Does this solder look OK?

[Jonathan_A]

Hi, I have an Samsung Syncmaster 2043NW that has had a long start up time (about 7 minutes lately) for well over a month (it has increased over time), and two days ago it didn't start for over 15 minutes so I decided to go to the bottom with the problem. I did some research and found out that replacing bad capacitors should fix it. So I researched about that and then I got the right tools, and finally today I replaced the two bad capacitors. Now, before I test it (so I don't blow anything up) I want to be sure that it looks all right.

Here's two pictures of how it looks. I found it kind of difficult to solder because the soldering was very "slippery" and tended to form it self to a ball that didn't connect the lead with the board well. So I soldered back and forth untill it got like this. And you see that it's some kind of brown/yellowish liquid around the soldering and I wonder if that is bad? Could it lead current where it's not supposed to be lead?


The new solders are the dark ones with some liquid around.

Also, it doesn't look similar to the soldering of the other capacitors. It seems to have been another type of soldering and also, which I didn't think of, the tips of the leads are turned towards the black markings on the board, which I didn't do with the new ones.

Under where it says C209 is an old capacitor solder.

[mariushm]

Re: Does this solder look OK?

It's acceptable.

It tended to get into a roll because you didn't heat up the pad and the wire enough.

The brown yellowish liquid is flux, which is a light acid that's supposed to remove the layer of oxidation that forms on the wire and the pad with time, so that the solder can adhere to the surface of the metal.
The flux is inside the solder wire you used - depending on what kind it is, you should clean it with isopropyl alcohol because otherwise in time, they can still "eat" into the copper or whatever is under them... If it's no clean flux you don't have to worry about it.

The solder also shines a bit differently because you probably used 60/40 or 64/37 which means the solder has lead, while the board originally used solder that has no lead. No need to worry, the lead solders are better.

[Jonathan_A]

Re: Does this solder look OK?

The solder I used was ERSIN 5-CORE 60/40 TIN-LEAD. On the package it says it "[...] contains non-corrosive extra active Ersin Flux. Five separate cores of flux [...]". So, should I clean it?

[370forlife]

Re: Does this solder look OK?

"non-corrosive" sounds like you don't have to.

[Jonathan_A]

Re: Does this solder look OK?

Aight! Thanks for your answers guys!
Unfortunately though, the monitor didn't work now when I tested it. I assume that it had allready taken too much damage in some way, that the replaced capacitors couldn't solve the problem. As i said, the monitor wouldn't start at all two days ago (waited 15 minutes for it, then I gave up), while earlier that day and all times before it started after several minutes. So maybe if I had replaced the capacitors earlier it might have helped, but I don't know, just a though i have.

I will try to investigate this further and if I can't find anything I'll simply have to get a new monitor, or use this old CRT :P, which I use now.

[mariushm]

Re: Does this solder look OK?

Well, it looks like you only replaced a couple of capacitors.

Some other capacitors may not be swollen yet outside the specification or maybe you've replaced the old capacitors that probably still worked OK with some capacitors that have specs below what's required..

Post pictures with both sides here, maybe other people can spot what may be wrong.

Also check the fuse, maybe you damaged it now - if you can't check it manually, a simple way to check is by measuring the voltage across that big capacitor (should be >110v dc in US, > 250v dc in Europe)

[Jonathan_A]

Re: Does this solder look OK?

All the other capacitors have a flat surface, and the two bulged capacitors I replaced had exactly the same specifications as the new ones (1000 uF 16 V 105 C), the new ones are only slightly taller. Unfortunately I don't have any multimeter, so I guess I can't measure the voltage of the big capacitor, at least not right now, maybe I can buy a multimeter later (or borrow one). One strange thing I noticed though, is that one small capacitor has some white/beige goo on it. I thougt that may be glue, cause it's also between two other parts, as you see on the first picture (attached, the first 3 pics are from before I replaced the caps, you can see that the old two caps are a little bulged).

Anyway, the problem with the monitor is still the same as Before I opened it and replaced the capacitors, so something must have happened before that. What actually happened last wednesday (when the monitor didn't start for over 15 min) was that I turned one the monitor as usual, expecting it would start after about 7 minutes. Normally the LED power indicator would flash like it would be i sleep mode, steady 1 second flashes with about 2 seconds in between. But that time the whole monitor flashed white for about 0.1 seconds and then the power indicator started to flash very shortly (about 0.2 seconds, with about 3 seconds in between). That short white flash have happened before, I remember it's happened a few times when I had went to bed and just turned off the computer and monitor, and suddenly it flashed white very shortly.

[mariushm]

Re: Does this solder look OK?

The white stuff is glue - usually it's not a problem. Sometimes if there's lots of heats it can become conductive and cause shorts on the board but I don't think that's the case here.


You could really use a multimeter to test the output voltage and everything else.
The two swollen capacitors are from a Samwha series that are low impedance... if i remember correctly.
This means you should not put just any brand of capacitors there but match the specifications (same capacity, same or higher voltage, equal or lower impedance, equal or higher ripple).

The other two capacitors near the ones you replace may also be a bit problematic but now that you put two new ones near them, if they worked together now they may be under much more stress (you know, like the weakest link in a chain).

Ideally you would replace those two other near the connector sending power to the board with the processor and the four on the way to the transformers for the lamps.

[Jonathan_A]

Re: Does this solder look OK?

Ok, sorry for not answering for so long... I kind of gave up and tried to look for a new monitor instead, but i haven't got one yet, and now I have borrowed a simple digital multimeter so I'll do what I can to fix the old monitor. Now I'm just wondering how to test the capacitors with the multimeter. I'm googleing on it atm, but if anyone has a short explanation of it I'd be happy for that!

[Uranium-235]

Re: Does this solder look OK?

testing a cap not soldered in any board...usually...I put the meter on ohms, and set the scale low (mine isn't automatic, yours probably is, so you might skip this step). and see the resistance curve, go from -x slowly to 0, and to +x (or reverse, depending on if you have the ground to the - or +). a slow resistance curve usually means the cap is ok...but thats not necessarily true. the speed it goes from -x to +x will vary from caps with different values. There are better ways of telling (ESR meters and such). the best way is to get new caps

[Jonathan_A]

Re: Does this solder look OK?

Ok, thanks! just a few questions, can I test the caps when they are soldered in the board, or must I remove them first? And where on the capacitor do I put the probes, just anywhere on it or on the poles? (Sorry, I'm not an electrician XD)

[mariushm]

Re: Does this solder look OK?

Have to take it apart, put the black cable probe on the MINUS (-) of the capacitor, and the red one on the other wire.
If you put it the other way around, depending on the multimeter, the capacitor may blow up in your hands.

Anyway, these tests are really not reliable, you'll get a lot of false readings or some bad capacitors will not be detected.

The very least, you should get a multimeter that has Capacitance measurement, which will tell you how many uF the capacitor charges to - if it has problems determining it, it's obvious the cap is bad.

But even this is not enough, some capacitors will hold as much uF as they're rated for but their internal resistance will go up when in operation messing up the circuit they're in - this can be measured reliable by an ESR tester, which costs 50-100$ (most common prices are at about 80$). That regular multimeter resistance check won't detect this issue.

[PCBONEZ]

Re: Does this solder look OK?

All the other capacitors have a flat surface, and the two bulged capacitors I replaced had exactly the same specifications as the new ones (1000 uF 16 V 105 C), the new ones are only slightly taller.

Two GCE's here:

#1: Only some bad caps bloat.

#2: uF, V, and temp are only 3 of the 5 important specs.
In low ESR applications the two you are missing are the most important.

.

[ratdude747]

Re: Does this solder look OK?

Two GCE's here:

#1: Only some bad caps bloat.

#2: uF, V, and temp are only 3 of the 5 important specs.
In low ESR applications the two you are missing are the most important.

.

with the other two being ESR and ripple.