Mac Mini circuit board soldering advice needed

[razmanugget]

I recently purchased a used Mac Mini (Mid 2010, MC270) from eBay and the seller stated that the superdrive wasn't working. I've been buying Apple products for a couple of years and have had great luck opening them up and fixing them.

This was my 1st time working with the new Unibody Mac Mini and when I tested it, I realized that I had another problem because the cooling fan was running like a vacuum cleaner on full blast under no load.

After pulling it apart (thanks to iFixit), I found the problem – the superdrive temp sensor was broken off the base. (see photo)

My plan
Use a drop of jbweld to glue the temp sensor base to the board
Solder the 2 leads of the base to the board
My question
What are the 2 squares above the leads that need to be soldered? Are they also contact points which need to be connected? I ask because the base looks like it has metal at those points. I also think they could be attachment points for the base.

Also, any advice you have on soldering the 2 leads would be appreciated. I plan to use a 15-watt soldering tool and 60-40 rosin-core solder wire.

Thank you

 

[MJL]

Don't try do it yourself - soldering SMD componentry is a specialist job. (I've done it and no longer want to do it)

 

[miles01110]

I can't see what the actual issue is. A close-up of the "What are these??" objects would help.

 

[razmanugget]

Thank you for the replies guys

MJL, could you give me some tips on the soldering work?

It seems like a shame to waste a perfectly good Mini because the fan won't slow down and it only needs 2 solder connections (or maybe 4 if those other points need solder).

Here is a closeup of the 2 square pads I am not sure about. I think they are just for mounting and don't carry current, but I want to confirm.

Thanks

 

[trance2]

I broke my fan temp sensor as well in my iMac while replacing a the DVD drive. I went with the software route and used SMCFanControl to control the speed of the fan.

Good luck!

 

[Mr. McMac]

Looks like the 2 in the front are your electrical connections, while the 2 in the back are just pads which are soldered to keep the connector from lifting. Looks like those lifted off the circuit board. It's best to repair it using an illuminated magnifying glass and low wattage soldering iron with a fine tip. Since the mounting pads look like they're gone, you will need to glue the connector in place, then solder the two connections. Be careful not to overheat the connections as they can lift off the board if overheated. BTW, I have over 40 years of soldering experience..

That said, if you have no soldering experience, have someone with experience do it..

 

[razmanugget]

Awesome. Thank you for the advice.

I use SMC for my Macbook, but I thought it could only increase the minimum fan speed. I didn't know it can also throttle the speed down.

 

[MJL]

With SMD a temperature controlled soldering station is almost a must. Items can be held down using a fine tipped tool. Very thin non-lead solder will need to be used and it may be ncessary to use desoldering braid to get rid of the overflow. If no experience (and no dedicated tools) then it is far better to let it up to a profesional, it will be more succesful and cheaper (if you add the cost of tools). As trance2 mentioned, just use SMC fan control.

 

[Ruahrc]

Given the low-stress situation that the connector is going to be in, and the minimal voltage and/or current that it must carry, it's possible that something like a carefully applied conductive adhesive or simple pressure contact would be sufficient to fix it, rather than trying to properly re-solder the joints. This might be a little safer as it risks less damage to the components in question.

 

[razmanugget]

I never thought about conductive adhesive. What about this (see photo too):
http://www.amazon.com/JVCC-CFL-5CA-...8SJK/ref=sr_1_1?ie=UTF8&qid=1317940202&sr=8-1

I like the smcFanControl idea and did some research on setting up the override, but I'm concerned that the machine will overheat. It will be used as a media player (boxee perhaps) and I can see some 1080p movies taxing it.

 

[razmanugget]

Oh yeah, and I just wanted to thank everyone for the comments. This doesn't seem like a typical type of thread for the forums and I really appreciate the feedback.

 

[Guzaking]

Add me to this already huge list that I see on many forums and threads that these fasteners are held down to the motherboard by only the solders and not any extra adhesive which is a joke really.

It's very easy to break off the solder mounts while pulling a plug out. OWC YouTube videos shouldn't promote to pull the whole thing apart and move the logic board, it's overkill and you don't need to do that.

You can clear the hard drive out of its slot by much manipulating it to clear over the DIMM slot braces. Unfortunately I did this after the Superdrive heat sensor broke off, now I'll have to resolder it back without ever soldering in my life.

What type of metal wire is used on these mac Mini logic boards, lead-free, or leaded, aluminum, steel, etc. I figure its got to be the same solder metal used by Apple during production for it to work without any problems.

 

[dyt1983]

edit: to remove personally identifying information not relevant to thread.

 

[Guzaking]

is a lead-based lower tin solder softer or harder than a lead-free for ROHS compliance, what characteristics makes the leaded one better?

Also, what is a copper trace? I see 4 points of silver colored what looks to be mounting spots, 2 up at the top of the connector close together and 2 farther apart towards the bottom of the connector. But I don't see anything copper colored? Nice Merc by the way

 

[dyt1983]

edit: to remove personally identifying information not relevant to thread.

 

[Guzaking]

Pics...

Fellow F1 Fan, here are the pics of the area and the now detached Molex mount. On the mount itself (photo showing the bottom of it) there are only 4 contact points to the motherboard so I'm guessing that the copper trace which you were talking about hopefully won't apply?

Also, these contact points are very very tiny so instead of heating up the solder point on the logic board I was thinking about heating up the wire wick only and doing a liquid metal drop onto the points and then quickly positioning the mounting clip in place before it dries and hardens up, what do you think?

 

[dyt1983]

edit: to remove personally identifying information not relevant to thread.

 

[Celerondon]

Practice!

Fellow F1 Fan, here are the pics of the area and the now detached Molex mount. On the mount itself (photo showing the bottom of it) there are only 4 contact points to the motherboard so I'm guessing that the copper trace which you were talking about hopefully won't apply?

Also, these contact points are very very tiny so instead of heating up the solder point on the logic board I was thinking about heating up the wire wick only and doing a liquid metal drop onto the points and then quickly positioning the mounting clip in place before it dries and hardens up, what do you think?

I agree with what dyt1983 said but I want to further stress Practice. Obtain a broken transistor radio or some other electronic device and practice soldering on the circuit board. Once you become proficient enough to attach wires to copper traces or to remove and install resistors or other semiconductor components, you will be prepared to attempt this repair.

As you gain experience with solder and soldering techniques, you will learn why pre-heating components is an impractical soldering strategy.

 

[gsahli]

I prefer MacsFanControl over SMCFancontrol:
http://www.crystalidea.com/macs-fan-control