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Harman Kardon 330C blowing fuses

These measurements were taken with the amp powered up using a DBT.
Emit Col Base
Q413--------- 6.73vdc 7.32vdc 6.81vdc
Q415______ 8.76vdc 9.35vdc 9.44vdc
Q417______ 8.80vdc 9.39vdc 8.80vdc
Q419______ -10.86vdc 7.47vdc -10.89vdc
 
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q413 appears to be fitted wrong . collector should be same as q419 base .
base to emitter voltages of all transistors are wacky . they should read approx 600mv difference .
both outputs bases are very high . they should be about 600mv .
rail voltages are very low so something is pulling that down .
q413 base should be negative .

could you post same voltages for the good channel to make this easier and less chance of errors in diagnosing .
 
This is the way I listed these and the computer did it's own thing.
Emit Col Base
Q413------- 6.73vdc 7.32vdc 6.81vdc
Q415____ 8.76vdc 9.35vdc 9.44vdc
Q417____ 8.80vdc 9.39vdc 8.80vdc
q419------- -10.86 7.47vdc -10.83vdc
 
OK. When I took those last readings, I had the receiver hooked up to speakers . I unhooked the speakers and took a new set of measurements for both sides of the board.

Left (Good) Channel Right Channel

Emit Col Base Emit Col Base
Q414 -.036vdc -13.89vdc -.459vdc Q413 11.71vdc -13.16vdc 11.09vdc
Q416 -.023vdc 13.80vdc .396vdc Q415 13.12vdc 13.75vdc 13.78vdc
Q418 -.035vdc 13.80vdc .023vdc Q417 12.44vdc 13.80vdc 13.13vdc
Q420 -13.81vdc -.028vdc -13.80vdc Q419 -13.17vdc 12.02vdc -13.81
 
Q414 E -.036vdc C-13.89vdc B -.459vdc
Q416 E -.023vdc C13.80vdc B .396vdc
Q418 E -.035vdc C13.80vdc B .023vdc
Q420 E -13.81vdc C-.028vdc B -13.80vdc

Q413 E 11.71vdc C-13.16vdc B 11.09vdc
Q415 E 13.12vdc C13.75vdc B 13.78vdc
Q417 E 12.44vdc C13.80vdc B 13.13vdc
Q419 E -13.17vdc C12.02vdc B -13.81
 
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Q407 E -14.06vdc C 11.26vdc B -13.49vdc
Q409 E 13.98vdc C 13.98vdc B 13.40vdc
Q421 E 11.20vdc C 13.90vdc B .001vdc

Q408 E -13.89vdc C .491vdc B -13.37
Q410 E 13.64vdc C .416vdc B .462vdc
Q422 E -.476vdc C .408vdc B .462
 
looking like d409 is bad or bad solder etc .. might be in backwards but i am not sure about that . best test it . should have approx 1.2v across it on diode test
 
I found a broken trace that connected the base of Q421 to D409. When I fixed that connection, I can now turn the 330C on , without DBT, and not blow the fuses. However, when I hook up the speakers and press the speaker button to "on", the DBT glows bright indicating a short. I measured the VDC at the speaker terminals and get a reading of .001vdc on the left side and 21.30vdc on the right side. I took new readings for Q413, 415, 417, and 419 since fixing the broken trace.

Q413 E 20.99vdc C -22.23vdc B 20.33vdc
Q415 E 21.93vdc C 22.93vdc B 22.55vdc
Q417 E -21.83 C 22.91vdc B 20.33vdc
Q419 E -22.93vdc C 21.15vdc B 20.33vdc
 
Q414 E -.036vdc C-13.89vdc B -.459vdc
Q416 E -.023vdc C13.80vdc B .396vdc
Q418 E -.035vdc C13.80vdc B .023vdc
Q420 E -13.81vdc C-.028vdc B -13.80vdc

Q413 E 20.99vdc C -22.23vdc B 20.33vdc
Q415 E 21.93vdc C 22.93vdc B 22.55vdc
Q417 E -21.83 C 22.91vdc B 20.33vdc
Q419 E -22.93vdc C 21.15vdc B 20.33vdc

i put readings together to make it easier .
 
q413 appears in wrong or your readings are wrong ...
odd thing is q417 base is same voltage as q413 q415 base ... :idea:
 
I did a retest on q413, q415 and q417 with basically the same results. I also did a new test on the left side of the board with new results.

Q414 E -20.77vdc C -22.01vdc B -21.44vdc
Q416 E -20.19vdc C 22.62vdc B-19.50vdc
Q418 E 20.60vdc C 22.68vdc B-20.23
Q420 E -22.74vdc C -19.80vdc B -21.16
 
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