View Single Post
Old 05-10-2016, 11:17 AM   #6
waldoalvarez00
Member
 
Join Date: Dec 2015
City & State: Santiago
My Country: Dominican Republic
Line Voltage: 110v
I'm a: Knowledge Seeker
Posts: 56
Default Re: Issue with acer v173 CCFL inverter

Quote:
Originally Posted by budm View Post
When you remove that PWM dimming control, the backlights brightness will be at full (100% duty cycle PWM signal, 3.3V).
From service manual.
Brightness PWM duty 35%~100%
*PWM:High=3.3V(3.00~3.60V),Low=0.0V,Frequency=4.0* V-Freq(Hz)

So if you have 0V then the backlights will not be on, the duty cycle range is from 35% ~100%.

So what Voltage do you have on the PWM control pin?
50% duty cycle = 3.3V *0.5 =1.65VDC.
Most monitors use about 200~300Hz for the PWM dimming frequency (spec sheet of the IC* Three channels of PWM DAC with programmable frequency from 100K to 100Hz.)
I have 0v at that pin. And that is what's strange. If I remove all pins from the controller board except +5v and ground, I turn it on and I apply 2.8 volts to the ON/OFF pin, the inverter turns on like a charm. If I turn off the board and keep applying the 2.8 volts it starts to flicker. Eventually it turns off seems some protection circuit triggers.

Last edited by waldoalvarez00; 05-10-2016 at 11:20 AM..
waldoalvarez00 is offline   Reply With Quote