New method to dry out wet electronics ??

[leitmotif]

So this guy buys via E bay a Curtis controller for his electric vehicle. Apparently finds out it does not work. So he bakes it in a microwave (I think see pictures below).

I find it a bit strange that we go to lengths to avoid EMI, then there is the military with EMP bombs designed to fry circuitry,
and this guy sticks it in a microwave??

I also wonder what happens to the chips attached to the copper buss when it heats up??
What would you call the heat sink acting in reverse when the microwave heats it? WOuld it then be the heat faucet??

http://picasaweb.google.com/ekaftan/BakedCurtis

Dan Bentler

Took a second look maybe that is not a microwave after all.

 

[TConnolly]

Looks like a toaster over. The first picture shows a red glowing heating element at the top. Looks like he messed up his oven as well.


We have successfully used vacuum dessicators at 55C (131F) and about 25% atmosphere pressure to dry out electronic devices before, but a dessicator is something completely different.

 

[surferb]

Alaric's right - it's a toaster oven not a microwave.

I imagine chips being heated by a copper bus respond similarly to being heated by another means.

A "heat sink" is an object that absorbs and dissapates heat by thermal contact - so it's still a heat sink when acting in the "other direction". You could also refer to it as a heat source.

So this guy buys via E bay a Curtis controller for his electric vehicle. Apparently finds out it does not work. So he bakes it in a microwave (I think see pictures below).

I find it a bit strange that we go to lengths to avoid EMI, then there is the military with EMP bombs designed to fry circuitry,
and this guy sticks it in a microwave??

I also wonder what happens to the chips attached to the copper buss when it heats up??
What would you call the heat sink acting in reverse when the microwave heats it? WOuld it then be the heat faucet??

http://picasaweb.google.com/ekaftan/BakedCurtis

Dan Bentler

Took a second look maybe that is not a microwave after all.

 

[OkiePC]

Sidenote: Curtis DC drive for EV.

Curtis. Yep I think that was it.

Thanks, Dan. I have been trying to remmeber that brand name for years. I used one to control a maintenance cart we built in Lawton since the bean counters couldn't afford a real front-bed EZ-Go unit.

The one Harvey built was ten times stronger, about 300lbs heavier, but that little regen controller worked great even with big DC contactors for a failsafe reverse. I ended up having to wire a circuit at 24vdc to run those reversing contators, and the Curtis unit basically bolted to the battery cables, had a speed pot input (connected to our footpedal/brake lever) a keyswitch input, and that was about it. I had no instructions to work with either, just a wiring sheet, and had to experiment with the speed pot range. I seem to recall it was backwards from what I was used to, with higher resistance at low speed...probably to ensure an open speed input resulted in a stopped motor for safety.

The regen I believe, had an analog input, that I wired through the reversse action of the fwd/stop pedal. The forward action was a speed reference to the drive, the reverse action was a NO contact switching a pot to the regen input. The pot was an attempt to tune the right sized fixed resistor for maximum braking efficinecy.

I never got it to work repeatable on regen braking alone. Som I put a fixed input on it, and relied on the mechanical lever operated drum brakes for about 2/3 total braking.

Still, though, we could use that thing for three days running parts and a person around the plant on a pretty quick charging time.

Very cool little drive.
How's the EV project coming?

 

[RussB]

The problem with drying wet electronics is that it leaves all of the mineral deposits behind, (salt, etc) which is why you should flush and/or rinse with DI (distilled) H2O first.
This information is worth every penny that you paid for it.

 

[leitmotif]

The problem with drying wet electronics is that it leaves all of the mineral deposits behind, (salt, etc) which is why you should flush and/or rinse with DI (distilled) H2O first.
This information is worth every penny that you paid for it.

Way back when ships were of wood and manned by men of iron,
I was taught to use soap and water then water, then alcohol, then dry in warm area. Worked well then and works well now - salvaged a Fluke VOM this way after I dropped it in a laundry tray full of dirty soapy water.

It is too bad the microwave turned out to be a toaster oven - I thought it would be good for a smile. What the guy was apparently doing was heating to get the encapsulant out.

EV project still on drawing board - piggy bank just about full enough to finance. Have eyes on 47 Dodge pickup to convert but open to any other pickup style vehicle - any one have old tin around they want to get rid of say 1925 to 1955??. Might as well do something kind of "funky" and unique while I am at it. There is another glitch that has occurred - work is relocating - move will come about starting in Feb and continuing thru spring. Foresee lots of overtime in that time frame - all kinds of money but no time to do EV project.

Dan Bentler

 

[keithkyll]

I've seen many boards that were non-rairable after having standing water. Copper is green, lime everywhere, etc.

DI is De-Ionized water. Distilled is clean, but not deionized.
I prefer Isopropyl Alcohol (IPA). I use 99%. Available off the shelf at 91% (drug store), 70% (standard), and 50% (cheap stuff). The other part is distilled water.

You could use any of the 3. With DI or distilled, you need to blow dry afterwards. It's optional with 99% IPA because it dries fast.

 

[tomalbright]

I still use the oven method for drying out or cleaning. Here's my recipe.

WET ELECTRONICS RECOVERY METHOD

Prep by removing any batteries and LCD screens. Set aside.

If something other than water spilled on a board:

1. slightly soapy water to clean. Everything used applied by hobby brush or toothbrush. (wife's)

2. a water rinse, NOT under the faucet. Distilled if you got it. If you are in trouble for accidentally spilling something you shouldn't have been drinking on something you shouldn't have been using while the family is out of the house, use tap water. Hurry.

If just water:

3. pour isopropyl alcohol on board. Use brush to push it under everything possible

4. Oven. My favorite part. 125-ish degrees! NO MORE! Please make sure you are alone in the house, so someone doesn't see the low setting and "help" you preheat the oven by cranking it up.

5. When the alcohol is visibly dry, pop it in the oven. No. Visibly.

6. About 3 hours is good. At least by this time you've showed off your vast knowledge of electronics repair.

7. Reassemble what you took out earlier. Don't worry, you don't need ALL the little screws.

8. It works, great. It doesn't work, you didn't lose anything but time. Hopefully you can get to the store to buy a replacement before they close.

 

[TimothyMoulder]

Here's a little gem from the days of floppy disks, read it in a magazine years ago:

A reporter working on an article had it saved on a 5" floppy. While eating breakfast at his desk, he spilled grape jam all over his disk, including the exposed portion of the floppy.

Dismayed, he showed it to his boss, who assured him he could fix it. He took a razor, slit open the side of the disk casing and removed the mylar disk. He took it to the sink and washed with with plain hand soap and water - scrubbed it pretty hard too. No mention of DI water.

After it dried, he then slit open the case of a blank floppy, replaced the new disk with the original, and taped the edge shut again with scotch tape. Popped it in the computer and copied the contents to a fresh disk.

Amazing what we used to be able to get away with, huh?

TM

 

[allscott]

Here's a little gem from the days of floppy disks, read it in a magazine years ago:

A reporter working on an article had it saved on a 5" floppy. While eating breakfast at his desk, he spilled grape jam all over his disk, including the exposed portion of the floppy.

Dismayed, he showed it to his boss, who assured him he could fix it. He took a razor, slit open the side of the disk casing and removed the mylar disk. He took it to the sink and washed with with plain hand soap and water - scrubbed it pretty hard too. No mention of DI water.

After it dried, he then slit open the case of a blank floppy, replaced the new disk with the original, and taped the edge shut again with scotch tape. Popped it in the computer and copied the contents to a fresh disk.

Amazing what we used to be able to get away with, huh?

TM

Do you remember notching out the side of those same disks (opposite to the factory side notch) and turning them into double sided disks?

 

[TimothyMoulder]

Do you remember notching out the side of those same disks (opposite to the factory side notch) and turning them into double sided disks?

Mwahaha, absolutely. Used to do it for my Commodore floppy drive all the time.

Remember that Commodore-specific software protection scheme that would grind the bejeezus out of your floppy drive every time you tried to load the program? Used a different sector scheme, so it would ram the R/W head into the hard stop to change the calibration. "Afterburner" used it, couple of others too.

Lost popularity after people reported their drives were breaking.

TM

 

[BudW]

A 5" what?? Just kidding, I am old enough to remember punch tape.

After the manufacturing process of circuits in circuit boards we would run them through a dishwasher to remove the flux. The heat cycle of the dishwasher was enough to dry them back out quickly.

Long ago I watched as a old Tektronix scope was dipped into a vat that looked like water (may have been Freon bath) before Tektronix started re-calibration and repairs.

Bud

 

[leitmotif]

A 5" what?? Just kidding, I am old enough to remember punch tape.

After the manufacturing process of circuits in circuit boards we would run them through a dishwasher to remove the flux. The heat cycle of the dishwasher was enough to dry them back out quickly.

Long ago I watched as a old Tektronix scope was dipped into a vat that looked like water (may have been Freon bath) before Tektronix started re-calibration and repairs.

Bud

Gee you gotta be REALLY old.

Dan Bentler