Repairing Hakko 926

[mac]

Hello all,
I am in the middle of repair frustration.

Recently had some issues with my Hakko 926 with a (what I thought was genuine) replacement tip that I had from many years ago warping and thus corrupting the tip enclosure on the 900m handle.

Replacement with a new tip, tip enclosure 900m-002 and nut 900m-006 resulted in the iron no longer switching on and off (simply heats and stays on until it glows red hot).

Hakko manuals suggest testing of the connections in the handle to ensure no shorts, to ensure the heating element is good and to ensure the cable is good. Also ensured proper grounding of the grounding spring through the unit from the tip to the ground lugs on the transformer. Pins 1 & 2 measured 49ohms - pins 4 & 5 2.9ohm - pin 3 and tip under 1ohm which were all within spec.

To be sure, (and in accordance with the Trouble Shooting manual for the 926), I ordered a new genuine replacement heating element A1321 and installed - same conditions of over heating remained.

I then remeasured all of the connections at the pcb to eliminate the possibility of the multipin connector or internal unit wiring being the culprit - no joy.

Manual then suggest testing of the triac resistances on the pcb - tested in circuit and then removed for testing but was found to be good. Reinstalled - same overheating condition remains.

AAAHRGH - running out of ideas on this one. All suggestions apart from binning the iron would be welcomed. All the new parts are sourced from Element14 and thus I trust are genuine.

Mac.