Squeal Like a Pig

[mike1762]

My SC will occasional emit a high frequency squeal (not unlike that emitted by Ned Beatty on a camping trip).  When it happens, there is no output from the bass other than the squeal.  I can get rid of it by plugging/unplugging the cord several times.  The cord is fine and the battery is new... it's definitely something in the bass.  Any ideas???
 
(Message edited by mike1762 on June 07, 2010)

[sonicus]

This might be an  internal calibration issue.  Perhaps ? Trim pots?  I would not go there before talking to Mica or Alembic personnel or others who can give an account of the correct procedure.

[lbpesq]

Mike:
 
I have no idea what could be causing this, but I would strongly advise DO NOT TAKE THE BASS ON A CANOE/CAMPING TRIP!  
 
hehehehe
 
Bill, tgo

[pace]

Do you notice this when the filters, or Q switch are wide open, or does this occur regardless of your settings?!?

[terryc]

Corrosion on the input jack can cause this or jack failure.
Without taking the cover plate off right now on my bass I think they are sealed jack sockets so you cann give the terminals a gentle rub with a fine abrasive paper.

[mike1762]

I'm not sure about the Q switch/filter thing... the next time it happens I'll see if changing them makes any difference.  Since exercising the jack seems to make it go away, that would indicate that the problem is there.  But I've never seen jack failure cause anything like this.  I'll try the sandpaper thing (on my bass... not on Ned).

[terryc]

The theory is on the corroded jack terminals is that there is micro arcing which is then amplified by your pre amp and then your amplifier.

[mike1762]

OK, that makes sense.  I'm out of town at the moment, but I'll clean the jack as soon as I get back home.

[mike1762]

All righty then... I have it narrowed down to something to do with the Q switch on the bridge PUP.  When the bass starts squealing, it slowly goes away as I pan over to the neck PUP.  When I start flipping the Q switch off/on, the character of the squeal will change and then suddenly dissappear (but the squeal, when it's occuring, happens whether the Q switch is on or off).  This is happening every time I pick-up the bass.  Any ideas?

[terryc]

Could be the mechanical part of the switch is faulty

[mike1762]

Mica???  Could it be something as simple as replacing the switch?  Is that something I can do myself?

[adriaan]

Mike - try a Google search on the Alembic Club for squeal - see what gives.
 
(Message edited by adriaan on August 15, 2010)

[mike1762]

This has continued to be an intermittent problem.  I was changing the battery today and was able to reproduce the problem when I accidentally nudged this ceramic(?) tube thingy (let me know if I'm getting too technical) that had some wire looped through it.  What is that thing?  It appears to have something to do with the problem.

[mike1762]

I found this post (http://club.alembic.com/Images/393/8949.html) regarding a similar (same?)problem.  I'm guessing the thingy is a ferrite bead.  But since I seem to have one, could it still be my problem?

[mica]

We test electronics for no charge, so you can send them in for a check-up.
 
The ferrite bead is non-conductive, and it wouldn't contribute to squeals.  
 
You can do the ol' exercise routine and flick the Q-switches bunches (think at least 50 times) and also turn the filter pots completely through their rotation,meaning reach both of the stops at least least 50 times each. This will eliminate corrosion as a culprit.  
 
Otherwise, we're going to have to check it out on the test bench.