EE's or PSU geeks, I need some help with a PSU issue.
 

Ok this is a PSU for a Intel Netstructure 470T switch. the 12v Rail coming out of it seems to be ... well not there. I get nothing out of it at all on that rail but the others are fine. No burnt components on the board, doesnt have that fresh fried smell either...

a model number that is not visible in the pics is ADP-75AP

I doubt that just by looking at anything can anyone come up with any theories but I thought I would post it here anyway.

the PSU puts out 3.3v on 6 pins, Ground on 7, and then 1 12v pin. the 12v is only used for running the fans in the switch. I have a 12v wall wart I can use for the LAN I have coming up but I would like to get the PSU working properly again. the 3.3 works fine.

the pics below are full 4MP res pics of the PCB.

http://clegg.procooling.com/psu/PCB-bottom.jpg
http://clegg.procooling.com/psu/PCB-top.jpg

Hey Joe, Turn that top view 180 for me, Thanks

taking a couple more top pics now.

More Top Pics.

http://clegg.procooling.com/psu/PCB-top2.jpg
http://clegg.procooling.com/psu/PCB-top3.jpg

Difficult to say by looking at the pic's but hit the solder pad where the 12v rail is, kinda looks like a cold solder joint. That is the pad you have marked with the arrow. also, take a pic of the board strait down from the top around the connector for the 12v. Thanks

ok, the pics arent as good as the others, the camera has some issues focusing on all of it and the flash is too bright for those areas.

http://clegg.procooling.com/psu/PCB-top4.jpg
http://clegg.procooling.com/psu/PCB-top5.jpg

Also bigmack Brians256 is pitching in via Pro/Chat you should jump in.

The 12v line is fed from the voltage regulator. You'll be limited to about 1 amp on that line.

Looks to me like the 12V pin is not connected to anything. If you look at the first two pictures, you can see that the pin for the 12V on the connector is not going through the PCB. Where have you measured voltage from? I would suggest putting a DMM on the pad on the bottom of the board, and measuring to see if it is at 12V.

Best of luck with that.

Bigmack and Brian in IRC both walked me through testing stuff, and it seems like theres notihing coming out of the transformer so it may be dead on that set of wires.

It looks like pin# 9 of the transformer output got hot (there's a reflow on the traces) and that the solder joint after that has been damaged.

Did you measure the transformer output at pin #9? (the pins are numbered from 7 to 15)

Otherwise pin# 9 feeds the 12 volt regulator.