Pages: [1]   Go Down

Author Topic: Iam seeking an internal schematic for the MFJ1300/MFJ1306 power supply module  (Read 235 times)

N4MQ

  • Member
  • Posts: 577

MFJ does not have info on the supply?   One of my supplies failed and I had it repaired at MFJ ( they swapped it out ) and I asked for it return.  The 300 volt bus is up but nothing else is operating, and Id like to fix it as a spare if possible.

Please let me know if you have worked on the 50 volt supply module, thank you, W  >:(  :D D Y
Logged

PE1HZG

  • Posts: 86
    • HomeURL

Developing a switch-mode power supply is fairly expensive, especially with all the regulatory and safety requirements these days, as well as the specialized (fire-resistant, isolation creep) components required. I don't think the volumes MFJ make are big enough to warrant development of an on-house power supply, not anno 2023.
Chances are that MFJ did not develop the power supply modules themselves but that they are OEM modules from another company and that they don't have schematics (most likely) or cannot supply because of NDA (also possible).

You should try to research it from that angle. What are the markings on the module?

And keep in mind that most SMPS modules are fairly similar. Typically, with some experience, a continuity tester and an ESR meter, you might not need schematics.
Logged

K6JH

  • Member
  • Posts: 701

I think I’d prefer having MFJ swap out a typical switcher, than worry about the caliber of technician they would have working on it. I’m an EE and have designed some simple dc/dc switcher stuff, and I don’t think I’d mess with it either. Too cheap to replace.
Logged
73
Jim K6JH

N4MQ

  • Member
  • Posts: 577

As a ham and EE I wanted to look into repairing it especially since I own 2 supplies ( 4 modules ) and they cost 500$ each to have replaced plus shipping.  Thats on the high side of cheap for sure. Woody
Logged

W9IQ

  • Member
  • Posts: 8862

As a ham and EE I wanted to look into repairing it especially since I own 2 supplies ( 4 modules ) and they cost 500$ each to have replaced plus shipping.  Thats on the high side of cheap for sure. Woody

Woody,

I repaired one a while back by using the switcher IC reference circuit as a rough guide to the design. It isn't a very complicated switcher if you have done switcher designs/repairs in the past.

There are a couple versions of that module based on pictures that I have seen posted. Can you post a couple high resolution pictures of your version(s)?

- Glenn W9IQ
Logged
- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

AC2RY

  • Member
  • Posts: 1054

MFJ does not have info on the supply?   One of my supplies failed and I had it repaired at MFJ ( they swapped it out ) and I asked for it return.  The 300 volt bus is up but nothing else is operating, and Id like to fix it as a spare if possible.

Please let me know if you have worked on the 50 volt supply module, thank you, W  >:(  :D D Y

I would start with replacing electrolytic capacitors in the feedback circuit. Also likely need to test all diodes and mosfets, to make sure they are not fried. Almost al switch mode supplies I repaired had faulty capacitors. To do deep troubleshooting on this type of supplies you will need ground isolated balanced oscilloscope probe, which may be more costly than power supply itself.
Logged
Pages: [1]   Go Up