Question re motherboard soldering

[Geaney]

I've been working on a dead PC and one of the faults was a dodgy electrolytic. I found it took considerable heat to remove the dud and then no amount of heat would suck the solder out of the holes. I struggled to fit the replacement but finally managed it. I assume the problem is the multiple layer on these types of board. Is there any special technique or tools that make replacing components like these easier?. This is my first attempt at fixing a motherboard. The newly fitted cap has done the trick and the machine is back in action. However, I'm not happy with the quality of the work and was wondering if there's an easier way to do it.

Cheers,

John

[AlanBeckett]

John,

If I have to change one I usually hack the old one off leaving two bits of wire sticking up and solder to those. Not pretty but it avoids damage to the PCB.
The other technique I've used is to suck from the other side to the one you've got the Soldering Iron Bit on. A pointed Bit traight into the hole usually works.

Alan

[Refugee]

I fixed a telephone exchange with a hard drive voice messaging system in it.
It had a bespoke motherboard and was due for sale on the web.
I used two 40W soldering irons held like chopsticks and an un- tinned wire to poke out the old solder.
The newer capacitors were a wider lead spacing than the old ones. All the V-core ones were bursting and it was a known problem on the model concerned.

[Skywave]

To do that sort of work you need a soldering iron that gets really hot - without dramatically over-heating the surrounding area of the pcb. For that purpose, I use a Metcal soldering iron. I have other makes / types of iron available, but the Metcal seems to be the only one that is up to the job. As for clearing out the holes, I use one of those green-coloured solder suckers, but always check that it is is good 'sucking' order first. That often entails a good clean out of its interior, perhaps a new washer and sealing ring and usually a new PTFE nozzle. Occasionally, the additional use of fine solder wick helps too.

Al.

[Radio Fixer]

I go with Alan and always try to connect to the old components leads. If there is enough wire then I use a 'Philips' connection (a spiral of thin wire).

Gary

[Geaney]

Thanks Guys,

I'll try out the various suggestions. Metcal gear is certainly on the costly side so I'm glad it has the oomph. Might add one of those to my list to Santa.

Since the graphics card died on the PC I can mess with that to improve my skills without making too much of a mess.

Cheers, John

[Geaney]

Turns out that a good strip and clean of the graphics card was all it needed. The heatsink assembly was so clogged with gunk that there was no airflow across it at all.

The PC is now fully back in action.

I got a nice letter from the tax man telling me I'd paid too much tax last year and a nice rebate is on it's way. So, I splashed out on a Metcal soldering setup (MX5000) complete with de-soldering gun.

Cheers, John

[Nick]

Which MX5000 units did you go for? - they're certainly not cheap, but, IMHO, generally the very best for fine professional work.

At home, I use the precursor - MX500P units... love them to bit, and user-serviceable too (not exotic parts, e.g. OTP uPs etc.)

[Skywave]

I splashed out on a Metcal soldering setup (MX5000) complete with de-soldering gun.

A wise investment that you won't regret. Let us know how you get on with it, please - and how its performance compares with other irons that you've used. Informed comment is always welcome.
Thanks.

Al.

[Geaney]

Which MX5000 units did you go for? - they're certainly not cheap, but, IMHO, generally the very best for fine professional work.

I got the MX-5051. Two port base station, soldering iron and desoldering gun. Unfortunately mine came without any cartridges - had to order them separately. I got a 2mm chisel point for general work, a fine point round for pcb work, and a desoldering cartridge for the gun.

So far I've just done a little with the iron and I'm very impressed. I'm hoping the de-soldering gun will run off my small airbrush compressor - will try it out at the weekend.

Cheers, John