Need troubleshooting advice for a MC275-v6

[John Jordan]

McIntosh covers the tubes on newly purchased equipment for 90 days.

[FreddieFerric]

Originally Posted by John Jordan

McIntosh covers the tubes on newly purchased equipment for 90 days.

Yes, I just edited my post to reflect that fact. In all likelihood I'll be investing in this, https://maximatcher.com/ when the time comes.

I've asked Ivan about it and he verifies that it can put enough voltage on the plate to ascertain if a KT88 is bad. (FWIW, that's a very big thing).

So, as to the OP's question, I will not (only for myself) be carrying a full set of power tube replacements, but rather only 2 at a time perhaps.

[paltomare]

My amp is still under warranty but as noted the tubes are not.
We'll see if the issue returns and what Chuck has to say as well.

[FreddieFerric]

Originally Posted by paltomare

My amp is still under warranty but as noted the tubes are not.
We'll see if the issue returns and what Chuck has to say as well.

Would like to know what they have to say once you've had that conversation with them. Please keep us updated if you can.

[paltomare]

Originally Posted by FreddieFerric

Would like to know what they have to say once you've had that conversation with them. Please keep us updated if you can.

Will do!

BTW, that tube tester looks nice. I suppose could use that for my guitar amps as well.

[Stahle]

Originally Posted by FreddieFerric

I'm hoping the OP doesn't have to go this route, but in truth if it is a tube failure wouldn't the amp shut down? Even my old Jolida shut down when a power tube failed.

My MC275VI did shut down. I waited a few and then powered it back up figuring the startup sequence would detect any problems. The lights came on as usual and then they all turned green so I thought everything was ok. I then played some music and that’s when I noticed the distortion in the left channel. I tried changing the tubes and it didn’t make a difference, the distortion was still there. I then contacted my dealer and they said that I needed to take it in for service. I then put all of the stock tubes back into the amp and in the same socket they were originally in so that if there was an issue, the service center would be able to identify the tube with the problem.

Once the service center had a look at it, they said the damage to the amp appeared to have been caused by a tube failure and were able to identify which tube was having the issue. They showed my the burnt circuits too. Why sentry monitor didn’t protect the amp, I don’t know nor do I understand why it would still power up. Anyway, after I got the amp back from the McIntosh authorized repair facility, I ended up trading the amp in for another MC275VI due to the cosmetic damage. The second MC275VI I only had for a few months because I decided to switch to an MC462. I didn’t want to have to worry again about the power tubes and I wanted more watts. I’m much happier with the MC462, it suits my needs. I still have tubes in my system, but they’re only the small signal tubes that are in my C22 IV.

[tdelahanty]

Originally Posted by Stahle

My MC275VI did shut down. I waited a few and then powered it back up figuring the startup sequence would detect any problems. The lights came on as usual and then they all turned green so I thought everything was ok. I then played some music and that’s when I noticed the distortion in the left channel. I tried changing the tubes and it didn’t make a difference, the distortion was still there. I then contacted my dealer and they said that I needed to take it in for service. I then put all of the stock tubes back into the amp and in the same socket they were originally in so that if there was an issue, the service center would be able to identify the tube with the problem.

Once the service center had a look at it, they said the damage to the amp appeared to have been caused by a tube failure and were able to identify which tube was having the issue. They showed my the burnt circuits too. Why sentry monitor didn’t protect the amp, I don’t know nor do I understand why it would still power up. Anyway, after I got the amp back from the McIntosh authorized repair facility, I ended up trading the amp in for another MC275VI due to the cosmetic damage. The second MC275VI I only had for a few months because I decided to switch to an MC462. I didn’t want to have to worry again about the power tubes and I wanted more watts. I’m much happier with the MC462, it suits my needs. I still have tubes in my system, but they’re only the small signal tubes that are in my C22 IV.

I've posted this many times. I used a MC275 in an industrial/military environment, the amp was used 16hrs a day and many times left on 24hrs a day. Rarely, if ever did this amp fail. For me it would be my (tube) amp of choice! That was many years ago and the one thing that is different, "the tubes". We always had U.S. made replacement tubes.

[Formerly YB-2]

Originally Posted by paltomare

Thanks for all of the suggestions run for a few hours. Happy to say I no longer hear the distortion, even pushing it harder than before, not sure why but if that does the trick, I'll be happy. And yes, I handled the tubes with gloves.
I like the idea of keeping a spare set on hand, are most of you keeping output tubes only or signal tubes as well?

Glad you got it going again. As I mentioned above, a not uncommon problem with tubes is some surface corrosion will form on the tube-pin contact(s) with the socket and removing & replacing the tube will 'wipe' it clean. Hopefully, that was the problem and it will not return. You can purchase a small cleaning kit (small brushes & fluid) to remove the corrosion, if needed.
As for spare tubes, I would keep a full set, but that's up to you. I have 4-sets of small signal tubes and 8-sets of power tubes for both my preamp (Cary SLP-98P) and power amp (Cary Rocket 88). However, I'm a tube-roller and like to play around with the sound of different tubes.
Whatever you decide (I recommend at least a full set of tubes - compared to the cost of the gear it is a small investment) you should 'run-in' your spare tubes for about 100hr to insure they are good. New tubes generally come with a 6-months (or less) warranty, so you want to insure they are good before putting them on the shelf for spares.

[FreddieFerric]

Originally Posted by Stahle

My MC275VI did shut down. I waited a few and then powered it back up figuring the startup sequence would detect any problems. The lights came on as usual and then they all turned green so I thought everything was ok. I then played some music and that’s when I noticed the distortion in the left channel. I tried changing the tubes and it didn’t make a difference, the distortion was still there. I then contacted my dealer and they said that I needed to take it in for service. I then put all of the stock tubes back into the amp and in the same socket they were originally in so that if there was an issue, the service center would be able to identify the tube with the problem.

Once the service center had a look at it, they said the damage to the amp appeared to have been caused by a tube failure and were able to identify which tube was having the issue. They showed my the burnt circuits too. Why sentry monitor didn’t protect the amp, I don’t know nor do I understand why it would still power up. Anyway, after I got the amp back from the McIntosh authorized repair facility, I ended up trading the amp in for another MC275VI due to the cosmetic damage. The second MC275VI I only had for a few months because I decided to switch to an MC462. I didn’t want to have to worry again about the power tubes and I wanted more watts. I’m much happier with the MC462, it suits my needs. I still have tubes in my system, but they’re only the small signal tubes that are in my C22 IV.

Interestingly I'm headed in the opposite direction. I went to my dealer in November to order an MC462. Turns out he had a NIB 462 in stock. I decided to put a 10% deposit on it for a couple of days because I had also been thinking about the MC1502. I went back 2 days later and paid for the 1502 instead.

I figure I've been on a SS amp for the last 6 years (MA8000), so it was time for a change. Once the new amp arrives I'll know pretty quick if I made the right call or not.

[Stahle]

Originally Posted by FreddieFerric

Interestingly I'm headed in the opposite direction. I went to my dealer in November to order an MC462. Turns out he had a NIB 462 in stock. I decided to put a 10% deposit on it for a couple of days because I had also been thinking about the MC1502. I went back 2 days later and paid for the 1502 instead.



I figure I've been on a SS amp for the last 6 years (MA8000), so it was time for a change. Once the new amp arrives I'll know pretty quick if I made the right call or not.

I considered the MC1502 when I purchased the MC462 but due to my personal experience with the MC275VI, I decided I wanted to try something different. I’m curious as to what you think of the MC1502 once you have listened to it for a while. Keep us posted.