Winter Project - 3 MC-40's to restore / Update?

I am going to call these done & button them up -

I ran them for 20+ hrs each at 20W continuous sine output with a 100w non-inductive dummy load, and then checked the voltages at idle - all were within 3-5% of nominal with a 120VAC input. Amps all drew +/- 1.25 - 1.5amp, at 20W, got moderately warm. At idle merely .75A current draw.

Then I ran some tests to see how the B+ changed with increased output:

B+ @ C16A - 1st filter Cap - Nominal = 470vdc
Amp #1 Amp #2
Idle 451 452
2W 451 450
5W 446 446
10W 444 441
20W 434 435
40W 422 425

Clipping in each had an onset of 50+ watts

(Will run the same test above on the 3rd amp, it has also been on for 20+ hrs, nominal voltages at idle)


Thanks for all who took the time and thoughts to comment and offer help and guidance!

For masochists, I started a thread of several questions relating to the next part of this - updating / renewing my friends Marantz 7C's and #1 Consolette in the TUBES section
 
Back
Top Bottom