Thank you for posting your question on Just Answer! I will be happy to help you with this problem
if you order the upper you should be ok if you have a meter would like for you to measure the VSCAN voltage
(Please click on high lighted words) this is my sample may not be the same model but doesn't matter the technology is the same.
Would like for you to take your meter and place it on DC voltage the positive end on every connector that says a voltage and the negative wire to the panel this is the best ground. Turn on and see if the voltage is present at the VS, VA, V-scan, According to the Panel label, Also remove each board from the power supply to make sure they are not holding down the voltage If you don't find one that's trying to climb, or shows close to what it should be, another method is to locate a short circuit place meter on ohms or beep test follow same procedure no voltage should be shorted to ground. And this is the problem, You can unplug each board one at a time, Starting with the Y-SUS then the Z-SUS.
Normally the parts for this unit is a kit Y-SUSTAIN AND UPPLER/LOWER BUFFERS, this is what most manufacturers would want you to do, purchase them. But go to high lighted words and go through all the voltage checks to find the bad part, here is also a chart that should help a lot, Also this is a picture that will help with identity.
Well Good luck friend, and if my efforts are appreciated, feedback and a bonus will be appreciated
Thanks Simplified click here