Suggestions for testing a never installed, 20-year boxed amp.

I’d contact Pass Labs. They may tell you to run the amplifier through a variac in order to allow the capacitors to reform safely. Best of luck. 👍

Just curious: How did you end up coming upon an unused for 20 years boxed up amplifier?

Many years ago I rebuilt a handful of very old (circa 1870-75) Acoustic Control Corp. solid state guitar/bass amplifiers.

I had this same question. Yontz, at Mad Scientist Audio (? - been a long time) suggested using a light bulb current limiter, basically a light bulb socket spliced into a short extension cord with a 60 watt bulb.

NEW electrolytic caps AND old, discharged ones appreciate slow voltage build-up. Worked like a charm.

Lately though I use a 20 amp variac on recapping projects. ADCOM preamps, amps, tube amps, 1.5 kW HF linear amps, etc.

Curious to know what you do and how it works out for you.

Buy a Chinese variac on eBay for around 100$. Power up slowly over 24hrs. Make sure you get the proper amp variac. You should be ok. Good luck. 

All good ideas. I'll try to contact Pass Labs Monday before doing anything. I already have a lightbulb current limiter setup, a variac, and some 250W 8ohm resistors.

My acquisition of this amp is a long story. The company I worked for, at the time, set up a number of QC stations and 3rd eye approval stations for mastering DVD movies for major studios. This amp was never used in any of the setups. It sat in the shop for years until the US operation was closed. I purchased this and some other equipment from the company before moving on. My plan was to set up a better home theater system with this amp. I also purchased a new Marantz AV7005 that's also still in its box. Basically, I couldn't find speakers that my wife could live with. Now I'm trying to decide what I should do with these items.

I'll let you know what Pass Labs tells me. Thanks again!