EasyIO or EasyI…uh Oh?
Posted: Fri Mar 19, 2021 12:58 am
Part 1 – First sniff
After hearing about inputs failing on the EasyIO FG-32 as a common fault, I decided to take a peek for myself. Thanks to a member in the community, I secured a used unit with several bad inputs for a reasonable price. Got the unit a week later and cracking it open, the first fault was staring at me. One of the supercapacitors had leaked over a PCB.
This is a common failure mode for electrolytic capacitors. Heat is the enemy of electrolytic capacitors. Long life high temp capacitors can be had, but at an added expense. When they fail this way, they lose all their capacitance and spill electrolyte on the PCB. The electrolyte is corrosive and has little issue eating thru the solder mask and any metal it contacts given enough time. The FG-32 has a conformal coating on it which is an added layer of protection. Also didn’t help here.
It should be noted that this device was manufactured late in 2014 judging by the date codes. Its common for ICs and PCBs to have a 4-digit date code on them that is formed from two digits for the week of the year and last two digits of the year. These date codes are just that. The date the IC / PCB was manufactured. An OEM could purchase many key parts and used them over serval years or a run of a common PCB that is used over a long period of time. Not a perfect measure of Inservice use, but with JIT manufacturing all the rage these are a good indicator of device age.
This unit had ICs and PCB dates all around 44th week of 2014. The person I purchased this from also confirmed it was installed in 2015. Likely installed early 2015 and early 2021 in my hands with 5 dead inputs. Six years to the point so many inputs failed it was replaced in this case. They also indicated the first few inputs became a problem a year earlier.
Diving deeper into the FG-32…
Removing the first supercap, cleaning and getting a clear look at the damaged.
Inputs 1-4 have traces that run under the large supercap that blead out. Two had failed with a third taking on damage. A larger trace next to these seems to supply power to the op-amps buffering the signal to the final ADC that reads the inputs. If that fails, it could cause failure of all the inputs in one shot.
Reading the datasheet and the serial console, this supercap is the one responsible for its orderly shutdown on power loss. Once this fails, that goes out the window. After replacing this cap and looking at the console during shutdown it appears to check the supercap health and if that passes copies a RAM disk to flash. Failure of this cap may lead to firmware / filesystem corruption or loss of data. The real time clock also uses supercaps to keep the clock running during power loss, so that may be lost as well. Would like to hear if anyone has had any issues with this. Also wonder if this supercap test was in the original firmware or added after complaints piled up.
Each input has a TVS diode across it which is the main protection on the inputs. If polarity is reversed it will cap reverse voltage downstream to ~-0.65v. In the correct polarity, it will start shorting at ~12v.
Reversed input schematic, all inputs are identical.
Looking around the PCB for test points, found a Linux console port near the SD card. Looks like instant root access into the device. Interface is 3.3v @ 115,200 baud. Sample boot up output.
Looks like this device also has a populated JTAG header near the super capacitors.
In the process of getting CPT and loading a small I/O test program, of course one must run a quick port scan. Besides what the documentation (EasyIO FG Series FAQ v1.3) lists as ports/services running, it also has telnet. This also seems to drop you into a shell. Not sure yet if this can be disabled or at minimum the user/pw changed from default. Seems like a train wreck to have telnet enabled, default creds and undocumented.
Kind of a scatter shot first look but that’s how things goes. Looks like poor quality supercaps from HCCCap are the first issue. Basic cybers smells as well. Next steps will be looking closer at the input protection, poking more at its cybers and whatever else crops up along the way. If someone has another failed unit or anything else in the EasyIO line that has failed, I may be interested in purchasing it. PM me.
After hearing about inputs failing on the EasyIO FG-32 as a common fault, I decided to take a peek for myself. Thanks to a member in the community, I secured a used unit with several bad inputs for a reasonable price. Got the unit a week later and cracking it open, the first fault was staring at me. One of the supercapacitors had leaked over a PCB.
- RIP SC.jpg (452.33 KiB) Viewed 99635 times
It should be noted that this device was manufactured late in 2014 judging by the date codes. Its common for ICs and PCBs to have a 4-digit date code on them that is formed from two digits for the week of the year and last two digits of the year. These date codes are just that. The date the IC / PCB was manufactured. An OEM could purchase many key parts and used them over serval years or a run of a common PCB that is used over a long period of time. Not a perfect measure of Inservice use, but with JIT manufacturing all the rage these are a good indicator of device age.
This unit had ICs and PCB dates all around 44th week of 2014. The person I purchased this from also confirmed it was installed in 2015. Likely installed early 2015 and early 2021 in my hands with 5 dead inputs. Six years to the point so many inputs failed it was replaced in this case. They also indicated the first few inputs became a problem a year earlier.
Diving deeper into the FG-32…
Removing the first supercap, cleaning and getting a clear look at the damaged.
- Broken traces under C18.jpg (465.77 KiB) Viewed 99635 times
Reading the datasheet and the serial console, this supercap is the one responsible for its orderly shutdown on power loss. Once this fails, that goes out the window. After replacing this cap and looking at the console during shutdown it appears to check the supercap health and if that passes copies a RAM disk to flash. Failure of this cap may lead to firmware / filesystem corruption or loss of data. The real time clock also uses supercaps to keep the clock running during power loss, so that may be lost as well. Would like to hear if anyone has had any issues with this. Also wonder if this supercap test was in the original firmware or added after complaints piled up.
Each input has a TVS diode across it which is the main protection on the inputs. If polarity is reversed it will cap reverse voltage downstream to ~-0.65v. In the correct polarity, it will start shorting at ~12v.
Reversed input schematic, all inputs are identical.
- Input Circuit.png (18.29 KiB) Viewed 99622 times
Looks like this device also has a populated JTAG header near the super capacitors.
In the process of getting CPT and loading a small I/O test program, of course one must run a quick port scan. Besides what the documentation (EasyIO FG Series FAQ v1.3) lists as ports/services running, it also has telnet. This also seems to drop you into a shell. Not sure yet if this can be disabled or at minimum the user/pw changed from default. Seems like a train wreck to have telnet enabled, default creds and undocumented.
Kind of a scatter shot first look but that’s how things goes. Looks like poor quality supercaps from HCCCap are the first issue. Basic cybers smells as well. Next steps will be looking closer at the input protection, poking more at its cybers and whatever else crops up along the way. If someone has another failed unit or anything else in the EasyIO line that has failed, I may be interested in purchasing it. PM me.
