Metcal MX-5000 repaired for not heating up

[gregpl]

Didn't see this posted anywhere so thought it might help someone one day.
Was using my metcal mx-5000 and turned it off to replace tip then it wouldn't
heat up anymore. Everything else would work. When I picked up the iron to use
the bar graph did nothing and of course would not heat up.

Took it apart and found SMD diode D12 bad. SK16 -  https://media.digikey.com/pdf/Data%20Sheets/Diodes%20PDFs/SK12-SK16.pdf

Replaced the diode and its working again. Almost bought a new one. Glad I took it apart.

[Zucca]

Thanks gregpl, great job!

[memed]

Hi.
I have same issue with my MX-5200.
Did Q4 MOSFET was heating up that time?
Diode  D12 was shorted?
Thanks

[gregpl]

I used an IR camera and could see D12 getting hot. It read shorted. Replaced it and its working now.
I didn't check any voltages or anything else. Just used the IR to see if anything was getting hot.