SBMS0 White LCD Screen Issue

[u.s.a.1776...@gmail.com]

Hello, 
I purchased an SBMS 0 from here back in 2021 for use in my solar/battery RV project.
It has been functioning continuous and flawless ever since......until a few days ago.
Even though I don't use my RV continuously, I use the solar/batteries system frequently for different things when I'm home.
Every time I turn on the inverter, I always look at the SBMS 0 display which is close by.
A few days ago, the screen was white and none of the information is visible.
I unplugged the ribbon cable for a while hoping it might reset, but after plugging it back in the lcd screen was still white.
I reviewed several mentions in the forum about white screens on a sbms0.
I checked the #1 & 2 ribbon cable wire connection on the battery, and the terminal was tight.
I performed a continuity test on that battery terminal connector to the two female pins on the 12-pin plug and there was continuity.
I understand humidity is also a possible concern.
I live in the central Midwest of the U.S., and we've had several weeks of high humidity his summer, but nothing out of the
 ordinary for this part of the country that the sbms0 hasn't experienced the last 4 summers.
However, I took the sbms0 apart and cleaned each section with Isopropyl alcohol on a microfiber cloth used to clean eyeglasses.
I used a hair dryer on the low setting to blow on both sides of the section with the lcd screen for 1-2 minutes.
I put the sbms0 back together again and plugged in only the 12-pin ribbon cable.
The lcd screen was still white with no information displaying.
Any suggestions and guidance anyone can provide will be greatly appreciated.
Thanks, Greg

[Dacian Todea (electrodacus)]

Greg,

Wish you took a few photos while SBMS0 was disassembled as maybe I could see what the issue was.

If there is high humidity it could be that corrosion could have corroded one of the PCB traces or soldered connection maybe at the micro controller or LCD.

The micro-controller communicates over SPI with the LCD so about 4 wires + power and backlight. If any of those 4 wires is disconnected for any reason (maybe corrosion) then LCD could just be white.

Of course if micro controller is damaged or LCD there will be the same symptom but since it worked and whit you not making any changes it just failed corrosion is the most likely possibility.

 If you have a multimeter set it on continuity and you can find if all those connections between LCD and micro controller are intact or maybe they damage is visible and that will be even faster to find.

If you used 70% or higher concentration isopropyl alcohol there was no need for the hair dryer just left in a dry place for an hour or two will have been sufficient.

[u.s.a.1776...@gmail.com]

Hello Dacian,
It appeared my 70-year-old eyes detected some corrosion on most if not all of the 12 pins on the sbms0, so I did my best to clean them, and I used an acetylene gas welding tip cleaner to try and clean the ribbon plug too.
However, that didn't rectify the issue.
Attached are several pictures for review.
Thanks, Greg

p.s.  Initial email with all photos was too large so I attached more photos in a second message.

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[Dacian Todea (electrodacus)]

Thanks for the photos Greg.

I do not see much corrosion. Maybe photos are done after you cleaned the 12 pin connector but the pins look totally fine in the photo.

The only two places I see some corrosion is close to the 16pin green connector the long trace that supplies the current shunt amplifiers and the two associated vias and maybe a bit at some of the pull up resistors near ISL94203.

But none of this will affect the LCD.

Maybe somehow the Battery+ was disconnected under load and that resulted in a damaged microcontroller. But normally a damaged microcontroller means shorted internally so the LCD will be black not illuminated white.

So I still think some microccontroller pin is disconnected maybe due to corrosion or something happened to the LCD. Where the Load and Charging enabled when you found the White LCD ? Because if so it means the microcontroller still works and controls the EXT IOx and so is just a issue with sending the display data to LCD.

 

Normally I will offer you free repair if you sent it to me but since this Monday I'm no longer able to ship to the US

Maybe there is some water still under the microcontroller or LCD due to cleaning with isopropyl  so it will help to have it opened in a dry place for 24h. A close up photo around the microcontroller to see better the pins maybe at an angle could help see if there is a problem especially the row of pins on the right side in the photo (pins 25 to 36). Pin 30 looks a bit suspicious from this angle but could just the the lighting. 

[u.s.a.1776...@gmail.com]

Hello Dacian,

Thank you for your quick response, especially since it was so late last Thursday evening.
After your response I took the SBMS0 apart and left it sit on a table inside my house until this morning (from Friday midnight until Saturday 10 AM CT).
I put it back together and plugged in the ribbon cable but the  LCD screen was still white.

Below are your questions from last Thursday evenings response along with my answers.

You said:
Maybe somehow the Battery+ was disconnected under load and that resulted in a damaged microcontroller. But normally a damaged microcontroller means shorted internally so the LCD will be black not illuminated white.

My answer:
I wasn't working on anything or messing with anything regarding the RV solar setup or with anything regarding the RV at all. I haven't touched the SBMS0
 for several years other than to activate the LCD screen info.
At the time I noticed the white screen issue, I have a table top water distiller that I run off the RV's solar/batteries. I had it plugged in and turned on, and then I turned on the inverter in the solar electrical cabinet. By habit, I always look at the SBMS0 screen after I power on the inverter. It was at that time I discovered the LCD screen was white.

========================================

Your said:
So I still think some microcontroller pin is disconnected maybe due to corrosion or something happened to the LCD. Where the Load and Charging enabled when you found the White LCD ? Because if so it means the microcontroller still works and controls the EXT IOx and so is just a issue with sending the display data to LCD.

My answer:
It was as sunny morning around 10 AM CT, and the solar charge controller was on ready to charge the batteries when needed. Usually, the SOC is either at 99% or 100%.
Usually and almost always the SOC is at 99%, and I expect it was at 99% SOC at that time and wasn't accepting a charge immediately when I turned on the inverter.

=======================================

You said:
Maybe there is some water still under the microcontroller or LCD due to cleaning with isopropyl  so it will help to have it opened in a dry place for 24h. A close up photo around the microcontroller to see better the pins maybe at an angle could help see if there is a problem especially the row of pins on the right side in the photo (pins 25 to 36). Pin 30 looks a bit suspicious from this angle but could just the lighting.

My answer:
After I received your response late last Thursday,  I took the SBMS0 apart and separated the sections and left them on a table in my house until today Saturday morning. This morning  I put the SBMS0 back together and plugged in the 12 pin ribbon cable, but unfortunately the LCD screen was still white with
 what appears to be a few splotches.
======================================

I provided a few new pictures.
Unless you have some additional thoughts and ideas, I'm guessing it is in need of repair.

Thanks,
Greg

[u.s.a.1776...@gmail.com]

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[u.s.a.1776...@gmail.com]

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[Dacian Todea (electrodacus)]

Based on what you say the inverter was still working while SBMS0 LCD was white. If inverter was controlled by the SBMS0 EXT IO3 it means that microcontroller and all the rest of the electronics still works.

In that case the problem is either one of the 4 pins from the microcontroller that connect to LCD or the LCD itself so repair should be as simple as reheating the microcontroller pins or worst case replace the LCD.

I think you are in US and unfortunately since a few day's ago I'm no longer able to ship to US else I will offer to repair it for you.

Maybe there is a way for you to print a USPS shipping label electronically and send that to me to print and put on the shipping box after I make the repair.

Canada Post will no longer allow me to print shipping labels that go to USA unless I make an account with some private US company named Zonos. 

Below I highlighted the 4 pins that control the LCD. If they are OK (they look OK in the photo but is hard to say maybe the one in the middle of that group of 3) then LCD solder or LCD itself failed for some reason.