JTAG vs Desoldering NAND?

[iceblue1980]

Morning guys,

I wanted to ask you, if I successfully connected to a router through JTAG, can I reprogram the NAND or are there any limitations compared to desoldering the chip and accessing it through an external programmer?

 

[JagoUK]

JTAG is easier if it works.
However sometimes there will.be times when jtag won't work and you will have to desolder.

 

[iceblue1980]

Thanks, that's pretty much what I thought. I own couple of Asus RT-AC88u and the JTAG headers are clearly marked, 2 of them in total (5pin headers). I reckon the 10pin unmarked header between the WAN and LAN1 port is also JTAG as one of the rows is all ground. From my understanding all JTAG ports are interconnected so it doesn't matter which one I connect to but as for the 3x ground pins, can I ground to chassis or does it have to be a specific pin on the board?

 

[JagoUK]

Thanks, that's pretty much what I thought. I own couple of Asus RT-AC88u and the JTAG headers are clearly marked, 2 of them in total (5pin headers). I reckon the 10pin unmarked header between the WAN and LAN1 port is also JTAG as one of the rows is all ground. From my understanding all JTAG ports are interconnected so it doesn't matter which one I connect to but as for the 3x ground pins, can I ground to chassis or does it have to be a specific pin on the board?

Ground is ground. Anything that is marked as ground is all connected together.

To be sure use a multimeter on continuity setting and it will beep if you touch two ground points.

Ground and negative are not the same though.

 

[iceblue1980]

Ground is ground. Anything that is marked as ground is all connected together.

To be sure use a multimeter on continuity setting and it will beep if you touch two ground points.

Ground and negative are not the same though.

Yeah done that (this is how I found that half of that 10pin header was grounded). Cheers