How does one find the value, voltage and type of unmarked SMD capacitors?

Also on an SMD capacitor there is SQ1, does anyone know what it means?

I have searched this forum and the Web but I'm still without answers.

Does the colour and shape of the SMD capacitor relate to it's values and type? If it does where can I find related information.

Thank you.

 

You might be able to get up a rig to connect one to a capacitance meter, but voltage might have to be guessed at. Use the voltage in the existing circuit as a guide.

There may be no way to tell a tantalum from an electrolytic cap. there should be polarity marks, though.

 

Bookmark this page:
http://www.educypedia.be/electronics/datacomponent.htm
It is VERY handy for looking up identification for SMD/SMT components.

Links for the information you seek are nearly 1/2 of the way down the page.

 

If you have an RLC meter,that would be a great way to approximate the value of your capacitors and resistors and also inductors in that case.

 

You might be able to get up a rig to connect one to a capacitance meter, but voltage might have to be guessed at. Use the voltage in the existing circuit as a guide.

There may be no way to tell a tantalum from an electrolytic cap. there should be polarity marks, though.

Thanks for reply.

Yes that could be the only alternative but it’s as you said one can never tell a Tantalum from an Electrolytic.

 

Bookmark this page:
http://www.educypedia.be/electronics/datacomponent.htm
It is VERY handy for looking up identification for SMD/SMT components.

Links for the information you seek are nearly 1/2 of the way down the page.

Thanks for link and reply.

I have been to that page before but I didn’t find my answers to “SQ1” and unmarked capacitors.

 

If you have an RLC meter,that would be a great way to approximate the value of your capacitors and resistors and also inductors in that case.

Thanks for reply.

Most probably that will be my only option. Can it be done with the component still on board or will I have to unsolder the component and test it off board?

 

OK, here's another page:
http://my.execpc.com/~endlr/markings.html
Scroll about halfway down.
Usually, SMT/SMD ceramic caps have just one letter and a number. The case of the letter is significant.
Now, from KEMET's site:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/weben/8C1829F0139DB7EECA2570A50016090A/$file/F3102_CeChPkg.pdf
An excerpt of the document is attached.
1st letter is the manufacturer code
2nd letter indicates the value; "Q" indicates 3.9
3rd character is the power of 10, in your case 10e1
So, the cap is 39pF. Don't know who the manufacturer is offhand.

As far as the unmarked capacitors, you'll need a capacitance meter to test them. Determining their breakdown voltage will likely turn into a destructive test. However, it's typical for 0603/0806 multilayer ceramic caps to have a rating of 50v.

Attempting to determine the value of unmarked SMT caps while soldered on a board will be very frustrating, particularly if they're low value.

 

OK, here's another page:
http://my.execpc.com/~endlr/markings.html
Scroll about halfway down.
Usually, SMT/SMD ceramic caps have just one letter and a number. The case of the letter is significant.
Now, from KEMET's site:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/weben/8C1829F0139DB7EECA2570A50016090A/$file/F3102_CeChPkg.pdf
An excerpt of the document is attached.
1st letter is the manufacturer code
2nd letter indicates the value; "Q" indicates 3.9
3rd character is the power of 10, in your case 10e1
So, the cap is 39pF. Don't know who the manufacturer is offhand.

As far as the unmarked capacitors, you'll need a capacitance meter to test them. Determining their breakdown voltage will likely turn into a destructive test. However, it's typical for 0603/0806 multilayer ceramic caps to have a rating of 50v.

Attempting to determine the value of unmarked SMT caps while soldered on a board will be very frustrating, particularly if they're low value.

Many thanks for the information looks like it is 39pF. The Kemet table states the marking is available only for Kemet chips, the capacitors don't have the K marking, only SQ1. Do you think this can make a difference? Should I double check with a capacitance meter?

As for the unmarked I will be getting a capacitance meter soon and will try to unsolder them and determine the values.

The only problem for unmarked smd capacitors is how to know if they are polarised or not. Any hints please.

If an smd capacitor is in parallel with an electrolytic capacitor would that mean that the smd capacitor is most probably and electrolytic too?

 

Sorry forgot to add.

Can smd components such as capacitors, resistors, etc be replaced with non smd components or will this effect the circuit?

Thanks