I like our modern front-load washer for many reasons. For one thing, the gentle action and large capacity means our camping gear, from tents to sleeping bags, will not get a lot of extra wear and tear in the laundry. I also like the warp-speed spin action, as it means things we dry in the dryer take less energy, and the things we dry on the clothes line dry quickly. All this comes with a cost in that an electronics module is required for motor speed control in lieu of the old-school mechanical timer.
I had a nagging problem with bad connections that I thought was due to fretting on the connectors (fretting is an oxide buildup due to vibration of a connection). The Internet was more than helpful in identifying the fretting issue specific to this washer, and I spent a good deal of time plugging and unplugging card edge connectors every few days to resolve the problem.
It was not until I took the top off and I had the door relay kick on that I noticed a curious flash near the circuit board. I then discovered a telltale spray of oxide and soot on the inside of the plastic housing underneath the circuit board where the relay resides. It was clear once I removed the circuit board that poor solder joints for the relay had finally gone from intermittent to hard failure. The connector tabs were outlined with a dark fracture in the solder joint.
I suspect the poor solder joints stem from early attempts at RoHS compliance. With a little work with a soldering iron, I repaired the connections for good, or at least the last two years. I can accept that, in lieu of the twice-a-week disassembly and jiggling connectors, with mixed success. While I was there, I retinned the card edge connectors to address fretting issues, just in case.
The lesson learned in this case is that there is still an amazing amount of electronics problems that can be identified by careful visual examination, with no test equipment required.
I still love front-load washers for their economy and performance, and now I have one that performs as it should.
This entry was submitted by Ken Lillemo and edited by Rob Spiegel.
Ken Lillemo has worked for the last 26 years as a process engineer in a low-pressure lab.
Tell us your experience in solving a knotty engineering problem. Send stories to Rob Spiegel for Sherlock Ohms.
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.
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.
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.
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.
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.
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.
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.
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?
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.
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".
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