HP M6 Blown transistor on LVDS circiut

[atsio]

Re: HP M6 Blown transistor on LVDS circiut

Lvds 3.3v power does not provide voltage to the inverter. It is the easiest way to see that you do not have any other problems.

[Mad_Professor]

Re: HP M6 Blown transistor on LVDS circiut

Q29 broke into two pieces, I barely touch the thing.

I removed Q28 dual FET in one piece. I bridged Q29 source to gate and tried it. It didn't work, but no smoke. I went back and took some readings, noticed pin 4 on lvds cable has continuity to the newly bridged Q29. I removed the bridge, and test further.

Source on Q29 goes to pin 4 on lvds. Q29 drain goes to pin 4 Q28 (upper right pin) but also goes to pin 2/3 on LVDS. There's 100 Ohms between Q28 pin 4 to lvds pin 2/3 but 0 ohms to drain on Q29.

if that makes any sense.

Also, Q29 source still has 3.3v reading but gate has 2.7v reading, which wasn't there before.

[Mad_Professor]

Re: HP M6 Blown transistor on LVDS circiut

Should I attempt to bridge source and drain on Q29?

[atsio]

Re: HP M6 Blown transistor on LVDS circiut

If you have voltage on gate of Q29 find a pnp fet and replace Q29. Also resolder Q28

[Mad_Professor]

Re: HP M6 Blown transistor on LVDS circiut

Will any PNP fet work or does it need certain specs?

[atsio]

Re: HP M6 Blown transistor on LVDS circiut

On the piece of the schematic I attached on my earlier post, it uses an AO3419.

http://elcodis.com/parts/402616/AO3419.html#datasheet

Find a similar (or the same) and replace it.

[Duncanbest]

Re: HP M6 Blown transistor on LVDS circiut

Q28


Q29

marking 01 STP7401
https://cdn.badcaps-static.com/pdfs/...5446c39a04.pdf

marking o1 Si2399DS
http://www.vishay.com/mosfets/list/product-67343/

[Mad_Professor]

Re: HP M6 Blown transistor on LVDS circiut


IT'S ALIVE!!!!
reference: https://www.youtube.com/watch?v=1qNeGSJaQ9Q

I was able to find suitable replacements from digikey, replaced both Q28 and Q29.
It was a pain getting the sot-363 back on, and I wasn't expecting it to work on the first try or at all.

THANK YOU SO MUCH atsio and Duncanbest.