Fixing my computer monitor

Thread Starter

Koluson

Joined Feb 12, 2023
56
Thanks

Its a 20 watt soldering iron with a 120 watt boost. I tried tinning it with both 20 watts and 120 watts.

The solder is lead free tin 99.3%/copper 0.7%.
 

Thread Starter

Koluson

Joined Feb 12, 2023
56
Hmmm. Actually, tinning it at the tip does nothing without boost. Maybe I have a horrifically low quality soldering iron. This is the feeling I get, given it says the wattage is different in the same sentence on the box, in the manual and on the device itself.
Also, the manual is written by someone in China who should not be writing English manuals. Lol
 

MrSalts

Joined Apr 2, 2020
2,767
Try adding some (small amount) fresh solder to the joint and then using solder wick to draw all of the solder out of the joint. Also, since you're changing the cap anyhow, you might want to snip the cap and keep snipping until you get two separate leads to pull out. That way, you don't have to have both leads molten at the same time to get it out.
 

MrAl

Joined Jun 17, 2014
11,396
So most of my caps came today except for one, because Element14 screwed up my order.

I used a soldering iron for the first time. The first cap came off easy, the second a bit harder, and I couldn't even melt the solder on the third.

I read the cause of my problem is not tinning the solder bit. Well, i saw online you can just use solder to tin it, but when I tried to use my solder the solder either dripped off into a ball or vaporised.

Tomorrow I am going to buy one of those hair gel type tins of proper solder tinner.

I teared the circuits on the board a bit, but I didn't break them. I think they will be fine once cleaned up and the new caps are soldered in.

I took a photo of the board for those wishing to admire my A grade soldering skills.

View attachment 288192




Hi,

Here is what you should try.
First, place the tip of the iron on the joint to be soldered or unsoldered. Make sure the tip actually touches the old solder.
Then, while holding the tip tight against the old joint solder, apply some solder to the tip of the iron right at the place where it touches the old solder, so the tip will melt the solder and the melted solder will touch the old solder joint. It's the place where the tip and the old solder form a crevice.
Sometimes you have to touch the tip a little more than the joint until the solder melts and sort of flows down to the joint, but it's a very tiny distance hardly mentionable.

The idea is that the tip melts the solder and the molten solder then melts the old solder which is extremely close to the tip.

Sometimes the tip has to be cleaned a little. If it looks black then it probably needs to be cleaned.
If the temperature is too high it will vaporize the solder and it wont stick to the tip.
Sometimes a little pressure from the tip to the joint helps too, but not so much that it breaks the tip or anything on the board.
 

Thread Starter

Koluson

Joined Feb 12, 2023
56
Thanks guys. I cleaned the tip last night and will try to tin it again today on better sleep. If it still won't tin then I will try the suggestions of using solder to melt solder.
 

Thread Starter

Koluson

Joined Feb 12, 2023
56
So, like in the video, I wrapped a clean tip in solder wire, minus the rosin flux, and 95% of it just slid off. I then stuck the soldering iron tip into the solified coil and it took 30 seconds for it to melt.

I'm not in a position at the moment to get flux, so perhaps I can keep the tip on the capacitor solder joint for a while to get it to heat up.

My soldering iron is 15 watts, so pretty weak.

I am going to give this a go first. I only need to get two more capacitors off. Soldering the new ones on won't be a problem.
 

Thread Starter

Koluson

Joined Feb 12, 2023
56
So I did soldering for the first time.

I did it without flux.

The first solder took half an hour, by the end 10 minutes. I made sure I bridged the torn circuits.

My 15 or 20 watt soldering iron sucks. I cant desolder or solder at the tip. Thats the problem I was having with desoldering. It doesn't get hot enough. I need to use the top of the tip.

I figured out why I was having trouble desoldering. I was trying to desolder the metal around the hole on the board. Haha

Well i did 5/7 caps but it didn't fix the problem. I think its the 2.2 uf/450 volt cap in the middle of the board that connects from the transformer. That's the one I'm waiting for.

It could be the big cap though. I have the big cap but didn't do it because it is suppose to be glued to the board with white silicon and I don't have any. I want to do it exactly how it is, but maybe I'll get desperate so we'll see when the other cap arrives.

Here is my art. The main soldering was done on the left. The blobs from having to use the top of the soldering tip.

IMG_20230224_200134.jpg

IMG_20230224_200231.jpg
 
Last edited:

MrAl

Joined Jun 17, 2014
11,396
So I did soldering for the first time.

I did it without flux.

The first solder took half an hour, by the end 10 minutes. I made sure I bridged the torn circuits.

My 15 or 20 watt soldering iron sucks. I cant desolder or solder at the tip. Thats the problem I was having with desoldering. It doesn't get hot enough. I need to use the top of the tip.

I figured out why I was having trouble desoldering. I was trying to desolder the metal around the hole on the board. Haha

Well i did 5/7 caps but it didn't fix the problem. I think its the 2.2 uf/450 volt cap in the middle of the board that connects from the transformer. That's the one I'm waiting for.

It could be the big cap though. I have the big cap but didn't do it because it is suppose to be glued to the board with white silicon and I don't have any. I want to do it exactly how it is, but maybe I'll get desperate so we'll see when the other cap arrives.

Here is my art. The main soldering was done on the left. The blobs from having to use the top of the soldering tip.

View attachment 288279

View attachment 288275




Hi,

Well nice to hear you made some progress anyway.
That big cap usually does not go bad, but you never know on this one it could be that.

Remember unfortunately there is a chance the problem was either not the caps or it was the caps plus something else wrong.
 

Thread Starter

Koluson

Joined Feb 12, 2023
56
Thanks

Yes, I was wondering if perhaps it's something else, but what else is there? Everything else looks solid-state.

It probably is that little cap. Little cap @ 450 volts next to big parts. It looks and sounds like it takes a lot of stress. And the fact this part was harder to source suggests it is a part that commonly fails.
 

MrAl

Joined Jun 17, 2014
11,396
Thanks

Yes, I was wondering if perhaps it's something else, but what else is there? Everything else looks solid-state.

It probably is that little cap. Little cap @ 450 volts next to big parts. It looks and sounds like it takes a lot of stress. And the fact this part was harder to source suggests it is a part that commonly fails.
Yes, i hope it is that i'd like to see you get this going again.
Also, you can test without the silicone then if it works apply that at a later date.
 
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