Friday, 20 June 2014

Unlocking the temperature on a Weller WSL or WSD 81 Solder Station

[Credit for the fix goes to Todd Wild]

Just had a weird problem with my Weller WSL with WMP pencil:

Symptom of initial failure:
The base unit was resetting and making a clicking noise while the iron temperature dropped.

When I looked closer the clicking noise was a screw I had put on the top of the base unit - every time it reset the screw jumped!

After opening the WMP pencil I discovered the strain relief failed and the wires inside the iron were shorting. After fixing that it worked perfectly but the base unit had become locked to 375°C! [Speculation is that the EEPROM in the micro was corrupted by all the hard resets and/or the EM pulses].

Symptom of locked base unit:
Trying to change the temperature failed with the display just flashing when up or down is pushed. Just in case you didn't know nearly all solder stations for production environments can be locked to prevent inexperienced people altering the soldering parameters.

Solution:
Purchase a WCB1 calibrator for $1500 (only joking! read on...)

-or-
Opened WSL / WSD81 base unit - the reset jumper is to the right of the "up button" at the top right

  1. Open the case (spudgers needed, start with prying open the keyholes sideways on either side of the heatsink on the back and then pry the case up from the slots along both sides starting at the back. It should pop off towards the front).
  2. Install a jumper on the empty 0.1" pitch pins to the right of the "Up" button on the top right of the PCB. In the picture they are just visible to the right of the black square which is the up button.
  3. Power on the base unit - watch out for the live 120/240V!
  4. Wait for the display to show FSE.
  5. Remove the jumper while it is powered on.
  6. ...
  7. Profit!
Hope this may be of some use to someone else.