Marquis Hot Tub, Instrument Panels (Balboa Instruments main and side auxillary) do not display the LED read out. Replaced main control panel twice, replaced 250 W. 3/10 fuse.

The topside controls aren't fused so the fuses wont be the cause.

It can only be either the PCB, the topside controls, or a bad connection at fault. Check that they are plugged in correctly, make sure that the PCB is configured correctly for your topside controls.

It's rare for both the main and auxilary topside controls to fail. You can try plugging in another main topside control without fully installing it... at least you can then return it (ask whether or not return are accepted, I don't personally accept any returns if parts are specially ordered) if it doesn't cure the problem.

Regards,
Ian.
http://hottub.synthasite.com