madbeanpedals::forum

Projects => General Questions => Topic started by: Clayford on September 17, 2013, 08:07:29 PM

Title: *Solved* Cap polarity placement.
Post by: Clayford on September 17, 2013, 08:07:29 PM
I have found some .22uf (220n) Kemet Tantalum Caps. Long lead and 2 Red Dots indicate the positive lead on them(in my experience) - So I need to check the orientation for placement the Weener Wah II. They are C3, C4, and C9. In looking over the layout and the schematic - I think the right side is the positive trace of those caps. Can anyone confirm this for me?I have 5 and need three so I can't afford them to blow. I know regular box caps would not matter - but on Tantalums it does. I'm told they stink to high heaven when you blow them and I'd rather not test placement that way.

(http://i.imgur.com/8t3HuJWl.jpg) (http://imgur.com/8t3HuJW)
(http://i.imgur.com/z09PSVRl.jpg?2) (http://imgur.com/z09PSVR)
Mojo-jo-jo. And yes that is a .0015 in C10. I know you load r's first - this is just a test fit to make sure there's room for everything.

Clay
Title: Re: Cap polarity placement.
Post by: kothoma on September 17, 2013, 09:54:58 PM
Quote from: Clayford on September 17, 2013, 08:07:29 PM
... C3, C4, and C9. In looking over the layout and the schematic - I think the right side is the positive trace of those caps.

Looking at the schematic, I'd say  C3 is +||- , C4 is -||+ , and C9 is +||- . So in the layout the LEFT sides would be the positive ones?
Title: Re: Cap polarity placement.
Post by: Clayford on September 17, 2013, 10:56:02 PM
I think you're right - after looking at this. Can anyone else confirm our suspicions?

(http://i.imgur.com/dJRirFV.png)
Title: Re: Cap polarity placement.
Post by: joegagan on September 18, 2013, 02:37:57 AM
c3 and c4 are not polarized on the weener schematic. in other wahs that use polarized caps in this location the + would be toward the trans, not the pot.

so, kothoma is correct on c3 and c4, not sure about the buffer.
Title: Re: Cap polarity placement.
Post by: joegagan on September 18, 2013, 02:52:38 AM
or boost, i guess q3 is a boost?
Title: Re: Cap polarity placement.
Post by: Clayford on September 18, 2013, 05:28:54 AM
Q3 is part of the boost circuit. At the advise of Joe - I'm not going to use those polarized caps. They could induce noise. Got some PIO's on the way instead.