Help, odd, potentially serious Lexicon MC-12 issue - AVS Forum
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post #1 of 19 Old 04-01-2013, 01:07 PM - Thread Starter
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Hi;

I was away for a week and had my system powered down and the main conditioners completely unplugged. I got back today plugged everything in and started turning everything on. When I got to my Lexicon MC-12Bv5EQ as soon as I flipped the main power switch on the back I heard what could best be described as a sort of popping/crunching sound the lasted a few seconds then went away. It more or less sounded like electrical popping, potentially arching, that type of sound. I immediately shut the unit off, waited about a minute and tried again, same problem and again it goes away within a few seconds. I put my nose up to the back of the unit by the power switch and smelt what I thought was a sort of electrical burning smell but it was very faint and doesn't seem to last long and is not there now after the unit has been on but in stand by for about 4 hours. Since I have never smelt the rear end of my unit before smile.gif maybe this is a normal smell as electricity flows through it but the sounds is definitely not normal.

Any ideas as to what might be happening? Could it be a problem with the power itself, loose solder, etc., some kind of short, or could it possibly be the fan maybe? I have never actually honestly heard the fan spinning before so I can't even say it has ever come on but if during initial power up the fan does engage for a few seconds then it's possible that's the issue and something is messed up with the fan.

Thanks,

Rod

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post #2 of 19 Old 04-01-2013, 06:40 PM
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UNPLUG IT AND GET IT IN FOR SERVICE!

I suspect a power supply problem - probably a bad capacitor which is quite common on switching power supplies. They can run for years on a bad capacitor because the capacitor is always partially charged when the supply is on. Note that the power supply stays on in the MC12 if just using the front panel switch. But once the unit is switched off from the rear switch or unplugged, the capacitor(s) discharge and cannot re-charge fully from a cold start. Again this is a common problem.

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post #3 of 19 Old 04-01-2013, 08:14 PM
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Agreed. The symptoms are 100% those of a switching power supply that is on the verge of failing. Send in the unit for service, or order a new power supply and replace it yourself (assuming this is an option for you).
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post #4 of 19 Old 04-02-2013, 07:31 AM - Thread Starter
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Thanks guys.

The unit is way out of warranty but my local shop would be abe to fix it I'm sure. The local shop is not where I purchased it from (that's on the other side of the country frown.gif ) nor are they a Lexicon dealer but if you're suggesting it's something one can do themself then getting the local shop to do it shouldn't pose any risk, or any more risk. Are you guys aware of any particular part number, etc I would need specifically for the MC-12 and once the cover is taken off, how hard is this device to get to, is it serviceable without taking out like a bunch of boards because it's buried deep inside or is it more or less accessable once the lid is off?

Thanks for you help.

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post #5 of 19 Old 04-02-2013, 07:50 AM
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Why not just ship it back to Lexicon? Likely a fast turnaround and things will guaranteed be corrected.


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post #6 of 19 Old 04-02-2013, 10:10 AM - Thread Starter
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Originally Posted by thebland View Post

Why not just ship it back to Lexicon? Likely a fast turnaround and things will guaranteed be corrected.

True but I'm in Canada and have no backup unit, not even a receiver and my tv has no speakers so minimizing any downtime is going to be critical. I would imagine sending it back to Lexicon, round trip would probably be 2 weeks easily not to mention pricey. i.e. shipping both ways, plus repair

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post #7 of 19 Old 04-02-2013, 10:50 AM
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If it is just the power supply any competent service shop should be able to replace it. It's just a PC board with two multipin connectors.

In addition Lexicon uses standard commercial OEM power supplies and not some custom unit like inside a cheap DVD player. These supplies are manufactured to industry standards so you can find replacements form several manufactures.

www.jameco.com has a large assortment of power supplies at surplus prices. The supplies are new, just excess inventory they bought up.

I have an MC8 service manual and can give you information on that supply but I don't know if the MC8 uses the same power supply as the larger MC12.

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post #8 of 19 Old 04-02-2013, 11:05 AM
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I had an MC-12 power supply replaced a few years ago, and my recollection is that Lexicon had me send it to an independent shop in the Boston area. I'm not sure they do their own repairs anymore, so you may be just as well off doing it locally if you can.

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post #9 of 19 Old 04-03-2013, 12:29 PM - Thread Starter
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Quote:
Originally Posted by Glimmie View Post

If it is just the power supply any competent service shop should be able to replace it. It's just a PC board with two multipin connectors.

In addition Lexicon uses standard commercial OEM power supplies and not some custom unit like inside a cheap DVD player. These supplies are manufactured to industry standards so you can find replacements form several manufactures.

www.jameco.com has a large assortment of power supplies at surplus prices. The supplies are new, just excess inventory they bought up.

I have an MC8 service manual and can give you information on that supply but I don't know if the MC8 uses the same power supply as the larger MC12.

Thanks

Yeah I'm not sure if the MC12 shares the same part or not. If you have the number I can take it down at least.

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post #10 of 19 Old 04-03-2013, 12:30 PM - Thread Starter
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Originally Posted by jmanthey View Post

I had an MC-12 power supply replaced a few years ago, and my recollection is that Lexicon had me send it to an independent shop in the Boston area. I'm not sure they do their own repairs anymore, so you may be just as well off doing it locally if you can.

I contacted Lexicon and they said to return it for service and provided me a list of the authorized service centers, unfortunately they are all in the US frown.gif

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post #11 of 19 Old 04-03-2013, 12:32 PM - Thread Starter
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Does anyone happen to have a digital copy of the MC-12 service manual? I'm going to at least have my local dealer look at it and if it's an obvious problem to them then having part numbers would be helpful.

Thanks

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post #12 of 19 Old 04-03-2013, 02:29 PM
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Quote:
Originally Posted by Rod#S View Post

Does anyone happen to have a digital copy of the MC-12 service manual? I'm going to at least have my local dealer look at it and if it's an obvious problem to them then having part numbers would be helpful.

Thanks
Several download sites may be found with a simple Google search e.g. http://www.2shared.com/document/7kOrghmX/lexicon_mc_12_service_manual_d.html, though I'd be sure I had effective anti-virus running, just in case.
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post #13 of 19 Old 04-03-2013, 05:16 PM
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Originally Posted by RUR View Post

Several download sites may be found with a simple Google search e.g. http://www.2shared.com/document/7kOrghmX/lexicon_mc_12_service_manual_d.html, though I'd be sure I had effective anti-virus running, just in case.

Did you try that link? It takes you on a roundabout that ask you to pay $11.99 for a document that may or may not be the service manual. (I'd bet it's the free user manual that you wlll end up paying for).
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post #14 of 19 Old 04-03-2013, 05:24 PM
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Originally Posted by Rod#S View Post

Does anyone happen to have a digital copy of the MC-12 service manual? I'm going to at least have my local dealer look at it and if it's an obvious problem to them then having part numbers would be helpful.

Unfortunately Harman only prodives the service manuals to authorized service centers. If I were in your shoes, I would open up the unit and have a look at the power supply and see how hard it is to replace. If it looks like a plug & play replacement (which it probably is), then have your dealer order the part for you. Strangely enough you can buy the spareparts although you can't get the service manual rolleyes.gif
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post #15 of 19 Old 04-03-2013, 06:31 PM
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Quote:
Originally Posted by Peter Nielsen View Post

Did you try that link? It takes you on a roundabout that ask you to pay $11.99 for a document that may or may not be the service manual. (I'd bet it's the free user manual that you wlll end up paying for).
Okay.... This one costs nothing (I registered with random info) and I just downloaded the 287pp service manual in .pdf format with no nasty viruses/trojans.
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post #16 of 19 Old 04-04-2013, 05:21 AM - Thread Starter
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Originally Posted by RUR View Post

Okay.... This one costs nothing (I registered with random info) and I just downloaded the 287pp service manual in .pdf format with no nasty viruses/trojans.

Thanks, I'll give it a try.

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post #17 of 19 Old 04-04-2013, 05:21 AM - Thread Starter
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Originally Posted by Peter Nielsen View Post

Unfortunately Harman only prodives the service manuals to authorized service centers. If I were in your shoes, I would open up the unit and have a look at the power supply and see how hard it is to replace. If it looks like a plug & play replacement (which it probably is), then have your dealer order the part for you. Strangely enough you can buy the spareparts although you can't get the service manual rolleyes.gif

The unit will be opened up tomorrow. My local dealer is sending over their tech.

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post #18 of 19 Old 04-04-2013, 06:07 AM
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Thanks, I'll give it a try.
Or, PM me with your email and I'll forward the file.
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post #19 of 19 Old 04-04-2013, 07:39 AM - Thread Starter
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Originally Posted by RUR View Post

Or, PM me with your email and I'll forward the file.

Thanks, PM sent.

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