SMD Capacitor Identification

How do you identify SMD electrolytic caps? I have a bord with some smd caps
on it and they are marked 100 16v.. Is that just a 100uF cap? I was going to
change out all the smt caps with regular caps because the board has been
giving me trouble and I believe one of them is bad but I didn't want to just
solder the wrong value of cap in and ruin something.

- Mike

 

That will be a 100uF 16v working cap. However, I would really not recommend
just replacing all the caps just for the hell of it. This is likely to
result in you compounding the original problem - which may not even be one
of the caps in the first place. Better to employ proper fault-finding
techniques to arrive at the cause of the problem, than guesswork. Also, you
should beware of replacing SM electros with conventional leaded types. The
ESR tends to be rather different between the two cap types, and I can think
of one circuit in particular - the servo board fitted to the bottom of the
deck on many Sony CD players from around 5 - 7 years ago - which WILL NOT
WORK if the SM caps, which fail regularly, are replaced with conventional
types.

Arfa

 

WILL NOT WORK if the SM caps, which fail regularly, are replaced with

Hmm.. thats good to know..

The problem is I don't own an ESR meter yet allthough I think I fould the
problem. I did change the larger caps that were on the power supply and
monitor seems to be working correctly now.

I do plan on buying a dick smith build it yourself ESR meter. I just don't
have $80 to spare right now. Maybe I'll get it for my birthday. : )

- Mike

 

A good move Mike, if you're intending doing lots of service work on SMPS's
and the like. As you've probably seen on other ESR posts that I've been
involved with, I own a DS meter, and swear by it as an excellent value for
money instrument. Have you been following the post further down regarding
discharging caps prior to using a DS ( or other ) ESR meter on them ? Have a
look if not. Lots of good advice on doing this, and protecting a DS against
accidental connection to charged resevoir caps.

Arfa

 

No I guess I missed that post.. I'll have to check it out.

I don't know that I'll be doing lots of work on smps but I'm trying to learn
the basics of electronics repair. I've known how to solder for a couple of
years and I'm pretty good at soldering now. I've even gotten good at
soldering smd components.

I've got a small collection of tools. I have all the basic soldering tools..
3 different iorns various solder sizes, flux, solder sucker and wick, a DMM,
and an old 1970's 30khz Heathkit O-Scope. I hav't gotten any use out of the
scope yet since I don't really know how to hook it up to something.. I can
get a wave on it if I hook it up to a 12vac transformer but I don't know how
many volts it can take so I've been afraid of hooking it up to things.

Hopefully I'll soon have the DS ESR meter to add to my list.. I think it
will be a great tool since people say that electrlytics are the most likely
thing to fail in electronics.

- Mike