PCB Repair / soldering

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Caporegime
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Hello :)

Sadly my monitor went bang today, at 37 months old. I love this monitor so will be repairing rather than replacing. I've stripped it down and the cause is a resistor on the PSU PCB which decided that it'd be cool to have its insides on the outside.

This is the PCB:

8neZ4oP_d.jpg


This is the resistor which went pop:

cHPwttn_d.jpg


And these are the solder joints:

ztS3K3p_d.jpg



Now I'm far from an electronics expert and can handle some hobby soldering but I've no idea how precise this has to be and don't want to make things worse so my question is will a hobby level of soldering suffice for this? If not I'll take it in somewhere for a pro to do but ideally I'd like to get it fixed sooner rather than later.

Thanks :)
 
Simple repair that is really, melt the solder and pull it out with some small long nose pliers. If you have a solder sucker it might make life easier to open up the holes to fit the new one, but if not then melt the solder again to put the new one in, and add a drop more solder if required.

Ive replaced capacitors and such on similar circuit boards, it's quite easy really.
 
Hobby soldering will be fine, be careful not to bridge any tracks, I'm assuming you'll be replacing the resister though.
 
Easiest way to get it out will probably be to actually add a bit of new solder to the old solder as you warm it up then either use a sucker or I usually have better results with braid to remove some of the solder before trying to pull it out so as to have a clean hole to remount.

From the size of those resistors I suspect they are fairly high wattage (bit hard to see for sure though) as well so don't go replacing them with like 1/4 watt jobbies.
 
Looks like a nice easy fix. PSUs like that aren't high precision microelectronics so the soldering isn't exactly delicate in the grand scheme of things. Bear in mind when you first power it back up that the resistor may well go again. I'd plug in the PSU board on its own on a desk before putting the whole monitor back together.
 
chuck990 said:
I'd plug in the PSU board on its own on a desk before putting the whole monitor back together.
Click to expand...

Be very very wary if there is mains voltage on that board (hard to see what input it takes but from the transformers, white demarcation marking and C14 looking socket I'm guessing is the case) and caps will still hold their charge potentially making it a risk when putting it back in the case - I agree though depending on what went wrong a good chance the resistor will go again.
 
Cool, thanks all. Now I just need to suss out what resistor it is. The rings are obviously the resistance, but what else do I need to know?
 
Rings will show the resistance value and tolerance (probably not too critical unless it is part of the circuitry used to set an output voltage and you used a really terrible tolerance) but you will also need to know roughly what wattage capability it is - usually the case size is a rough guide.
 
Great, thanks Rroff. At the prices these things go for I'll just order afew different sizes and replace like for like.
 
At a guess I'd probably say they are 2-3 watt but hard to be sure - the case length might give a rough guide.
 
Quite often those green components are inductors. Check the PCB for the notation of the component.

If it's R154 or something it is a resistor, however L154 means it is an inductor. Inductors like to hang around in power supplies and often live close to transformers.

You might also want to check that diode. It could have failed and caused the heating of the resistor/inductor. It's not altogether easy to see from the photos.
 
Tealc said:
Quite often those green components are inductors. Check the PCB for the notation of the component.

If it's R154 or something it is a resistor, however L154 means it is an inductor. Inductors like to hang around in power supplies and often live close to transformers.

You might also want to check that diode. It could have failed and caused the heating of the resistor/inductor. It's not altogether easy to see from the photos.
Click to expand...

That some of them are gunked in paste could indicate they are inductors as that is often used to reduce whine.

I really should have noticed that.
 
firstborn said:
Can you clarify why you think it's that component?
Click to expand...

I think the clue is the fact that it's somewhat burned.

3N7L2MY.png


You really need to find a schematic to see exactly what value that is. They're cheap enough and it should be a simple job to replace that.
 
Resistors fail, they often use close to, or below the minimum wattage required - they weren't designed to last forever.
 
Yep as already said make sure you add fresh solder to the joint while putting the iron on it otherwise you'll burn the board and have solder all over the area. I would look for a video on YT. You can also buy a desoldering pump to suck the solder while the iron is on. Need to have tweezers or pliers pulling from the other side while the iron is on. Really need four hands or proper equipment to do it right but a hack job usually works.
 
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