Scott Dorsey mod on mxl 2001

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imloggedin

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Dec 17, 2005
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mid-usa
I finished stuffing the PCB and the mic works but theres alot of noise. Ive defluxed it like 10 times now and its a little better than it was but its still much worse than my other mics. Whats the deal? Has anyone else put this together?
 
did you use one of Scott's boards? Are you sure you built on the right side of the PCB? It's hard to tell front from back IIRC.
 
well i guess i dunno, i assumed that the front was where his name was written. you tell me...

P1000880.JPG


P1000882.JPG


scratched board to make sure nothing was between points.
 
I think you built on the wrong side. I'm pretty sure I built on the same side as you (following the same reasoning) & I built on the wrong side. You might email Mr. Dorsey to see what's what.
 
I don't have the mic anymore, but I might have some pics. It'll be tomorrow before I can check, though.
 
Are the PNPs EBC pinout? If so it looks like you have the emitter connected together looking at both pictures. If this is true all you might have to do is turn the PNPs around on the side they are on now so the collectors are together if the transistors are still good, check with a meter.

Check the pinout of the fet from a data sheet and make sure it is installed correctly, gate to ?, drain to resistor to +, source to resistor to ground.

I can't see the tant cap marking for + or -

Check circuit nodes with a meter set to Ohms and compare to a schematic
 
if you still have problems read this article. it has the schematic for the project with voltages.

http://www.pfarrell.com/music/shanghaimic.html

at the bottom is a link to photos of a stock and a modded mic. scott writes that the mic in the photo was populated on the wrong side of the pcb. it looks like its populated on the same side of the pcb as your mod.

http://www.pfarrell.com/music/shanghai/s201.jpg

take a look for yourself to see if i read this correctly.

read the erratta too. hope this helps
 
Gus was exactly right. THANKS GUS!

I stuffed this board according to the layout on the pcb in the original article. The transistors AND fet are placed wrong on the mask. So far sounds good.
 
[quote author="seavote"]if you still have problems read this article. it has the schematic for the project with voltages.

http://www.pfarrell.com/music/shanghaimic.html
[/quote]

i have the original article

at the bottom is a link to photos of a stock and a modded mic. scott writes that the mic in the photo was populated on the wrong side of the pcb. it looks like its populated on the same side of the pcb as your mod.

http://www.pfarrell.com/music/shanghai/s201.jpg

mine is populated on the correct side. that picture he did it on the opposite side that i did mine.

take a look for yourself to see if i read this correctly.

read the erratta too. hope this helps
the errata is for the really old boards, he doesnt ship those anymore.
 
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