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Author Topic:   Fluke Repair
jimh posted 07-14-2006 07:54 AM ET (US)   Profile for jimh   Send Email to jimh  
When on extended cruising, I usually carry a digital multi-meter onboard to use in any electrical trouble-shooting. Since my boat is a Boston Whaler, it seems appropriate to use a FLUKE meter.

Last summer in Wisconsin we went to sleep one evening and had about 3-inches of rain fall overnight. It just rained buckets for hours. When I awoke I realized that the FLUKE meter was sitting down in the live well at the stern of the cockpit. I began to be concerned about how much water was in the live well from all the rain; a lot of rain water in the cockpit could have drained into the live well. I pulled the hatch off the live well--the water was right at the deck level! The live well was full to the brim, and everything in it was immersed or trying to float against the hatch cover.

I fished out the Fluke meter. It was quite wet. I opened the plastic case and removed the battery. I shook and blew most of the water out of the circuit board and gave it a spray with WD-40. When the sun came out, I let the circuit board dry in the sun. There was some corrosion at the battery terminals, but otherwise the board looked good. I scrubbed off the corrosion with a toothbrush and more WD-40. When the circuit board had thoroughly dried, I put a new 9-volt battery in place, re-assembled the meter, and crossed my fingers. To my relief, the meter came back to life and seemed to work normally. It was a tribute to good quality and the gentle effects of pure rainwater.

However, when I went to use the meter this spring, I was disappointed to find it had some residual problems, probably due to the immersion last summer. The intensity of the LCD display was erratic, and it was becoming hard to tell if a segment of a display digit was supposed to be on or off. There is nothing more annoying than trying to diagnose electrical problems with intermittent test equipment, so I was upset with the Fluke meter's condition. It worked, but it would no longer be a pleasure to use it.

I called Fluke to see about repair or replacement and warranty. Not much coverage for this particular product and age. (They now have lifetime warranty on many instruments, but exclude water damage.) A new meter was going to be expensive. I was in a funk.

Last Saturday I decided to take another look at the Fluke. I disassembled it again. The circuit board looked good, and there were no signs of any corrosion. The only component left to disassemble was the LCD display itself. I removed the four screws holding the display to the circuit board. I was very surprised by the connections between the display and the board. They looked like little pads of felt. They must be some type of flexible conductor. I had not seen this type of connector technology before.

At this point I figured I did not have too much to lose with the meter, so I gave the circuit board pads and lands in the area where the LCD mounts a good spray with WD-40. I also wiped down the LCD display connector with some WD-40. I blew everything dry, and set it in the sun to dry off. About an hour later I reassembled the meter.

To my surprise, the LCD display returned to normal function! The meter was cured. I am probably not the first guy whose digital multi-meter got a bit damp on their boat, so I thought it might be useful to mention the WD-40 repair therapy. In the event you get some moisture into your electronics, WD-40 is a good way to remove it.

Also, I bought two PLANO gasketed tackle boxes for holding all the stuff that I keep in the live well. And I installed an automatic pump to keep it dry in situations like the night-long rain I described above.

JayR posted 07-14-2006 09:33 AM ET (US)     Profile for JayR  Send Email to JayR     
While in the Air Force, I was trained to repair electronics that had been immersed in water. First course of action was dropping the item or circuit board into a bucket of WD-40.

Always worked like a charm.

WD-40 was developed as a water displacement for just this purpose.

JayR posted 07-14-2006 09:37 AM ET (US)     Profile for JayR  Send Email to JayR     
Interesting history http://www.wd40.com/AboutUs/our_history.html
Whaler_bob posted 07-14-2006 09:54 AM ET (US)     Profile for Whaler_bob    
quote:
I was very surprised by the connections between the display and the board. They looked like little pads of felt. They must be some type of flexible conductor. I had not seen this type of connector technology before.... jimh

Unfortunately, this type of flex conductor is used extensively for the LCD displays on cell phones, pagers, and PDA's now. It's a fair electrical contact at best. If the wrong compound was used in it's construction- it becomes very sensitive to heat and cold due to shrinkage or expansion. It also has no tolerance for moisture. If you have one of these products that employs this technology and the display has a missing segment, twist the unit slightly and you may see the "dead" segment come back to life temporarily. It's use helps keep down manufacturing coasts by speeding component placement and it's solder-less. Nokia had major problems with this technology several years ago with a very popular series of cell phones. Many-many phones got repaired/replaced under warranty due to a bad polymer mix in the flex conductor.

Jerry Townsend posted 07-14-2006 12:39 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Jimh - good information - thanks. But - I hope that I never have to use your information. I have bought a 'gob' of Fluke test equipment over some 50 years before I retired - and never had the problem you mentioned - but then, never had a technician or engineer leave one in a live-well on a Whaler. Darn - I wish that I had been in the environment of being around Whalers.

Whaler_bob - good information regarding the flexible contacts - thanks. I suspect that Fluke is using the best materials and components available as, frankly, their decisions are based solely on quality and performance. --- Jerry/Idaho

Whaler_bob posted 07-14-2006 01:15 PM ET (US)     Profile for Whaler_bob    
Fluke may not have a choice with their LCD's.
The LCD's are all made in Korea or china now. Fluke and everybody else just buys what is offered by the LCD factories. Unless they want to pay for a custom run, there may no loger be a stock LCD made that has the old ribbon cable connectors or solder pins used in the past. Even if there was an old style LCD available, it's probably too expensive and time consuming to employ. I imagine Flukes decision to use this technology was $$ motivated too.
It's a shame, even high quality test equipment is not "servicable" any more.
where2 posted 07-16-2006 11:49 PM ET (US)     Profile for where2  Send Email to where2     
Being an electronics geek, I've disassembled more stuff that didn't work, than you may ever imagine. (you learn a bunch when you disassemble something. If it wasn't working when you started, what do you have to lose?) I think I first encountered that little flexible conductor strip back in the mid '80s when I disassembled an LCD calculator or a broken Casio watch. It's good stuff when it works right, and apparently a nightmare when it is formulated wrong.

Good luck with the Fluke, I've always aspired to own one, but never outgrown my fear of damaging such an expensive tool. (ironically, I have to twist my Radio Shack DVM to get it to work after 15 years. I've had to do this for the last 8 years or so. I just do it reflexively now, or I look for the Harbor Freight cheapo unit.) The Harbor Freight unit typically travels in the boat tool box. For under $10, it can diagnose whether I have 8v or 13v on a particular terminal.

davej14 posted 07-18-2006 08:29 AM ET (US)     Profile for davej14  Send Email to davej14     
The connector type you are referring to is called an "elastomeric" connector. It has been around for a long time and is very reliable if it is properly designed. The strips are alternating layers of conductive material and dielectric material. The thickness of the "layers" and their material composition is variable. The conductors are typically loaded with carbon for low cost but for higher reliability and severe environments they could be precious metals. You can guess what is probably in the Fluke meter.

The spacing of the conductive layers should be designed to make sure that redundant conductor paths are present between the correct PCB pad and the ITO coating on the glass without the possibility of shorting to an adjacent pad. The pressure of the elastomeric between the PCB and the glass is very critical to achieve a gas tight connection. You can imagine all the tolerances and environmental conditions which must be carefully considered to get this right. Unfortunately many of the designers using this material either do not take the time or are not up to the task. Here is one source that has technical information about this type of connector:

http://www.zaxisconnector.com/index.htm


LCD's present problems in manufacturing because they are fragile and do not tolerate the temperature extremes of a typical PCB assembly process. This means that they are typically assembled after the other components are soldered to the PCB. Some type of interface is required and an elastomeric connector is one of the better choices. It it not the least costly solution. Other options are PC pins, heat seal and edge mount connectors. These alternative methods also have reliability issues.

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