Well, Think I Found That Burning Smell

[IBWino]

I think you made the right call. Those type of inexpensive electrolytic capacitors typically wearout after a few thousand hours of operation, but they are relatively easy to replace. I recently repaired our Samsung flat screen monitor by replacing eight such capacitors, and the total cost was less than $6 from Digikey.

Regards,
Wino

 

[Sunset]

I think replacing the Caps is a great choice, since you will barely risk anything as the board will fail completely some day, and you would need a new board/computer anyhow.
This way you chose the time and have it all backed up and replacement plans in place.

 

[grasshopper]

I haven't soldered anything since I built a Heathkit short-wave radio. Ms G's tablet needed a new battery, had to solder in place good to go for 2 months so far.

 

[easysurfer]

So, thought I'd go ahead an practice desoldering capacitors on a dead motherboard (MB) I have around. The MB is the original for my computer before I had to replace about a year or two ago.

I had no luck trying to desolder. I used a good Weller soldering iron but there was so little solder to remove that nothing really melted. Yet at the same time the capacitor is snug in place. This fix might not be as easy as I thought.

 

[Lakewood90712]

So, thought I'd go ahead an practice desoldering capacitors on a dead motherboard (MB) I have around. The MB is the original for my computer before I had to replace about a year or two ago.

I had no luck trying to desolder. I used a good Weller soldering iron but there was so little solder to remove that nothing really melted. Yet at the same time the capacitor is snug in place. This fix might not be as easy as I thought.

When I was a young-in, about 20, did a bit of pcb solder work. We cut the component off as close to the board as poss. Then used a spring loaded vacuum solder sucker device called a "sold-a-pult" to pull the molten solder off the back side of the board . Takes some practice. Trying to remove solder with a copper wick is another method , not very effective.

Don't even want to think about how much lead I inhaled

 

[easysurfer]

When I was a young-in, about 20, did a bit of pcb solder work. We cut the component off as close to the board as poss. Then used a spring loaded vacuum solder sucker device called a "sold-a-pult" to pull the molten solder off the back side of the board . Takes some practice. Trying to remove solder with a copper wick is another method , not very effective.

Don't even want to think about how much lead I inhaled

I have one of those spring loaded suckers along with the iron, but as I mentioned there was very little solder to melt. Didn't have something handy to cut the component but haven't tried that yet.

But now, I'm looking at reviews of a desolder gun. Definitely the right tool for the job. That looks sweet:

 

[ERD50]

I have one of those spring loaded suckers along with the iron, but as I mentioned there was very little solder to melt. Didn't have something handy to cut the component but haven't tried that yet.
...

Though it seems counter-intuitive, it sometimes helps to add solder, then use the sucking tool to draw it all out together.

I think adding solder helps to transfer the heat all the way through, gives the sucker more to work with, and then surface tension helps pull it all out together.

-ERD50

 

[easysurfer]

Though it seems counter-intuitive, it sometimes helps to add solder, then use the sucking tool to draw it all out together.

I think adding solder helps to transfer the heat all the way through, gives the sucker more to work with, and then surface tension helps pull it all out together.

-ERD50

I've put my solder [-]toys[/-] equipment away for the night, so won't try this til next time. Of course, if I get something like that desoldering gun this can all be a moot point (still less expensive than a good replacement pc) .

 

[Winemaker]

Dell products are garbage. I have had better luck with Lenovo boxes.

I still run a Dell 4100 from 1999, and am on a Dell laptop from 2008. I have had very little problems.
It's the same with cars; I always buy used GMs vehicles. Always got over 200,000 miles and the best was over 450,000 miles. YMMV.

 

[target2019]

I've put my solder [-]toys[/-] equipment away for the night, so won't try this til next time. Of course, if I get something like that desoldering gun this can all be a moot point (still less expensive than a good replacement pc) .

I don't think you mentioned the specific Dell model.
Sometimes it is possible to find a chassis with motherboard. For example:

https://www.amazon.com/755-Processor-Authentic-Dell-Reinstallatiion/dp/B00465QFEA

I do admire your effort to desolder, though.

 

[easysurfer]

I don't think you mentioned the specific Dell model.
Sometimes it is possible to find a chassis with motherboard. For example:

https://www.amazon.com/755-Processor-Authentic-Dell-Reinstallatiion/dp/B00465QFEA

I do admire your effort to desolder, though.

I have a used Optiplex 740 Minitower. Actually, I went that route, getting a chassis with MB last time when the a power supplied died and took out the MB from my original chassis.

I do like the case of the 740's minitower case. Nice and sturdy but I've never been too crazy about tool less bay mounting.

 

[jetpack]

Everyone should learn to solder. I've done a few capacitor operations. One on a 50" flatscreen TV, another on a 22" monitor. Also, a few other times when there is just something wrong w/ a solder joint. Good luck!

 

[target2019]

I have a used Optiplex 740 Minitower. Actually, I went that route, getting a chassis with MB last time when the a power supplied died and took out the MB from my original chassis.

I do like the case of the 740's minitower case. Nice and sturdy but I've never been too crazy about tool less bay mounting.

Ok, that's the AMD model, right?
I tossed one of those last year, for some serious reason I can't remember.
We had those as well as Pentium 755 models. One sitting in my office that I play with every so often.

 

[easysurfer]

Ok, that's the AMD model, right?
I tossed one of those last year, for some serious reason I can't remember.
We had those as well as Pentium 755 models. One sitting in my office that I play with every so often.

The one I have is AMD. Not sure if all 740 models are AMD or not. If I could do thing all over again, I wouldn't have got the used Dell and got a gamer instead. But as like I said, the case is nice (very very quiet case fan) and happy with the upgrades I made.

 

[target2019]

The one I have is AMD. Not sure if all 740 models are AMD or not. If I could do thing all over again, I wouldn't have got the used Dell and got a gamer instead. But as like I said, the case is nice (very very quiet case fan) and happy with the upgrades I made.

Yes, that is AMD only. The motherboards are different than the pentium ones. I'm pretty sure yours is model 740SFF. Small Form Factor.

https://www.amazon.com/Dell-Optiplex-740-Desktop-80GB/dp/B007W2VRJW

They came in larger cases too. All very confusing to those charged with buying.

Some of these SFF models developed a problem where the CPU fan would go into high speed, and it was really disturbing.

 

[easysurfer]

Yes, that is AMD only. The motherboards are different than the pentium ones. I'm pretty sure yours is model 740SFF. Small Form Factor.

https://www.amazon.com/Dell-Optiplex-740-Desktop-80GB/dp/B007W2VRJW

They came in larger cases too. All very confusing to those charged with buying.

Some of these SFF models developed a problem where the CPU fan would go into high speed, and it was really disturbing.

Actually, the one I have is in the larger case:

https://www.amazon.com/Dell-OptiPle...0&sr=1-4&keywords=dell+optiplex+740+minitower

But, yes confusing as I think there are 3 Optiplex 740 models with different boards and a bit of a misnomer, since though the one I have is named minitower, the case actually is pretty big (which I like as my hands aren't steady enough to work in a small sized case ).

 

[bjorn2bwild]

My highly effective, not for the timid, de-soldering method -
Heat the target from the backside of the circuit board with a clean tipped, hot soldering iron. With the tip still on the lead, blast with shot of compressed air. Repeat for the second leg of the cap. Remove the cap.
I do this in the garage and use an air compressor with a fine rubber nozzle. Blast in a safe direction. I don't know if canned air would have enough oomph, worth a try. Splattered solder can easily be brushed/scrapped off the board. Works for me every time. YMMV

 

[easysurfer]

A quick update on my desoldering project to fix the motherboard of my PC.

Haven't worked on the live motherboard yet, but only the not functioning practice board.

Well, I tried doing the desoldering manually (solder iron tip and manual spring sucker). No way would I get the capacitors off. I tried adding some solder than trying and trying but couldn't remove. Might be because my of lack of skill or just that there is so little a spot where to capacitor connects to.

So, I went ahead a caved and bought that Hakko desoldering gun. From what came with the package, still couldn't remove the capacitor as the opening the desoldering nozzle that came with is too big (1mm). So, I ordered a smaller nozzle (.8 mm, smallest size for that tool). I struggled and fiddled around and was able to remove the capacitors, but it wasn't easy. Mainly, I need a smaller nozzle, but there isn't one for that tool. Using that tool on other capacitors on that board was a piece of cake.

Probably won't get around to "the surgery" until late October or November.

 

[Peter]

Are these surface mount caps or through-hole?

 

[easysurfer]

Are these surface mount caps or through-hole?

Through-hole.

 

[exnavynuke]

I never understood why the fans blow air out of the box. That just allows more dust in through all the cracks and crevices. Why don't they reverse the fan so it sucks air through the fan? That way you could have a cleanable filter to keep the dust down? And the air would exit through the cracks.

Blowing hot air out vs blowing cool air in doesn't really change the total airflow (in vs out) nor change how many particles are going into the case by itself. Without "out" fans, however, the higher temps may not be what is escaping (if you just blow in, the cooler air in the case may leave the case at a much higher rate than the hot air, resulting in overheating). Many cases these days (such as mine), utilize filtered vents to encourage airflow in through those, with optional fan mounts at the filter.

 

[ERD50]

I never understood why the fans blow air out of the box. That just allows more dust in through all the cracks and crevices. Why don't they reverse the fan so it sucks air through the fan? That way you could have a cleanable filter to keep the dust down? And the air would exit through the cracks.

Blowing hot air out vs blowing cool air in doesn't really change the total airflow (in vs out) nor change how many particles are going into the case by itself. Without "out" fans, however, the higher temps may not be what is escaping (if you just blow in, the cooler air in the case may leave the case at a much higher rate than the hot air, resulting in overheating). Many cases these days (such as mine), utilize filtered vents to encourage airflow in through those, with optional fan mounts at the filter.

For the equipment I built, if fans were needed, we always had a filter on the fan, and had the fan blow that filtered air into the case. As folivier says, if you do it the other way, dust is sucked in through every crevice.

This was production equipment, and very many cardboard boxes of components were opened near the line, and that created a lot of dust over time. Equipment with unfiltered fans would just fill up with dust in a few months.

-ERD50

 

[niven]

I'm not a soldering expert but I've done a fair share of it through the years. On something like these capacitors, I'd heat each lead alternately and "walk" it out by pushing the top of the capacitor on the side you're heating. No need to try and desolder until you get the capacitor out. Even then I usually just reverse the process to put in the replacement then add some solder if needed.

 

[Souschef]

Everyone should learn to solder. I've done a few capacitor operations. One on a 50" flatscreen TV, another on a 22" monitor. Also, a few other times when there is just something wrong w/ a solder joint. Good luck!

This may be dating me, but I hate to think how many Heathkits I put together

 

[easysurfer]

The surgery to replace the capacitors on my Dell's motherboard has started...