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Lexicon MPX1 - no power
Old 16th February 2007
  #1
Gear Nut
 
🎧 10 years
Lexicon MPX1 - no power

Hi all

Maybe you can help me: I can't switch on my Lexicon MPX1 anymore. It's just as if it doesn't receive any power. I checked / changed the internal fuse without any success.

Any suggestions (in laymens terms please, don't know much about electronics )

Thanks
Old 16th February 2007
  #2
Gear Maniac
 
🎧 15 years
the switch mode power supplies in these things are notoriously bad. they go with no warning. if you are confident with high voltages, you can probe the front end of the supply, the "primary" side. this is where 120volts/ AC comes in from the wall. it would be straight from the power switch. if you get 120, then check the secondary, +- 15 and +5 volts DC. this is where is goes out to the rest of the unit. Ill bet you dont have all these. 5 volts for general computing (wont boot) and +- 15 for analog output.

these switch supplies are notoriously bad and cheap (to build, expensive to buy). call lexicon to get a new one.
Old 29th December 2014
  #3
Here for the gear
 
🎧 5 years
Summary

I know this is an ancient thread, but I figure more MPX1s might be developing faulty power supplies. I've recently found a direct replacement power supply unit for my MPX1: the Artesyn LPT25. This can be sourced from numerous suppliers (Farnell part 1638584, Digikey part 454-1357-ND, RS components part 192-1122, Mouser part 826-LPT25, etc).

A bit more detail:

The original PSU in my MPX1 was a fairly generic switch mode power supply made by Artesyn Technologies, part ref NAN25-7610, which supplies +5.1v @ 2A, +15v @ 1.5A and -15v @ 0.2A.

After a bit of research I found a replacement unit from Artesyn, part ref LPT25 (it's also listed under manufacturer Astec, part of the same firm). This unit out-performs the original on current supply and can supply +5v @ 3A, +15v @ 1.5A and -15v @ 0.5A. The data sheet gives a peak-to-peak ripple on the voltage rails which is at least as good as the original unit.

The new unit is a drop-in replacement for the faulty original, the respective board sizes and component height are the same, and the mounting screw holes are also a match. Although the Molex connector part refs given in the two data sheets aren't the same, I can confirm that the new unit mates correctly with the leads in the MPX1, voltages are presented to pins in the same order and the connectors on the replacement unit are roughly in the same place. I've attached a picture of the replacement unit in my MPX1 - the red circles show the existing MPX1 leads connected to the new PSU, with no modification required.

Most importantly my MPX1 has sprung back into life.

Hope this helps.
Attached Thumbnails
Lexicon MPX1 - no power-mpx1psu.jpg  
Old 27th May 2015 | Show parent
  #4
Here for the gear
 
🎧 5 years
@ digitalaudioproj

I had the same problem and followed your post. Now it works again.
Thank you a lot for the detailed post!
Old 13th February 2018
  #5
Here for the gear
 
🎧 5 years
@ digitalaudioproj

one more time; big thank you , repaired my mpx1 with your advice
Old 3rd March 2018
  #6
Here for the gear
 
🎧 5 years
@ Gimmi , @ chaitanyo Thanks for taking the time feed back, guys I love the internet
Old 24th February 2020
  #7
Lives for gear
 
Gerax's Avatar
 
🎧 15 years
Excellent informations!
My dead MPX-1 wasn't powering up due to that faulty power supply board.
Now that I have taken the time to dig deeper do some research on the replacement I stumbled upon your post, and lo and behold I'm about to order one, probably from RS components which has direct shipping from Italy.

I'll let you know how it goes.

Best

L.
Old 25th February 2020
  #8
Gear Guru
Digi Key also sells these power supplies for $47. Part # NFS40-7610J. Mouser also sells them but is OOS. Get them now as they are discontinued and at "end of life".
Old 31st October 2020
  #9
Lives for gear
 
satissounds's Avatar
 
1 Review written
🎧 10 years
Thanks to this thread I got my nearly 25 yr old MPX1 back up and running after it went dead on me. Ordered from RS and now works a dream again.

Very easy to fit the new power supply in these units, so thank you.
Old 16th December 2020 | Show parent
  #10
Lives for gear
 
Gerax's Avatar
 
🎧 15 years
Quote:
Originally Posted by Jim Williams ➑️
Digi Key also sells these power supplies for $47. Part # NFS40-7610J. Mouser also sells them but is OOS. Get them now as they are discontinued and at "end of life".
Hey, I'm about to order one.

Can you confirm voltages and connections work with the MPX-1?
I see it's also universal voltage, as I0m from Italy so I need it to accept 220V.

Thanx a lot

L.
Old 16th December 2020 | Show parent
  #11
Gear Maniac
 
🎧 10 years
https://www.artesyn.com/assets/lpt20...4686751_ds.pdf

Input Voltage: 85 - 264 Vac
Old 16th December 2020 | Show parent
  #12
Lives for gear
 
Gerax's Avatar
 
🎧 15 years
Right, I checked specs too, just wondering if that replacement fits the MPX-1 as it's not the original one.

Thanx
Old 17th December 2020
  #13
Gear Guru
It worked here for me.
Old 29th March 2021 | Show parent
  #14
Here for the gear
 
Quote:
Originally Posted by satissounds ➑️
Thanks to this thread I got my nearly 25 yr old MPX1 back up and running after it went dead on me. Ordered from RS and now works a dream again.

Very easy to fit the new power supply in these units, so thank you.
Hey mate which one did you ordered??

Thanks I’m advance
Old 30th March 2021
  #15
Here for the gear
 
https://uk.rs-online.com/web/p/embed...-smps/1830054/

Would that work? It’s 55W and amps on out 1&2 are higher by 1AMP AND 0,5Amp.
Old 31st March 2021 | Show parent
  #16
Lives for gear
 
satissounds's Avatar
 
1 Review written
🎧 10 years
Hi, I see the one I used is discontinued now so I don't know if the alternative will work. You could contact them and ask.
Old 31st March 2021 | Show parent
  #17
Here for the gear
 
Ask lexicon tech??
Old 31st March 2021
  #18
Gear Maniac
 
🎧 10 years
I think they meant ask Artesyn if this new model meets exceeds the spec of the older no-longer-available one. And if there are any changes in size or connector pinout.
Old 2nd April 2021 | Show parent
  #19
Here for the gear
 
Thank you very much for help. I will try got in touch with them.
Old 4 weeks ago | Show parent
  #20
Here for the gear
 
Ok thank you.
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