[RE-wrenches] Mouse pee in the SW

Exeltech exeltech at yahoo.com
Fri Aug 16 12:46:07 PDT 2013 

William,

Sounds like the coating on the board wasn't of the best quality.  It reacted with the alcohol (which good conformal coatings won't), but has since dried, and should be OK.  (The better silicone-based conformal coatings react only with acetone, and then very slowly at that.)

Visual appearances aside, as you mentioned .. the circuit board works.  Congrats.  The powdery appearance won't affect the circuit board or components.  However, this is one time where, if after a period of a couple of weeks or so, the circuit board continues to work properly and remains glitch-free, I might suggest purchasing a can of a quality conformal coating and carefully going back over the board (front and back) with a couple of thin layers.

On the other hand .. if it ain't broke....

Dan

--------------------------------------------
On Fri, 8/16/13, William <william at millersolar.com> wrote:

 Subject: Re: [RE-wrenches] Mouse pee in the SW
 To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
 Date: Friday, August 16, 2013, 1:48 PM
 
 Friends:
 
 So I tried the experiment below. The board looked pristine
 when I set it out in the sun to dry but one hour later it
 looks terrible!  It is covered top and bottom by a
 white, powdery residue.  I'll get a photo up on my
 website. 
 
 But......  It works!!!!  The inverter is cobbled
 together on my tailgate quietly humming. Granted this
 problem has been intermittent all along so I am still
 skeptical. 
 
 If I were to do it again I'd skip the alcohol and dry it
 slowly and carefully. It is amazing how resilient
 electronics can be. I even laundered my Bluetooth. 
 
 I will let you know after I install it if it stop works. 
 
 William
 
 On Aug 15, 2013, at 4:33 PM, Exeltech <exeltech at yahoo.com>
 wrote:
 
 > William,
 > 
 > Urine is conductive, and apparently has formed some
 unwanted electrical pathways between components.  This
 conductivity could easily continue after the board has
 "dried" due to humidity in the air.
 > 
 > If the need is dire, you can try the following:
 > 
 > You will need two 9" x 12" ceramic ("Pyrex" etc.) cake
 pans (or of a size appropriate for the PCB); a gallon of
 *steam distilled* water (not de-ionized, not "purified", but
 >steam distilled<); and some 91% rubbing alcohol (the
 70% variety has too much water content):
 > 
 > 1) Remove the contaminated PC boards from the
 inverter.
 > 
 > 2) If there are no water-sensitive components (where
 water ingress would be problematic), wash (agitate) the
 board gently in a ceramic pan filled with approx 1/2" to 1"
 of *steam distilled* water.  Nothing less.  Water
 depth should be adequate to submerge and cover the affected
 area.   Do this for approximately 10
 minutes.  The objective is to dissolve the
 contaminants.  This can take time, especially if in
 tight areas between components where water doesn't readily
 circulate.
 > 
 > 3) Remove the PCB from the distilled water.
 > 
 > 4) Gently rinse the PCB in another ceramic pan filled
 with sufficient alcohol to at least partially cover the PCB
 components.  The objective here is to displace the
 distilled water.
 > 
 > 5) Put the PCB in a *LIGHTLY* warm oven or a sunny warm
 location.  Allow the alcohol to completely
 evaporate.  This may take time (an hour or more), as
 the alcohol may have entered various tight areas on the PCB
 where air doesn't readily penetrate.
 > 
 > 6) Once dry, reinstall the PCB in the inverter .. and
 hope.
 > 
 > Follow normal precautions for work with AC power and
 for static electricity abatement.  Be wary of any large
 high-voltage capacitors that may have retained some charge.
 > 
 > Also .. more than one PCB may be affected.
 > 
 > 
 > And as always .. do so at your own risk.
 > 
 > Dan Lepinski
 > Industry Veteran
 > 
 > --------------------------------------------
 > On Thu, 8/15/13, Allan Sindelar <allan at positiveenergysolar.com>
 wrote:
 > 
 > Subject: Re: [RE-wrenches] Mouse pee in the SW
 > To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
 > Date: Thursday, August 15, 2013, 5:39 PM
 > 
 > 
 > William,
 > 
 > I don't have a definitive answer, but I doubt it's
 either display or chipset; more likely in the boards. The
 chips are EEPROMs that contain programming for the firmware;
 unless there's a bad socket connection from the pee, they
 won't be affected. The display is pretty much self-contained
 within its plastic case, and not where the corrosive pee is
 likely to end up. I'd more suspect circuit board troubles,
 but I can't tell you which ones.
 > 
 > Allan
 > 
 > Allan Sindelar
 > Allan at positiveenergysolar.com
 > NABCEP Certified PV Installation Professional 
 > NABCEP Certified Technical Sales Professional
 > New Mexico EE98J Journeyman Electrician
 > Founder and Chief Technology Officer
 > Positive Energy, Inc., a Certified B CorporationTM
 > 3209 Richards Lane
 > Santa Fe, New Mexico 87507
 > 505 424-1112 office 780-2738 cell
 > www.positiveenergysolar.com 
 > 
 > 
 > 
 > 
 > 
 > On 8/15/2013 3:36 PM, William Miller wrote:
 > 
 > Friends:
 > 
 > I had a mouse take up residency in an SW inverter
 (SW4024).
 > 
 > It peed on the top circuit board and chewed on one
 wire, at least that we found.  We have had this happen
 before and solved the problem by cleaning and drying. 
 > 
 > 
 > This time the mouse pee was minimal and cleaned off
 easily and what appeared to be throughly.  However we
 can't get the inverter to work reliably.  Sometimes it
 works and sometimes it does not.  The overload light is
 solid and the error light flashes.  The controls work
 on some menus and not on others.  If I shut the
 inverter down it won't come back on. 
 > 
 > I take off the cover, look around, connect and
 disconnect ribon cables and it comes back on, only to go out
 a day later.        
 > 
 > I have a spare display and chipset.  I am
 considering changing out one then the other.
 > 
 > Any adivce would be appreciated.
 > 
 > As always, I am very grateful to all of you.  It
 seems I have been receiving more advice than I have been
 giving lately so I look forwards to the opportuntiy to
 reciprocate.
 > 
 > Sincerely,
 > 
 > William Miller
 > 
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