Hi all, i normally repair PSU units (all types) on the bench & rarely get to see a complete TV but this week someone dropped an LG LED tv in that they said wouldn't start up. Not having much experience of LED TV drive circuit's i would appreciate some advice.
The PSU number is; EAY62169801 (pics attached) & i couldn't find a circuit anywhere (typical LG) . I did find a training manual for the 55LW5600 model which showed almost identical PSU (even down to the component refs). Has anyone a circuit diagram for this PSU
Ok, i found that on power up, the standby LED is on, & the 3.5v standby is ok. On startup, the LED goes to white then goes off & the 12v & 24v come on ok. The voltage to the LED Drive though is only at 35.9 volts (screen never illuminates) & this is where i am unsure. The training manual says (for the 55LW5600) that the Drive voltage should be 56 volts going to 63 volts. The 35.9 v that i am seeing seems way too low to me (it never changes even with the LED strips unplugged). Also i monitored the DRV_ON pin from the mainboard & it never ever went high to 3.5v just sat there at almost zero. I forced the DRV_ON by connecting to the 3.5v line & the Drive voltage never changed from 35.9v
To be honest i'm not even sure if there's a fault on the PSU & the main board because when i go to switch the TV off the front panel LED goes to RED but then immediately goes white & then off as if it's switched itself on again, strange. Also , at no time do i seem to get a DRV_ON signal from the mainboard.
Anyone any thoughts ? is the drive voltage way too low at 35.9v , anyone got a circuit for this PSU ?
Any assistance appreciated.
Thanks
Graham
The PSU number is; EAY62169801 (pics attached) & i couldn't find a circuit anywhere (typical LG) . I did find a training manual for the 55LW5600 model which showed almost identical PSU (even down to the component refs). Has anyone a circuit diagram for this PSU
Ok, i found that on power up, the standby LED is on, & the 3.5v standby is ok. On startup, the LED goes to white then goes off & the 12v & 24v come on ok. The voltage to the LED Drive though is only at 35.9 volts (screen never illuminates) & this is where i am unsure. The training manual says (for the 55LW5600) that the Drive voltage should be 56 volts going to 63 volts. The 35.9 v that i am seeing seems way too low to me (it never changes even with the LED strips unplugged). Also i monitored the DRV_ON pin from the mainboard & it never ever went high to 3.5v just sat there at almost zero. I forced the DRV_ON by connecting to the 3.5v line & the Drive voltage never changed from 35.9v
To be honest i'm not even sure if there's a fault on the PSU & the main board because when i go to switch the TV off the front panel LED goes to RED but then immediately goes white & then off as if it's switched itself on again, strange. Also , at no time do i seem to get a DRV_ON signal from the mainboard.
Anyone any thoughts ? is the drive voltage way too low at 35.9v , anyone got a circuit for this PSU ?
Any assistance appreciated.
Thanks
Graham
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