planet audio bb2400.1

Perry Babin · 2011-08-28 10:42 pm

What is U4?

Is it shorted?

bdgf2004 · 2011-08-28 10:52 pm

U4 is KIA431.

it's not shorted

Perry Babin · 2011-08-28 11:02 pm

Does R40 connect to one of the pins on the closest opto-coupler?

If so, which pin?

bdgf2004 · 2011-08-28 11:12 pm

yes, it is directly connected to pin #5 of U5 (TLP521-2).

Perry Babin · 2011-08-28 11:32 pm

Are you sure that it's pin 5?

I'm working off of a schematic of an amp that I believe is similar and it looks like it should go to either pin 1 or pin 3.

bdgf2004 · 2011-08-28 11:53 pm

R40 is connected to the pin with the red dot.

Perry Babin · 2011-08-29 12:03 am

Did you follow the trace or did you find the connection with your meter?

bdgf2004 · 2011-08-29 12:04 am

both. first the meter. then i followed the trace and it leads directly to R40

Perry Babin · 2011-08-29 12:10 am

I'm assuming that the circuit is like the one below but the diodes of the opto-coupler are on the low side (pins 1-4). Can you find any resemblance between this circuit and the one in your amp?

bdgf2004 · 2011-08-29 12:41 am

yes, i believe they're similar.

pin #9 on SG3525 is connected to pin #8 (collector) of TLP521 and pin #7 (emitter) of TLP521 is 1k ohms from ground

Perry Babin · 2011-08-29 12:51 am

Are any other pins on that opto-coupler connected to pin 5 of the opto-coupler?

bdgf2004 · 2011-08-29 12:54 am

Perry Babin · 2011-08-29 2:14 am

Will the amp produce audio?

Do you have rail to rail oscillation on the output transistors?

bdgf2004 · 2011-08-29 3:27 am

no, the amp will not produce audio.

output fets
Q16, 18, 20, 31, 3= pin1=0v pin2=71v pin3=0v
Q17, 19, 21, 30, 4= pin1=71v pin=0v pin3=71v

Perry Babin · 2011-08-29 6:23 am

Counting from the RCA end of the amplifier, pin 6 on the driver board...

Does it begin at rail voltage then drop to ~0v after a bit of a delay?

Does the protect LED ever go off?

bdgf2004 · 2011-08-29 6:28 am

pin 6 goes up to ~86vdc when remote is applied after about a second the protection light goes off the green light comes on and the voltage on pin 6 drops to near 0vdc

Perry Babin · 2011-08-29 7:50 am

What is the DC voltage across R50 before and after the protect LED goes off?

bdgf2004 · 2011-08-29 8:09 am

there is no voltage present across R50 at any time

Perry Babin · 2011-08-29 8:41 am

With the black probe on leg 1 of Q47, post the DC voltage on legs 2 and 3 after the delay.

bdgf2004 · 2011-08-29 8:54 am

pin 2=0vdc
pin 3=0.676vdc

planet audio bb2400.1

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