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Hello,
I'm so glad to see this forum is still alive! I got a used XS8 from GC. (My 2nd time) It was a very good deal. The box arrived soak and wet and crushed from UPS. Fortunately they wrapped the unit like a mummy in bubble wrap so it wasn't wet. But it took one heck of a ding directly in the center of the body above the LCD screen.
The unit performs as normal, except the screen contrast cannot be adjusted with the contrast knob. It's currently at a tint I have to bob up and down to make out what it's displaying. I have a copy of the Service Manual and ran the appropriate test. The LCD and Backlight passed. I suspect the problem is either at the knob itself or a connection to the LCD. I have removed, inspected and and reinserted the LCD and it's the same. No problems noted on the connections. Fortunately it appears nothing on this inside took a hit.
It there anyone who can offer advice on my next troubleshooting steps? I don't want to go in there poking around with a Multimeter especially not knowing the correct values.
GC made very good on the damage. Kudos to them! I mentioned this was my 2nd XS8. I bought my first one new when they came out. Hard times fell on me last year (as it did most) and I had to trade it away in a deal to replace my car. I went almost a year without my synth. I missed it so much. It was My Axe. It's so cool, it only took a week or so to get my playing back to where I left off and remembering my little programming short cuts.
I want to dig deeper into this beast studying MIDI more and customizing sound. But the screen is a HUGE deterrent! I know it's old tech now, but I really enjoy it. The Montage is wayyyy out of my league as I have retired. The MODXM maybe an upgrade someday. I love it has the eight sliders again. Thanks for reading. God Bless. (Ps I was able to bang out the dent in the metal case as much as possible, but it's still kinda visible.)
Posted : 23/01/2026 5:49 pm
Well, I know what I'd do.
I would take a multimeter on Volts and hook up the negative lead to signal ground and positive lead would start poking around:
On same board as contrast variable resistor (aka "DM" board) ...
1) DM board's IC827 pin 1. Move contrast adjustment and see if voltage goes up and down.
If that's ok ...
2) Move positive lead to CN824 pin 13 (turn contrast, look for voltage going up and down). If not ok, inspect series resistor.
On JKAN-LC board (which is cabled to DM board's CN824) ...
3) Move positive lead to JKAN-LC board's CN202 pin 13 (same test moving contrast). If not ok, suspect cable connection on either DM or JKAN-LC side.
4) Move positive lead to CN203 pin 8. Same test.
... And follow the bouncing ball all the way to the LCD.
If the first step fails (measuring at the opamp output) then I'd disconnect the cable from CN824 and remeasure. If that's still not OK then I would start inspecting the components on the DM board for operation. Turn off and unplug the keyboard and then use resistance to check ohms across the variable resistor to make sure it's changing when you move the contrast. And if that checks out walk through the various components. Make sure the op amp power checks out. Etc.
This is fairly straightforward to someone who's done tech work or any electronic design. Shouldn't be difficult to find someone in your area to take a look. There's certified techs Yamaha has listed or you can go elsewhere. This one shouldn't require the highest proficiency with Yamaha gear.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R
Posted : 27/01/2026 5:38 pm
Btw: I had something similar happen to me. Not GC but a different retail store. They paid for the repairs and I took the equipment to my own repair center. Wonder if that's something GC would entertain.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R
Posted : 27/01/2026 5:43 pm
