Yamaha PSR OR700 dead (or almost)

May 16, 2023
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Hi, I like repairing vintage radio equipment (tube radios and the like) and a few months ago I also repaired a dead Hammond B3 Organ! Knowing that, a friend gave me a not functioning Yamaha PSR OR700 Keyboard.
The symptoms: when I turn it on, only one LED on the registration module turns on and it is orange (not green). The LCD is completely dead, other preset keys do not turn on and of course there is absolutely no sound.
I got the user's and Service manuals and tried to make some checks.
The factory reset (turning on and holding the rightmost key) doesn't change anything.
I checked the power supply and it is working (16V)
I checked the voltages the best I could. I think the AM module (power supply and main connectors) is ok. The capacitors on that board look fine.
Because the LCD doesn't turn on at all, I checked the voltage on the pink and white wire on the INV board leading to the CCFL. To my understanding, it should be a high AC voltage (a few hundreds volts) but I only get 1.7 V AC... !

Well, this is as far as I can get... Any hints????

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