Hifonics BXI 2010 D

[Perry Babin]

Did the diode possibly short again?

 

[mike49504]

Checked the diode and it tests fine. Replaced the A1275 that its connected to also. Amp is still stuck in protection

 

[Perry Babin]

Are these associated with the protection circuit?

 

[mike49504]

The diode location Is D20 1 end connects to the Middle leg of the 7815 and the same side of the diode also connects to the first leg of an A1275 (Q238) and also connects to D21

 

[mike49504]

Heres some pics so you have an idea on what part of the board im talking about.

 

[Perry Babin]

Are the two transistors near the shunt resistors (rectangular metal loop resistors) connected to the shunt resistors (via smaller resistors possibly)?

If so, have you checked those transistors?

 

[mike49504]

Theese transistors?? If so i replaced both of them

 

[Perry Babin]

Do you see a quick pulse of DC on either of the output filter inductors at the instant that it goes into protect?

 

[mike49504]

Yes i see it on both of them

 

[Perry Babin]

I wouldn't expect there to be any DC with the outputs out of the circuit. Are there any solder bridges between any of the pads for the outputs?

 

[mike49504]

If i remove both output filter inductors amp will power up and idle If i put 1 back in amp goes into protection Any ideas?

 

[Perry Babin]

Do you mean that either filter inductor will make it go into protect mode?

Did you check for solder bridges?

 

[mike49504]

I checked for solder bridges didnt find any . Yeah if i put either of the inductors in it it goes into protection

 

[Perry Babin]

What is the DC voltage on the pads for the inductors (inductors out of the circuit)?

 

[mike49504]

PAD1:-68.6

PAD2:0

PAD3:0

PAD4:-68.5

This is with them removed

 

[Perry Babin]

What's the resistance between the negative rail and the pads with -68v?

 

[mike49504]

Where would i place the black meter probe on this amp for the negative rail?

 

[mike49504]

I placed black meter probe on leg 3's pad for the outputs and red probe on the output inductors pad

1:0.04 ohms

2:2.4 ohms

 

[mike49504]

Ok i figured out that problem amp is powerd up now.

Next question is are theese the 2 transistors your talking about?

AS you can see this board was worked on before by someone else.

 

[mike49504]

Ok replaced thoose 2 transistors. Amp powers up but starts drawing excessive current. And the outputs on both sides heat up within secs. If i remove the driver board amp idles perfectly. Any ideas on what to look for?