n72 Troubleshooting - r45 Smokes when powered

[svenc24]

Hi,

This thread is for the second n72 v3.3 module I am trying to assemble.

I have gone through the BOM line by line to verify each component, its placement on the board, and its orientation. Checked the input and
output transformer wiring. Checked for solder bridges, bad solder joints, and checked the traces for problems / bits of metal etc as best as I can.

When I check the power connector J1, Pins - 1 and 2 / 2 and 3 - I get high ohm readings.

I've Turned R39 counter clockwise until it clicks before applying power, then I apply power.

R45 then starts to smoke and I quickly turn off power.
R45 did have some black coloring and it read ok when I tested its resistance, but I replaced it anyways.
Re Apply power and it begins to smoke, so I then again turn off power immediately.

I then re flowed all solder joints, rechecked everything mentioned above, made sure the screws for Q6 and the output transformer weren't too
loose or tight, made sure R39 was rotated CCW until it starts to click, made sure Q7 and Q8 were correctly placed, checked that C29/c30 are not backwards, and looked for shorts around C29, C30, R48, R45, R50, SW2, and elsewhere. When applying power, R45 still begins to smoke.

Any ideas what may be going on or of other things to try?

Thanks!

Here are some pictures below:

https://imageshack.com/i/ewL7FqPQj
https://imageshack.com/i/ip3KQ9Txj
https://imageshack.com/i/ezk0t2Ojj
https://imageshack.com/i/ewymKr1bj
https://imageshack.com/i/kpGU3Lmnj

[svenc24]

Followed the following steps for testing transistors (http://electronicsclub.info/multimeters.htm / http://electronicsclub.info/transistors.htm)

Results:
(.0l = reverse biased)

Q1
BE: .668 / .0l
BC: .668 / .0l
CE: .0l / .0l

Q2
BE: .668 / .0l
BC: .668 / .0l
CE: .0l / .0l

Q3
BE: .668 / .0l
BC: .668 / .0l
CE: .0l / .0l

Q4
BE: .668 / .0l
BC: .668 / .0l
CE: .0l / .0l

Q5
BE: .668 / .0l
BC: .668 / .0l
CE: .0l / .0l

Q6 (hard to get consistent results)
BE: .51 / .95
BC: .71 / fluctuates between(.69 - .9)
CE: .51 / .61

Q7
BE: .58 / .0l
BC: .6 / .0l
CE: .0l / .0l

Q8
BE: .61 / .0l
BC: .61 / .0l
CE: .001 / .001

Diodes: (tested while still on the board..)
D1: .53 /.0l
D2: .71 / .496
D3: .086 / .086
D4: .53 / .0l

I replaced C29 and C30, re-flowed Q7, Q8, R45, R48, R50, and when applying power R45 still smokes.

Q8 - doesn't seem right, I was expecting CE to be .0l/.0l - Should Q8 be replaced?
Q6 - not sure what to think. The measurements were hard to get consistent results. Sometimes I'd see a .0l flash, but it would never stay at .0l.
D3 + D4 - I thought I was suppose to see .0l one way

[svenc24]

This module is now working. Sounds great!