TP-Link router wih no +3,3 V

[Behemot]

It is a TL-WR1043ND with +12 V supply. Inside are 3 voltages: +5 V, +3,3 V and +1,8 V. The +5 V is fine.

However, +3,3 V is no present and since +1,8 V is driven from that, there is no voltage too. I discovered there is APW7120 PWM controller running dual N-channel MOSFET 4228BGM.

Since the dual MOSFET measures OK and the PWM is hot like hell when I plug in +12 V transformer (well, there is 14,5 V when pluged in, but I think its normal for these supply transformers, right), I guess the PWM is dead…is there anything I can do for proving it before I will try to look for replacement?

[tom66]

Re: TP-Link router wih no +3,3 V

3.3V DC-DC module? http://www.ebay.co.uk/itm/DC-DC-Volt...item43ae948a6b

[Behemot]

Re: TP-Link router wih no +3,3 V

Oh, well, I can solder in +3,3 V and +5 V directly from AT PSU, totally skipping the +12 V, right? Good point!

[ben7]

Re: TP-Link router wih no +3,3 V

Yep, that chip is surely dead.

You can try to hook up a 3.3v regulator. Or, try an LM317. Idk if it will be able to provide enough current - if it doesn't then you can use a series pass transistor.

However, using a linear regulator on the 12v supply or 5v supply of the router might cause it to be overloaded by the not-so-efficient liner regulator.

[Behemot]

Re: TP-Link router wih no +3,3 V

Well I am thinking of hooking in AT PSU, it does enough current for everything. Top rating is 1,5 A on 12 V, so its 18 W max, but I guess thats for using all five ports at 1000Base-T and all three antennas.

[severach]

Re: TP-Link router wih no +3,3 V

Linear regulators are hard to burn out. 3.3v could be shorted leading the regulator to shut down and leaving 1.8v out in the cold. I'd inject 3.3v from a bench power supply to see if the voltage can be maintained at a "normal" current draw and the product works.

You could also hook up the ATX power supply and watch for sparks.

[Behemot]

Re: TP-Link router wih no +3,3 V

OK, connected ATX PSU, got green power on diode but thats all. I guess the main processor is damaged thus making switch non-workable. Anyway, even though it's GbE/802.11 n router, it is not so expensive to waste time with that any longer…not mentioning the guy got it for free I think (as most of the routers he has ).