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Post subject: Volume controlled by Bass and Treble controls?
Posted: Fri Jun 22, 2012 3:54 pm
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Joined: Sat Jan 17, 2009 9:34 am
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Location: Putnam County, NY
Hi Folks!

I have this little 10G, which is great for just checking out guitars and basses for proper electronic functions, but something has happened: I get no sound with Volume on "10", and Bass and Treble on "0"??? Turn up Bass or Treble controls, and I get sound??? WTH?

Something short-circuited? Anybody ever seen this before?

It was working fine, then...

Thanks for any input!

John

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Post subject: Re: Volume controlled by Bass and Treble controls?
Posted: Fri Jun 22, 2012 8:58 pm
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Is this the first time that you have turned the treble and bass controls all the way down and noticed this happening or have you done it before and things worked normally?

Looking at the schematic, it appears that when the bass control is turned all the way down, all the low frequencies are shorted to ground. Plus what appears to be a fixed midrange control (R17 and C13) is also shorted out. Turn down the treble all the way and there is not much signal left to pass on to the following circuitry.

http://support.fender.com/schematics/gu ... _Rev-B.pdf

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Post subject: Re: Volume controlled by Bass and Treble controls?
Posted: Sat Jun 23, 2012 10:54 am
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Very good info. Thanks, Blue!

Actually, come to think of it, I don't think I HAVE ever had both the T and B down to zero before!

I get output with them both down at zero, but EXTREMELY attenuated... I guess I just never noticed this behavior before. Interesting!

Many thanks! (for the schematic, also!)

JL

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Post subject: Re: Volume controlled by Bass and Treble controls?
Posted: Sat Jun 23, 2012 11:17 am
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Location: Natural Bridge, Virginia
You're welcome. Come back anytime you have amp questions. Lot's of folk here able to help. :D

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Post subject: Re: Volume controlled by Bass and Treble controls?
Posted: Sat Jun 23, 2012 8:35 pm
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Well, since you asked, and seem quite knowledgeable about Fender Amps...

I've got a Bassman 200 Combo amp here, I think it's c. 2003? (I can get the S/N, but it's kinda buried right now) The problem is that it has an EXTREMELY loud hum, which gets louder as you up the volume. There is NO hum, with nothing plugged into the input, but as soon as I plug in, HMMMMM! I can't believe this is just a shielding/grounding problem with the bass (MIM J-Bass).

I have read there were problems with the Bassman series in the early 2000 models. Might you have any insight? Again, any and all info much appreciated!

John

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Post subject: Re: Volume controlled by Bass and Treble controls?
Posted: Sat Jun 23, 2012 11:20 pm
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Location: Natural Bridge, Virginia
The tip of the input jack is shorted to ground when there is nothing plugged into the amp. Check the grounding of the jack sleeve itself when a cable is plugged in.

http://support.fender.com/schematics/ba ... ematic.pdf

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Post subject: Re: Volume controlled by Bass and Treble controls?
Posted: Sat Jun 23, 2012 11:46 pm
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Will do! Thanks again for the schematic. I really haven't dealt with this amp in a bit, but since we were on the subject, I was reminded that I had it sitting buried over in the corner! :-)

I'll let you know how I make out...

John

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