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Viewing topic "Motif XF LCD backlight issue - repair/diagnostics help… please."

     
Posted on: December 15, 2016 @ 10:47 AM
jasonsjwou
Total Posts:  5
Joined  12-15-2016
status: Newcomer

Hi everyone..

I am new to the forum, but I have been using several models of MOTIFs over the years.

I need some help on diagnosing the LCD screen on XF.

I recenly bought a used XF8 cheap on craigslist. Guy was selling it cheap because few keys were popped out and he didn’t want to mess with it. Rest of the system works fine, so I took it home.

As I have done this repair on S90XS before, I opened it up and fixed all the keys. Nothing was broken or chipped off, so it was to be an easy 30min repair.

Then it happened. The top panel came off of the hinge, and yanked two cables from the bottom board (PCB board that has bunch of audio output jacks) to the top board (PCD board that has main volume slider and 4 sliders/knobs) . I reconnected the two cables, closed the top panel. Power up, and the LCD didn’t lit up.

Everything else works. It boots up and plays fine, buttons and keys all respond. I can even see the graphics on the LCD panel when I shine a light on the LCD panel.

SIGH.... easy 30min fix turned into a mess....

Obviously I am thinking… something has happened to the LCD back light. Power, Connection, CCFL itself, etc etc.

I couldn’t find XF repair manual, but found a XS repair manual online, and downloaded it. XF and XS appears very very similar.

I’d greatly appreciate any help on diagnostics… anyone done this repair before? What’s the usual suspect?

Thank you....

  [ Ignore ]  

Posted on: December 15, 2016 @ 12:41 PM
5pinDIN
Avatar
Total Posts:  9423
Joined  09-16-2010
status: Guru

Welcome to the forum.

See this thread…
http://www.motifator.com/index.php/forum/viewthread/452509/
...and consider the posts concerning the rear panel LCD contrast control.

I’m attaching a data sheet for a Kyocera LCD panel. There are several versions of these panels - brightness, contrast ratio, viewing angle, etc., vary - but the electrical information (pinout, etc.) in this sheet should match.

There are two cables from the JKAN-LC board to the LCD panel, a 20-pin one for logic supply, data, etc., and the 2-pin CCFL one. Make sure the 2-pin connection is intact.

Best of luck in getting this resolved.

WARNING: There are very high voltages (hundreds of volts) used to supply the CCFL backlight. Anyone who doesn’t have experience working on electronic equipment, especially gear having such voltages, should not attempt to repair their Motif. Don’t risk yourself or your gear - please refer such problems to a competent electronic technician.

File Attachments
KCG057QV1DB-G00.zip  (File Size: 792KB - Downloads: 56)
  [ Ignore ]  

Posted on: December 15, 2016 @ 09:14 PM
jasonsjwou
Total Posts:  5
Joined  12-15-2016
status: Newcomer

Thank you 5pinDIN.

Couple questions.

On the JKAN-LC board, what voltage should I be reading on the CN201 (little blue cable connector, not the pink-white connector) Should I be reading something like 5VDC?

  [ Ignore ]  

Posted on: December 15, 2016 @ 10:01 PM
jasonsjwou
Total Posts:  5
Joined  12-15-2016
status: Newcomer

YEEEEAHHHHHHH

I found the problem.

I assumed that CN201 should show some meaningful voltage (such as 3.3v or 5vdc), because it was only showing 0.17vdc.

So I traced that cable.... I had to disassemble the housing, to find out that the other end of CN201 (which is inside the housing on JKAN-ML board) was yanked out from its socket.

Plugged it back in and VOILA!!! i get backlight.

Everything is working now.

Thank you for your help.

  [ Ignore ]  

Posted on: December 16, 2016 @ 05:04 AM
5pinDIN
Avatar
Total Posts:  9423
Joined  09-16-2010
status: Guru
jasonsjwou - 15 December 2016 10:01 PM

YEEEEAHHHHHHH

I found the problem. [...]

You’re welcome, and congratulations!

For future reference…
The cable you referred to connects from CN201 on JKAN-LC to CN300 on JKAN-ML. The supply should be 5 volts.

  [ Ignore ]