Switching Power Supply Repair - worth it? Thoughts on replacement.

Discussion in 'Ham Radio Discussions' started by KJ5T, Jul 29, 2020.

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  1. KJ5T

    KJ5T Premium Subscriber QRZ Page

    Well, after nearly a decade my workhorse Samlex 1235M has "died". By died I mean no output, I opened it up just to physically look to see if there were signs of burnt parts, I noticed a blown fuse.

    I will admit I am an Extra class ham who doesn't have the knowledge to really troubleshoot this, my meter is even a cheap Chinese meter. My dad would be ashamed of me for not learning the things he tried to teach me. Anyhow, I am wondering if it is worth it to bother sending it off for repair. I guess the question is really, does anyone have experience with sending off their Switching Power supply for repair in terms of cost and/or time?

    For now I can run off my 20Ah Bioenno battery for my needs; however, I am debating if I go the replacement route what I should do. I am leaning towards around Samlex just because they are so cost effective for a decent PS and they don't take up much space. My FT-1000 has a built in power supply so the Samlex currently powers my KX2 and 857D (not typically at the same time). I may in the next couple of years invest in a KXPA100 which draws 20 amps, though it may make sense to just run that off it's own Power Supply.

    Anyone have any experience with the Astron switching power supplies? I started with RS-20A and I don't know what ever happened to it (long story involving a family friend holding stuff in storage and some deaths along the way). The RS-35A is a big guy, maybe too big for my current desk but they are built like a rock. I think the only thing Dad ever did with the Astron RS-20A's was replace the full-wave bridge rectifier.

    Anyone have any experience with the Powerwerx Solid State amps? That is what Elecraft sells as a companion for the KXPA100. $120.

    I have heard negative things about the MFJ power supplies, though I know some people have no problems. Though the 30A supplies aren't much cheaper.

    Lots of options out there for the appliance ham and lots of places to buy from. If I were a real ham I would probably not half to repair this power supply because I would have built my own from scratch to start with.
  2. WE4E

    WE4E Premium Subscriber QRZ Page

    So replace the blown fuse. If it blows a second time you'll know whether it needs to be repaired or not. You might get lucky.

    At $130 or so for a new one, you reach the point of diminished returns quickly.
    K0UO and K4VBB like this.
  3. KJ5T

    KJ5T Premium Subscriber QRZ Page

    I probably should proof read my posts before hitting submit, I completely left off the part where I replaced the 8A/250V fuse and it instantly blew again when powered on (no load on it). Clearly something is faulty, I suppose if I was capable of diagnosing and repairing myself it would be a different story. I'll probably end up shopping around for a replacement, just so I don't wear out my Bioenno battery too much. Maybe I will give this bad amp to my buddy who isn't active on the air but has a whole lab set-up and used to work with electronics professionally before entering the software world, if he wants to fix it he can have the thing!
    W2AI likes this.
  4. W4IOA

    W4IOA Ham Member QRZ Page

    I just gave a Samlex away to a new ham. It was well used when given to me but I wouldn't hesitate to buy another if need be.
    I have an Astron 35, they are great and I never worry about noise from fans. At my previous home I set it up on a shelf. Here now I have it on a milk crate under the desk. I don't leave it on when I'm not using it though for a few years I always left it on.
    My point, they're set it and forget it.
    WA9SVD and KJ5T like this.
  5. PA5COR

    PA5COR Ham Member QRZ Page

    My new Nissei NS 2230D 28 amp continuous and 30 amp surge digital read out PSU cost a whopping 85 Euro's.
    Mostly the switching transistors conk out on these supplies, and take some other parts with them, cost of repairing nearing the price of a new PSU. ( and still left with a well used PSU that can go poof from other faults.),
    So, sad as it is for the current prices with my new PSU comes with a full 2 year warranty, i'd rather buy a new one just to be safe looking at the costly equipment connected to it.
    Make sure like the Nissei it is fully protected for output voltage, short circuit protection etc.
  6. K6CLS

    K6CLS Ham Member QRZ Page

    I have several of the little cubical MFJ 25A switching supplies
    They work justfine and deliver smooth power up to their 25A rating. They are lightweight and compact so very portable.

    One really old one started delivering 4VDC. I opened it up, but with no schematic, couldn't get anywhere. MFJ wanted $40 to repair, and with $40 shopping I said fergetit. Bought a new one for $90. With meters!

    I have many Astrons, and they are jusst solud, reliablte, quiet performers. They are heavy and large so not really portable.

    I have several other switchers, from Alinco, Diamond, and another, sorry can't remember the brand right now. They all work fine.
    PA5COR likes this.
  7. WA9SVD

    WA9SVD Ham Member QRZ Page

  8. WA9SVD

    WA9SVD Ham Member QRZ Page

    The point of co$t of repair vs, replacement is important. (Some electronics I have actually demanded more for repair than the actual purchase price or a new unit; obviously, I try to buy a competitor's item if I have to replace something.) So inquire before you choose. Most switching supplies, sadly, have proprietary components, and are either not identifiable, or are unobtainable from the manufacturer, and without a schematic, can be almost impossible to repair.

    THAT said, my LINEAR Astron RS-35 has been in service continuously for over 25 years... (and can easily be repaired, if even need be.) For what it's worth, YMMV.
  9. W5ESE

    W5ESE Ham Member QRZ Page

    I have a Ten-Tec power supply (which is essentially an Astron with a Ten-Tec logo) running my Omni VI.

    It's been working reliably since 2003, when I bought it at the same time as the Omni Vi.
  10. KA8NCR

    KA8NCR Ham Member QRZ Page

    Deep dive repair of switching supplies requires isolating your 'scope. Failure to do so will blow the tip off your probe and make whatever ails the power supply much worse.

    When troubleshooting a failed switching supply, I start with the caps, especially those around big silicon where it gets warm. Don't even need a print for that. That is, unless there are traces blown off the circuit board from a catastrophic failure or someone using a 'scope that wasn't isolated.
    W4NNF likes this.

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