Reflowing the solder in DME's

[mikepellegrini]

It seems like cold solder joints in DME's are a common problem, the cure for which is reflowing the solder.

My son did this on the DME of his 951 - it took him maybe an hour or so with a soldering iron - a real PITA. But it worked. Where before he'd had intermittent no-start problems, reflowing the solder cured it.

My PS3 died maybe 2-3 months ago. Yellow Light of Death. I did some checking around and found that basically it was the same problem. Over the years, the CPU heating up and cooling loosened the solder joints and the cure was to reflow the joints. here's a video demonstration of the repairs from IFixIt. Yellow Light of Death Repair - iFixit

What was novel is that the way they reflowed the solder - using a heat gun - it took maybe a few minutes (plus an hour and a half to tear the PS3 apart, and another couple hours to reassemble - god there were so many little parts...).

But when I finally got it together, it worked!

I did the same thing to my son's PS3 and fixed it too. It's simply amazing!

So easy.

I find the application to reflowing solder on a DME extremely intriguing - take an hour of tedious work with a soldering iron and do it all in 5 minutes.

Basically, what they had you do is heat the whole PS3 board up to operating temperature (100F - which took maybe 1 minute), then you place the board on a flat surface (so the solder doesn't run when hot), and heat up the area around the CPU and memory chips to about 250F. They suggested 30 seconds with the heat gun on low; I used a heat gun on high and brought the affected areas up to 250F measured with an infrared thermometer). Total time less than 5 minutes. Then you let it cool to room temperature before reinstalling.

I'm not sure which particular areas on the DME board are problems; if I were doing it, I'd probably heat the whole thing up.

I don't currently have a bad DME (Yea!) but if and when I do, this is the way I'm gonna try to fix it.

[Gawernator]

Nice!

[924RACR]

Makes perfect sense, since this mimics the OEM production process on modern boards for the vast majority of components - surface mount technology. They just pass through a heated tunnel - think like the pizza conveyer oven - and the solder flows and wets the joints.

[rhett]

Just a cautionary word of warning here...our DME's were not manufactured in the same way as todays modern PCBs and also used different solders, etc. Todays components and materials are designed for the 'heated tunnel' approach, the old DME is not. Solder technology has moved on tremendously and todays solders are lead-free and flow differently to the old lead-based solder that would have been applied to the DME using a 'wave' technique. So, just heating up the old DME board may not achieve the results you are looking for, and may actually damage the board and some of the more temperature-sensitive components. Years of oxide will have developed on the exposed solder joints and this will cause problems with the joint if it is simply reheated without the presence of a good flux to clean it off. I would rather do it the long way than take the risk...modern boards, not a problem, older ones, could be.

However, as always...its entirely up to you!

[Slam]

Did this with my cruise control brain. Worked for a week. Did it again. Worked for another week. Did it a third time and cooked the thing. I believe next time I'll do it the 'old fashioned' way. If you have a spare DME why not try it? Nothing to lose.

[mikepellegrini]

Originally Posted by rhett

Just a cautionary word of warning here...our DME's were not manufactured in the same way as todays modern PCBs and also used different solders, etc. Todays components and materials are designed for the 'heated tunnel' approach, the old DME is not. Solder technology has moved on tremendously and todays solders are lead-free and flow differently to the old lead-based solder that would have been applied to the DME using a 'wave' technique. So, just heating up the old DME board may not achieve the results you are looking for, and may actually damage the board and some of the more temperature-sensitive components. Years of oxide will have developed on the exposed solder joints and this will cause problems with the joint if it is simply reheated without the presence of a good flux to clean it off. I would rather do it the long way than take the risk...modern boards, not a problem, older ones, could be.

However, as always...its entirely up to you!

The people I know who've done this simply re-heated the solder and didn't use new flux.

Perhaps rather than blindly heat the board to 250F, it'd make more sense to test some of the solder joints with a soldering iron to try to see what temp it liquefied, then shoot for that.

[simssj]

Just to add to the conversation a little bit, I re-flowed each and every connection on my DME last night.

I used a pin-point 30W pencil-type iron I've had "forever." I didn't use any new flux, but I did have to add a little bit of rosin core solder on a couple of the driver transistors and also on the pins that connect the board to the plug "just to be safe."

Before I started reflowing connections I scrubbed the boards meticulously with a soft toothbrush and distilled water to remove a little bit of "grunge" that had built up on the boards over the years. I followed that with a spray of rubbing alcohol to remove all traces of moisture. Then hit it with the iron.

Elapsed time from breaking the logic boards out of the case to reassembly was ~90 minutes, but I worked *slowly* and methodically.

The good news is, when I plugged it back in the car, it worked!

The bad news is, I still have my "doesn't want to start when it's cold" problem.

[mikepellegrini]

Bad O2 sensor or maybe ICV?

What are the symptoms?

[simssj]

My symptoms are very straight-forward: The likelihood of the car starting is inversely proportional to the ambient temperature. This morning, at about 50F it started after ~10 seconds of cranking. At 40F it might take two or three agonizingly-long 30-second grinds. Below 30F it's probably not going to start.

I've verified pretty much *everything* works except (forehead-slap) the AFM and the ICV.
So far I've confirmed: Spark is good; fuel pressure is good; each injector fires; no vacuum leaks discovered; DME Temp Sensor replaced; on and on.

I'm at my wit's end.

Anyone in Florida or SoCal want an otherwise great 924S? :-)

[75ohm]

No way in hell you should put that much heat on ANY pcb or surface mount component, let alone any layered PCB with IC's, but I digress; people do it and some times have success. Reflowing on a DME for surface mount -- I would not recommend it. I'd remove the solder on the bad joints and reflow it... I do a lot of solder work on electronics so this is not cumbersome for me... seriously though, too much heat with a heat gun... like using a sledge hammer for a thumbtack.

Regarding PS3 or any gaming station repairs, prevention is important -- ensure your heat dissipation components are functional (fans/sinks/copper/paste/thermal pads) and are unobstructed with dust/cat-hair/etc... my two cents worth.

[djnolan]

Here is a possibility: Vacuum leaks can make a car very sluggish when cold. Check the major lines to the ICV and the AOS, make sure there are no cracks, and they are clamped properly. Also check the throttle body and some of the other vacuum lines that connect there such as the brake booster and the small vacuum lines.

One way to be sure these are not the problem is to systematically go over every line for cracking problems. Check the routing and then the condition of the lines and make sure there are clamps where they are supposed to be and they are tight...

[MB968]

I was a bit concerned myself about putting too much heat into a weak component, or just one that doesn't like heat. How about using some clip on heat sinks at each component when soldering. These would be easy and would provide a bit of protection. I'm not familiar with the DME. Is it designed/manufactured in such a way that one could employ these?

[75ohm]

Also, reflowing is one thing, removing old solder and resoldering is recommended.

[djnolan]

I was always a little concerned when repairing cold solder joints. For one you can overheat the components or the board. I think a 15w iron is recommended. And there are a lot of joints on a DME and most of them don't need repair. I think there is a guide pointing out the most likely joints to go bad. Use a magnifying glass to help spot the bad joints...

[djnolan]

Read over post 22 for some excellent tips...

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