What type of solder?

[Anonymous user]

Hello, I need to replace the large film cap between unused relay connections in my SU 3000 INET, because it chirps.

The board is 640-0735G rev 7.

I dont know if I should use the lead or non-lead type of solder.

[Anonymous user]

If you are doing a repair - you can use any kind of solder you want.

The only reason for using unleaded solder is for RoHS requirements.

Repairs (as well as other equipment if you look in the RoHS docs) are exempt.

When you are repairing though, any solder you want is acceptable.

However, UNSOLDERING will require the equipment that can provide the needed temps to melt the applicable solder.

Cheers,

-Ben

p.s. I just got this in email this morning.

[BillP]

I noticed no answers to date on this so I thought I'd let you know that I have seen your post.  How old is your SU3000INET?  I suspect pretty old and, if so, it was probably manufactured with 60/40 or 63/37 leaded solder.  I still have quite a large supply of leaded solder and will continue to use it until I run out.  I also have 4% silver solder, un-leaded, that I choose to use when I build audio cables, etc.

I think the choice of which type of solder to use is yours and what you have on hand at the time.

[Anonymous user]

Thanks for answers, I will use the lead-tin type of solder. I heard that you should not mix silver-tin and lead-tin solder, that it why I asked.

The cap reads 106K. Does it mean 10 and six zeros pF that is 10 microF +- 10%?

Under 100K is 100H. No voltage mentioned. Does this mean 100V cap?

Under 100H are three dots, two dots space and one dot. What do these dots mean?

My unit might be rather old (15 years?), should I replace all electrolytic caps, even though I do not see any bulged ones?

What about that three huge caps?

[Anonymous user]

With code of 106K you are corrrect the capacitor value is 10 uF (micro farads), and tolerance of +/- 10 %.

Probably a 100 volt cap, yes.

How do you know it is bad ?

I have never heard of anyone recapping a UPS before (it generally happens more with flatscreen TV's and PC Motherboards & power supplies due to the "bad capacitor plague" of the mid to late 2000's), but if you have access to an ESR tester you could quickly scan for leaky ones.

If you look at the serial numer of your UPS the first two numeric digits represent the last two digits of the year of manufacture. Eg "06" = "2006"

...Dave

[Anonymous user]

Make sure -Not- to use the acid core solder meant for pipes on anything electrical. Otherwise standard 60-40 lead/tin solder should be fine.

Very old electrolytic caps had a limited life. But even 15 years ago they lasted much longer and might be fine. The risk of problems changing them might be as high as the risk of a failure. Unless, of course, one has already failed.

HTH

[Anonymous user]

It chirps - makes high frequency sound. It may be OK electrically, but probably has some loose layers which vibrate. I hate this sound.

My serial number starts with 98, it is really 14-15 years old.

[Anonymous user]

yes yes, I should have specified...

Any solder for ELECTRONICS work. Not plumbing. (Good call Tinker)

I'm concerned that you are in high voltage/high energy electronics considering your experience level. (i.e. if you need to ask about component markings, maybe you shouldn't be poking around electronics that can potentially hurt or even kill you.)

Please be VERY careful!

These are NOT cell phones and PDA's. The energy levels found in a UPS can lead to death. (the shock may not kill you - but when you get jolted and fall against something that impales you... well there you have it.)

It's not a laughing matter.

Be safe,

-Ben

[Anonymous user]

Now that I think about it, are you sure the thing chirping is not a PIEZO sounding unit?

Maybe you should  post a photo of the part in question.

  -ben

[Anonymous user]

Certain APC ups will emit a high pitched chirp sound - rapid beeping many times per second - if their batteries are badly deteriorated(IE heavily sulphated and either in or near a state of thermal runaway) at which time the UPS's charging circuits are heavily loaded or even overloaded (which can destroy the ups if left too long). I've heard Matrix and smart-ups do this...and even little PS250/450's from years back.

I second Bkamen's warning about being CAREFUL... even with the batteries disconnected and the ups unplugged the capacitors on the main board can maintain a healthy charge which can take hours to dissipate and is very exposed on those screw-on wiring connections to the inverter heat sinks.

Dave

[Anonymous user]

I'll repeat the other's warning about the voltages, because they could "put the hurt on you". I don't know about the UPS circuits, but capacitors can definitely hold a charge (sometimes for a long time after the power is shut off). And some of those caps are on the high voltage side.

The problem sounds like it is probably the battery. These batteries are only spec'ed to last three to five years. Sometimes they are good for longer, but they are made to remain always plugged in. So if it has been idle the battery is probably in sad shape after that long, and maybe even if it was plugged in.

I would not go tearing into it unless one of the caps is obviously swelling up and/or leaking.

HTH

[Anonymous user]

I am still alive, the cap just has not arrived yet.

I disconnected mains, disconnected batteries, discharged the large caps - I hope I am safe.

BTW when I was discharging the large caps one lead from the resistor I used for it was not properly insulated and it seems that I completelly shorted the caps to the case. It was quite a spark.

I hope I havent killed them? Can these caps survive one short?

[Anonymous user]

No, it is the large orange foil cap which is in the place of the missing relays. I searched the UPS with a hose in my ear while it was running to find the "guilty part".

[Anonymous user]

Allright, I got the cap, this one is in plastic case and epoxy, it fits nicelly, looks better that the previous "bare" cap, everything works fine, chirping is gone, so I call it a success!

Thanks to everyone for kind advice and warnings!

[BillP]

The cap will be fine.  Please be careful as you could really hurt yourself

[BillP · Accepted solution]

Great job!  I'm sure it's a good feeling knowing that you've kept the "old girl" alive for a while longer.