Aoyue Int 768 - I smoked the built-in power supply

[whotopia]

I inadvertently burned out the power supply portion of my Aoyue soldering/hot air station.   It happened due to the leads shorting for a long period of time on my work bench, but I didn't notice.   Ooops!    Symptoms are now no output voltage.   No matter where the POT is set Voltage reads 21.2V and Amps reads 0.04A.

I guess I will crack the thing open and start debugging.   I've been in there before, and it looks like pretty simple, single layer through-hole boards.

I was wondering if anyone else here has done this before and has any pointers, or you know of any schematics or service manuals available.   

Thanks.

[Aodhan145]

Hi, I did the exact same thing mines reads around 21V as well. I cracked it open and saw that R43 was burnt to a crisp, I contacted the manufacturer to confirm the specs of the resistor it was a 360 ohm 0.6W resistor. So I got one out then realized I don't have another soldering iron so after a while of searching i found a shitty unregulated iron. I soldered it back together and It didn't work its still broke. I recommend checking if yours is blown and replacing it. Hopefully you have more luck than me.

[whotopia]

Hi Aodhan145

I finally got around to opening up and attempting repair on my Aoyue Int768 unit power supply circuitry.
When I opened the unit, indeed R43 was fried.   Suspecting there was more broken, based on your post, I bought a few more parts from Digi-key and replaced the LM723CN,  C9012 Transistor ,  and the 1000uF 25V.  That seemed to do the trick.  The unit is working fine again.   I included annotated picture below.   

If anyone else has this problem, make sure to photograph all the connectors before disassembly!


Cheers.
 

[Aodhan145]

I was able to return mine and they replaced the board for free I never bothered to fix it myself. I have a real bench psu so it didnt matter that much anyway but I only use the ouput from the soldering station to power the fan I use to blow the soldering fumes away.