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ljzmcm · 12-Jun-2008, 08:01 PM #1

Hey all,

So I have an HP f1703 monitor. Apparently, there was a massive recall on these things. Forgive me if I use the terminology wrong - but the general consensus is they have "cold solder joints" that go bad.

I read a little bit on how to spot them.
(http://www.tangible-technology.com/a...nt_update.html)
I think I may have found it. Does this look bad to anyone?

Need Soldering Help! (Spotting a cold solder)-solder.jpg

Thanks...

leroys1000 · 12-Jun-2008, 10:13 PM #2

Looks like it might have a bubble from oxidation.
Use a little bit of rosin flux and reheat it.

ljzmcm · 10:27 AM

You'll have to forgive me - I'm an amateur at this.

Is Rosin Flux a type of solder? Right now I have .022 diameter Silver Bearing Solder

Thanks.

Plater · 13-Jun-2008, 06:46 AM #4

No. Flux is the medium that helps the solder flow. The joint must be cleaned probably best with the end of a very small flat screwdriver. Only scrape the joint and not the board. any scratch on the board could cause current to track to another connection. Another point to take into account, is heat. You have to use a solder gun with an instant on/off switch with a very small point. The job has to be done quickly to stop the heat tranfer loosening other joints. If the board is not important to you. eg. it's not working anyway, have a go, nothing to lose & a lot to learn. Otherwise, take it to a Professional.

**JohnWill** · 13-Jun-2008, 09:51 AM #5

I can't tell from that picture, but you don't need silver bearing solder, just plain rosin core solder. Rosin flux is embedded to clean the joint and allow the solder to bind to the components.

ljzmcm · 13-Jun-2008, 10:26 AM #6

Quote:

Originally Posted by JohnWill

I can't tell from that picture, but you don't need silver bearing solder, just plain rosin core solder. Rosin flux is embedded to clean the joint and allow the solder to bind to the components.

Awesome thanks. I'll go get the Rosin kind.

Should I braid it off first or is it usually okay to just resolder?

leroys1000 · 13-Jun-2008, 11:46 AM #7

It would be better to remove the old solder.
Just be careful not to pull up on the desoldering
braid if it is stuck to the board.
Lift it when it is hot enough.
Don't want to pull the trace off the board.

**JohnWill** · 17-Jun-2008, 09:13 AM #8

I agree that removing a lot of the old solder is a good idea.

ljzmcm · 17-Jun-2008, 10:33 AM #9

Cool, thanks guys. Gonna give it a shot today after work and let ya know how it goes.

sup2a · 18-Jun-2008, 05:52 AM **#10**

yea as suggested only put on 5 seconds of heat, any more and it could cause problems, the average life span of a pad is 20 seconds and trust me its true, the glue will lift right off, make sure you give the area a good chemical clean afterwards to remove excess flux.

ljzmcm · 18-Jun-2008, 10:17 AM **#11**

What is a "pad"?

I went at it this morning before work. Luckily I caught your post of "no more than 5 seconds"! It braided off clean and rubbed it down with a little acne facial pad. Havent bought the Rosin Flux yet...

More later!

sup2a · 18-Jun-2008, 07:44 PM **#12**

the track the joints are soldered on are pads.... in other words the copper or whatever things glued onto the actual board

**JohnWill** · 18-Jun-2008, 08:53 PM **#13**

It's copper, and it's bonded to the PCB material. OTOH, you are quite correct that too much heat for too long will indeed lift the pads. In truth, it's the temperature more than the time that lifts pads. I use a temperature controlled soldering iron at 650F, and lifting pads is rarely an issue. OTOH, using a hotter iron (almost any unregulated one), will lift them much quicker than using the correct temperature.

sup2a · 18-Jun-2008, 10:05 PM **#14**

thats a good point, sorry still rather new to soldering, currently studying it, at the recommended temperature we use (350c perfect for wetting) the max you can hold it on there for is 20 seconds, on another temperature (450c) it did take less time and i managed to lift a few pads (as part of the exercise) and caused serious damage to the test boards, you really don't need to put the iron on there for long anyway, just take into consideration that this item has already been soldered... therefore taking a few seconds of its life...

ljzmcm · 19-Jun-2008, 10:10 AM **#15**

Yikes haha. This sounds much more complicated that I initially thought.
I've yet to try resoldering with the rosin flux but I'm pretty sure I braded everything off real nice =)

Thanks for all this info guys. Extremely helpful

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