SY99 backlight repair problem

The Yamaha SY99 is a synthesiser combining frequency modulation synthesis (branded as Advanced FM) and sample-based synthesis (branded as Advanced Wave Memory 2) and the direct successor to Yamaha's SY77/TG77

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m1rk0
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SY99 backlight repair problem

Unread post by m1rk0 » Mon Nov 17, 2008 1:17 pm

Hi,

I spent most of yesterday taking apart my SY99 to install the the new EL foil I purchased from http://www.midi-rakete.de . Thanks to EX5_Etc and Derek for your instructions!

What a nightmare :)! I took the SY99 apart, put the new foil between the old one and the LCD glass, like Derek describes in his guide, then soldered the connectors to the board and finally reassambled the machine, only to find that... I still have no working backlight :( . Everything seems to work as before, but the new foil doesn't do its job.

I feel a bit reluctant to disassemble the myriads of PCBs and cables again, unless I have a good idea what the problem might be. Is there another typical cause for a non-working backlight than degradation of the foil? Or may I have damaged it while soldering it to the board?

Also, if I try to do this again, is there a way to test the function of the backlight, what cables must be connected in order to "see the light", so to speak.

One good outcome of all this is that the SY99 doesn't seem to make the hissing sound it made before (not on the line-outs, but the machine itself made a very high tone). Could this be related to my disconnecting the old foil?

Mirko



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Unread post by Clyde » Mon Nov 17, 2008 2:17 pm

Not sure what is causing your current backlight issue, perhaps someone experienced with the lcd and backlight can provide more info. The high pitched whine you described has to do with the power inverter for the lcd (or something like that), those users that have changed over to the new blue lighted lcd screen have all commented on the noise being gone.
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Unread post by m1rk0 » Mon Nov 17, 2008 2:33 pm

Thanks, Clyde! I guess the power inverter is for the light, which needs a high frequency AC voltage, not the LCD itself? That could mean the whine is gone on my unit because the inverter doesn't work anymore. Would a bad connection of the black/red cable that connects to the display cause the whine (and the light) to stop? It looked like a power connection to me, though I'm not 100% sure.

Mirko



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Unread post by Clyde » Mon Nov 17, 2008 2:39 pm

Mirko, that sounds logical to me, but someone with more knowledge of that area would be better qualified to give you a definitive answer.
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Unread post by Derek » Mon Nov 17, 2008 8:15 pm

Sorry to hear that you're having trouble.

If ou have no high frequency whine, is it a sign that the LCD backlight foil is not correctly connected or indeed it may be faulty?

I can't really offer much in the way of help as mine worked first time. As the inverter gives an AC voltage, I don't think there would be polarization issues.

I don't think you'll avoid having to take it all apart again. :(

Maybe if you email midi-rakete (which is where I got my foil from as well), they may be able to give you some advice on how to test the foil?


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Unread post by m1rk0 » Mon Dec 15, 2008 12:06 am

I couldn't motivate myself to open the SY99 again so I ordered the blue display and have now disassabled everything again. The new display seems to be a bit thicker than the old one (also mentioned by EX5_Etc in the other forum) to the effect that I cannot fit in the other PCB (the one that holds the buttons below and left to the display). Especially, the quartz component on the display seems to be in the way. How did other people solve this? I wonder why nobody mentioned this as a obstacle, or am I missing something?

I thought of removing the quartz and putting it somewhere else with a cable, but this seems quite an unorthodox method when everybody else is able to do this without modification...

Mirko



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Unread post by Clyde » Mon Dec 15, 2008 1:46 am

I re-read the thread on the blue displays at the EX5Tech forums and from what I understood the PCB needed to be carefully trimmed/modified to fit. Since I have not done this mod I would highly suggest you wait until someone that has done it responds to your question.
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Unread post by Derek » Mon Dec 15, 2008 5:56 pm

IIRC I had this issue with putting the blue display in my SY77. The display is thicker, but I found there was enough flex in the PCB that goes behind it to tighten the PCB down without causing any problems


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Unread post by xpi0t0s » Wed Dec 17, 2008 11:06 am

General principle worth observing when dismantling stuff: make sure it works BEFORE you put it back together. Watch out though, there will be exposed parts at mains voltage that you have to be careful about, and make sure there's no possibility of anything shorting out (e.g. if a PCB is not in its usual mount, make sure it's not sitting on something conductive before you power up).



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Unread post by m1rk0 » Mon Dec 29, 2008 2:02 pm

xpi0t0s wrote:General principle worth observing when dismantling stuff: make sure it works BEFORE you put it back together. Watch out though, there will be exposed parts at mains voltage that you have to be careful about, and make sure there's no possibility of anything shorting out (e.g. if a PCB is not in its usual mount, make sure it's not sitting on something conductive before you power up).
Yes, but have you ever dismantled an SY99 :)? I doubt it's possible to test anything without putting it together. At least, I think you wouldn't be able to fit everything together without disconnecting the circuit boards again before you actually fasten all the components.

Anyway, I have put it all together (with bent PCB, like Derek suggested) and I am now the proud owner of a (working) SY99 with blue display. Again, thanks for all your help!

Mirko



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Unread post by Clyde » Thu Jan 01, 2009 9:56 pm

And doesn't that blue display look awesome!! I want to put that in both of my SYs.
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Re: SY99 backlight repair problem

Unread post by radiolite22 » Sun Aug 23, 2015 5:56 pm

Hi sorry to bring up an old post.

Recenty I tried to replace the backlight of my sy99.

followed Christopher Baxter's guide as I couldn't get the old backlight out.

After reassembled everything and powered on, the light works but the lcd dot matrix are only half readable. There are a few vertical lines on the lcd.

http://i841.photobucket.com/albums/zz33 ... 182618.jpg

Image

http://i841.photobucket.com/albums/zz33 ... 182546.jpg

Image

The lcd was working fine and all wordings are clear. Was just pretty dim so I wanted to replace the back light.

So I thought I may have reassembled the lcd wrongly and dismantled everything again, fixed back and now it seems worst. More vertical lines. .. :( Now it is hardly readable.

Lcd reading was working fine prior to replacing the backlight so I dun think it's faulty.

Anyone can help? :(



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Re: SY99 backlight repair problem

Unread post by Derek » Sun Aug 23, 2015 7:17 pm

Hi

It's hard to diagnose these things remotely, but if I were you I'd take it apart again and check the continuity of all the data lines on the ribbon.


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Re: SY99 backlight repair problem

Unread post by Derek » Sun Aug 23, 2015 7:19 pm

I've closed this thread to consolidate the responses on the other thread that you started (please avoid multiple posts on the same subject :) )

http://www.yamahaforums.co.uk/forum/vie ... =55&t=8283


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