My soldering station is a Weller WES51 for a long time. Today the station died, the LED didn't turn on and the tip doesn't heat.

I opened the station and checked the transformer power switch and voltages in the controller board. Everything appears to be ok.

When i tried to verify the clock in the micro controller (PIC) and touch the oscilloscope ground probe in the common of the controller the station works.

I tested the continuity with success in every common point that I've found. The station starts to work as soon as i connect ANY of the common points to ground(Which is weird).

If i connect the transformer core (that is grounded) to one of the secondary outputs the station works

There is continuity between the tip of the station and the ground terminal.

Any ideas why this is happening?

I couldn't find he weller wes51 schematic. Anybody know where i can find it?

Thanks.enter image description here

  • \$\begingroup\$ Sorry your station died. Cool problem though! \$\endgroup\$ – Leroy105 Aug 24 '18 at 20:36

I think what's happening here is that your oscilloscope ground and your soldering iron common are connected to the same node, however the soldering iron common connection is broken somewhere.

By connecting the iron's common to the oscilliscope ground, you are effectively completing the circuit so that the current can flow again.

I recommend checking for any broken ground connections. To do this, I would probe all the ground connections along the soldering iron electronics while it is off, checking to see that all the nodes are in fact connected to each other. If there's a broken connection somewhere, that's probably your issue.

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