Wednesday 18 October 2017

Metcal MX-PS5000 repair.

Been very busy, in a commercial sense, building some transmitting equipment ...

... and just as I'm about to solder the last two wires on the front panel of said equipment, the iron goes cold ...

The soldering iron in question is the very, very wonderful Metcal MX-PS5000 system. I used to think Weller made the rolls-royce of soldering irons, but these things are just in a different league!

They heat the element by RF induction heating. 13.560 MHz to be precise. It's got all manner of error detecting, it'll put itself to sleep when not in use, and also has outputs for two irons. It's also expensive.

So I think, it's probably gone to sleep ... nope.
Perhaps the tip has failed? No... (takes two seconds to change too!!)

Damn ... the emergency iron is flagged into service, and the job finished...

A new MX-PS5200 is ordered (at about £500!.. ouch). We simply can't be without it.

But let's see if we can't do anything about the old one...

Firstly, remove the retaining nuts from each of the F-connectors.

Flip the unit over, and remove the 4 security torx screws, one in each corner.

Right, that's got it out. To remove the board there are several small screws to undo, and remove the screws from the heat sinked (heat sunk?) devices, noting which are insulated from the heatsink, and which are not. The wires connecting the power supply in the back and the main board are quite short.

First thing was to check the presence of the +48V  and  +24V supplies from the switched mode mounted in the rear third of the enclosure.. all present and correct... damn.. out goes any ideas of a blown fuse and a quick-fix! There's no hope of getting a schematic, so it's down to the poke-and-hope method of fault-finding....

Checking a few parts, shows the main output FET to be dead short ... It is (or rather was) an IXFH12N50P, which is no longer available. An IXFH16N50P looks like a good candidate, and is pressed into service.... still not warming the iron... damn. It's gate is driven by a drive amplifier, which is in turn driven by an oscillator formed by a crystal, and a 74HC04 hex inverter... the hex inverter is duff, and is replaced, and so is the supply to the drive amplifier...

It's an LM2576-ADJ (not that you'd know from the photo) .... and replacing that restores the supply to the second stage of the drive amp, but not all of it .... damn.

The final piece of the jigsaw is D12 in the small switched mode buck converter .... it too was dead short ... lord knows what the original is, there's no circuit anywhere on the web, so I selected a 1N5819HW for the job, based on the datasheet for U3. It's physically smaller than the diode it replaced, but it seems to work! I've got a hot iron!

Excellent ! We now have a spare in the workshop.

Not sure I like Metcal's new logo much ...


  1. Hi (from france),

    Many thanks for your blog, i have successfully repair my MX-PS5000 with your guidelines.

    My MX5000 see 'power' with output power to 0, and i found the U3 very hot , without any signal output signal to D12/L4...

    D12 is a SK16 (
    I have replace it by a SK36B witch have the same direct and reverse voltage , but 3A (SK16 is only 1A).
    All works well !

    some pictures after repair:

  2. Très bien! Nice to know the article has been of help. My smaller D12 is still working well!

  3. Hi.
    I have same issue with my MX-5000.
    Diode D12 shorted!


  4. Also I found bad soldering joints around the trough hole components (inductors).

  5. I just bought a Metcal MX-PS5000 on ebay that does not work, I did not know this manufacturer, and I was looking for a more professional soldering station than the one I have, I got one and ended up on your blog, you help me repair it and, I tell you which diode is D12, in my
    board is a SK38B, but mine is in good condition, the damaged component in mine at the moment is the IXFH12N50F, do tests and I will comment on the news, thanks for sharing

    1. Good luck. I still haven't used a better iron.

  6. Hi.
    very interesting this page. Very well Doz.
    i have a broken Mx5200 that when i power it don't heat the element.
    i find in short circuit the 12n50 mosfet. i replace it but nothing. i check the lm2574 and lm2576 the 2574 is correct, but in the 2576 i have always 48V in output and i don't see the frequency before the inductor output, i alredy see the 48v. i think it i broken. now i try to replace it.
    then i check the output of 74hc04, is correct that i find a sinusoid wave at 13.56MHz? i think that i must find a square wave at 13.56Mhz.
    then is correct that in the parallel capacitor of the inductor output i measure 3kohm of impedence. i think it is too low.

    many thank Luca

  7. Hi.
    Got the same fail with my MX-PS5000.
    Diode D12 was shorted. I replaced it with MBRS190T3 and now all works as should.
    Many thanks for shared info!

  8. I also found D12 shorted at Metcal MX5000. Thanks it’s good information.