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Enabling the ESP120

Here’s how you turn on the ESP120 server power supply. Here’s the main ESP120 article.

You will connect the three pins together. A 3-pin connector commonly used for servos in RC toys is perfect for this.

3-pin RC Connector

 

 

Photo of ESP120 back end

 

Small RC Connector

 

Comments

32 responses to “Enabling the ESP120”

  1. S.W.ROBINSON Avatar
    S.W.ROBINSON

    ABOUT TIME SOMEONE MADE IT CLEAR HOW TO USE THIS UNIT TO POWER A LDMOS AMP. I APPRECIATE YOU MAKING THIS INFO AVAILABLE.SAVES ME A LOT OF TIME AND DRAMA. MAHALO KC6SWR.

    Reply
    1. N4GA - Rob Avatar
      N4GA – Rob

      SW,

      YOU’RE WELCOME!

      😉

      Thanks for the comment.

      Reply
    2. Bruce Avatar
      Bruce

      Do you tie the two negative together and the same for the positive or do you use only one set to get max power?
      Tnx Bruce, AH0U

      Reply
  2. Leroy Ounanian K6LLO Avatar
    Leroy Ounanian K6LLO

    I have purchased two of these to power an LDMOS amplifier. When I power up the PS, the output fluctuates between 44-50 volts with about a one cycle per second frequency. It continues with a load on the PS. The amp is new and I do not yet want to take a chance trying this out. I cannot seem to open the case to this PS- built like a tank- yes. Is this likely to be a leaky capacitor? Both of the PS purchased on e-bay (from same seller) have this behavior.

    Reply
    1. N4GA - Rob Avatar
      N4GA – Rob

      Thanks for your comment Leroy. I WISH I could help you. I’ve never had an issue with any of my ESP120s and as such have only opened them up to slow down the fans.

      Pretty advanced complicated computerized SMPS. Would not know where to even begin.

      Sorry and good luck!

      Reply
      1. KI4US Avatar
        KI4US

        Leroy, how much load did you put on the amp?
        I suspect it takes about 50-100 watts to get stable …

        Reply
    2. John Avatar
      John

      This is Normal for an HPS3kW modules. Not compatible ESP120 model!
      I have two unit that have the same behavior!

      You Must short the 3 pins indicate in this web site but you must short the Pin PSON to the 5Vsbrtn
      too!

      On my 2 unit its works!

      Good luck!
      73 QRO.

      Reply
      1. N4GA - Rob Avatar
        N4GA – Rob

        Can’t really follow that, but in case it’s helpful for someone else, thanks for the post!

        Reply
  3. N7CXI Avatar
    N7CXI

    Have you bridged two ESP120’s ?
    If so, I’m curious what is used for isolation.

    Thanks,
    Jim N7CXI

    Reply
    1. N4GA - Rob Avatar
      N4GA – Rob

      Jim,

      How are ya!

      I have not ever had the need for 100A so I have no experience with strapping them together. But a friend of mine has and his info is here.

      Good luck with your projects!

      Reply
      1. N7CXI Avatar
        N7CXI

        It looks, at least like he didn’t actually bridge them, but ran each module from a separate PSU.

        I’ll have to think about that one – I wonder if any output differences would show up in the combiner… If the regulation is good enough I don’t suppose it would matter.

        Thanks for publishing the connection data. It’s appreciated.

        73,
        Jim N7CXI

        Reply
  4. Mark Daniel Avatar
    Mark Daniel

    Will the protection circuit in the 120 ESP allow them to be connected in parallel?

    Reply
    1. N4GA - Rob Avatar
      N4GA – Rob

      I’ve never done it but I know others that have and it worked.

      Reply
    2. Thomas Avatar
      Thomas

      I have and it worked fine. I put 2 separate Common Mode chokes on each output along with 100A 1600v Diodes In series with the Positive DC Output Wires. I as well made sure that each wire was the exact length to the bus. The Diodes was probably enough but for good measure I did the length trick as well. So each power supply has no idea that it is NOT running by it self via the Diodes only allowing the Voltage to flow that one direction. Hope this helps. I know a guy that paralleled 4 of these boogers lol. Crazy. He will not be able to actually run that much on a 50A 220v Mains I don’t think but he only did it for duty cycle purposes. Same reason I just built a 4xBLF188XR Amplifier. Duty cycle purposes.

      Reply
  5. cornelis Avatar
    cornelis

    hello, here pa5six, from holland.
    i have a eps 120 ps can i make the voltage higher to about 56-58 v dc ?
    what is the best way to do mvg many thanks .
    cornelis .r. pa5six 73

    Reply
    1. N4GA - Rob Avatar
      N4GA – Rob

      Hello!

      There’s a potentiometer in the case somewhere that will allow you to minimally adjust the voltage, but the range is not great and I do not believe you can adjust it that high.

      73s and Happy Holidays!

      Reply
      1. Cor Avatar
        Cor

        hello Rob, i cannot see where in the case maybe there is a picture for this place,i need 53v dc thanks for your time and all the best in the next cor pa5six 73

        Reply
  6. cornelis rietdijk Avatar
    cornelis rietdijk

    hello. rob,
    exuses for your language i have never englisch at school, i am 77 years so what? i tray it.
    i have changed the eps120 too 53,9v dc. if you seen in the suplay, the place where the potmeter must soldered , first the take the smd
    resister outof the board ,this is about 2,3 kohm.
    then soldered 2 wires on the two upper sold. places on the another side of the wires the pot meter, if youturn the pot.meter can you regulated too 53,9 vdc the potmeter is 5kohm miniatuur .
    i make a new case with a meterand shunt – v meter all analoog.
    a digital meter is to lasy by ssb. maby i u ased analoog and digital ??the fans are now also stil with the resisters a,, 15 ohm in the connection of the fans also i can used the 12volts dc from the fans as externe power for the digitale meters . have a nice time cor pa5six 73

    Reply
  7. Michael Moran Avatar
    Michael Moran

    Hello,
    I really like what you are doing here and have been trying to read EVERYTHING.
    How would you recommend wiring the 240V to the chassis. Did you source the connector and break the wires out externally, or did you crack open the PS, remove the external connector and wire the cord inside? Also, is there switch on this Power Supply or is that something you should wire in as well?
    Take care and stay safe,
    –Mike

    Reply
    1. N4GA - Rob Avatar
      N4GA – Rob

      Mike,

      Thank you!

      Unfortunately, I have not done any of that. I left the ESP120 in its original case and I use it externally to the amplifier. I soldered directly to the lugs on the back of the ESP. I did wire a on/off switch using a dual gang switch from good ole HomeDepot. If you look at the photo on the home page, you can see the ESP sitting in the unit that the amp is sitting on.

      Thanks again you stay safe as well! Rob

      Reply
      1. Michael Moran Avatar
        Michael Moran

        Thanks for the reply Rob,
        I have my PSUs now I am ready to wire up a plug. We use four wires for 220V, two hot a neutral and a ground. How would you suggest I connect the ground wire? the the Chassis?
        The receptacle is a 14-30R if you’re interested in the exact plug type I intend to use.

        Take care and stay safe,
        –Mike
        KD2HLK

        Reply
  8. freddie Avatar
    freddie

    I have tried two different power supplies put three wire to get her powered up nothing on output what am I doing wrong fans run etc

    Reply
  9. thierry Avatar
    thierry

    Hello
    on my HP ESP120 power supply I have a yellow led which lights up and no longer gives me 48v from which it can come thank you

    Reply
    1. N4GA - Rob Avatar
      N4GA – Rob

      Means its not enabled via the logic pins. Or, it might be broken.

      Reply
  10. Frank Carcia Avatar
    Frank Carcia

    Hi All,
    I have been running two parallel ESP120s for a few years now. I bought the case that goes in the server that will hold 4 modules. There is a 4 pin connector on the back that allows multiple modules to be bridged. I am looking for information to bridge the two sides so I could run 4 modules. It is set up for positive ground so need to swap that around. It has two 240 30 amp line cords with breakers coming off it. I built a 160m – 6m amp with 4 – 1200 watt MRI surplus amplifiers into a combiner.2 power supply modules limit my power to about 3kW PEP. Worse case I’ll just brute force the supplier on with jumpers but it would be cool to see if the logic board in the back controls and communicates between modules. There are two RJ45 on the back that would go to the server controller.

    Reply
    1. Timothy S. Kraus Avatar
      Timothy S. Kraus

      That was my latest project.

      I paralleled two ESP-120 through .1 ohm ceramic resistors. One end of each resistor is connected to the positive side. The other ends are joined together and then a single lead to the load.

      The resistors were twenty-2 ohm, 10 watters in parallel. Got forty from Antique Electronic Supply.

      Didn’t connect anything else except the three pins to get the ESP-120 to shoot out 51.4 volts.

      Good luck.

      Kraus/KC4ZGP

      Reply
  11. Kiran vu2xe Avatar
    Kiran vu2xe

    I have been using this unit for few years without any issue with my w6pql hf amp. But during a last cqww contest due to high swr, few times my amp tripped cutting off mains to this unit. After couple of such frequent tripping, now dc supply is showing zero volt output. Fan is working but caution ⚠️ led is lit. Any hints to troubleshoot this issue?

    Thanks in advance
    Kiran

    Reply
    1. N4GA - Rob Avatar
      N4GA – Rob

      I wish I could help you. These supplies are complicated!

      Reply
      1. Kiran Avatar
        Kiran

        Thats ok Rob, i will post here if i find any fix. Meanwhile,I am getting used eltek flatpack 48/3000w with similar specs, but with much lower weight and costing less than $60 equivalent.

        Kiran VU2XE

        Reply
    2. Dominic Cafolla Avatar
      Dominic Cafolla

      Hi Kiran
      Did you ever get yout problem resolved?
      I have a similar issue.

      Regards
      Dom

      Reply
  12. Mike Webb Avatar
    Mike Webb

    Is it possible to see the modification diagram for the voltage control pot

    Thanks

    Reply
    1. N4GA - Rob Avatar
      N4GA – Rob

      Hi Mike – not from this site. I’ve never played with that.

      You might pose the Q here: https://www.facebook.com/groups/172956609870876

      I’ve seen it discussed in that Group before.

      73

      Reply

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