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Sherlock Ohms

Flawed Connections Need Careful Examining

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Beth Stackpole
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Repair people need similar training
Beth Stackpole   2/23/2012 7:51:15 AM
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Ken, I could totally use your attention to detail right now. I have a front loader that is experiencing difficulty powering up after having to break the latch to get the clothing out (don't ask). Parts have been replaced and the repair man has been out multiple times with half-baked suggestions and solutions. No one is looking closely at connections or doing any kind of hard-core engineering troubleshooting or soldering work. I wish repair men were trained more along the lines of your approach. If they were, perhaps we could move beyond our "throw-away" society that has people like me already contemplating the pain of having to replace what is a relatively new washer.

BrusselsSprout
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Gold
Re: Repair people need similar training
BrusselsSprout   2/23/2012 9:20:04 AM
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Beth, the relay with the bad solder joints I repaired controlled the front door latch.  I think the symptoms you describe are very close to the symptoms we experienced.

I don't need to ask about breaking the front door latch, I was nearly driven to that circumstance myself.

One good thing about this washer design is the system controller is easy to get at.    Since the controls are on the front panel the top has no electrical components attached.  Just a few screws are required to remove the top and the system controller is right there.

 

Wildbush
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Silver
Re: Repair people need similar training
Wildbush   2/24/2012 11:30:03 AM
We had the same problem with the front loading door latch many years ago when we wanted to add softener to the final rinse. We could stop the washer with the timer b y pulling out on the knob, but the door remained locked. The simple fix was to unplug the unit.  The door then opened easily. I rewired the power outlet by replacing the two-outlet box with a four-outlet box, in which I installed two outlets and a switch for the washer outlet. (The gas dryer plugged into the other outlet.) When it was time for the softener addition, we pulled the timer switch, threw the wall switch, opened the door, added the cap of softener and retuirned the washer to normal operation with the door shut and power on.

The new (last year) washer has a softener dispenser.  I finally lost the battle to my wife, who complains, "When you are married to a man who fixes things, you never get anything new".

dox
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Silver
Same Issue with Fridge and Flashlight
dox   2/24/2012 12:30:21 PM
I had a similar problem with the ice dispenser in my high-end fridge.  It would run intermittently, at best.  After removing the assembly and examining how the drive motor was soldered to the control board it appeared that they only bothered to solder two of the four tabs to the board, probably just to provide mechanical support.  The other two leads were unsoldered and were a poor press-fit.  Adding another few grams of solder corrected the problem.

I also bought a wind-up LED flashlight that had three LEDs.  After a few weeks only one LED remained operational.  In this case all three LEDs were simply press-fit into the board - square pins in round holes.  Six drops of solder and it's still working years later.

How much of this stuff ends up in landfills due to poor engineering decisions and/or manufacturing processes?

"Ken Lillemo has worked... in a low-pressure lab."
I wish more employers would provide their employees with a "low-pressure" work environment!


BrusselsSprout
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Gold
Re: Same Issue with Fridge and Flashlight
BrusselsSprout   2/24/2012 3:54:19 PM
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Nice comment on our "low pressure" work environment.  Yes, I could have said "Vacuum Lab" as that is how the sign outside the door reads.  But, this being a high brow engineering publication, the invetable discussion would start about there being no such thing as a vacuum.

We do have a whole series of jokes around the office poking fun at our work.  Most are along the lines of:

"This job sucks" and
"If at the end of the day I have absolutely nothing to show for my work, I have done a good job."

ksaldutti
User Rank
Silver
Launch Pad Connectors
ksaldutti   2/26/2012 1:08:25 PM
We are on an ocean literality just a few hundred yards away and we are also if that is not hostel enough we deal with rocket launches that exhaust spent solid rocket fuel that is highly corrosive. We have hundreds of connectors at theses launch pads for photo systems that are essential for engineering data. What is a technician to do to keep these system going? Well we have constant quality control meetings on improving our systems that very much have to do with electrical and data signal connections. We have worked with connection manufactures and suppliers for recommendation and field trails of many types and technologies of connections. Chemicals to protect connection pins. Cleaners and sealers for maintenance of connections. We even are trying transportation sealed connectors used under vehicle hoods that are out in the elements and deal with extreme heat, cold and of course liquid and chemical infusion. So we are always visibly looking at our connections as a practice and we take it very seriously that every system element works all the time. We understand that physical inspections can not be substituted.

BrusselsSprout
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Gold
Re: Launch Pad Connectors
BrusselsSprout   2/28/2012 9:42:19 AM
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Your tale reminds me what else I did.  After I re-tinned the card edge connectors I cleaned them with a contact cleaner that, besides removing oxide, leaves a little mineral oil on the surface to reduce contact oxidation.


OLD_CURMUDGEON
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Platinum
BLAMING SOMEONE ....
OLD_CURMUDGEON   2/27/2012 8:19:39 AM
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IF you want to "blame" someone for this short-sighted engineering, blame MOTOROLA!  For those of you old enough to remember, MOTOROLA made a big advertising campaign out of their newly designed & configured TV sets & other home entertainment products with the "WORKS in a DRAWER" concept in the late 1950s & 1960s.  They incorporated all of the low level circuits onto printed circuit boards.  That was a distinct departure from the hand-wired sets of the era. 

They advertised that IF a module went bad, the serviceman could come and easily replace the entire module, and you'd be back in businees in no time flat.  It was meant as a counter to the common policy that service people would remove your TV or other component to repair it at the "shop".  It was cast as a money-saving idea.  From there, the floodgates literally opened, since many other companies adopted similar design guidelines, so that EVERYTHING one buys today has become a modular "throw away".

 

Ann R. Thryft
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Blogger
Early attempts at RoHS compliance?
Ann R. Thryft   2/29/2012 1:25:25 PM
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Ken, I'd like to know more about what you mean by the poor solder joints being due to early attempts at RoHS compliance. I can guess--some years ago I wrote in some detail about the problems associated with solder replacements to meet RoHS requirements. Can you elaborate a bit?


BrusselsSprout
User Rank
Gold
Re: Early attempts at RoHS compliance?
BrusselsSprout   3/1/2012 5:47:41 PM
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Sure Ann, I should state first off, I am only talking about an impression. I have not looked at the date of manufacture to accurately place the timeline with general RoHS compliance or to look for any detailed marking on the PWB. I think the module is at least 5 or 6 years old.

I confess I have more 37/63 Pb/Sn solder in various gauges than I will be able to consume in my lifetime. The only nod to lead replacement I have made in my personal life is to replace all the water pipes in our home and use Sb/Sn. Having a ready supply of "the Good Stuff" I repaired the fractured solder joints and retinned all the card edge connections with Pb/Sn.

I am afraid I only have anecdotal evidence and suspicions to cast aspersions on early RoHS compliance failures.. However, overall the solder job on this board I would rank as terrible, even by my amateur standards.

Ann R. Thryft
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Blogger
Re: Early attempts at RoHS compliance?
Ann R. Thryft   3/2/2012 11:54:49 AM
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Thanks for the reply. You may well be right. RoHS compliance in electronics is just about 5 or 6 years old now. I began writing about it a couple of years before that. The problems in finding solder replacements that were good enough and didn't require cooking the board at much higher temperatures than tin/lead--thus melting other materials or at least shortening their lifespans, as well as all kinds of differential CTE problems--were legendary. Re the health issues, I'm grateful we don't have lead water pipes out here. One of these days I'll be able to replace all our galvanized steel plumbing with copper.


Rob Spiegel
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Blogger
Re: Early attempts at RoHS compliance?
Rob Spiegel   3/2/2012 3:57:29 PM
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I didn't realize you covered RoHS, Ann. I did too. For a couple years before and after the RoHS deadline, I ran a Lead-Free Zone mini-website here at Design News. It was a hot site until the RoHS deadline came and went, at which point I shifted to covering REACH and all the different flavors of RoHS (China, Korea, California). Now it seems to be a fairly quiet subject.




Ann R. Thryft
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Blogger
Re: Early attempts at RoHS compliance?
Ann R. Thryft   3/6/2012 1:02:58 PM
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My RoHS coverage was focused on what was happening on the PCB and how replacing various materials, most obviously lead solder materials, had various effects on production and performance. That coverage slowed down, as apparently yours did, when the problems started getting solved.


Rob Spiegel
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Blogger
Re: Early attempts at RoHS compliance?
Rob Spiegel   3/6/2012 1:23:32 PM
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I know there are still those out there who says the problem hasn't been solved. At this ploint, that doesn't seem to be a widely held position. Even so, when electronics fail, there is a number of people who yell, "Tin Whiskers." That voice rose up when Toyota was having its accelerator problems.

Larry M
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Platinum
Re: Early attempts at RoHS compliance?
Larry M   3/6/2012 4:15:20 PM
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Rob,

Whether or not you choose to deny it, the tin whiskers problem is real, as are the problems with brittle joints and components stressed by overheating during assembly. Many of the complaints we hear about and read in Design News relating to poor American design or Chinese manufacturing and the short life of electronics including appliances, cameras, cellphones, computers, and MP3 players are due to problems with solder.

I've repaired my son's dryer (brittle solder joints between the relay pins and the circuit board) and the remote control for my DVR (probably tin whiskers, as the problem was resolved by brushing the closely-spaced leads of all surface-mount components with a fine brass "toothbrush." Probably a half-dozen other such repairs too.

Rob Spiegel
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Blogger
Re: Early attempts at RoHS compliance?
Rob Spiegel   3/7/2012 2:37:38 PM
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Larry, you very well may be right. Yet I would think the problem would be even more widespread, enough for component manufacturers and brand owners to raise a stink about it. Yet none of them are saying much that I can see. The electronics industry seems pretty blasé about the subject these days.

 

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