The Boogie Board

Mark III Fan
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Author:  UpNorthMark [ Fri Jan 12, 2018 3:14 pm ]
Post subject:  Mark III Fan

Hey guys I just picked up a Mark III Blue stripe head I am totally digging. It’s got a noisy fan and wondered if anyone had a suggestion for a place with s suitable replacement? Your help is appreciated


Author:  jediguitarist [ Thu Jan 18, 2018 12:56 pm ]
Post subject:  Re: Mark III Fan

Howard Industries 3-15-2470 is the original from what I can remember.

Globe Motors a47-b15a-15t1 is in the newer Marks.

I've swapped a noisy Globe Motors in my Mark IV for the Howard Industries which I found on eBay. Direct replacement, no issues. Just be aware of the model number. There are slight variation which seem to denote wattage.

This place sells replacement fans. They usually have a few different choices

Author:  UpNorthMark [ Thu Jan 18, 2018 2:59 pm ]
Post subject:  Re: Mark III Fan

Thanks, I appreciate the link

Author:  deskman [ Sun Jan 28, 2018 7:39 pm ]
Post subject:  Re: Mark III Fan

I tried a different fan in my IV and IIC+ and didn't really find any difference in noise levels.

The main thing I found is that the noise is really coming from how it's mounted to the cabinet / chassis.
I ended up putting some rubber washers on the bolts / screws to decouple it and it made a huge difference.

Then my tech rewired the grounding switch on the rear to be a fan on/off switch anyway.

You can run the amp with the fan turned off, it's not going to hurt it. Maybe reduce tube life a little.

Author:  darkbluemurder [ Mon Jan 29, 2018 3:43 am ]
Post subject:  Re: Mark III Fan

What noise is exactly buggin' you - the noise of the fan turning or is there a hum that shouldn't be?

If it is the fan turning maybe a tech could lower the voltage to the fan to make it turn slower. Alternatively, if you are not going to crank the amp on a regular basis the fan could be put on a switch so it can be turned off. Can be handy in a studio environment.

Good luck,

Author:  UpNorthMark [ Mon Jan 29, 2018 8:09 am ]
Post subject:  Re: Mark III Fan

The fan was actually hitting the housing and scraping as it went around. I shimmed it up which fixed it up. When it was installed at some point someone over torqued one side distorting the housing. It’s still much louder than the one in my JP-2C but no longer audible when I play at low volume.
Thanks for the help guys,

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