7.99v
Vin 10.1v
J3 on the mainboard (lower right in pic2) goes to cn1 on the inverter board:
The inverter board is a PCBINV043-06L Rev. 1. Cn1 where the mainboard J3 connects on the inverter board (pic 3) has no legend or pin out label.
P1, P2, and P3 at J3 on mainboard are all 10.1v with the DMM and are connected to F1
P4, P5, and P6 are all 0v on mainboard as they trace back to gnd but are coupled to P1,2,&3 through a pair of caps.
P7 gives a DMM of .89v (Dimming/brightness?)
P8 is 4.26v (Inverter control?)
Attached Files