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Old 02-10-2018, 06:05 PM
eddiel eddiel is offline
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Default MC2102 - No sound but powers up

Hi All

My MC2102 seems to have developed an issue since I last used it a couple of weeks ago.

It powers up but there's no sound at all. I did the usual checks, cables, etc. I also made sure to check it wasn't the C220 Pre. I plugged in the headphones and I had music.

During my check I noticed something odd. Not all of the tubes were lit up. I could feel some were warm and some were dead cold.

Four of the KT88's weren't lighting up at all and all 4 of the 12AT7's aren't lighting up either. I attached a mapping showing which ones I have issues with.

2018-02-10 04.48.21.jpg

I had some spare 12AT7s and plugged those in. I swapped the KT88s and I also plugged in two spares I had. But the same sockets were dead. So I know it's not a tube issue.

When I turned it on, I heard no noise, there was no smell and no indication that something is wrong on the amp. The only issue I've had with it lately is that the meter bulbs are burning out.

I'll be taking it into the local dealer next weekend but I thought I'd post on here in case anyone might have a clue as to what it might be. Of course it's hard to tell exactly what could be wrong but I'm wondering if anyone else had an issue similar to this or if there are some usual culprits that might be to blame.

As an aside, I've been contemplating getting out of the tube game, at least at the power amp level for awhile now. I think this might be a sign to move that along.

Eddie
Attached Files
File Type: pdf mc2102tubemap_ok_notok.pdf (1.39 MB, 16 views)

Last edited by eddiel; 02-10-2018 at 06:14 PM.
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  #2  
Old 02-10-2018, 10:50 PM
jadedavid jadedavid is offline
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Do you have a schematic? Maybe from the owners manual?
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Old 02-11-2018, 02:51 AM
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JPrest JPrest is offline
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Sorry you're having issues, my first thought is a blown resistor from a power tube drawing too much current. If the fuse doesn't blow the small resistors usually go next. Have you checked the fuses on the unit. Wish I could be more helpful...
Good Luck
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Old 02-11-2018, 07:53 AM
BlueSky BlueSky is offline
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I'm thinking something common in the heater circuits for the affected tubes. W/O a schematic it's hard to tell.
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Old 02-11-2018, 12:47 PM
eddiel eddiel is offline
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I do have the service manual (pdf) but not sure how to post it. It has the schematics in the manual.

I'll find out soon enough what the official word is when I bring it in. I was just hoping to get an idea of how serious it might be, or could possibly be.

I'm wondering if it's a possible dust issue. My place is really dusty and I keep the unit covered (after letting it cool down completely) and clean it to keep the dust off. My place is quite dusty and it doesn't take long for it to build up.

I've only have a couple of issues since I've owned this unit, which I guess is about 10 years now. So not too bad.

Last time I had an issue, it cost quite a bit as I had to replace all the KT88 tubes. Luckily this time I know they all actually work still and haven't been ruined.

But I think I'll look into going solid state after I get this fixed. I think a solid state amp might suit my current lifestyle and usage better. I use my 2ch for movie audio and it feels wrong when I warm up the tubes to watch a movie
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Old 02-11-2018, 01:20 PM
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tdelahanty tdelahanty is offline
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IF the tubes aren't lighting up the first place I'd look is the filament power supply, maybe a fuse has blown. I don't know the filament voltage for the KT-88. However the 12AT7's have 12v filaments. Sometimes they wire both filaments (in each tube) in series so your filament voltage should be 12 or 24 volts. As a technician that is where I'd start. The amp may also have a soft start circuit for the filaments and that is also a likely culprit.
Good luck Mac tube amps are usually very reliable, I've seen them survive in commercial/military environments for many years without trouble.
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Old 02-11-2018, 01:35 PM
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JWJW JWJW is offline
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Quote:
Originally Posted by eddiel View Post
Hi All

My MC2102 seems to have developed an issue since I last used it a couple of weeks ago.

It powers up but there's no sound at all. I did the usual checks, cables, etc. I also made sure to check it wasn't the C220 Pre. I plugged in the headphones and I had music.

During my check I noticed something odd. Not all of the tubes were lit up. I could feel some were warm and some were dead cold.

Four of the KT88's weren't lighting up at all and all 4 of the 12AT7's aren't lighting up either. I attached a mapping showing which ones I have issues with.

Attachment 53929

I had some spare 12AT7s and plugged those in. I swapped the KT88s and I also plugged in two spares I had. But the same sockets were dead. So I know it's not a tube issue.

When I turned it on, I heard no noise, there was no smell and no indication that something is wrong on the amp. The only issue I've had with it lately is that the meter bulbs are burning out.

I'll be taking it into the local dealer next weekend but I thought I'd post on here in case anyone might have a clue as to what it might be. Of course it's hard to tell exactly what could be wrong but I'm wondering if anyone else had an issue similar to this or if there are some usual culprits that might be to blame.

As an aside, I've been contemplating getting out of the tube game, at least at the power amp level for awhile now. I think this might be a sign to move that along.

Eddie
I recently had issues with a Mc component. I sent it to Audio Classics and used it as a trade towards another component. Was nice not to hassle with the repair and the trade-in-price was fair/about the same as a working unit.
If you are truly looking at "getting out of the tube game." this may be a win-win for sure. A new MC611's or a new MC452 may be options!
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Old 02-11-2018, 02:48 PM
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vintage_tube vintage_tube is offline
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Hey Eddie -- I tried in vain to figure out what is wrong with your MC2102 -- but did find the link to the manual and schematics -- look these over.

http://www.berners.ch/McIntosh/Downloads/MC2102_ser.pdf

In addition, back in 2113, you reported a somewhat similar issue and it was a bad tube that knocked it out of commission. Is this the same problem -- just revisiting 5 years later? It's here:

http://www.audioaficionado.org/showthread.php?t=18156

How long have you had the tubes ?? Any idea of hours? Doesn't mean a lot but thought I'd ask.

Hope it's a simple issue as it's strange that it knocked out V8L & V6L in addition to the right side V8R and V6R. I'm wondering if it's not a 12AT7 issue regarding those 12v tubes in slots V4L and V4R. Strange -- but those fire up & drive the KT88's. But then you replaced the 12AT7's with good ones.

Best Sir,

Bob
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Last edited by vintage_tube; 02-11-2018 at 03:06 PM.
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  #9  
Old 02-11-2018, 03:57 PM
eddiel eddiel is offline
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Hey Bob

I remember that thread and thought of it as soon as this new problem occurred.

Looking back at my order history, I bought the original 8 Gold Lion (Made in Russia) KT88s back in 2013 to replace the tubes that had gone bad (the original McIntosh tubes).

I checked my order history at thetubestore.com (where I purchased everything since 2013) and I bought 4 in June 2015. I can't remember why and I don't remember any tubes burning out but they must have so I must have replaced 4 of the KT88's then.

Then in April 2016, I replaced 1 of them when I noticed it had burnt out. That I remember. I bought spares at the time and I used those to test the KT88 slots to make sure it wasn't a tube issue again.

The AT7's are JAN-Philips and I bought them in 2015. I suppose there is a chance that the other set I have (not JAN-Philips) could be dead too. They've been in storage since 2015 in their original boxes and wrapped in a few layers of bubble wrap.

I couldn't say what the usage hours are. I go through stages with a lot of listening and then not so much. But I use my 2ch set up for movies, dvd, BR watching as well. I'd say easily over the course of 2015 and 2016 the unit was in use every weekend for 6-12 hours. In 2017 I'd say close enough to the same for most of the year. That doesn't even include weekday use, which varied but at most it would be about 3 hours per night not including warm up time.
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Old 02-11-2018, 04:06 PM
eddiel eddiel is offline
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Quote:
Originally Posted by JWJW View Post
I recently had issues with a Mc component. I sent it to Audio Classics and used it as a trade towards another component. Was nice not to hassle with the repair and the trade-in-price was fair/about the same as a working unit.
If you are truly looking at "getting out of the tube game." this may be a win-win for sure. A new MC611's or a new MC452 may be options!
I was looking at the MC452 as a possible option.

I recall a favourable review by Alberto of a C220/MC252 set up and might try and track down a used MC252.

I'd like to do business with Audio Classics but since they are in the US it makes it difficult due to taxes and exchange rates. So sourcing something locally would be more advantageous. My local dealer does get trade-ins and consignment sales from time to time so I'll discuss it with them.

What I haven't decided yet is whether i should sell the C220 pre and the MC2102 and move to an integrated set up or just the MC2102. I think I might keep my set up as pre/power but we'll see.

I was thinking of going beyond McIntosh but I want to, well have to, keep my B&W805s' and I know McIntosh is a good match. Not sure I want to mess around with other brands until I find something that works.
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