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Author Topic: Sunn Alpha Six PA - LOUD HUM  (Read 4281 times)

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Offline mattz

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Sunn Alpha Six PA - LOUD HUM
« on: December 30, 2014, 05:49:16 pm »
Hi all,

I was testing my Sunn Alpha Six PA earlier today and while messing with the volume and EQ knobs I noticed some scratchy, fluctuating volume... Does this mean the pots need to be cleaned? Also, while turning up the amp with the channel volume at 2 and the master volume approaching 4, the sound cut out and now all I get is a loud hum. Could this be a loose solder? Blown fuse? From what I understand there are more than 1 fuse in this PA. Could this potentially be a larger problem? As you can tell, I don't have much experience with this piece of equipment and barely used it personally, just trying to get it in working order.

Any/all info is very much appreciated!

Thanks!
« Last Edit: December 31, 2014, 07:38:56 am by EdBass »
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Offline loudthud

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Re: Sunn Alpha Six PA - LOUD HUM
« Reply #1 on: December 30, 2014, 07:21:54 pm »
The scratchy pots could just need to be cleaned, but more than likely indicate that the mixer needs a cap job. There are about twenty 2.2uF Non-polar electrolytic caps that should be replaced. Beta series amps have the same problem. A blown internal fuse is indicative of serious problems. This is not a job for an amateur and taking it to a tech won't be cheap.
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Offline EdBass

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Re: Sunn Alpha Six PA - LOUD HUM
« Reply #2 on: December 30, 2014, 07:22:58 pm »
With those multiple issues, it would probably be difficult to diagnose via an online forum. I would suggest either taking it to a qualified tech and getting it sorted out.
« Last Edit: December 31, 2014, 07:39:48 am by EdBass »
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Offline loudthud

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Re: Sunn Alpha Six PA - LOUD HUM
« Reply #3 on: December 30, 2014, 08:13:16 pm »
Just as a note to the do it yourselfer, the power amp and power supply are basically the same as a Beta Lead or Beta Bass so it can be used as a power slave or spare parts.
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Offline mattz

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Re: Sunn Alpha Six PA - LOUD HUM
« Reply #4 on: December 31, 2014, 05:38:45 am »
Thanks for the replies! I suppose I'll bring the amp to the shop when I get my Marshall MOSFET Lead 100 back. I'll let a professional diagnose the problem, just wanted to see if this might be a quick fix that an amateur (like myself) could complete. No worries about this turning into a classified post, as I won't be selling this amp online. Thanks again!
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Offline Watson

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Re: Sunn Alpha Six PA - LOUD HUM
« Reply #5 on: December 31, 2014, 09:38:03 am »
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