Michael A. Terrell wrote:

larry moe 'n curly wrote:

http://www.harborfreight.com/1500-watt-dual-temperature-heat-gun-572-1112-96289.html
$19.99 regular price. On sale for $9.99 at times.

I received their weekly e-mail right after I posted. It is on sale
for $7.99 with the coupon below:

http://www.harborfreightusa.com/html...7/images/2.jpg

Here is the user manual:

http://images.harborfreight.com/manu...6999/96289.pdf

The power switched popped out 3/16" when I pressed it (2 samples)

Then why did you buy one? Mine is fine, and I just picked one off
the shelf, yesterday. I already have an old B&D, and a five year old HF
heat gun. The case on the B&D melted when I had to preheat some 1.5"
copper pipe while assembling the cooling system on an old TTU-25B UHF TV
transmitter. I also needed an acetylene torch & a 175W Weller iron to
remove some damaged copper pipe from some custom 30 year old brass
fittings RCA used in that transmitter. The HF has been used to remove
floor tiles, on heat shrink, and to expand metal castings to remove
bearings.

The diode in series with the heating element is a 1N5408, rated
for 3 amps average. The heater draws 8A average on low.

So my question is, how long will this 3A diode last?

Where is the 1N5408 diode? It isn't listed in the parts list or
shown in the drawings:

http://images.harborfreight.com/manu...6999/96289.pdf

How long to you use a heat gun per application? Can you read a
datasheet, or only skim one? That 3 A rating is for continuous duty at
a high operating temperature, not intermittent. The peak current rating
is 200A. The case would likely melt before the diode would fail.

http://www.datasheetcatalog.org/datasheet/GeneralSemiconductor/mXyztrxt.pdf

I've seen four 1N4004 diodes in a bridge, in series with the heater in
a hair dryer to power the dc motor on the fan. Are you claiming that a
tool like that can only provide less than 120 watts of heat?

I bought the HF heat gun yesterday, and it has a manufacturing date of
Jan, 2010. Here's a photo of the inside, showing the 1N5408 diode
across the two poles of the switch:

http://farm4.static.flickr.com/3315/...3af89634_o.jpg

The switch popped out because the lower locking tab was squashed and
couldn't lock. I think there's a bridge of small diodes at the end of
the fan motor.

Doesn't the continuous amp rating for a diode apply for any load
lasting more than something like one 60 Hz cycle (or half-cycle?). I
normally run a heat gun a lot longer than that, maybe up to 2
minutes at a time.