VL-1000 Quadra power supply failure

Discussion in 'Amateur Radio Amplifiers' started by K7SWS, Feb 8, 2019.

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  1. WE4E

    WE4E Premium Subscriber QRZ Page

    Update. Got the amplifier apart finally and although there's a LOT of screws and things to remove, it's fairly straightforward. N8NN has a nice write up on the steps to get it apart, and that takes out a lot of the guesswork.

    Interesting find, my VP-1000 doesn't have the three 5.6Ω resistors. It has two 10Ω and a wire jumper. It looks like it could have been a factory tweak, as mine is relatively new (2012) as the Quadra goes. I called Yaesu tech support and they didn't have a record of that as a formal ECN. There's some flux residue on the resistors solder side, so it seems likely that those have been out once. The jumper didn't look just hacked in, and kinda looks like a 0Ω part.

    The resistors were indeed open.


    This is effectively a step-start. The three resistors are in series with the AC mains, and the relay coil is driven off of the +12v, so once the power supply starts, the relay pulls in and the resistors are bypassed.


    I have the three OEM 5.6Ω parts on their way, and I'm planning to put it back to print. I sent an email off to AB4OJ just to see if it rings any bells.
    W9GB and W1TRY like this.
  2. K6BRN

    K6BRN XML Subscriber QRZ Page

    Hmmmm. You might want to check the resistors AND relay. Please keep us in the loop!

    Brian - K6BRN
  3. WE4E

    WE4E Premium Subscriber QRZ Page

    I'll probably walk that general part of the circuit just to be certain. These have a reputation for failing on inrush, but my luck the relay or Q3299 or something else is bad. I did order six of the resistors however. $0.93/each. Figure if I actually have spares on hand I'll never have to change them again. :D:eek:
    KI5X and W1TRY like this.
  4. G0GSR

    G0GSR Ham Member QRZ Page

    I would check for a short on the output side of the soft start, also the HV DC rail.
    Maybe the resistors were subject to excess current?

  5. WE4E

    WE4E Premium Subscriber QRZ Page

    So a little update. I ordered the parts and Yaesu said they were in stock, no problem. What they meant was, one resistor was in stock and the others were backordered. I found a couple of sources. Digikey has what appears to be the correct thing, so as a hedge I ordered some. As I was reading the shipping confirmation email, Yaesu called to tell me the parts were in and would ship shortly. The Digikey order arrived yesterday, not sure if Yaesu has shipped or not. I tend to think not, as they're usually good about emailing.

    I'm tied up through the weekend, so I'll move forward probably Monday with the Digikey parts. That'll be a sure way to get the Yaesu parts in my mailbox on Tuesday. Either way, hope to have a report next week.
  6. KI5X

    KI5X Premium Subscriber QRZ Page

    Are you running this on 240v? What's your actual supply voltage? I spoke with Yaesu prior to buying a used Quadra and that was their first question. My supply side (to the outlet) was 248V. I used a buck/boost between the service panel and the outlet to drop that down to 230v. Yaesu says that will keep those in-rush resistors from frying. Just my 2-cents!
    K4AVF likes this.
  7. WE4E

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    Way ahead of ya. I had that conversation with Yaesu when I bought it, they said 240v max. My line voltage runs ~252 in the winter. I installed a buck-boost transformer as well. It's a little lower than that in the summer with all the air conditioners running. This thing was introduced in 1997, and the "220v" lines in the US were lower then.

    Interesting that the VL-1000 is still a current product, 22 years later. The longest running in the Yaesu line.
    K4AVF and KI5X like this.
  8. WE4E

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    Drum roll please. Number five is alive!


    The Yaesu parts arrived before I had time to work on this, so I put them in. I'm overrun with resistors now, so if anyone needs some...


    Some notes. Far and away the hardest part, if you can call it that, is the mechanical aspect. There's a bazillion screws to take out and keep track of. I kept them sorted by stages of completion, just so they didn't get all comingled. You have to be careful desoldering. The traces will lift if you make eye contact with them. One particular lead gave me the fits and I eventually lifted the donut, but the via was still good and that's the one that mattered, so no harm no foul. Got it all disassembled, repaired, reassembled, and lit off with no drama. It sounds a lot worse than it is.

    I've attached some pix below if you want to see what the guts of this thing looks like at the various stages of disassembly.

    Attached Files:

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  9. WE4E

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    Pix that didn't fit the previous message.

    Attached Files:

    K4AVF and W1TRY like this.
  10. KI5X

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    That tells you what a rock-solid product the Quadra system is. If all you have to do is replace 3 resistors, life's pretty doggone good! Love mine. "It just works"
    K4AVF and WE4E like this.

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