Problem with AR Ref 300 Mk II - any experience?

If you are on the West Coast, Gary (Hifigeek1) is an authorized ARC service tech and can he you. You can e mail him through the A'gon system. If not, call ARC and ask for Kal. He can put you in contact with a local ARC authorized service center, be it in the CONUS or elsewhere.

I'm not electronics savvy, so take with this with a half a grain of salt. But if all the power tubes are subject to the same problem, it sounds like a common power supply issue.

Good luck

Ozatschek, 2 quick follow-up points. One -- each amp weighs 132 pounds. I would try and find someone who does house calls. No joke. There's an ARC authorized service tech who lives near my house and makes house calls. He was over about 2 or 3 weeks ago to fix an open bias resister. The fix took all of 30 minutes.

Two - here's something else you can take with a grain of salt since I'm not a tech. I read the ARCDB web site description of the Ref 300. I see that it has a bunch of regulator tubes in the power supply. Wild arsed guess here .. but did you check all of the tubes, particularly the PS regulators for life? Just asking. If a blown PS tube controls the output power tubes, it might affect all of the output tubes, which is your situation.

Incidentally, regardless of how you make out, I would still contact ARC to see if the tech folks have any preventative maintenance suggestions such as replacing tubes, caps, etc. Your amp is not ready to be retired, but it ain't no spring chicken either.

Good luck and let us know how you make out.

BIF

Otto, you mused, "I wonder if a bad tube can cause this (assuming that the replacement tube I purchased at ebay is bad - despite its detailled description)." The answer is yes. If a tube arc'ed it can take out passives such as bias resisters. An old cap can also flames out too.

You also querried whether "the amp had an old problem (I recognised some fixed circuit paths on the V5-V8 circuit board) [which is] responsible for this." Could be. That's why I renew my suggestion that you have a training tech look the amp over. In fact both amps.

Even better, I would line up an ARC authorized tech to look the amps over. If you need help locating an ARC authorized tech, call Kal at ARC. He can help

Typo -- was in a rush. The penultimate sentence in the second paragraph should read "That's why I renew my suggestion that you have a [skilled] tech look the amp over."

Otto, you wrote:

(1) "I already decided to have our local ARC service guy look at the whole amp..."

Me: Good call.

(2) "One question regarding my original V5 tube: when checking it with the right meter on the front panel, it did not reach the green area any more. I tried to adjust it, but even in the "full" position, the meter was not in the green area (but close to). There was no acustic [sic] impact to be heard though. Is this a sign of age of the tube?"

Me: It could be.

(3) "Is it necessary to replace then - or should I wait for any acustic impact before replacing it?"

Me: Absolutely not!! If those tubes are outside the 2000 use marker, as Gary (Hifigeek) said, you are living on borrowed time. The tube's propensity to fail and take out passives (e.g., bias resisters) increases with age.

Otto ... it appears that you are not sure how much time has been racked up on the tubes. I am hesitant to recommend this, but if you have serious doubts about hours of use, replace the tubes as soon as possible.

One more suggestion -- the amp is not that terribly old by ARC standards. Having said that, I find it odd that the amp may have blown other passives like caps, or required some circuit board repairs. I suggest you contact Kalvin Dahl or Chris Ossana (the Service Manager) at ARC and ask them if the local ARC tech should specifically perform certain diagnostics to ascertain whether other parts need to be replaced.

I am also hesitant to suggest my next point, but I would certainly include it in the conversation. If one of the circuit boards looks discolored because of a passive failure, I would ask Kal or Chris whether it would make more sense to simply replace the suspect board.

The Ref 300 is an expensive piece of gear. To sound its best, it should be put into tip-top operating order. That includes fresh tubes if warranted. And as I said above, I would make sure that both amps are thoroughly looked over.

P.S. Did you recently but the Ref 300? If so, I wonder if its worth returning it if that's an option.