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Audio Alchemy DAC in The Box Repaired

By on December 18, 2014
Alchemy power adapter repair









The complaint of this device was no power. It comes with an AC power adapter and the output voltages are positive and negative 14 volt dc.

Alchemy power adapter

When I checked on the output I found that it had zero volts. This means the adapter is the cause of the problem.


Once the adapter cover was removed I could see the linear transformer but the top section winding was burn-see the photo below.

power adapter 2

The small square thermal fuse and the MKT capacitor were open circuit. The secondary side small bridge rectifier and two filter capacitors were tested good.

power adapter 4

Since I’m getting a new transformer (centre tap 9, 0, 9 v transformer)- see the photo below.

center tapped transformer 9 0 9v

I have also decided to replace all the five components. I even bought a new power supply casing. As for the input and output cables I’m using back the original one.

power adapter 8

power adapter 9

power adapter 6

power adapter 7

After fixing everything and checked on the output I got only -13.1v and + 13.1 volt which is quite near to 14 volt. I tested it on the device and it was powering on and working perfectly fine.

power adapter 5

Below is the hand drawn schematic diagram of the Audio Alchemy Power Adapter:

alchemy schematic

This article is contributed by an anonymous repairer.

Please give a support by clicking  on the social buttons below. By the way if you have any good repair article that you want me to publish in this blog please do contact me HERE.



  1. Tito

    December 18, 2014 at 11:08 am

    Nice article unknown.

    • Alphonsus Lim

      December 18, 2014 at 1:30 pm

      Thank You Justin Yong,

      For sharing these knowledge to everyone, your charitable work will always be rewarded by GOD.

      I wish you and family a joyous and wonderful time this Christmas. Merry and Happy Christmas.


      • admin

        December 18, 2014 at 7:33 pm

        HI Alphonsus,



      • Joseph Fernandes

        December 18, 2014 at 8:42 pm

        Yes Thanks a Lot Justin Young for all the beautiful articles i mysellf learned a lot and still learning by reading your articles

        May GOD Bless you a lot and Wish you a Merry Christmas and Happy New Year

        Thanks and Regards, Joe

        • admin

          December 18, 2014 at 9:09 pm

          Hi Joe,

          You are welcome!


    • G Poongavanam

      December 19, 2014 at 9:04 am

      nice article very useful to me thanks lot

    • margarito sanchez

      December 22, 2014 at 12:38 am

      Hello Mr. Justin Yong Master I send warm greetings and a big hug and congratulations that this Christmas and New Year your wishes are followed
      he deserves all the teachings we get from you thank you very much
      see you soon.

      • admin

        December 22, 2014 at 10:35 am

        Hi Magarito,



    • Gobinda Dey.

      December 23, 2014 at 9:15 pm

      Very nice , happy up comming a Wonderful New year.

  2. biruk aweke

    December 18, 2014 at 12:32 pm

    nice but why connect the metal body to the secondary transformer on circut diagram it is not cleaer to me?

  3. Amendar

    December 18, 2014 at 1:16 pm

    Thanks for sharing.
    Why you did not stick thermal sw. To transformer body?

  4. yogesh Panchal

    December 18, 2014 at 1:20 pm

    Good article please keep up posting your experience.

  5. Taofiki ishola Akinleye

    December 18, 2014 at 8:48 pm

    The article is fine pls keep it up.

  6. Brian

    December 18, 2014 at 10:37 pm

    Why did you overfuse the primary? The rating on the power supply clearly is 15W. 2 Ampere fused primary at 240V means the fuse would blow if the power draw was more than 480VA, hard to imagine the fuse blowing before smoking the secondary winding. I'd have gone with a T250 mA fuse in the primary.

  7. Tom Struthers

    December 18, 2014 at 10:50 pm

    Mr. Yong, Thank you for all the wonderful and informative articles you have provided and your great books. I have learned a lot from you and have been able to complete many repairs with your help. Merry Christmas and Happy New Year, Tom

    • admin

      December 19, 2014 at 11:29 am

      Hi Tom,

      Thanks and wishing you Merry Christmas and Happy New Year.



        December 30, 2014 at 8:05 pm


  8. Bernie Scott

    December 19, 2014 at 12:10 am

    Great articles Jestine...Keep up the good work.....Wishing you and your's a very Merry Christmas and a prosperous Happy New Year....

    • admin

      December 19, 2014 at 11:28 am

      Hi Bernie,

      Thanks and wishing you Merry Christmas and a prosperous New Year too.


  9. Andre Gopee

    December 19, 2014 at 7:12 am

    Nice work Mr. Jestine.

  10. james

    December 19, 2014 at 9:52 am

    For learning electronics purpose it is ok. But it may cheaper to buy a complete switching mode power supply to instead.

  11. boopathiraj

    December 19, 2014 at 1:02 pm

    nice job dual power supply

  12. Waleed Rishmawi

    December 19, 2014 at 6:46 pm

    totally agree with James, buying a new one would be a lot cheaper and better. on the other hand, good learning experience to share. thanks for sharing

  13. Joshua Oloo

    December 19, 2014 at 8:18 pm

    Thanks Mr.Yong for sharing several repair articles.I appreciate your good work otherwise Merry Xmas and Happy 2015.

  14. Rey

    December 20, 2014 at 9:23 pm

    Merry Christmas Sir Jestine, wishing you and family a prosperous new year always. Your sharing to us on this SMPS power supply problem is very valuable, it refreshes us on SMPS troubleshooting. More power and God Bless always.

    • admin

      December 20, 2014 at 11:27 pm

      HI Rey,



  15. Abdul

    December 23, 2014 at 9:36 am

    Thanks for the articles Jestine.
    Merry Christmas and Happy New Year 2015.

  16. Amir Mukhtar

    December 23, 2014 at 3:17 pm

    Sir, Jestine
    Thanks you for sharing Article about on Supply.
    However, A question Popup in my mind.
    there are two negative connections in Output Supply with using of back Caps and Center Tap.(Shows in Circuit Diagram).
    Please ask the sharer to Define Circuit . I think its not workable with respect from Output connections / Also, it Was No need to use bridge rectifier on center tap.
    only two diodes makes possible to provide DC Volts using center tap for negative point.
    This is for information only not for Criticizing. Please.

    Thanks you
    Amir Mukhtar
    A Student of Masters in Industrial Electronics.

  17. Goh KS

    December 23, 2014 at 4:06 pm

    The decision to replace the transformer is good as the original one has been damaged by heat. However, the way the thermal fuse is placed in the new transformer doesn't make sense as it is too far away from the windings; in which case, it wouldn't matter iif the thermal fuse is used or not. Furthermore, it is not adviseable to solder thermal fuse as the heat from the soldering iron may cause the thermal fuse to open-circuit. The thermal fuse used is rated at 120 degrees Celcius whereas soldering occurs around 180 to 220 degrees Celcius.

  18. juaqn aranda a

    December 23, 2014 at 10:51 pm

    Thank You Justin Yong,
    For sharing these knowledge to everyone, your charitable work will always be rewarded by GOD.
    I wish you and family a joyous and wonderful time this Christmas. Merry and Happy Christmas.

  19. Nimal

    December 25, 2014 at 2:21 pm

    May I wish you a Merry Christmas Mr Jestine. Thanks for showing how to make a compact power supply. Very helpful.

  20. Tesfaye kebede

    December 26, 2014 at 7:40 am

    Hi jestine

    it is a nice article i learn more

  21. Taring K Arioka

    December 29, 2014 at 5:35 pm

    Nice work. Please keep it up.

  22. Kiet T. Le

    January 31, 2015 at 10:10 pm

    Good job anonymous repairer!

  23. sujoy bhattacherjee

    March 19, 2015 at 10:48 pm

    Hi jestine young,sharing all of your knowledge to every one is a very good job ,it will encourage all like me .thanks a lot .God bless you,sujoy

  24. do

    October 18, 2017 at 5:23 pm

    i want power suply alcheny power emplifer om 150, but i dont fint it, thank


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