Help! closing j10 causes tk2050 overheating!

[coky]

hi guys, first of all I beg your pardon for my poor english,

I started mounting an amp4, and soldered all the surface mount components, the 9v and 5v tests were fine, so far so good.

so I mounted all the hole-through components, and after closing J10 the tripath main chip (tk2050) started to smell and runs HOT, quickly unpowered the board (btw I use an old AT trafo from a pentium1 pc connecting the +12 and -12 to ac1 and ac2, all went fine since now) and discovered that the 2,2k r59 was burned, got a new 2,2k connected the +5v(trafo) to ac1(board) and gnd(trafo) to gnd(board)... and the 2050 still was overheating and... r59 was again burned with only 5v!!!


Considerations:

All the smt components are soldered pretty clean

both chips are again well soldered (after the overheating could the 2050 be burned?), checked and re-checked many times

The amp is nearly finished i have to mount only the nmos and pmos (q4, q5, q6 and u10, u11, u12)

My board is rev 1.1 and I mounted the voltage supervisor straight (not rotated 120deg counterclokwise)

I used Rin 20Kohm (r21 and r29) and Rfeedback 49,9Kohm (r23 and r31) as I'd like to use a 50K pot as read in the instructions.

Any suggestions, tips, miracles?

coky.

[coky]

Edit: with J5 open (and of course J10) and 12v dc source the 5v section is good (5.02 v) and the 9v is also good (around 7v)
closing J5 the 5v section drops to 1.2v and the 9v drops to around 3v...

I think there's some shortage somewere but I have no idea where it could be...

again, any suggestions?

coky.

[xenob]

Check soldering of tc2001 and TP2050. Visual examination is not enough. Best is, heat all the joints again and measure afterwards for shorts.

[coky]

xenob, you're right:
I desoldered the 2050 chip for a complete clean up and I noticed 2 black stains on the pcb... the 2050 is gone and some of the tracks/buses were burned too... i can't figure out how could be happened such a thing I soldered really carefully both chips... c'est la vie.

results:
1) Amp is dead
2) buy a new amp4 kit