Finding Capacitance? of Capacitors

[BoostAddict]

I stripped down one of my dad's old LASERDISC players  for some caps, resistors and some diodes.  I ran outta caps and I wanted to build this overdrive that supposedly supposed to sound close or similar to a COT50.  So I had all the correct parts except for one cap which was suposed to be a .0047uF cap.  I just grabbed a random poly film from my dads laserdisc with no markings on it and installed it.  It still sounds a little buzzy/fizzy and I really want to find the value of it, so maybe I can get the others I found and run it in series/parallel to get teh correct value.  How do I find its value with my DMM?

[soulsonic]

You can't really find it's value with a standard DMM. You need a meter that reads caps. Some DMMs will have that function built in, but if yours did I assume you wouldn't be asking how to do it because it's just another obvious function of the meter like reading resistance or voltage.
I have one of these:
http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&category%5Fname=3830521&product%5Fid=72%2D8150
It works well and the price is right.

[BoostAddict]

My DMM is from Circuit Specialist.  It was this one but I checked now and they no longer sell it there.

http://cableorganizer.com/triplett/digital-multimeter/digital-multimeter-my68.htm

I connected the probes to COM and mA/Cx, set the mode to uF (I tried nF also) .  touched the 2 leads and nada    So I'm guessing this one can't do it I see 

[aron]

That meter looks quite decent. Yes, set it to nF or uF and then put the leads on the capacitor. It should read something.

[soulsonic]

Hmmm.... that is strange. Have you tried measuring a cap yet? Like Aron said, it should work they way you have it set up - though you shouldn't get any reading if you just touch the leads together without a cap because there won't be an capacitance there to show up.

OR!!!

You're problem might be that the caps you are trying to read are out of range for that particular meter. It didn't give any specs for capacitance range on the site, but it could very well be that the caps you're trying to read are too low of a value for that meter. I have a Capacitance/ESR meter that's designed for measuring big electrolytics and it won't read anything much lower than 1uF.

Try  testing a large cap - like say 10uF - with the meter and see if it says anything. Then try something maybe a little smaller - like 100nF. Then try something very small like - 250pF. I wouldn't be suprised if the small cap doesn't show up and that the caps you got out of the VCR are small like that. The cap being very small might also explain the sound you're getting.

[BoostAddict]

Tried a 100uF electrolytic cap I had lying around and it still reads nada.  So strange.

[soulsonic]

Maybe the meter has a blown protection fuse?

[aron]

Good one. Yeah, I once blew the fuse and the meter did act up.

[BoostAddict]

ahah you guys are smart!  busted fuse.  sucks I gotta take it apart to get to the fuse but whatever I found the problem.  Thank you Soulsonic and Aron for the help!

PS With my problem (I think its OCD) I dug around the house and remembered I built a mosrite fuzzrite.  Stole the 2x .0022uF caps from it, wired it in parallel and stuck it in place of where that .0047uF shoulda been and it sounds GREEEEEEEEEEEATTT 

[aron]

Great!!!!!!! I remember getting the 5 year replacement warranty for my Radio Shack meter. 5 years? I'll never have to worry. Wow, that was a while ago!