MarkM Minidriver question

[waltk]

Hi All,

There's a layout for a "MiniDriver II" in the gallery by MarkM here http://www.aronnelson.com/gallery/main.php/v/MarkMs-Gallery/album15/album76/MiniDRIVER_II_LAYOUT.gif.html.  The C6 cap is marked as ".05pF".  Does anyone know what value that cap is really supposed to be?

[mdaudet]

0,047uF should work since 0,05uF does not exist (or readily available).

[waltk]

Hi Matt,

Thanks for the reply.  I figured that .047 of something would work.  You are probably correct about it being .047uF.  My reasoning goes like this:

The layout says .05pF - which is most likely a typo.
He probably didn't mean to write .05nF, because he doesn't use nF anywhere else in the layout, and he probably would have written it as 50pF if that's what he had in mind.  So he probably meant .05uF, and I'll substitute a .047uf cap for that.

[markm]

Yeah, I think that was a typo. Sorry!   

[waltk]

Hi Mark,

Thanks for the reply, and thanks for sharing your work on this layout in the first place!

I etched and built the board with the C6 cap (and transistors) socketed so I could easily change them.  My first guess about the cap was wrong, and I tried a 50pF cap.  Then the trouble started...  The first time I powered up the board, I had the power polarity reversed.  I noticed it about 30 seconds later when my LM317 voltage regulator started to get really hot .  Nothing actually smoked, but it must have been drawing a boatload of power, and could easily have fried something.

I replaced the transistors, and used a 47nF cap for C6, but I still don't get any sound out of it (aside from a couple clicks and pops when I apply power).  So something else might be fried, or I could just have a bad connection somewhere else.  The trace side is pretty clean, with no obvious bad joints, but the pot wiring is suspect.  My next debugging step is to get out the old audio probe and start tracing the circuit, but if you have any suggestions about where to look, I would be happy to get any advice you can offer.

Question: you take the output from lug 2 on the volume pot, right?

Regards,
Walt

Here's a couple pictures:

[euronymous0001]

hi!

i created this and i think that mine has overtly way too much mids 

should i tinker with the tonestack by adjusting R13 or do i need to change something in the circuit aside from that resistor 

posted for easier viewing, please remove if i violated any rule(s) thanks