After a nearby lightning strike, the C5 causes a short-circuit on the power supply. I’d like to try to repair it (perhaps it’s just a transient suppressor that did its job) before recycling it. But I can’t seem to be able to open the case - is it glued permanently, or is there a trick to open it without destroying it? The device is after warranty, and it was earthed through the cable shield.
I don’t think there is a non-destructive way to disassemble the C5.
That said, if you are willing to use epoxy, I bet you can get the thing apart along the seam and put it back together and get a pretty decent seal…
Taking a C5 apart will destroy the board.
Out of curiosity and with nothing to lose anyway, I managed to disassemble the C5 with board left intact (destroying the enclosure instead). The PoE chip exploded (hole in the center), only part of the markings can be read, it starts with S and ends with 2. My guess (I’m an electronics engineer, and happened to research various PD controller chips recently while working on some PoE powered design) is the chip was a Si3402. Not sure about revision A or B (need some changes in external components). Cheap non-isolated design (negative buck, not flyback) so I expected the overvoltage to be passed to the low voltage electronics and fry it too. But when I applied 5V DC to the 470uF output capacitor (bypassing PoE completely) , the device started just fine, with configuration intact and working gigabit ethernet link. So the ethernet port itself was well protected, just the PoE part failed (no surprise since the Si3402 has overvoltage protection inside and tiny QFN package can only dissipate so much energy - external surge suppressor part would be better as it would fail shorted and protect the rest).
So, I’d like to try replacing the exploded PoE chip - could you confirm its type and revision? Si3402 both A and B revisions are available in China for about $10 per 10 pcs (free shipping) even though revision A is EOL. If I succeed, at least I will have a portable CPE to do site surveys (enclosure damaged when disassembling is no longer rain resistant). I must say I’m disappointed when things (not that cheap) are designed to be difficult to repair, please consider this in your future designs (for me it’s the same kind of thing as smartphones with non-replaceable batteries etc.).
@Marek2, Thank you very much for the super detailed tear-down of a C5!!! I appreciate your candor and knowledge. (Particularly your willingness to share)
I would guess Mimosa wouldn’t use a EOL chip for an antenna that is 3 years old. So I would go with the B revision, but that’s just me. I might have a C5 that we dropped and I can take it apart to take a look for you.
very interesting post. Do you have any news about the repair?