Maker Pro
Maker Pro

Capacitor Value issues (simple)

RandyTWarris

Jun 22, 2013
7
Joined
Jun 22, 2013
Messages
7
I'm very new to electronic circuitry and currently only started repairing equipment as a "work" hobby and just got stumped on this HF coupling capacitor.

In line with the tweeter's positive line there were two capacitors paralleled together, the leads broke off and they appear to be a silver mica capacitor or possibly a polyester film capacitor.

The important aspect is the value as they need to be changed because the leads are completely severed.

They are rather large and old, blue colored in a really hard enamel-like substance and has the writing:

Ti
12K100V
Mexico

Just like that.

I'm predominantly only used to 3 digit codes or plain printed.

Thank you!
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
They are rather large and old, blue colored in a really hard enamel-like substance and has the writing:

Ti
12K100V
Mexico

Just like that.

I'm predominantly only used to 3 digit codes or plain printed.

Thank you!

I believe that would read 1.2uF rated @ 100V but a photo would confirm it. Put a penny next to them for size reference.

EDIT: Welcome to EP. ;)

Chris
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
12000pF or 12nF?

Actually, I think you're correct. I misplaced the decimal point! My first clue should have been that the OP thinks it's a Silver Mica.... Duh!

Chris
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
8,393
Joined
Nov 28, 2011
Messages
8,393
Just for diversity of opinion... I doubt that the k means kilo-picofarads; K on capacitors normally means 10% tolerance. I've never seen it used to mean "thousand" on any component marking. Only on some old schematics.

In that case, the capacitors would be 12 pF, which is far too small for tweeter coupling capacitors. I guess it could be 12 uF but that seems pretty high for a tweeter coupling capacitor. Or maybe the OP has omitted a number at the start?
 

RandyTWarris

Jun 22, 2013
7
Joined
Jun 22, 2013
Messages
7
This is a picture of the capacitor with a penny for reference.

Hopefully this helps!
 

Attachments

  • image.jpg
    image.jpg
    150.5 KB · Views: 167

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
8,393
Joined
Nov 28, 2011
Messages
8,393
It looks pretty big. I don't know how big a penny is (and the Wikipedia article doesn't help); perhaps a ruler would have been a more international reference!

My guess is it's 12 uF. I thought it might be 1.2 uF with the decimal point not printed properly, but there's no room for one.

I guess you could always borrow a capacitance meter and touch the probes onto the little bits of metal you can still see. That would clear it up.

If it's 12 uF here's a suitable replacement from Digikey: http://www.digikey.com/product-detail/en/B32794D3126K/495-4141-ND/2182159
 

RandyTWarris

Jun 22, 2013
7
Joined
Jun 22, 2013
Messages
7
A penny is 19.05mm in diameter or 0.75 (3/4) inch.

Edit: I'll try to get a picture with a ruler :p
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
8,393
Joined
Nov 28, 2011
Messages
8,393
That's OK, I get the idea.

It's impossible to say for sure. I think it's probably 12 uF but I think you should try to borrow a capacitance meter. Perhaps take your capacitor into a shop that sells multimeters and ask them if they'll measure it for you.

That might work here. I don't know how obliging sales staff are around your way.
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
I think it's probably 12 uF >>>

I'm through guessing because what I thought was an educated guess is looking more and more like just a plain old guess. We don't usually do that here. ;) .

Chris
 

RandyTWarris

Jun 22, 2013
7
Joined
Jun 22, 2013
Messages
7
Ok so I finally bought a capacitance meter (local shop wouldnt let me just use theirs) and it is 12uf and 100v with a 5% tolerance.

Im not sure what kind of type it is, i thought possibly silver mica or film but it is polarized so maybe a weird electrolytic?

Tyler Warris

(thank you for the help thus far!)
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,506
Joined
Jan 21, 2010
Messages
25,506
Not sure exactly how big a penny is (here they were about an inch across before they were phased out in 1966).

That capacitor looks like a greencap (metalised polyester film).

1.5uF is a large value, but not that unlikely
 

RandyTWarris

Jun 22, 2013
7
Joined
Jun 22, 2013
Messages
7
Yeah, it will only read capacitance from my meter in one direction, so I am presuming it is polarized,or broken lol
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
8,393
Joined
Nov 28, 2011
Messages
8,393
That doesn't make sense. Try it again and make sure both probes are making good contact both ways round.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,506
Joined
Jan 21, 2010
Messages
25,506
Capacitance meters use very low voltages (typically) and even electrolytics which are very sensitive to polarity will test fine both ways.

If it really doesn't work one way around, measure the resistance one way then the other.

I've never heard of a fault that introduced diode action, but like the existence of the Loch Ness monster, I can't rule it out.
 

RandyTWarris

Jun 22, 2013
7
Joined
Jun 22, 2013
Messages
7
Well, I got it looked at by a someone nearby whom works on fixing audio electronics. From what he said it is a 12uf 100v 5% tolerance film capacitor which is bipolar.

As far as the polarized aspect of it, I was simply just testing it with poor contact hence it wasn't reading right.

Thank you everyone though! I ordered a replacement and got the High Frequency capacitors changed out and it works like a charm.

Tyler
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
This is going to make us all feel better because capacitance in only one direction didn't make sense,

Chris
 
Top