AGILENT E3632A - CORRECT FAN POSITION

[Ussovak]

Hi everyone,

I saw in various post many had questions regarding the Agilent E3632A series PS and the correct direction of air flow and mounting of the fan. I too bought one of Ebay and I also noticed my fan was mounted with air blowing into the case. I believe this is incorrect.

The User manual clearing says how the fan operates. The air is pulled through the side vents and blown out the back of the unit. See capture from manual below.

Makes most sense. Why would one want hot air to be blown towards the front of the case. This would heat up all of the components and the VFD.

[pigrew]

Huh, I hadn't contemplated the fan direction on these units.

I just checked an E3631A (had a failure in its voltage reference circuit, a resistor was open, IIRC), and it pulls air INTO the back and OUT the sides. The E3631A user manual says that it should blow out its sides (as it does). The E3633A manual states the same as the E3631A. I'm not sure why they would specify it one way on one model, and the opposite on the others.

One advantage of the fan sucking in air is that a filter could be fitted externally, but I don't think that was ever an option for the E363xA series. Perhaps they also want to keep the fan cool? Sucking in the back means that the hot air won't heat the fan motor.

[Ussovak]

It's in the E3632A manual as I described. And think about it, - these units also have a rack mount option. Would one really like to pull the extremely hot air from behind the rack and send it out the sides? They say it won't matter but anyone who's worked with rack mounted equipment knows that temps can get really high.

Not sure why E3631A would be any different but per the manual, they are different.

[Kwakerman]

The power transistor heatsinks are normally mounted close to the fan, cooling is probably better if directly behind fam blast rather than from air being drawn in from surrounding area within the case?