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EQUIPMENT FORUMS >> MINI TORII >> Left channel is off!
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Message started by Fireblade on 10/26/12 at 19:50:03

Title: Left channel is off!
Post by Fireblade on 10/26/12 at 19:50:03

Hi!

I was listening to my Mini Tori-based rig, and all of a sudden my left channel went off. On inspection I noticed the large OA3 output voltage regulator tube on the left channel was off. All other tubes seemed lit (except for the OC2 input voltage regulators, which don't ever really show light that can be seen during daytime).

I switched the OA3's to make sure this was the faulty tube and, alas, this time around the suspect OA3 when lit on the right channel and the other one off on the left. On even closer inspection, I noticed that now my left-hand channel's EZ81 rectifier was off!

So, apparently my JJ EZ81 went off, and this probably killed the feed to the OA3 on that side. Since I now know both OA3's are fine, I'm concluding the faulty tube is indeed the JJ EZ81.

This is consistent with the history of faulty JJ EZ81 rectifiers with the Mini, as per forum reports. Anyway, I was making plans already to do some tube-rolling, including these, so I'll just have to wait ... Bummer!

Any ideas what may have caused this, other than the QC issue with JJ's?

The faulty tube's description: JJ EZ81

Title: Re: Left channel is off!
Post by Lon on 10/26/12 at 19:54:26

Truly a bummer! Tube failures can be mysterious, sometimes their number is just up so to speak. I'm no expert, but as all other tubes seem functional I would wager that any problem is specific to the tube. Have you tried "wiggling" the tube in the socket a bit to see if it will fire up? On my Torii the right rectifier sometimes needs this attention. I really can't seem to send it back to be looked at. . . .

Hopefully you can find a replacement Sylvania or a pair locally.

Title: Re: Left channel is off!
Post by Fireblade on 10/26/12 at 20:30:19

Lon,

I'm sorry. I just edited my original message. Turns out the faulty tube is the JJ EZ81, not the OA3. Apparently this rectifier controls the feed to the OA3, so when the JJ EZ81 went off it turned off the OA3. Both OA3's lit when coupled with the still working JJ EZ81.

Regarding local tube replacement, it's not possible that I know of. Very few people here appreciate this tube amp hobby. The only valve amp audio store I know sells only McIntosh amps, and these probably do not use this type of rectifier.

I will try your suggestion of 'wiggling' the tube in its socket. This, of course, is done when the amp is off, right?

I may be asking Les to send me some over from Florida. Thanks, Lon.

Title: Re: Left channel is off!
Post by Lon on 10/26/12 at 21:35:22

That's the way it works in the Torii Mk III as well, the rectifier feeds the two voltage regulation tubes, the rectifier can be out or not working and the power tubes and input tubes glow.

It just occurs to me the test that you probably have already done is to swap the rectifier tubes to ascertain whether the left tube works in the right position.

The good news is that the rectifier may be easier to find locally than the OA3, OB3, etc. You may also find a pair of the other rectifier types used in the amps through the McIntosh dealer; they likely use one type of these tubes.

Title: Re: Left channel is off!
Post by Fireblade on 10/26/12 at 22:23:55

Lon,

Yes, I tried swapping the rectifiers to corroborate the faulty one. There's no doubt. I also tried 'wiggling' it in its socket, to no avail.

I will try to contact this McIntosh store just to check, as per your suggestion. We'll see.

Thanks,
David

Title: Re: Left channel is off!
Post by Lon on 10/26/12 at 22:28:30

David, I'm really hoping they can provide tubes. I know what it's like to have your amp down! I know you'll keep us posted.

Title: Re: Left channel is off!
Post by Fireblade on 10/26/12 at 22:41:59

Yeah, freakish! Oh well, this way I get involved in tube-rolling earlier than I thought, although 'the hard way' :) Thanks for the good wishes!

Title: Re: Left channel is off!
Post by Rivieraranch on 10/27/12 at 00:12:49

Les who?

And this illustrates why you should have spare tubes.

Title: Re: Left channel is off!
Post by Lon on 10/27/12 at 01:07:01

That would be Les Lammers, one of our "Senior Members." :)

Title: Re: Left channel is off!
Post by Fireblade on 10/27/12 at 01:30:44

That's right, Rivieraranch, I think you warned me a long time ago . .. You were right!

Title: Re: Left channel is off!
Post by opnly_bafld on 10/27/12 at 01:33:33

"And this illustrates why you should have spare tubes."

....or several amps. ;)

Title: Re: Left channel is off!
Post by Fireblade on 10/27/12 at 01:55:16

Yeah! But I don't feel like selling my bike anytime soon! :)

BTW, have you acquired a Decware amp already?

Title: Re: Left channel is off!
Post by opnly_bafld on 10/27/12 at 02:36:36

"Yeah! But I don't feel like selling my bike anytime soon!"

I can understand that. ;)

"BTW, have you acquired a Decware amp already?"

Nope

Hope you get the MT up and running 100% again real soon.

Title: Re: Left channel is off!
Post by Fireblade on 10/27/12 at 15:33:50

Thanks for your good wishes, Lin.

Title: Re: Left channel is off!
Post by Lon on 10/27/12 at 16:20:54

You're welcome David. Despite possible misunderstandings in the recent past, that's all I've ever had towards you.

Hopefully the amp can be running again very soon!

Title: Re: Left channel is off!
Post by Fireblade on 10/27/12 at 23:57:57

Same here, Lon, absolutely. Thanks for expressing that, it reflects on you! :)

Title: Re: Left channel is off!
Post by Lon on 10/28/12 at 01:07:52

Been thinking about your amp being disabled. Listening to any one speaker mono? :)

Title: Re: Left channel is off!
Post by Fireblade on 10/28/12 at 03:23:51

Now that you mention it, I do have some Furtwangler, Toscanini, Nikish, Solomon, Kempff, Lipatti, Casals, Gigli, and the like, in monaural recordings. Most are great historical interpretations. There are also some Swing and early Bebop jazz monos too ...

I will give them a try, although I don't usually enjoy the harsh sound. I haven't listened to these since acquiring the Decware gear, but the music itself is great indeed.

Good suggestion! Thanks, Lon.

Title: Re: Left channel is off!
Post by Lon on 10/28/12 at 12:42:50

Those might sound better on the Decware equipment. When I got my first Decware amp 14 years or so ago I was amazed at how it made music from the 'teens through the 'forties sound so good. And mono with one speaker is a trip! :)