Alinco DM-330MVE repair + some tips

Switching power supplies are great, unless you connect them to an HF rig. Just like any other piece of electronics, they can break down. Due to the complexity of the switching circuitry, defects are often more difficult to find. This Alinco was even more of a challenge, as I could not find the schematics anywhere. All I could do is look at it, and draw a basic schematic diagram myself, so I could figure out the construction and the most likely suspects.

This PSU, brought here by another HAM, blew its fuse continuously, and it took a few more fuses before the owner determined that the problem was bigger than he initially hoped for. These were the likely suspects:

  • Rectifiers (all diodes and bridges proved to be OK)
  • 2x 26N50 power MOSFETS (both dead as a dodo)
  • 1x 2SC5353 (NPN transistor, also dead)
  • bad connections or short circuit problems (none in this case)

1) 26N50 MOSFETS. 2) 2SC5353 position

When FETS blow it is often clearly visible – a common nickname for a FET is ‘Fire Emitting Transistor’…  In this case there were no visible signs of fire or explosions, so I used test equipment instead. Both MOSFETS were completely shorted internally. You can test this by using a simple multimeter, and without removing the components.

Tip 1: When testing within a circuit, make sure you use a multimeter with at least 10MΩ/V DC,
Tip 2: Make sure nothing is live, and no single capacitor holds any charge,
Tip 3: If you want to know how to test a MOSFET with an ordinary multimeter, go here.

The 2SC5353 had to be removed before I could test it properly. No signs of life. The outcome proved to be completely in line with previous repairs where MOSFETS were involved. If one goes, the other goes too, and they will drag any driver with them into the grave.

No local shop here could sell me the two MOSFETS, nor the NPN transistor. Grrrr. Replacement components were eventually ordered on eBay and sent here from Singapore. The biggest hurdle though was removing the defective parts. The Alinco DM-330MVE is built according to RoHS standards, which means that lead-free solder is used, and my simple 25Watt soldering iron was not up to that task.

Tip 4: lead-free solder has a much higher melting point. Even with the proper solder/desolder equipment you have to be very careful, yet work as fast as you can. Due to the higher temperatures involved, it is easy to destroy the printed circuit board.

Thanks to Guus PA2FAB, who had an unused soldering station in his shack, I could finish the repair. He even doesn’t want it back. What can I say? Thanks a lot, mate!

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17 comments on “Alinco DM-330MVE repair + some tips

  1. Mooi stukje….maar eh als ik de eerste zin lees…..dan mag ik dus geen HF set op de Alinco aanlsluiten? Oei, valt een FT817 daar ook onder? Ik heb deze Alinco ook namelijk ;-). Nee, zal wel niet zo bedoeld zijn. Ik heb er al 30A van af gehaald kortstondig en het ding leeft nog. Maar voor hoge en langdurige belastingen zoals bij een contest gebruik ik liever mijn Astron 50A voeding van 25 Kg. Overigens heb ik in het verleden ook een geschakelde voeding kapot gehad, het betrof een kathrein modulaire voeding van 5A uit de kabel TV techniek die ik gebruikte voor een 24/7 packetnode. Bleek dat een klein trafootje de geest had gegeven, gelukkig hadden ze bij Conrad er nog één liggen. 73, Bas

  2. Ha die Bas,

    die opmerking van mij betreft de storing die die dingen genereren. Geweldige voeding verder, die Alinco!

    Hans

    • hello hans, I have a ALINCO dm330mvt, defective turned on the red light protected, can you tell me how to fix it, I am just beginner to philippine amature radio, hopefully you can help me, teach me to be whether do, I read the last told you about ALINCO dm330mve, sir do they both just componnent and lay out, I stock it, a great honor to read what you published concerning the ALINCO dm330mve, thank you and 73’s

      • Hi Jeffrey,

        it is impossible from a distance to tell what is wrong. All you can do is test the usual suspects one by one (diodes / rectifiers, power MOS FET’s and drivers). The red light in itself is only an indication that the protection circuit was activated, but it won’t tell you exactly where to look.

        Please do not forget to drain all capacitors before testing components!

      • ok thank you sir hans but 2sc4157 is not available here in the phillipines can i subtitute 2sc3307 please let me know sir.

        Jeffrey

        Re: possible replacements are 2SC3450, 2SC3831, or 2SC4058.

        Hans

  3. HELLO MY RADIO FREND I HAVE HERE ALINCO 330 MVE I REPLACED TRANSISTORS BUY VIA EBAY HI ALL 3 – 2X 2SC4157 AND 1X 2SC5353 POWERS UP BT NO VOLTS ON VOLT METER AND TERMINALS (RED LED PROTECT IS ON NONSTOP) POWER GREEN LED ALSO ON AND PRESELECT GREEN LED ALSO ON OK ANY SUGESTION OR HELP TO REPAIR WELCOME-FOR POSIBLE FAULT IM STUCK NOW HI IS POSIBLE POWER DIODA TO BE DEAD OR OTHER FAULT? I HAVE SHEMATICH SEVICE MANUAL IF YOU NEED SOME IS IN PDF 73 DE S56EPX FRANJO

    • Recently repaired one successfully myself. As per ur result it is understood that the control IC TL 494 or the H bridge lineup ( any of the pnp/npn transisters or both) C2336/A1006 became faulty. Kindly try. If any difficulty kindly contact me. My e-mail is is vu2rdl@gmail.com. Have a successful repair.

    • Hi Adrian,

      I got hold of an (incomplete) copy of the service manual, but it’s almost impossible to read. All I can make out from the circuit diagram, is that U10 is a NPN transistor, and U11 is PNP.

      If lightning destroyed these, chances are that the damage is extensive and that you have to replace a lot more.

      Hans

  4. Fixed Protect light/leds/fan/controller Vcc circuit by replacing opened capacitors C29&C30 in T3 output circuit (D5, D6 side).
    Noticed that D4, R24, D5, D6 looked like they had been heated up a little, resoldered.
    I hope to put a load on it tonight and see what gets hot.

  5. Load tested to 14 amps and temp of case got to around 125 to 130 degrees F.
    Tested my other DM-330MV after resoldering D4,5,6, R24.
    D4 looked like it got so hot that it had melted the solder around the leads at some point.
    I am going to email Alinco and ask if there has been any changes in that part of the circuit.
    Bob

  6. LS
    Er is nu een nieuwe versie, de DM-330MW Mk II

    Optische verschillen:
    de 3 ledjes op de voorkant zitten niet meer in een ‘driehoeks-formatie’ maar netjes onder elkaar.

    Ik las op Amazon dat er in het MK-II model sprake was van ‘improved filtering’.

    Ik heb er een besteld bij Portoshop.nl in Leusden, was niet op vooraad dus effe weekie w88.
    Ik ga hem gebruiken voor een ICOM IC-7600.

    Ik zal hier, als hij eenmaal warm staat te draaien, even een duik onder de motorkap doen, om te kijken wat voor chinees vlees we in de kuip hebben, en verslag doen hier op deze mooie site.

    73 de Robbert / PA3BKL

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