Columbia Model 229B 78 rpm Record playing unit

[DrStrangelove]

The easy way is to use an analogue meter if you have got one.

That's why I have kept the AVO. A plastic tube with Lithium coin cells does the HT battery with 10 years life and no leaking.

Thanks, that's a good idea, though I never noticed the B121 layer cell doing much leaking. (Then again I haven't seen one in 30 years).