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Topic: Nashville 400 mod help |
Mark Durante
From:
St. Pete Beach FL
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Posted 21 May 2004 5:13 pm |
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I'm in the middle of installing the Nash 400 mod and I have a question hopefully some of you might be able to answer. If not I will call Peavey Monday although I kinda wanted to try it out at a gig Sunday.
It concerns the installation of capacitors C1 and C8, (.1uf to 2.2uf).
The question is do I need to observe polarity with the 2.2uf caps and if so is this the same polarity as with the C5 and C6, for instance, or the opposite? Thanks |
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Bob Lawrence
From:
Beaver Bank, Nova Scotia, Canada
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Posted 21 May 2004 8:42 pm
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Mark,
It's been many years since I did the mod on my 400 amp but at that time both cap's you listed were electrolytic capacitors (part number's 70320011 or 70320200)which are polarized. Try the link below and scroll down to have a look at the pictures of the electrolytic capacitors. Notice the down arrow with the - - - - going down the side. That's the neg side.
http://www.allaboutcircuits.com/vol_1/chpt_13/5.html
According to the Peavey schematic the neg side (the side with the curve on the schematic = the ground side of the cap)of C1 goes to R3,CR1,CR2 and pin 5 of the op-amp U1A. The neg side of C8 goes to R10,CR5,CR6 and pin 3 of op-amp U1B.
To answer your question:
"is this the same polarity as with the C5 and C6"
No they are opposite. C6 has the pos side going to the op-amp pin 7. C1 has the neg side going to pin 5 of the Op-amp and the pos going to R1.
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[This message was edited by Bob Lawrence on 21 May 2004 at 09:49 PM.] |
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Ray Minich
From:
Bradford, Pa. Frozen Tundra
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Posted 21 May 2004 8:48 pm
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And you can get a copy of the board layout at:
http://www.peavey.com/media/pdf/steelguitar/Nashville400.pdf
to help with figuring this challenge out. It requires Acrobat reader and if you have a more recent version of the reader you can rotate the image on your screen and view it without need to print it out.
Straight side = +, curved side = - (minus).[This message was edited by Ray Minich on 21 May 2004 at 09:49 PM.] [This message was edited by Ray Minich on 21 May 2004 at 09:52 PM.] |
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John Daugherty
From:
Rolla, Missouri, USA
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Posted 22 May 2004 4:50 am
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Mark, When in doubt about a polarity issue, use a voltmeter. Attach the negative meter lead to chassis. read the voltage on the two pads where the component is attached.
The higher voltage will be the (+) side of the capacitor in your case.
Good Luck........ John .. |
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Mark Durante
From:
St. Pete Beach FL
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Posted 22 May 2004 2:01 pm
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| Thanks for the info guys, I'll give it a try and let you know. |
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Mark Durante
From:
St. Pete Beach FL
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Posted 24 May 2004 3:02 am
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Finished installing the mod and played the gig last nite and yes there is a considerable improvement in the tone quality.
Much smoother and less of the harsh frequencies. Thanks again for your advice guys and thanks again to b0b for this great forum. |
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Mike Brown
From:
Meridian, Mississippi USA
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Posted 24 May 2004 6:31 am
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I'm glad that you got the answer that you needed over the weekend. Let us know if we can be of assistance to you.
Mike Brown
Peavey Electronics Corporation |
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