[RE-wrenches] Mouse pee in the SW

[Exeltech]

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