Hisense f42k20e turns on, screen goes dark

[x_orange90_x]

Re: Hisense f42k20e turns on, screen goes dark

Well, you already know that you have BRI 0V which you reported, so now you force the BRI by jumping the BRI to Voltage source then you have backlights which is why you can no longer control the backlights level via user menu. Typical BRI analog control is that at 5V = max backlights, 0V = FULLY DIM.
I already suggested you to try lowering the BRI feeding Voltage to see it will vary the backlights level or not.
https://www.badcaps.net/forum/attach...4&d=1579461631
BTW, it looks like you have strand of wire touching GND pin, you need to clean that up that is why I recommend resistor.

Reconnecting the BRI wire while having BRI and SW jumpered.. Backlights turn off after a few seconds.
The main control BRI but the main board is having problem and keeping that line grounded instead of providing the Voltage level for the BRI.
You know, you are lucky so far from blowing parts on the main board not using resistor for protection.

I see what you're saying about the strands touching the ground. I have fixed the those stragglers so if 5v is Max backlight, then 3.8v should be somewhere around 75% backlight. I'd be comfortable with that. Do you think this is a long term fix?

[budm]

Re: Hisense f42k20e turns on, screen goes dark

Di you try lowering the Voltage to see what happen?
It will be a long term semi fix since you can no longer adjust the backlights level using user manual.
As I indicated, typical control Voltage is 0 ~ 5V, yours may no be the same, it can be 0 ~ 3V (or what ever the design is for the panel) too, that is why I told you to do the experiment.

[x_orange90_x]

Re: Hisense f42k20e turns on, screen goes dark

Di you try lowering the Voltage to see what happen?
It will be a long term semi fix since you can no longer adjust the backlights level using user manual.
As I indicated, typical control Voltage is 0 ~ 5V, yours may no be the same, it can be 0 ~ 3V (or what ever the design is for the panel) too, that is why I told you to do the experiment.

How would I connect AA batteries to it though? Obviously the + would connect to BRI pin, but where would the negative end of the battery connect to?

[budm]

Re: Hisense f42k20e turns on, screen goes dark

Ground pin, or use the chassis, and no BRI wire from main board connected to anything.

[x_orange90_x]

Re: Hisense f42k20e turns on, screen goes dark

Ground pin, or use the chassis, and no BRI wire from main board connected to anything.

1.52v AA Battery = No Backlights
3.21v AA battery x2 = Backlights

The 3.2v looked the same as 3.8v from SW pin as far as brightness goes. So either the range starts somewhere OVER 1.52V, or it starts at 0 and anything below ~2v-3v is unusable. Looking at it I wouldn't pin it being 100% Backlight even at 3.8v. maybe closer to 60-70% range in comparison to my other LED TVs (however this is edge lit I believe, the others are backlit).

[x_orange90_x]

Re: Hisense f42k20e turns on, screen goes dark

At this point I believe the 3.8v supplied by the SW pin is withinin range of acceptance. I paid $10 for this TV 2 years ago and it appears it's finally paid off with a simple jump wire. I've taped and secured the jump wire and BRI wire, and I'm about to close this thing up for use.

Edit:

My son loves it lol