When the one I was repairing blew up I did a quick Google search and the following tales popped up:
[I am interested in ARC because the sound is great intimate and truly beautiful.I am an original owner of PH5, CD3mkII and LS26 and over two years I never had troubles. They all work beautifully
But the few malfunctions I experienced with the amps were different.
My newer VS115 at approx. 165 hours during the warm up period suffered a fairly catastrophic failure.
The V1 tube was glowing with a white colour, a capacitor or perhaps a resistor became overheated and flamed out with blast and smoke.
Luckily the rest of the equipment were not damaged.
After two weeks the local ARC service repaired the unit and I had to pay for the tube.
At approx. 255 hours it happens again. This time I heard only a blast.I returned the unit to the local ARC and I am waiting but I am very disappointed.
(I checked the Bias and the wall voltage every time I heard music)
The same happened 2 years ago to my VS55 I previously owned at approx. 400 hours. At that case ARC had sent me through the local dealer a new circuit board. ]
Most recently, I purchased the ARC 610s and I was stunned when one of the maps blew up within 7 seconds of turning it on. I sent the amp back to ARC, only to find that my other amp blew 2 within 2 weeks while the first amp was being repaired. That was the final straw for me. Unfortunately, I am not alone as this has happened to several others. What I found particularly dumb, is that ARC should have been cognizant of these failures and at the very least, designed their latest amps so the power resistors can be easily accessed for front of board repair. At the very least, they should have raised the resistors high enough off the board so the board does not char when the resistor blows.
Regarding power amps, had a D70 for a year, and then a D125 for 8 years(both second hand) - in both cases they developed faults which the local (Sydney, Australia)technicians could not fix, despite repeated costly attempts. Loved the sound, especially of the D125, but ownership was frustrating - for the last two years the D125 pretty much sat unused, and old Luxman SS amp filled the gap.
I'm afraid I wouldn't buy another ARC power amp.
[ok correct it should be 65mV and the multimeter is not defect, but this is not the point. By "blast" i mean a noisily explosion -- although i was scared i checked the bias and i measured at all tubes 89-90 mV. ]
Years ago, I owned a D-250 Servo. After a few months, with not that many hours on the stock ARC 'selected' tubes, a loud dramatic explosion occurred with smoke, etc. I had to send "Big Bertha" back to Minnesota for repairs. When it returned, I sold it.
Its a common problem for ARC. The same thing happened to my VT-100. When it blew, a piece of the resistor hit me right in the face while sitting in my listening chair.
I had two VT50s over the review period. The first broke in well and everything was progressing nicely until, in the middle of a quiet listening session, one of the bias-control resistors literally blew apart. The bang was quite loud and accompanied by a flash and smoke,
One of the issues with the one I was repairing was that the mains transformer was grossly under-rated for its job of supplying 8 x KT88 tubes. This is exacerbated by the fact it seems to be designed for 60hz not 50hz and it is also rated at 230 so the the circa 250v UK mains is a killer blow.