Rockford Fosgate BD1000

seankane · 18th March 2011, 06:11 AM

Hello I have a bd1000 I am repairing. The power supply was completely fried. I replaced all the IRF3205 fets and all their gates. The amp powers up fine and does not draw excess current but has no output. When the speakers are hooked up it is just silent with no noise or static. Any ideas??

seankane · 18th March 2011, 06:13 AM

Just to eliminate any other questions I replaced all the output transistors ( IRF 3415 and IRF 6215 ) and still no output. ??????

Perry Babin · 18th March 2011, 09:34 AM

What's the DC voltage on the pins of U21?

Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:

seankane · 18th March 2011, 06:55 PM

Pin1: -8.25v
Pin2: 0v
Pin3: -8.75v
Pin4: -9.60v
Pin5: 4.98v
Pin6: 8.27v
Pin7: -8.32v
Pin8: 9.77v

These are from U21 TL072C

seankane · 18th March 2011, 06:59 PM

These were obtained by holding the ground from my meter to the amps ground and testing the pins with the positive probe.

Perry Babin · 18th March 2011, 07:06 PM

That appears to be OK.

What's the resistance from the 3rd leg of Q101 to the positive speaker terminal (no power applied to the amp)?

seankane · 18th March 2011, 07:26 PM

Looking down on Q101 last leg to the right resistance between that and the positive terminal no power applied what so ever is .1 ohm

seankane · 18th March 2011, 07:35 PM

If I hold the leads on for a little while it starts at .5 ohms then bleeds down to .1 ohms and eventually 0 ohms. Dont know if this matters???

Perry Babin · 18th March 2011, 07:54 PM

Check it again but this time, move the output filter inductor. Does it change significantly?

What's the DC voltage measured directly across the black and red twisted wired?

seankane · 18th March 2011, 08:08 PM

Output filter inductor? As in the crossover adjustment knob? The voltage from the power supply side to the the output side measure across??

18th March 2011, 06:11 AM	#1
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Rockford Fosgate BD1000 Hello I have a bd1000 I am repairing. The power supply was completely fried. I replaced all the IRF3205 fets and all their gates. The amp powers up fine and does not draw excess current but has no output. When the speakers are hooked up it is just silent with no noise or static. Any ideas??

18th March 2011, 09:34 AM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What's the DC voltage on the pins of U21? Pin 1: Pin 2: Pin 3: Pin 4: Pin 5: Pin 6: Pin 7: Pin 8: __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

18th March 2011, 07:06 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	That appears to be OK. What's the resistance from the 3rd leg of Q101 to the positive speaker terminal (no power applied to the amp)? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

18th March 2011, 07:54 PM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Check it again but this time, move the output filter inductor. Does it change significantly? What's the DC voltage measured directly across the black and red twisted wired? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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18th March 2011, 06:13 AM	#2
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Just to eliminate any other questions I replaced all the output transistors ( IRF 3415 and IRF 6215 ) and still no output. ??????

18th March 2011, 06:55 PM	#4
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Pin1: -8.25v Pin2: 0v Pin3: -8.75v Pin4: -9.60v Pin5: 4.98v Pin6: 8.27v Pin7: -8.32v Pin8: 9.77v These are from U21 TL072C

18th March 2011, 06:59 PM	#5
seankane diyAudio Member Join Date: May 2010 Location: Washington State	These were obtained by holding the ground from my meter to the amps ground and testing the pins with the positive probe.

18th March 2011, 07:26 PM	#7
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Looking down on Q101 last leg to the right resistance between that and the positive terminal no power applied what so ever is .1 ohm

18th March 2011, 07:35 PM	#8
seankane diyAudio Member Join Date: May 2010 Location: Washington State	If I hold the leads on for a little while it starts at .5 ohms then bleeds down to .1 ohms and eventually 0 ohms. Dont know if this matters???

18th March 2011, 08:08 PM	#10
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Output filter inductor? As in the crossover adjustment knob? The voltage from the power supply side to the the output side measure across??

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