862D+ solder station iron out of control when fan on

[liquidzorch]

Hello.
I have a soldering station, 862D+, and every time the hot air gun is on, even if it is just cooling off, the soldering iron controller stops controlling. Let me explain what has happened so far, as it took a while to get to this.
First, the switch that turns on the hot air gun started to fail, the light came on, but temp never rose, I would have to switch it multiple time to get the gun to start heating, this was due to the contact inside being carbonized. I opened the switch up, clean the contacts, and it would work fin for a while until carbonized again. So, I ordered a switch to replace it. While waiting for the switch to arrive (from china) I kept using the iron and gun (never had an issue with the iron), but one day I switched on the gun, and there was a buzz coming from the inside of the station, seems like transformer buzz, and I didn’t notice at the time, but the iron would go from being on normal, to being on without control.
I kept using it without even noticing that the iron was getting superhot, since it was normally just a few seconds of hot air being used. I ended up swapping the switch and it worked the same way, with a buzz any time the fan was on. Then one day the fan just stayed on, no matter what, I would have to disconnect the whole station to get it to turn off. So I swapped the TIP122 on the fan controller side, and back to normal, no buzz, but the iron will heat infinitely any time the fan is on.
I don’t know what would cause this issue. The only thing I can think of is the microcontroller, since it seems to be the only link between the fan and the iron. But the iron work perfectly when the fan is off. Any ideas?

[stj]

lets see some intside pictures
i bet the soldering looks like shit.

[sam_sam_sam]

I would also like to see the board or boards on this unit for the same reason I suspect bad soldering joints as well

[liquidzorch]

I'll have to disassemble it, it is the only iron I have, so it is still in use. Once I can get some time to do so, I will upload the pictures.

[liquidzorch]

I finally had some spare time to open it up. It ended up being a bad capacitor right after the bridge rectifier diodes, on the line that goes to the fan control TIP. It was a 50v 220uf capacitor. Replaced it and it is back to normal.

[Th3_uN1Qu3]

Was sure it was a bad cap. You know which forum you're on. Anyway, congrats for fixing it, and make sure to replace 'em all, it isn't too much work and will ensure you reliability for a good few years.