Re: Help needed with fried SWMPS - RING RSC612/RESC612

There is a typo in post #23, Z3 should read

Z3 is a 1N4746A, 18V Zener

Re: Help needed with fried SWMPS - RING RSC612/RESC612

I noted a couple of interesting points on the boards. The earlier 2015 unit has signs of corrosion on some of the wire links on the top of the board, this is in the form of green verdigris and although still intact, it shows that moisture is getting into the unit, which is kept in the garage or placed under the bonnet of the car when operating.

On the 2015 board, I noted around 10 joints that looked to be iffy from a dry joint perspective. I don't think any had got to failure yet, but there were clearly visible...

Re: Help needed with fried SWMPS - RING RSC612/RESC612

Whilst poking around in these two units, I found a number of differences between them, which I'll record here. The assembly datecode is on the back of the unit at the bottom, under the plastic bump case. I have a late 2015 model and an early 2020 model.
[LIST][*]The 2015 model has a power cable quick disconnect based on a 4 way SAE battery connector, the later model doesn't[*]R17 is 10R 1/8W (2015) and 20R 1/8W (2020). This is adjacent to the transformer[*]R43 is no longer fitted in the 2020 model, this is the bleed resistor...

Re: Help needed with fried SWMPS - RING RSC612/RESC612

Now, onto the failure mode.

Once I'd located the two Zener's and tested them on my Zener tester as OK, I checked them in circuit when powered on. There is what I now know to be VCC, pin 5 on U5, this is the trace below D8 when the silk screen text is the right way up. This was measuring around 17V and I initially thought it was OK as it was close to the Zener voltage of 18V for Z3 (1N4746A). This supply also goes via JP24 to the 8 pin SO8 ST 3842B.

This pin has two power feeds into it, the initial...

Re: Help needed with fried SWMPS - RING RSC612/RESC612

Looking at the pictures earlier in this forum, it appears that mandan1 has the later version of the board.

I can confirm that N5 is an NPN BJT with an HFE of 200, the pinout (using the pin numbers in mandan1's post) is C, B, E. Similarly, Q9, is a PNP BJT with an HFE of 210, the pinout is C, B, E

In my case, I could see the input filtering and initial AC to DC conversion taking place, resulting in 338V DC but nothing else was operating, the +12 and +5V rails on the low voltage side were at zero....

Re: Help needed with fried SWMPS - RING RSC612/RESC612

I have two of the same units, one from 2015 and one from 2020, which was sent by Ring to me when the earlier unit, although out of warranty started playing up - thanks Ring !.

The fault started as intermittent F03 errors, which according to the manual is is unable to control charge current. I also noted that it would stop charging, showing a full battery, when the battery was not in fact fully charged. I had this on my bench for a bit handling a battery used for an off-grid purpose, the charger then completely failed...