Hifonics BRUTUS BX1500D Problem

blabay · 10th November 2010, 02:08 AM

Several Mosfets and two dual diodes had broken leads on one side of the amp. I replaced them and checked the rest. Found no more broken leads. The amp powers up and comes out of protect but doesn't pass audio. I checked the low voltage supply, but I'm not sure what to check next. Are there supposed to be symetrical high voltage rails? I found +59 volts on the diodes, but no negative 59 volts. DC voltages on the mosfets on both sides of the amp match and it doesn't seem to be drawing excessive current. My 12v supply is only 5A and doesn't sag when the amp powers up. Does anyone know where I can find a schematic for this amp?
Thanks

Perry Babin · 10th November 2010, 06:51 AM

You're unlikely to find a schematic diagram for this amp.

The amp has only a positive rail for the outputs. It has both positive and negative 15v rails for the preamp section.

Does the relay engage?

Does the HIP4080 get hot quickly?

blabay · 10th November 2010, 03:48 PM

The relay enagages after two or three seconds and the 4080 barely gets warm. It's drawing 1.3A at idle.

Perry Babin · 10th November 2010, 04:15 PM

Have you tried operating all of the switches and pots (the ones on the front panel) through their entire range to see if audio would play through?

blabay · 10th November 2010, 04:44 PM

Yes. I have a scope and traced signal to the HIP4080. I see three signals on this chip. on pins 5,6,7 I see the audio, and two pins have high frequency oscillation. Looking at the datasheet for this IC, it appears to be dead. It seems to have input, but no drive signal for the mosfets. I'm going to check some more things. Make sure it has Vdd, etc.

Perry Babin · 10th November 2010, 05:48 PM

Do you have ~6v DC on those terminals?

5 is a square wave. 6 is a triangle waveform and 7 is audio.

blabay · 10th November 2010, 11:20 PM

That is exactly what I see there. I don't see any thing on the outputs however. The IC has 12vdc at the appropriate pins. Shouldn't the drive output be a modulated square wave? I see only a tiny amount of noise on the drive outputs that doesn't change with change in input level/frequency.

Perry Babin · 11th November 2010, 05:43 AM

What is the DC voltage on pins 2 and 3?

blabay · 13th November 2010, 12:55 AM

Here are the DC voltages on each pin:
1. 12v
2. 12.61v
3. 12.62v
4. 0 v
5. 6.36v
6. 6.65v
7. 6.81v
8. 5.21v
9. 5.21v
10. 11.98v
11. 11.97v
12. 8.82v
13. 0v
14. 0v
15. 12.65v
16. 12.65v
17. 0v
18. 0v
19. 8.83v
20. 8.83v

Perry Babin · 13th November 2010, 02:04 AM

If pin 3 is near 12v, the protect LED should be on. Are you sure its off?

10th November 2010, 02:08 AM	#1
blabay diyAudio Member Join Date: Nov 2010	Hifonics BRUTUS BX1500D Problem Several Mosfets and two dual diodes had broken leads on one side of the amp. I replaced them and checked the rest. Found no more broken leads. The amp powers up and comes out of protect but doesn't pass audio. I checked the low voltage supply, but I'm not sure what to check next. Are there supposed to be symetrical high voltage rails? I found +59 volts on the diodes, but no negative 59 volts. DC voltages on the mosfets on both sides of the amp match and it doesn't seem to be drawing excessive current. My 12v supply is only 5A and doesn't sag when the amp powers up. Does anyone know where I can find a schematic for this amp? Thanks

10th November 2010, 06:51 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	You're unlikely to find a schematic diagram for this amp. The amp has only a positive rail for the outputs. It has both positive and negative 15v rails for the preamp section. Does the relay engage? Does the HIP4080 get hot quickly? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

10th November 2010, 04:15 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Have you tried operating all of the switches and pots (the ones on the front panel) through their entire range to see if audio would play through? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

10th November 2010, 05:48 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have ~6v DC on those terminals? 5 is a square wave. 6 is a triangle waveform and 7 is audio. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

11th November 2010, 05:43 AM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What is the DC voltage on pins 2 and 3? __________________ 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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10th November 2010, 03:48 PM	#3
blabay diyAudio Member Join Date: Nov 2010	The relay enagages after two or three seconds and the 4080 barely gets warm. It's drawing 1.3A at idle.

10th November 2010, 04:44 PM	#5
blabay diyAudio Member Join Date: Nov 2010	Yes. I have a scope and traced signal to the HIP4080. I see three signals on this chip. on pins 5,6,7 I see the audio, and two pins have high frequency oscillation. Looking at the datasheet for this IC, it appears to be dead. It seems to have input, but no drive signal for the mosfets. I'm going to check some more things. Make sure it has Vdd, etc.

10th November 2010, 11:20 PM	#7
blabay diyAudio Member Join Date: Nov 2010	That is exactly what I see there. I don't see any thing on the outputs however. The IC has 12vdc at the appropriate pins. Shouldn't the drive output be a modulated square wave? I see only a tiny amount of noise on the drive outputs that doesn't change with change in input level/frequency.

13th November 2010, 12:55 AM	#9
blabay diyAudio Member Join Date: Nov 2010	Here are the DC voltages on each pin: 1. 12v 2. 12.61v 3. 12.62v 4. 0 v 5. 6.36v 6. 6.65v 7. 6.81v 8. 5.21v 9. 5.21v 10. 11.98v 11. 11.97v 12. 8.82v 13. 0v 14. 0v 15. 12.65v 16. 12.65v 17. 0v 18. 0v 19. 8.83v 20. 8.83v

13th November 2010, 02:04 AM	#10
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If pin 3 is near 12v, the protect LED should be on. Are you sure its off? __________________ 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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