LK-202-25 v1.4 -

Coco210 · Post by **Coco210** » Mon Sep 29, 2008 1:24 pm

Hi all,

I am new here, but am using quite a long time this LCD for my home made high-end amp.

Now it just occured to me that a small transistor burned out.
I then retried to re-plug the LCD...and it still works except the back-light
is flickering a little bit.

Now: I am just looking for some schematics in order to get the ref. of the burned out component.

My LCD is: LK202-25, rev 1.4

Any ideas, I just don't want to buy a new one.

Thanks a lot for helping me. My reward would be some nice photos of my amp using this LCD

Cheers
Chris

Clark · Post by **Clark** » Mon Sep 29, 2008 4:21 pm

Hi Chris,

Sorry to hear you've burned out the back light transistor on your LK202-25 Rev1.4, it sounds like it's had a pretty good run.

The MOSFET transistor up there should be labeled 6Z on one side. The part number for that will be MMBF170-7-F; just a simple N-Channel MOSFET.

If you want a little added protection for that part, you might consider replacing the soldered wire near it with a zero ohm resistor. The resistor is cheaper and easier to replace. Although this kind of failure is definitely rare, it sounds like you've become pretty attached to that screen, so it might be something to think about.

If you need any more info, just let me know, in the mean time I'll be looking forward to those photos

Thanks,
~Troy

Coco210 · Post by **Coco210** » Tue Sep 30, 2008 10:07 am

Hello Troy,

Thanks for the fast anwer.
Ok, I found a substitute: FDV303N, Digital FET, N-Channel.

Now, you called this part a "backlight transistor", so this guy mainly
simply switches on/off LCD backlight or is there any PWM intensity
modulation going through as well?

Other question: do I have a chance to get full schematics of the LK202-25?
Thanks to be specific to that regard.

Clark · Post by **Clark** » Wed Oct 01, 2008 1:58 pm

Hi Chris,

Sorry for the delay, I was just double checking with engineering on that MOSFET and possible PWM. Currently, our units all have PWM for back light, to control brightness, however, many of our older units only had on/off capability, so no PWM.

The Rev1.4 was around long before me, but looking through the manual I only see commands for on and off, so I'm thinking no PWM.

As for the schematics, we cannot publish those.

If you are looking for anything in particular, just post it up and I'll do my best to look into it for you.

Finally, I've got to say, that's one impressive looking amp, thanks for the photos!

~Troy