Hi guys, I have an old, original Variax 300 that works great with the power adaptor and special cable. However, when installing a battery pack (or even a 9V battery) I get no output at all. Is there a way to check my inside connections to make sure they're right? Is there a spot on the board I can check for DC voltage to see if it's getting the proper 9V? Is there a common issue I can troubleshoot here? Thanks for your help.