For entertainment purposes only ;) How to calibrate - or modify - a Furman AR-117 voltage regulator. This specimen is from circa 1995 - probably the best year they were made. They were made in Furman's previous plant in Greenbrae (where I was once given a free tour!). They then moved up to Petaluma, California where Mesa-Boogie is also headquartered.
If you feel confident you can do this, make sure you plug everthing into an Isolation Transformer, wear rubber gloves of some kind (and goggles can't hurt), and also rubber shoes (I'm not kidding Sol Rosenberg).
ALWAYS have a load when any voltage regulator is switched on; at least 1A or about 125 watts. Never keep them on with no load. These are not power strips.
Another warning: never plug in anything besides electronics into an AR-117 (don't plug your fridge, electric motor, fan, AC, and probably a halogen light - like you see in this video, etc). This is just for audio-related electronics.
I also recommend (if you have an older unit like this one) pulling out the 15A fuse, and replacing it with a 5A (or whatever your studio draws in current). Start with a 10A fuse maybe...
Using a 5/64" (about 2mm) allen wrench (or hex key), adjust trimpot R36 - carefully.
Something not covered in the video: there is an empty cut-out space above the power cord grommet, which allows for a switch to change it from an output of 117v down to 100v (voltage used in Japan - but could be useful for old tube amplifiers). Back in the 90s Furman said they would add this switch for free. (wished I knew that earlier). This prompted me into thinking it's a relatively simple add-on, so....if you know how to do it, comment?
The Furman AR-1215 was released after the AR-117 was discontinued. That happened circa 1998? Both models cost around $750 total (inflation-adjusted to year 2021 dollars). The AR-1215 models started out being made in USA, but unfortunately were made in virus-ridden Ch_na :(
The earliest AR-117s had original mother and daughter boards - designed circa 1989. I do not have a specimen to operate on, sorry. I think I remember that the 1989 motherboard had not four, but three trimpots...
Lastly, whether you have an AR-117, AR-230, AR-PRO, AR-1215, AR-1230, etc, never leave these devices powered up with nothing drawing power from them. They cook themselves. (you can actually hear a louder hum when they don't have anywhere to send the power to).
This video took me about six hours of preparation time, and I did it for free, so you better make YOUR contribution!
Canon ELPH 110HS camera; background music: S.Pumpkins pastich. medl.