Problem with AR Ref 300 Mk II - any experience?

Corrected the subject (ARC for Audio Research, not AR)

Thanks to everybody for the valuable input!
I took the amp to out local ARC service center today, and asked them already for the things you suggest (cueck the circuit board, check all tubes,...).

[Because someone asked: I bought the amps 3 years ago, from
a dealer, with warrenty, at a fair but not cheap price.
So I guess this was ok, given that these amps were no
longer available. But I agree that there is always some
incertainty regarding the real hours on the tubes...]

Again: thanks to all of you, your input was valuable, I learnt a lot, and it gave me confidence that I do the right thing (having the amp checked in detail).

Regards,
Otto

Hi BIF: thank you for your suggestions - quite correct
(see below)

Hi Beersum8,
hi Gert,

thanks for the reply - you have been absolutly correct: the fuse war broken! I took the one from the other amp and it was up and running again.
I recognised that the broken fuse had a very thin wire within the glass cylinder, while the working one had a much thicker, spiral-like wire inside. Obviously a less sensitive type.

My original intention (when I ended up with the no-signal on all valves) was to replace the V5, that seemed to have a particular problem (it was not possible to adjust it sufficently to get the meter into the green range - although it was close to it, thats why there was no sonic
effect until now).

So I replaced it again, with the result that one component
(close to V5) got burnt, and two parts (on the V14-15-16 circuit board) kind of exploded.

I wonder if a bad tube can cause this (assuming that the replacement tube I purchased at ebay is bad - despite its detailled description). My other suspicion is, that the amp
had an old problem (I recognised some fixed circuit paths on the V5-V8 circuit board) are responsible for this.

I also wonder which type of fuse is the correct one?
If the replacement valve is really the cause for all this,
then the "thin" fuse prevented the amp the first time
(by getting broken) - but the "thick" fuse did not so
(it is still ok, althought parts of the amp got burnt).

I hope the service center of my local dealer can fix the Amp and answer my questions as well...

Best regards
Otto

Hi Bifwynne,

thank you for your input! I already decided to have our local ARC service guy look at the whole amp...
[in fact: a few days after having bought the amps, the other one has had a problem, and I had it checked completely then].

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 impact to be heard though.
Is this a sign of age of the tube?
Is it necessary to replace then - or should I wait for any acustic impact before replacing it?

Again, thank you very much,
best regards,
Otto