Hi JonFo,
When I measured that string of diodes notice that the last 4 was opened so I thought zener are gone.
Replaced with new zener , well it was still open when tested with dvm so am scratching my head on this.
Thought problem was resolved as 1 panel is lower in volume. Good news though after replacement of zener
volume is up but it's still lower by 2-3 db. Been surfing to find info on how to balance out the sound level
but found nothing in relation to this particular board . Perhaps you can advice on this Jon.
Thank you