[[SOLVED]] Dual problems with SY77

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thefonz003
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[[SOLVED]] Dual problems with SY77

Post by thefonz003 » Fri Oct 30, 2015 4:14 pm

I have an SY77. I've had it for six years and it's been very reliable for the most part. There's a pair of problems that come up occasionally; they usually don't last for more than a few minutes, but they recurred a few days ago and haven't yet gone away.

The first is that the display doesn't...well, display. It'll sometimes show a flash when it's first booted up but then it goes blank.

The second is that the pitch-bend wheel doesn't work properly. If I bend down, it will work, but when I let it go it settles on a pitch a whole-step (I think) higher than the original. If I bend up, it doesn't do anything.

These two problems have always come in tandem, and have always righted themselves in the past. I don't really know what to do now. I've taken off the bottom cover and haven't found anything amiss inside, but I'm not an electrician and have never soldered or anything like that, so I could be missing something. I'm definitely going to clean it out with one of those electronics-cleaning air cans, because there is some dust in there. Beyond that, though, I don't know what to do. I'm just hoping that once it's had a good cleaning and I put it back together and boot it up, it'll work again. I hope I don't have to replace the display, as nifty as the "Cool Blue" displays look.
Last edited by thefonz003 on Mon Nov 09, 2015 11:06 pm, edited 2 times in total.

Sonus
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Re: Dual problems with SY77

Post by Sonus » Fri Oct 30, 2015 8:04 pm

Connector CN115 for pitch and modulation wheels is located on the DM1 board:

Image

thefonz003
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Re: Dual problems with SY77

Post by thefonz003 » Fri Oct 30, 2015 8:35 pm

Sonus wrote:Connector CN115 for pitch and modulation wheels is located on the DM1 board:

Image
So, the yellow thing is the battery, and the thing with the red box around it is the CN115? Thanks, that saves some time.

thefonz003
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Re: Dual problems with SY77

Post by thefonz003 » Tue Nov 03, 2015 11:38 pm

I feel very overwhelmed here. I don't even know how to figure out what the problem is, much less fix it. Are there any common diagnostic procedures for an SY77?

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Re: Dual problems with SY77

Post by Sonus » Wed Nov 04, 2015 1:38 pm

thefonz003 wrote:Are there any common diagnostic procedures for an SY77?
http://www.synthzone.com/midi/yamaha/sy ... rvice.html

press and hold [VOICE] [D] [8]
manual test program [+1]
pitch bend test 10 [ENTER]

50 -> 99 move wheel from center to maximum
99 -> 00 move wheel from maximum to minimum
00 -> 50 move wheel from minimum to center

... NG or OK ... [EXIT]

thefonz003
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Re: Dual problems with SY77

Post by thefonz003 » Wed Nov 04, 2015 5:34 pm

Sonus wrote:
thefonz003 wrote:Are there any common diagnostic procedures for an SY77?
http://www.synthzone.com/midi/yamaha/sy ... rvice.html

press and hold [VOICE] [D] [8]
manual test program [+1]
pitch bend test 10 [ENTER]

50 -> 99 move wheel from center to maximum
99 -> 00 move wheel from maximum to minimum
00 -> 50 move wheel from minimum to center

... NG or OK ... [EXIT]
Awesome, thanks! That makes me wonder, though...how much of this info is supposed to show up on screen? Because the screen's one of my problems. I'll just do the LCD diagnostic first, I guess.

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Re: Dual problems with SY77

Post by madtheory » Wed Nov 04, 2015 5:48 pm


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Re: Dual problems with SY77

Post by synthRodriguez » Mon Nov 09, 2015 1:14 pm

Fixed it.

The solder joints for the 5 VDC header pins from the power supply board going to the DM1 board needed reflowing. Solder-Wicked out the old and flowed-in new.

Were cracked in the usual manner from age. Needed a 10x glass to see it though.
Last edited by synthRodriguez on Mon Nov 09, 2015 9:45 pm, edited 2 times in total.

thefonz003
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Re: Dual problems with SY77

Post by thefonz003 » Mon Nov 09, 2015 6:39 pm

scottrod wrote:Fixed it for him.

The solder joints for the 5 VDC power header pins coming off the power supply board going to the DM1 board needed reflowing. Were cracked in the usual manner from age. Needed a 10x glass to see it though.

^This guy. He's the best. Just needed some more solder, but, as he mentioned, not noticeable to the naked eye. The SY77 now works perfectly again...well, except for the stuck buttons, but neither of us felt like digging all the way through from the back to the front.

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