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Viewing topic "xs display backlight defect?"

   
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Posted on: December 24, 2010 @ 09:21 AM
muzikoloog
Total Posts:  25
Joined  01-15-2003
status: Regular

Hi,

Today i started up my motif xs. The display was very dark on startup, and i could’nt fix it with brightness control on the back. So i think that my backlight is broken. Has anyone had this same problem?

I think i will try to fix it myself. Does someone know the backlight type/partnumber and where to order?

Anyone fixed this before? Maybe some usefull feedback?

Greetings Mark.

Thanx

  [ Ignore ]  

Posted on: December 24, 2010 @ 11:21 AM
sciuriware
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Nog in de garantie? Meteen (nou ja, Maandag) terugbrengen.
Waar heb je hem gekocht?

Prettige Feestdagen nog.
;JOOP!

  [ Ignore ]  

Posted on: December 24, 2010 @ 11:44 AM
muzikoloog
Total Posts:  25
Joined  01-15-2003
status: Regular

The xs is at least two years old, so no warranty. (Ik reageer even in het engels Joop, voor iedereen die het wil lezen).

But i don’t think repair is very difficult, if it is the backlight.

But maybe i am wrong. We will see.

I keep you guys and girls posted.

I bought it at Dacapo in the Netherlands in a little place called Nietap.

any ideas for repair are very welcome. Or else i will dive right into the challenge.

Greetings Mark.

Prettige dagen iedereen.

  [ Ignore ]  

Posted on: December 24, 2010 @ 12:07 PM
sciuriware
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Toch even in het Grunnings:
er zijn meer van die klachten geweest aan de Classic en de ES
en het was vaak een los draadje.
Die jongens uit Verweg kunnen niet zo goed solderen.
Dus: HEEL voorzichtig openen en de draden naar de display nagaan.
Als het dat niet is .... naar de winkel terug.
Niet zelf een display vervangen.
Mijn mening.
Groeten,
;JOOP!

  [ Ignore ]  

Posted on: December 24, 2010 @ 01:20 PM
muzikoloog
Total Posts:  25
Joined  01-15-2003
status: Regular

Wiring was oke. I got the backlight tube out, it was a nice challenge.

The motif xs is not very service friendly like the motif classic was, but this is my opinion.

Now my question. Does anyone know the specs of the backlight tube?

The measured diameter of the backlight is 2mm. The length is 125mm.

What are the electrical specs of the tube? (yamaha????)

It would be stupid to replace the complete display if only the tube is defective. The display functions properly, because when i put a light on it, everything is visible and functional.

thanks ahead for much needed info.

Greetings Mark.

  [ Ignore ]  

Posted on: December 24, 2010 @ 02:23 PM
5pinDIN
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muzikoloog - 24 December 2010 01:20 PM

[...]Now my question. Does anyone know the specs of the backlight tube?

The measured diameter of the backlight is 2mm. The length is 125mm.

What are the electrical specs of the tube? (yamaha????)[...]

It’s likely that almost any tube that is 2mm x 125mm will be electrically okay. That size CCFL will typically run on about 400 volts (starting voltage no more than double that), and draw about 5 milliamps. Those specs are NOT specific to the tube in the XS.

However, make sure that you get a “full spectrum” (white) lamp, or the display colors will be wrong.

There will likely be silicone end caps over each electrode where the wire attaches. If they can’t be removed without damage, buy replacements. Make your solder joints as smooth as possible so that the caps don’t get pierced when slid back over the ends.

  [ Ignore ]  

Posted on: December 24, 2010 @ 02:47 PM
muzikoloog
Total Posts:  25
Joined  01-15-2003
status: Regular

Thanks for your quick respons. Very usefull.
I did some internet research. The ccfl lamp standard is 120mm or 130mm. I think that 125mm is a strange length in the ccfl world. i mailed to http://www.invertech.de

I hope they will reply soon if they can deliver.

I keep you posted.

Greetings Mark.

  [ Ignore ]  

Posted on: December 24, 2010 @ 03:15 PM
5pinDIN
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muzikoloog - 24 December 2010 02:47 PM

Thanks for your quick respons. Very usefull.

You’re quite welcome.

I did some internet research. The ccfl lamp standard is 120mm or 130mm. I think that 125mm is a strange length in the ccfl world. i mailed to http://www.invertech.de

The 125mm length should be available. See, for example:
http://ccflwarehouse.com/20.html
--and--
http://www.lcdparts.net/CCFL13D.aspx

The European distributors should also be able to supply that size.

  [ Ignore ]  

Posted on: December 24, 2010 @ 03:29 PM
muzikoloog
Total Posts:  25
Joined  01-15-2003
status: Regular

Thanks a lot again.
Question:

Do you know if and how to check if the ccfl lamp is defect? Cold Cathode principal?

Because It could also be a powersupply or inverter issue

I can measure the output to the ccfl lamp, but my motif xs is completely disassembed at the moment so a lamp check (if possible would be quicker).

Greetings Mark.

  [ Ignore ]  

Posted on: December 24, 2010 @ 05:00 PM
5pinDIN
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As you might suspect, the best test for the inverter is to connect a known-good lamp, and the best test for the lamp is to connect it to a known-good inverter. ;-)

Since CCFLs don’t have heaters, they are started ("struck") by applying a voltage higher than the normal operating voltage. The inverter then senses the lamp current, and the applied voltage is reduced so that the current is within an appropriate range. (If the current is excessive, either the inverter will shut itself off, or a fuse may blow.)

Due to this regulating action, it isn’t easy to check the inverter’s output by substituting a fixed resistive load in place of the tube (the tube normally presents a dynamic load). Nor is it easy to supply the correct voltage/frequency to a tube while limiting the current in order to test it without just using another inverter. (CCFL inverters typically run at about 40kHz.)

A failing tube can make itself evident if the display has been gradually dimming, flickering, and/or turning more orange/red/pink in color. While it’s not impossible for a bad tube to fail “overnight”, if none of those conditions preceded the loss of light output, it’s more likely to be related to the inverter or its power supply. In rare circumstances, the inverter fuse can blow with no apparent cause, so do check for that.

You could probably find procedures on the internet for testing the inverter output, but be careful. It isn’t hard to damage a good inverter by overloading it.

While I haven’t worked on an XS backlight, I’ve repaired numerous LCD monitors where the backlight was out. In nearly every case the problem was due to one or more bad capacitors, causing problems with the inverter. Still, since you’ve already removed the tube, it would probably be worthwhile to try a new one if the inverter doesn’t have a blown fuse or other sign of problems.

  [ Ignore ]  

Posted on: December 25, 2010 @ 02:33 AM
muzikoloog
Total Posts:  25
Joined  01-15-2003
status: Regular

nice to have this expertise on the forum. I made a photo of the ccfl inverter. There are two components i believe to be 150amp fuses. But i’m not sure because they are revered to with “C” like capacitor. They also look like capacitors, but the info on them have nothing to do with caps. “x4 150A UD”.
I’m pretty sure they are fuses.

Please your opinion.

Image Attachments
DSC02089.JPG
  [ Ignore ]  

Posted on: December 25, 2010 @ 03:26 AM
CrocAUS
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they are solid state capacitors not fuses

  [ Ignore ]  

Posted on: December 25, 2010 @ 04:23 AM
5pinDIN
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C202 & C209 are surface-mount electrolytic capacitors, apparently 150µF in value. Along with L200, they form a filter that minimizes high-frequency noise from the inverter getting back into the rest of the XS’s circuitry.

I don’t see any fuses on the board. Are there any components mounted to the side not shown in the photo?

Connector CN201 (near C202/209) appears to be the input where the DC supply is connected. You could check the voltage there—typically, I’d expect around 5 volts or so, and likely pin #1 is the positive terminal. Of course, be careful not to short the terminals— and don’t touch anything near the lamp output (T200/C200/CN200), due to shock if the inverter is working.

You could also check the transformer (T200) windings for continuity. The secondary (the two terminals to the left in the picture, connecting to C200 and “R202") should probably measure a few hundred ohms. The primary is of much fewer turns and heavier gauge wire, and between any of the five terminals you would likely measure no more than about one ohm or so.

I have sometimes seen inverter transformer terminals be poorly soldered to the board. If the DC voltage to the board (at CN201) is okay, and the transformer windings show continuity, it could be worthwhile to look closely at the joints using some magnification.

Good luck. Let us know what you find.

  [ Ignore ]  

Posted on: December 26, 2010 @ 08:41 AM
floris
Total Posts:  23
Joined  11-26-2008
status: Regular

maybe you can change the backlit with led’s or change the whole lcd for an tft screen

  [ Ignore ]  

Posted on: December 26, 2010 @ 01:14 PM
muzikoloog
Total Posts:  25
Joined  01-15-2003
status: Regular

Thanks so far for all the comments and suggestions. The story will continue. The first thing i will do is order some backlight tubes. They are not very expensive. This will be the most easy way to check. On one side of the tube of my xs the soldering pin broke. So i need a new tube anyway. I must say that it broke very quickly, while the other pin is firmly attached. So maybe this was the problem in the first place.

I will try to find them at an european distributor first. If this doesn’t work i will follow up on the suggestions of “5pindin”.

At the same time i will do some measurements on the inverter print. If the new tube doesn’t work and i can’t find the problem, Do you people expect that i can order this inverter print at a yamaha distributor? I don’t like to sent my motif to a repair centre, but if yamaha doesn’t deliver loose parts, then i have no other choice.

I will keep you people posted.

Greetings Mark.

  [ Ignore ]  

Posted on: December 27, 2010 @ 08:11 AM
muzikoloog
Total Posts:  25
Joined  01-15-2003
status: Regular

new developments.

i found the complete display for 98usd in China.
http://www.alibaba.com/product-gs/343371650/KCG057QV1DB_G77_lcd_display.html

For that price i ordered a complete display. I hope they will deliver soon. Still i’m going to try to fix my old screen first. I ordered some ccfl tubes online. If it works then i have a complete lcd new as a backup for the coming years. I will never sell my motif xs.

Now let’s hope that the inverter was not the problem.

Anyway if you people ever need a complete new screen then you know were to order.

keep you guys posted.

  [ Ignore ]  


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