VARIAC: Procedure??? 2 old 30 wpc tube amps, unused for 4 years

This is the procedure for an H-K Citation 2,
a 60 W/channel power amplifier.You can adapt the steps for your own amp:
Powering up a long unused Citation II

1. Check continuity of all the grounds. Check there
are no shorts to ground from the B+, bias, or heater
supplies. Turn the bias pots fully clockwise. Center
the AC balance pots. Put a load resistor on each
channel's output (8 ohms or 16 ohms is fine, just
connect it to the corresponding terminal.).

2. Install the 12BY7A's - (line level tubes) DO NOT install
the power tubes yet. Bring the amp up on the variac 30
volts at a time. Be sure the bias voltage at pin 5 increases
along with the line voltage from the variac. Run the variac
up to 110 volts or so and you'll see 60+ volts at each pin 5.
Be sure all the tube heaters are lit once you get up to 90
volts or so.

3. Shut the amp down, let the charge bleed off the caps
(you may have to wait a while or carefully use a bleeder
to speed it up). Don't get bit by those caps - they'll knock
you on your ass!!

4. Install the remaining tubes (the power tubes). Bring
the variac up 30 volts at a time, watch for the bias voltage
to climb as it should and check the B+. Be sure all the tube
heaters are lit once you get up to 90 volts or so.

5. Once you get to normal line voltage on the variac,
then start biasing the power tubes. Start slow, set the bias
for each tube at the mid point of the meter (or about 50 ma).
Let it run there, watch for any problems, check voltages, etc.
Let it run 10 minutes, keep checking all the tubes. Then run it
to just below spec (a couple widths of the needle below
the mark on the meter). Do the same thing as before - give
it 10 minutes. Finally, run the bias to spec, and monitor/
readjust as needed for about 1/2 hour.

Once that's all done the AC balance can be set, and you're
ready to listen! But do check the balance often in the first
10 hours of use, then again around 25 and 100. After that it's
just once every 3-6 months.

Agreed on the dim bulb tester.  That said, I use an isolation transformer feeding a variance feeding a dim bulb tester for all tube equipment under test.  But for a 4 year old device, I’d start with the variance at 100 percent but the dim bulb tester at say 30%. Assumes a multi-bulb unit. Any problems will be obvious in a minute or two.   Good luck!

Ideally, a power meter, or at least an ammeter would be used with a variac, but the bulb is a passable workaround.  Also as mentioned before, you should keep well below the recommended bias reading until the amp is fully powered, and has been on for some time. And yes, dummy resistors or speakers must be connected.  Bad idea to run a tube amp with no load.  

thanks everyone, a good mix of input as always. and great sounding results!

What I did: the 5v4 only: Variac 50V for 30m; 75v for 30m; 90v for 30m. then all tubes in, repeat.
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I tested the tubes, they are all good. They had quad matched EL34 (RCA’s made in Great Brittan), they are still matched in strength on the meter. They had original Mullard EL37’s when I inherited them, but eventually they got weak, and EL37’s cost too much way back then. I don’t need the extra power, many options exist.

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Before they were fed from my McIntosh SS C28 Preamp (or source direct). Now everything goes thru my McIntosh mx110z Tube Tuner/Preamp recently overhauled by Audio Classics. They are dead quiet together up to my max volume setting (as I hoped they would be/used to be with C28).

One of the reasons I love the Cayin is because it sounds like these Fisher’s do (with added features and remote volume). Now, the Fisher’s sound like the Cayin. Hah.

They are Hard Lookers. Donna says they look ’interesting’.

they look like this pair of 80-AZ:  I never had the metal cages, they were concealed in the console.

https://reverb.com/item/40173234-pair-vintage-the-fisher-model-80-az-tube-amplifier-rare-military-ve...

my Cayin looks one day old.

https://6moons.com/audioreviews/cayin/a88t.html
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thanks as always, you are a great bunch hear,

Elliott

One simple solution is to use an inrush current limiter.  You just plug your amplifier into it and flip the switch.  Maximum voltage is applied in about 15 seconds.  I purchased mine at sigtomics.com, however I see that website is no longer active. The email address on my unit is tsiglin@sigtomics.com.

hope this helps.