I am working on a Sharp lc-90le657u at a customer's home.
It would occasionally click the relay, turn on the backlight for a fraction of a second, turn off, click relay off. More often than not it will do nothing at all.
On the first trip i replace the power supply, on the second i replaced the main board. Today i spent about an hour testing various things.
Tested all LED + - wires. all exactly 196v with backlight tester, and could see each strip light up. With ameter in series the current was identical on every strip.
Primary side voltages appear to check out fine.
Only voltage present on secondary side is the 5V standby.
Power button has 3.3v on it and goes to zero when switch is closed as expected.
with no main board connected power supply does not turn on, but i dont know if it should.
With PSU_ON tied high the power supply does not turn on / create higher voltages.
Unplugged TCON cables, nothing changed.
Either i am completely missing something, or i got bad parts maybe?
Anyone have an experience at all with this tv? Anything else i can check.
Coppell lists a repair service for the power supply, that is often an indicator of a known issue, but im not seeing anything anywhere else.
It would occasionally click the relay, turn on the backlight for a fraction of a second, turn off, click relay off. More often than not it will do nothing at all.
On the first trip i replace the power supply, on the second i replaced the main board. Today i spent about an hour testing various things.
Tested all LED + - wires. all exactly 196v with backlight tester, and could see each strip light up. With ameter in series the current was identical on every strip.
Primary side voltages appear to check out fine.
Only voltage present on secondary side is the 5V standby.
Power button has 3.3v on it and goes to zero when switch is closed as expected.
with no main board connected power supply does not turn on, but i dont know if it should.
With PSU_ON tied high the power supply does not turn on / create higher voltages.
Unplugged TCON cables, nothing changed.
Either i am completely missing something, or i got bad parts maybe?
Anyone have an experience at all with this tv? Anything else i can check.
Coppell lists a repair service for the power supply, that is often an indicator of a known issue, but im not seeing anything anywhere else.
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