Hafler DH500 fan went

[KP11520]

Hi all,

My friend has a used early 80s Kit DH500 and the fan just quit (noisey first).

He looked for a replacement fan and can't find any. David Hafler doesn't have anything to replace it or want to do the work.

Might anyone have experience with this? Suggestions?

Thanks!!!!

Regards//Keith

[Glowbug]

Measure it to get an idea of the size, then I'd try a place like this: Quiet PC USA - Quiet Computer Hardware Sales and Distribution for a quiet replacement

[BobEllis]

It's a 4" 120VAC induction motor fan. Replaced one a few years back. In home operation it runs slowly and is inaudible almost all the time even though it is a standard fan. I believe it's rated around 7W, it's marked on the original fan to give you an idea what to shop for.

[BobEllis]

or maybe its 120 mm, can't remember but the bolt pattern around the vent on the back of the amp is the same as the fan

[wwenze]

Hmm 7W is pretty powerful for 120mm, using a rated 3W @ 12V fan undervolted to 5V on the table to cool myself.

I'd replace with something with the same airflow or RPM, more or less depending on whether you want quietness or equipment longevity. Google the fan model number for that info.

[BobEllis]

There are a pair of 300R resistors in series with the fan, so it initially runs pretty slowly. As the temperature rises the thermal switches bypass each resistor at different temperatures, giving it three speed operation.

I've never had it hit full speed at home as my subwoofer amp. Sometimes a lot of low bass content will kick it up to the middle speed, but not for long. Too much dust collected in the tunnel can also cause the fan to run fast.

[bear]

remove fan
clean with degreaser
rinse
lube bearings with synthetic motor oil (doesn't gum)
should be fine
those fans are hard to smoke the motors on - the bearings often gum up.

the blades come off and you can just buy a motor if the motor is fried - they're quite common...
microwave ovens often use them to cool the Magnetron (free!!)

[BobEllis]

I broke a blade off of the impeller when I tried to pull it off to access the bearings. IIRC, they are sealed, about the size suitable for inline skates and I thought a set of high quality bearings would quiet it down.

I tacked the fan on to an ApexJr order for a few bucks (~$5), but Steve isn't showing any 120VAC fans at the moment, but drop him a line.

This 115 VAC 120 MM COOLING FAN | AllElectronics.com would probably work for $15.

[Andrew Eckhardt]

Those fans were exceptional in all their cheapness for having very low motor noise. They used sleeve bearings. As bear recommended you might try cleaning and relubing them rather than going to a box fan with a noisier circular stator. If you do replace it look for one of similar design.

[KP11520]

Gentlemen,

Thank you for the ideas. I will pass this onto him and see if he will give any a try!

He is somewhat intimidated by all the wires that surround servicing the fan. Like 29 he said. I'd help him out but he lives in VA and I'm on Long Island.

Looks like he's gonna have to roll up his sleeves! This shouldn't be too bad. He designed and builds Guitar and Bass pickups (top notched and well known), so if he can find the time I bet he can do it!

Thanks again!

Regards//Keith