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OLDER DECWARE GEAR SUPPORT >> SE84A, SE84B, SE84C, SE84C+,SE84CKC >> I have developed some hum!
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Message started by DirtDawg on 05/08/14 at 06:21:54

Title: I have developed some hum!
Post by DirtDawg on 05/08/14 at 06:21:54

One of my SB84C units, all are original as far as I know, has developed a hum.

I might not have noticed it, but the unit that is in question is mono-ed across my lows. Yeah, I hear hum. HOnestly, it is tiny, but if my old "deafened by thirty years of rocknroll ears" can hear it ten feet away, then it surely means I have an issue.

It is very minor at this point. I thought I heard it a few days ago, but as I have begun to test things, I definitely have a hum, which I can move from side to side, depending upon how I hook up the amps.

I have replace all the tubes, even subbed in known good tubes from amps that did not hum.

I KNOW that this is new. NO, really, I would have noticed this before. This IS new.

On another note, I have already replaced all my power cords, all my inputs, I have gone nuts lifting grounds and even left this unit ungrounded and grounded, with every thing else lifted.

I have unplugged everything, gone straight to speaker from cd player with only the amp in the circuit, then just shut everything down, unplugged everything and with just the amp running with shorted inputs across a speaker, I have a hum.

Any other ideas, guys?

I know that these ten year old, second hand amps are not something that Steve will want to have to deal with, but I am losing my "magic time."

Any help would be greatly apreciated.

Title: Re: I have developed some hum!
Post by DirtDawg on 05/09/14 at 02:53:47

bumping.

Did anyone see this?

Title: Re: I have developed some hum!
Post by deucekazoo on 05/09/14 at 13:31:16

The first thing I would look at is the volume knob. Sweep it from low to hi and see if you get any noises. Also I know you replaced the tubes but see if you can clean the tube sockets. After that I would send it in for Steve to check.

Title: Re: I have developed some hum!
Post by ZYGI on 05/09/14 at 15:17:12

Try this and get back to us...

https://www.decware.com/paper41.htm

Title: Re: I have developed some hum!
Post by DirtDawg on 08/05/14 at 06:11:35

Sorry to take so long to get back, but with my so called life, things, such as what I do for my own enjoyment, can get sidetracked.

Anyway, I got really brave one day, took the back off and found a dreaded cold solder joint.

One quick solder suck routine and some fresh silver bearing solder on that one spot fixed everything.

No more hum, no buzzes, just sweet sounds.

Title: Re: I have developed some hum!
Post by deucekazoo on 08/05/14 at 14:38:00

Awsome.
That is one nice thing about these amps. They are simple. No boards to wory about. You can crack it open and see what is wrong with it.
[smiley=thumbsup.gif]

Title: Re: I have developed some hum!
Post by DirtDawg on 08/07/14 at 06:04:39

Yeah.

It actually kind of surprised me.

This the second one I bought used of three and never had any such anomalies before, but we are all human.
No problem.

All is resolved.

Now this one sounds as close to the other two as I can imagine.
I am once again happy.