Bottlehead Forum

General Category => Technical topics => Topic started by: mSummers on March 30, 2014, 06:23:33 AM

Title: Film Capacitor Question
Post by: mSummers on March 30, 2014, 06:23:33 AM

I'm getting ready to upgrade the output caps and the last power supply cap in my Crack and have a question on film caps.  In the manual, we're told to pay attention to the orientation of the stripe on the electrolytic caps.  Are film caps directional in the same way?  If so, how can I tell which is the correct lead to put on the same side as the stripe on the electrolytic cap?  Specifically, I'm using Mundorf M Caps which have no markings on them except the name.

Title: Re: Film Capacitor Question
Post by: galyons on March 30, 2014, 06:36:02 AM

The electrolytic caps in the kit are polarized.  It is fatally critical to get the orientation correct. Your film caps are not.  There maybe be some very slight noise benefit in orienting the inner and outer foil, but for the most part, either orientation is fine and safe.

Cheers,
Geary

Title: Re: Film Capacitor Question
Post by: JamieMcC on March 30, 2014, 06:37:40 AM

Are the leads of equal length?

Title: Re: Film Capacitor Question
Post by: mSummers on March 30, 2014, 07:41:43 AM

Thanks Geary.  Is there a way to tell the inner/outer foil orientation?

Jamie, the leads are pretty close to identical on length (less than 1/16" difference)

Title: Re: Film Capacitor Question
Post by: galyons on March 30, 2014, 08:01:06 AM

Quote from: mSummers on March 30, 2014, 07:41:43 AM

Thanks Geary.  Is there a way to tell the inner/outer foil orientation?

There is no consistency between manufacturers.  Some use differing lead lengths, differing lead cover coloring, various graphical markings or simply the old way, a line around the circumference of the cap.  You will have to look at the manufacturer's information or data sheet to see how and if they differentiate.

Cheers,
Geary

Title: Re: Film Capacitor Question
Post by: mcandmar on March 30, 2014, 08:40:25 AM

With the Mundorfs there is no marked orientation.  If you have a scope you can check to see which end is the inner and outer foil but its not worth worrying about, just make sure both are the same.

Title: Re: Film Capacitor Question
Post by: mSummers on March 30, 2014, 08:57:20 AM

Thanks, guys.  I don't have a scope, so I can't check it that way.  I did notice that if I set my meter to vDC, if I put the probes on the leads one way, it read positive volts and the other way read negative volts.  Does that tell me anything?

If not, I'll just pick a direction and install them

Title: Re: Film Capacitor Question
Post by: galyons on March 30, 2014, 09:17:35 AM

Quote from: mSummers on March 30, 2014, 08:57:20 AM

...just pick a direction and install them

You got it. Just orient both caps/channels the same.

Cheers,
Geary

Title: Re: Film Capacitor Question
Post by: Grainger49 on April 01, 2014, 04:06:37 AM

My two cents worth... I orient the capacitors as the manufacturer suggests.  But only if they have that recorded somewhere.  All other capacitors I have swapped out, and there are many, I just put in with the writing the same way.

I don't have any noise problems in my system.