Lexicon MC-12 Power supply

It looks like my MC-12 (older non-balanced version) died Sunday. We had a power outage and when power returned, I got the dreaded flashing yellow light. I unplugged overnight, but no go. I am relieved that there are solutions other than sending back to Lexicon.

allhartfidelity are your two power supplies the older Shindengen models or the newer EOS? If the original, I'd be interested in buying one from you.

pfigg did you happen to jot down the capacitor parts list?

Thanks for any and all help. I'm an electrical engineer, so I can handle either the re-cap of the original or connector mods on the newer. 'Just trying to figure out the easiest path to getting my MC12 back. She's been wonderful for more than 10 years!
 
It looks like my MC-12 (older non-balanced version) died Sunday. We had a power outage and when power returned, I got the dreaded flashing yellow light. I unplugged overnight, but no go. I am relieved that there are solutions other than sending back to Lexicon.

allhartfidelity are your two power supplies the older Shindengen models or the newer EOS? If the original, I'd be interested in buying one from you.

pfigg did you happen to jot down the capacitor parts list?

Thanks for any and all help. I'm an electrical engineer, so I can handle either the re-cap of the original or connector mods on the newer. 'Just trying to figure out the easiest path to getting my MC12 back. She's been wonderful for more than 10 years!
Not sure any more, been so long since i bought them. Currently away on vacation or i would look. Back on the 11th
 
It looks like my MC-12 (older non-balanced version) died Sunday. We had a power outage and when power returned, I got the dreaded flashing yellow light. I unplugged overnight, but no go. I am relieved that there are solutions other than sending back to Lexicon.

allhartfidelity are your two power supplies the older Shindengen models or the newer EOS? If the original, I'd be interested in buying one from you.

pfigg did you happen to jot down the capacitor parts list?

Thanks for any and all help. I'm an electrical engineer, so I can handle either the re-cap of the original or connector mods on the newer. 'Just trying to figure out the easiest path to getting my MC12 back. She's been wonderful for more than 10 years!
Wildcataz,
I'm an EE too, don't even bother fixing the old one, for about 85 bucks you get the newer better supply and it's a drop in with the connector mods. Have fun and get that baby up and running!
Kevin
 
Wildcataz,
I'm an EE too, don't even bother fixing the old one, for about 85 bucks you get the newer better supply and it's a drop in with the connector mods. Have fun and get that baby up and running!
Kevin
I took your advice and bought the medical version of the suggested EOS power supply. 'Did the connector mod, installed, and my MC-12 appears to be working now. It ran through its diagnostic tests and everything passed. YAY!!

However, I noticed that the little fan at the end of the power supply "well" was not spinning. Is it supposed to run all the time? Or thermostat controlled? I may just place a quiet PC fan at the chassis ventilation holes on that side.
 
Also,
Lexicon must have planned to use that EOS supply as the holes in the internal mounting panel lined up perfectly. Too much of a coincidence. I'm glad I didn't have to disassemble the chassis to drill new mounting holes.
 
I'm an EE too, don't even bother fixing the old one, for about 85 bucks you get the newer better supply and it's a drop in with the connector mods. Have fun and get that baby up and running!
Kevin

Kevin,

Question regarding Molex/Wire repositions:

Are the individual Red and Black wires unique in purpose thus requiring specific placement in the new Molex? Or is placement order entirely random? E.g - your pic of the new Molex configuration displays three Red wires starting at the left side of the connector. I'm guessing their specific placement order inside the connector does not matter? Same with the Black wires. Is there a specific placement order into the new connector? Again I'm guessing their placement/location does not matter as long as they are placed into the proper new connector location.

I see the re-positiong of the Yellow, Blue, and Gray wires ...

Thanks.

-paul.
 
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Just installed EOS power supply let me know please if you added a fan
Bobur, I found the exact fan that is in the MC-12 online just by googling the part number printed (in tiny font) on the old fan. I haven't installed it yet because I have two 4" computer fans running 24/7 to ventilate the rack space my MC-12 sits in.

Are the individual Red and Black wires unique
No, they are not unique. Any 5v red wire in any position; any black ground wire in any position.

New problem 1: When I got my MC-12 running with the new power supply, I had to completely re-do the setup; it had forgotten everything! Fortunately, I penciled the settings in the table in the back of the owner's manual 10 years ago. Should I have replaced the coin battery on the motherboard when i was replacing the power supply? I didn't think of it at the time.

New problem 2: Channel 1 of my Lexicon 225 power amp, aka Bryston 4BST (that I use for front mains), is inop. Both front panel lights are green but no output from channel 1. I checked all connections and cables. Eventually, I took it out of the rack and drove it with my iPhone (and a stereo Y cable) and other known good speakers. Nothing on 1. Channel 2 works fine. I reversed inputs; still no output on 1. Any thoughts on likely failure mode? If I decide to have someone else repair, should I send it to Lexicon, or Bryston, or find a local repair shop?

Not my month for AV...
 
I found on the schematic there should be a fan at j30 on the main board and install r282 for 12v fan or r281 for 5v fan my fan was plugged into the j3 on the power supply which is:
Power Fail/Good Signal: Signal goes high after a delay of 100 ms once main output is within regulation band. Signal goes low 1 ms advance before output goes out of regulation due to mains failure

Page 8-161 of service manual shows fan going to j30 of main board r282 and r281 are jumpers 0 ohms
Mine is set for 12v which my fan is.
Fan works on bench supply but have not got the fan to run on j30 yet.
 
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Spoke to Lexicon today they did not know which, j3 power supply or j30 main board that the fan should be connected to but said the power supply would have to be screaming hot for the fan to come on.
 
I installed the EOS PS last eve. Let me first thank Kevin for posting his documentation.

My Experience:

My first impression of the EOS unit is that it feels much lighter in weight than the stock (MC-12) model. Of course my original unit is encased in a metal/aluminum enclosure that I presume acts as a heatsink and protective frame. The enclosure also provides some sort of thin, antistatic and/or solder joint protection barrier the sits between the enclosure and the bottom of the circuit board. Interesting that this piece of plastic or whatever it is composed of does not cover the entire under surface of the board. The underside of the EOS unit is 100% exposed. Not ideal IMHO. However, following Kevin's lead - the recommended standoffs supply ample space between the bottom of the circuit board and the facing mounting area on the chassis panel. By the way I did not remove the mounting panel. I was able to carefully lower the wired PS into the installation area with no problem. The exposed, threaded ends of the four standoffs easily inserted into the pre-existing mounting holes on the chassis panel. And yes - it's great that these supplied holes perfectly match the EOS PS.

The Molex modification using the new connector did not work for me. First, after removing the wires from the existing Molex connectors (there are 2) - I noticed the small, sort of spring locking contact wire connectors were not the same as what Kevin displayed in his pic. I was unable to securly seat the repositioned wires in the new Molex connector. I tried bending the pins, re-shaping, etc. No luck. I attempted to leave the connectors loosely positioned inside the new Molex, hoping that the PS pins, when inserted - would tighten things up thus securing the loose inside wire connectors. The problem with this approach was that the holes in the new Molex connector along with the loosely seated wire connectors made it extremely difficult to seat the Molex on the PS pins.

I decided to revert back to the original Molex (x2) connectors. My thought was the wires would fit more snugly after proper re-positioning. Keep in mind the EOS board supplies 12 pins. The stock PS supplies 13.

In the pic below of the EOS unit, notice the gap between the left end of the pin area and the circuit board mounting hole. This gap effectively enables the use of the existing Molex connectors by simply ignoring the first/left side wire insertion hole on one of the original Molex connectors. The unused hole on the Molex overhangs and occupies the noted gap. In this configuration, I successfully seated the properly re-positioned wire connectors inside the original Molex connectors (x2) and seated them snugly on the EOS unit's pins.


forum-PS-pins.png



Reminder: The use of the existing Molex (x2) connector still requires wire reconfiguration for EOS unit compatibility.

As far as the necessity to invert the wires inside the power/line feed connector, this is true. I did this, hoping I would not have issues when attempting to securely lock the repositioned wires. I was successful here. It worked as expected. One note - the color coded (brown/blue) wires have interfacing female blade connectors that are secured to male blade connectors located on the opposite side (located inside the MC-12) of the A/C plug connector that feeds external power to the unit. Theoretically you can simply disconnect the blade connectors and invert them, in which case you would not need to flip the placement of the wires inside the PS connector. I elected NOT to do this, simply becuase I would be compromising the color coding consistancy between the male and female blade connectors that receive/pass the external power.

That's about it. Aside from the slight delay caused by my inability to use the replacement Molex connector - this modification is straight forward. I think I've heard "authorized" techs charging $500-$600 to replace the PS in these units, plus added shipping costs? Absolutely crazy and totally unnecessary. If you are careful and can handle a screwdriver - you should be set. I paid $100 for the new EOS PS (including tax and expedited delivery). I purchased it from Sager Electronics.

Finally, I'm not concerned about the internal fan and it's compatibility. I'm installing a fan above mine. It will be controlled by some sort of timer or programmable smart outlet for intermittent cooling.

-paul.
@produceNewMedia
 
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Good to see that there is a thread about this. FWIW, this is the second time that I've had to replace the PS on my MC-12B. The first time my dealer sent it back to Lexicon for repair. I don't recall the exact amount to have it repaired, but it was something like $500. The second time it needed to be replaced my dealer said that they talked to Lexicon and the power supply is no longer available and the only option was to try and find a local tech who might be able to repair it. I ended up putting it in a box and buying an Anthem. But after reading this thread it sounds like I can resurrect the MC-12B and either sell it or give it away.

I ordered the EOS PS and will report back if I'm able to get the MC-12B back up and running. Thanks everyone for contributing to this thread.
 
But after reading this thread it sounds like I can resurrect the MC-12B and either sell it or give it away.

Looking forward to hearing how it works out for you. Happy to help if I can. Kevin's documentation -->> stellar.

You should be able to get a decent amount of $$ for it, albeit there are multiple listings on eBay. If as a last resort you are compelled to "give it away" ... I'd be happy to accept it! ;). In all seriousness they sell (I would estimate) for upwards of $1500. Of course it depends on it's functional and cosmetic condition.

I'm thinking about looking into porting the Configuration utility app. over to the Mac. I have no idea if it's even possible. The downloaded data is really nothing more than a .txt file. I just bought a 12 year old Dell laptop running Windows XP Pro to backup my MC-12 and update the software to ver.5.25. No issues.

Good luck.

-paul.
@produceNewMedia
 
Just wanted to mention that I replaced the PS in my Lex MC-12B and it worked perfect! Awesome thread! Thanks everyone who commented. For me it was a drop in replacement and the part number was a match. My PS had been replaced once before with what I thought was a Lexicon PS but perhaps it had been swapped for a Sager at that time. But bottom line it took about 10 minutes and was a simple bolt on then reconnect the cables. No soldering or muss or fuss. Awesome thread!
 
I installed the EOS PS last eve. Let me first thank Kevin for posting his documentation.

My Experience:

My first impression of the EOS unit is that it feels much lighter in weight than the stock (MC-12) model. Of course my original unit is encased in a metal/aluminum enclosure that I presume acts as a heatsink and protective frame. The enclosure also provides some sort of thin, antistatic and/or solder joint protection barrier the sits between the enclosure and the bottom of the circuit board. Interesting that this piece of plastic or whatever it is composed of does not cover the entire under surface of the board. The underside of the EOS unit is 100% exposed. Not ideal IMHO. However, following Kevin's lead - the recommended standoffs supply ample space between the bottom of the circuit board and the facing mounting area on the chassis panel. By the way I did not remove the mounting panel. I was able to carefully lower the wired PS into the installation area with no problem. The exposed, threaded ends of the four standoffs easily inserted into the pre-existing mounting holes on the chassis panel. And yes - it's great that these supplied holes perfectly match the EOS PS.

The Molex modification using the new connector did not work for me. First, after removing the wires from the existing Molex connectors (there are 2) - I noticed the small, sort of spring locking contact wire connectors were not the same as what Kevin displayed in his pic. I was unable to securly seat the repositioned wires in the new Molex connector. I tried bending the pins, re-shaping, etc. No luck. I attempted to leave the connectors loosely positioned inside the new Molex, hoping that the PS pins, when inserted - would tighten things up thus securing the loose inside wire connectors. The problem with this approach was that the holes in the new Molex connector along with the loosely seated wire connectors made it extremely difficult to seat the Molex on the PS pins.

I decided to revert back to the original Molex (x2) connectors. My thought was the wires would fit more snugly after proper re-positioning. Keep in mind the EOS board supplies 12 pins. The stock PS supplies 13.

In the pic below of the EOS unit, notice the gap between the left end of the pin area and the circuit board mounting hole. This gap effectively enables the use of the existing Molex connectors by simply ignoring the first/left side wire insertion hole on one of the original Molex connectors. The unused hole on the Molex overhangs and occupies the noted gap. In this configuration, I successfully seated the properly re-positioned wire connectors inside the original Molex connectors (x2) and seated them snugly on the EOS unit's pins.


forum-PS-pins.png



Reminder: The use of the existing Molex (x2) connector still requires wire reconfiguration for EOS unit compatibility.

As far as the necessity to invert the wires inside the power/line feed connector, this is true. I did this, hoping I would not have issues when attempting to securely lock the repositioned wires. I was successful here. It worked as expected. One note - the color coded (brown/blue) wires have interfacing female blade connectors that are secured to male blade connectors located on the opposite side (located inside the MC-12) of the A/C plug connector that feeds external power to the unit. Theoretically you can simply disconnect the blade connectors and invert them, in which case you would not need to flip the placement of the wires inside the PS connector. I elected NOT to do this, simply becuase I would be compromising the color coding consistancy between the male and female blade connectors that receive/pass the external power.

That's about it. Aside from the slight delay caused by my inability to use the replacement Molex connector - this modification is straight forward. I think I've heard "authorized" techs charging $500-$600 to replace the PS in these units, plus added shipping costs? Absolutely crazy and totally unnecessary. If you are careful and can handle a screwdriver - you should be set. I paid $100 for the new EOS PS (including tax and expedited delivery). I purchased it from Sager Electronics.

Finally, I'm not concerned about the internal fan and it's compatibility. I'm installing a fan above mine. It will be controlled by some sort of timer or programmable smart outlet for intermittent cooling.

-paul.
@produceNewMedia
Hi Paul, I'm psyched people are benefiting from this. Your contacts have to have the small locking tab in the right position to lock into the molex connector. When you depress them to get them out you can over exert a little and the locking tab gets pushed in. I use an xacto knife blade to carefully pull it back up a little so it wii "snap" in once you push it into the new connector. Let me know if you have any other questions.
Thanks,
Kevin
 
I took your advice and bought the medical version of the suggested EOS power supply. 'Did the connector mod, installed, and my MC-12 appears to be working now. It ran through its diagnostic tests and everything passed. YAY!!

However, I noticed that the little fan at the end of the power supply "well" was not spinning. Is it supposed to run all the time? Or thermostat controlled? I may just place a quiet PC fan at the chassis ventilation holes on that side.
Hi Wild,
The fan only runs when the internal temperature reaches the setpoint, which I don't know what that is. I would guess around 70-80C. There is a thermocouple sensor.
Kevin
 
Kevin,

Question regarding Molex/Wire repositions:

Are the individual Red and Black wires unique in purpose thus requiring specific placement in the new Molex? Or is placement order entirely random? E.g - your pic of the new Molex configuration displays three Red wires starting at the left side of the connector. I'm guessing their specific placement order inside the connector does not matter? Same with the Black wires. Is there a specific placement order into the new connector? Again I'm guessing their placement/location does not matter as long as they are placed into the proper new connector location.

I see the re-positiong of the Yellow, Blue, and Gray wires ...

Thanks.

-paul.
Hi Paul,
I provided the color code for the voltages involved. It is just multiple wires used for each supply rail so the red wires, for example, have no order. I just positioned them so they would fit neatly according to how they were twisted.
Kevin
 
Hello! I have been meaning to fix my MC-12 power supply issue for sometime now and saw this thread. Great thread!

I am confused about what power supply part to purchase from Sager. There is the drop in part and then there is a medical variant. How do I find out which one to purchase?

Thanks!

Mike
 
Hello! I have been meaning to fix my MC-12 power supply issue for sometime now and saw this thread. Great thread!

I am confused about what power supply part to purchase from Sager. There is the drop in part and then there is a medical variant. How do I find out which one to purchase?

Thanks!

Mike
Hi Mike, did you get this answered yet? You can use either the medical or non-medical version. The part # is the same except for the "M", hence LFMVLT110-4302. Remove the "M" for the standard version.
Kevin
 
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