Backlight fades out after 10 seconds

General mods that are considered worth doing; regardless of the end firmware you use.
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Backlight fades out after 10 seconds

Post by muzzer » Tue Nov 05, 2013 2:22 pm

Hi folks, got a quick question regarding the backlight mod.
Done the prerequisite search, but came up with nothing.

I've installed a blue HK backlight as per the guide here: ... _Backlight
I used a 2N7000 FET as it was what I had on hand (making sure I reversed the D and S connections from what is in the guide).
I've checked all the connections and they're OK, but when I turn the Tx on the backlight comes on as expected, then gradually fades out after about 10 seconds.

Anyone got any ideas what this might be?
I'll see if I can check the backlight panel for correct operation on it's own, and order up a couple of BS170 FETs just in case.

Thanks in advance.

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Re: Backlight fades out after 10 seconds

Post by ShowMaster » Tue Nov 05, 2013 7:07 pm

Maybe check the voltage source into the FET to see if it fades out. Also please post the FW version your using as it may be a new feature. I got do many TXs and FW's going I'm not in a position to comment there. You could also just bias the gate to +5 let's say and see if it stays lit. This will tell you if it's a led or supply voltage fade or coming from the processor.
You could also monitor the FET gate input wire to see if it stays at 5v when the led fades out. I say the wire because that will be the last input to the gate and the important place you want the +5 to remain solid.
Don't panic until others comment on your FW version your going to post.

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