Hello, needing help with LittleBear B4-X

Hello,

I joined hoping to find a solution to my problem, seen some threads from guys that are very knowledgeable about the circuits and components, figure to give it a shot here and maybe learn a thing or 2.

My B4-X recently stopped working and I've been trying to fix, but I am very new to this kinda thing. The tubes no longer light up or heat up but I'm not sure which part would need replacing or fixing (DC-DC Converter or tube or something else?)
I've done what I can with a multi-meter and seen that the battery is fine, sitting at ~12.5 V. Where would I probe to check the DC-DC converter and the tubes and what should I expect to see? What else might have failed to cause this?

Thankful for any information

Cheers!
 
Welcome to diyAudio :^)


JMQ413-N_12_1199x1199.jpg


This: https://doukaudio.com/en-ca/product...-vacuum-tube-headphone-amplifier-balanced-amp


dave