Thank you for posting your question on Just Answer! I will be happy to help you with this problem.
A POP is usually the Y-SUSTAIN and possibly the driver boards hooked to it
read bellow for best procedure in repairing it.
Normally the parts for this unit is a kit Y-SUSTAINBOARD and Z-SUSTAIN BOARD, this is how most manufacturers would want you to do but you can check for open fuses on the y and z boards yourself and get lucky and find the bad board, also measure your VS and VA and V SCAN voltages make sure they are coming out of your power supply. It is possible for having a bad FET some were. What they should be is labeled inside of the panel VS 140v VE 60v and VSCAN -190v. Your VS voltages are carried by the Y board which is on the left side and VE carried by the Z board on the right which ever is missing by measuring the plug at the power supply is your bad board. You can also disconnect from the power supply one at a time to see if you get any changes, the bad board would cause a different situation when powered on. Also remember there are driver boards connected to the Y board they have chips on it look closely at the chips sometimes they blow up and they will have small pin size holes in them, hope this helps you friend and
Good luck friend, and if unit works fine, feedback and a bonus will be appreciated