Electronics > Repair
Power Over Ethernet camera repair
tyrel:
Hi,
I try to repair a network camera (Axis Q6032-E) that has died suddenly after more than 10 years of service.
I strongly suspect that the problem is in the Power Over Ethernet power supply board, and more specifically in the flyback converter, since i measure no voltage at the output of the converter.
There is no other way than POE to power the camera.
Visually, i see nothing wrong on the board. The capacitors look good, and their measured value is ok (i have not measured esr).
The power supply is composed of two isolated flyback converters controlled by two NCP1081 (https://www.onsemi.com/pub/Collateral/NCP1081-D.PDF).
The circuit seems very close to the schematic in figure 2 of the datasheet, except that it uses the extra winding (see figure 4), and two completely separate converters in parallel for data pairs and spare pairs.
I have measured several voltage (DC) at various points of the two NCP1081 (see below), and the results look definitly odd, but i can't understand what is going on exactly.
The measured voltages are the same whether the other boards of the camera are connected or not.
converter 1 (from spare pairs)
VPORTP-VPORTN : 53.8V (ok)
ARTN-VPORTN : 52.2V
VDDH : 1.3V
VDDL : -0.1V
VCpd : 1.6V
converter 2 (from data pairs)
VPORTP-VPORTN : 53.8V (ok)
ARTN-VPORTN : ramp down, reset to 53.8V (symetric to VCpd)
VDDH : 0V
VDDL : 0V
VCpd : slowly ramp up to variable voltage (seen up to 42V), go to 0, repeat
Any idea?
Thanks.
james_s:
Between two friends and I, I think we had 5 Axis 206 cameras fail over the course of about 4 years, I haven't bought any more since then.
station240:
So converter 1 looks like it's working briefly, but is overloaded somehow.
converter 2 appears totally dead.
If you look closer at the internal diagram, you can see ARTN to VPORTNx is the negative path, but has current limiting.
So the reason converter 2 appears totally dead, is there is a short on the output that is shutting everything down.
Check for bad diodes and capacitors that measure bad or run hot.
PKTKS:
Check also that so called SHUNT regulator which I will guess should be the TL431 or clone
It that is still matching the proper reference or just gone wild.
Paul
tyrel:
Thanks for your ideas, i don't have the board right here to test, but i will try tomorrow.
Everything after the flyback looks ok, when i connect a 19V power supply at the output capacitor, the camera boards boots (at least i see the led turn on).
Also, something i forgot to mention is that it is not one, but two of those cameras (same model, same installation date) that have failed in two months.
I have no access to the second camera for now unfortunalty (11 meters above the ground).
--- Quote ---If you look closer at the internal diagram, you can see ARTN to VPORTNx is the negative path, but has current limiting.
So the reason converter 2 appears totally dead, is there is a short on the output that is shutting everything down.
Check for bad diodes and capacitors that measure bad or run hot.
--- End quote ---
Yes, you are right, there is likely a short at converter 2 output.
I have checked most capacitors and diodes, but i will check again more thoroughly in that area.
There is probably something wrong on the controller 1 too (or he is affected by controller 2), because the ramp slope on VCpd (about 0.3V/s, for a 100uF capacitor iirc) is too slow for a normal current limit.
--- Quote ---Check also that so called SHUNT regulator which I will guess should be the TL431 or clone
--- End quote ---
I did not think to check that, will do, thanks
--- Quote ---Between two friends and I, I think we had 5 Axis 206 cameras fail over the course of about 4 years, I haven't bought any more since then.
--- End quote ---
I don't have had any bad experience like that with Axis, but i have not used their 'low-end' cameras much. Were your cameras indoor or outdoor?
In my case, a lifetime of 12 years for an outdoor camera does not seem too bad for me.
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