Help, odd, potentially serious Lexicon MC-12 issue - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 24 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 24 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 24 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 24 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 24 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 24 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 24 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 24 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 24 Old 04-03-2013, 12:29 PM - Thread Starter
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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 24 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 24 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 24 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 24 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 24 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 24 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 24 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 24 Old 04-04-2013, 05:21 AM - Thread Starter
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Quote:
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 24 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 24 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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post #20 of 24 Old 06-15-2016, 07:50 AM
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Originally Posted by Rod#S View Post
<div class="quote-container" data-huddler-embed="/t/1466238/help-odd-potentially-serious-lexicon-mc-12-issue#post_23163163" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>RUR</strong> <a href="/t/1466238/help-odd-potentially-serious-lexicon-mc-12-issue#post_23163163"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
Or, PM me with your email and I'll forward the file.</div>
</div>
<br>
Thanks, PM sent.
This thread got me to a solution and I wish to share it as with the MC12B ageing, a failing power supply may well happen more and more often.
I tried to find the original power supply but it's been discontinued, so I contacted the local agent for Lexicon. They will not sell the power supply, but want the unit to be shipped in. Costs are anything upward from Euro 550 ($620) excl. shipping as they insist on doing a full check of the unit and will not just replace the power supply... So, considering my previous experience with them, the actual costs will be higher for sure.
This caused me to search for a replacement power supply with the same spec. It is the: Mean Well PQ-100C which cost me Euro 45 ($50) including DHL shipping. Exchanging it for the old power supply was simple.
I was pleasantly surprised that the sound was immediately noticeably much better as well. I guess the old power supply had been degrading slowly over a longer period of time.
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post #21 of 24 Old 06-16-2016, 03:26 PM
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Rod,


Had a similar problem with my MC12HDEQ. Turned it off to move it and it would not power back up. Switch mode power supply had failed. I shipped it to Pyramid, I'm also in Canada. They replaced the power supply with a better unit as this is apparently a common failure also the original SMP is no longer available. The plus was that they also upgraded some of the processor board capacitors and some of the DACs that were known problem areas.


I was fortunate that I was only just outside of warranty and Lexicon stepped up to the plate and covered the repair costs. Return shipping was about $500 from Calgary to Texas.


I'd recommend sending it to Pyramid, they know the units and would probably offer to change out the other known problem components then you have a unit that will perform for a long time.
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post #22 of 24 Old 06-16-2016, 04:03 PM - Thread Starter
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My issue was fixed with a power switch replacement I believe. I can't believe it's been over 3 years since that happened. Crazy, where does the time go. The unit was long out of warranty at that time, I've now had my MC-12 12.5 years so I guess I've been lucky that was the only major problem. I know there is a problem with the left rear surround, which has been there probably longer than the power issue. The signal distorts and I think probably contributed to blowing a tweeter in my at the time surround left speaker. I went from 7.1 to 5.1 during that time period due to a room reconfiguration and since I don't need my 6 & 7 channels I've never had to worry about it since.

I started looking around for a used MC-12HD about a year or so ago but could never find one in Canada and with the Canadian dollar being so bad against the US buying from the US just didn't make sense as they prices were way out of wack after conversion.

What I think I'll do now in order to get HDMI switching and get away from having to use 7.1 analog inputs for DVD-A, SACD, high res. digital files, etc. is turn my attention to the future rather than the past for my next SSP. A Trinnov Altitude32 or possibly Theta Casablanca E would be worthy successors.

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post #23 of 24 Old 06-16-2016, 05:24 PM
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Rod,


Glad to hear your unit is working.


I'm in a similar situation regards processor. Just installed a new JVC RS600 and so far the Lexicon is switching the HDMI fine but I'm waiting to buy the new OPPO player. I more than suspect that the Lexicon will not switch the new 2.0a/2.2 standards so will have to run a split A/V signal from the OPPO to the projector and the Lexicon and use the OPPO to switch between itself and my satellite TV receiver. The downside is that it will mean losing the Lexicon on-screen display. Options are a new processor or install an auxiliary small monitor to see the lexicon on screen info. Given the northern peso, AKA Canadian dollar, exchange rate I'm leaning very heavily to the second option.
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Quote:
Originally Posted by rb20 View Post
This thread got me to a solution and I wish to share it as with the MC12B ageing, a failing power supply may well happen more and more often.
I tried to find the original power supply but it's been discontinued, so I contacted the local agent for Lexicon. They will not sell the power supply, but want the unit to be shipped in. Costs are anything upward from Euro 550 ($620) excl. shipping as they insist on doing a full check of the unit and will not just replace the power supply... So, considering my previous experience with them, the actual costs will be higher for sure.
This caused me to search for a replacement power supply with the same spec. It is the: Mean Well PQ-100C which cost me Euro 45 ($50) including DHL shipping. Exchanging it for the old power supply was simple.
I was pleasantly surprised that the sound was immediately noticeably much better as well. I guess the old power supply had been degrading slowly over a longer period of time.
Thank you for the input, power went down during a storm when it recovered my MC-12 would no longer power up and just cycles the front panel LED on and off. I haven't had the time to debug the power supply yet and found your post during a search. This will make life a little easier!
Kevin
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