MB Quart RAA2400 - Page 3

mike49504 · 7th February 2010, 11:43 PM

never got it to produce rail voltage yet

Perry Babin · 8th February 2010, 03:45 AM

That would be the first thing you need to do. Does it go into protect with the audio driver board out of the amp?

mike49504 · 8th February 2010, 11:22 AM

it doesnt go into prtection at all with the audio board in or out of the amp.

Thye 7812 is connected to the 0.1 pico farad caps then goes to the driver board.

Can i raplace the resistor looking caps with any 0.1 pico farad cap since i accidently broke the lead off one of them?

Perry Babin · 8th February 2010, 01:09 PM

0.1uF, not pF.

Virtually any type would work. The original was likely a ceramic capacitor. A mylar/film capacitor would also be OK.

Post the voltages on the power supply IC.

IC#
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:

mike49504 · 8th February 2010, 08:47 PM

They are using a Sg3525ap on the power supply driver board

pin1=0
pin2=5.16
pin3=0.2
pin4=0.24
pin5=2.06
pin6=3.69
pin7=2.04
pin8=4.91
pin9=5.70
pin10=.07
pin11=5.17
pin12=.01
pin13=12.31
pin14=5.14
pin15=12.31
pin16=5.16

Perry Babin · 8th February 2010, 08:51 PM

If it doesn't have rail voltage, the power supply FETs have failed or the rectifiers have failed.

Do you have 5, 12 and 0v (G, D, S) on each of the power supply FETs?

mike49504 · 8th February 2010, 09:32 PM

leg 1= 5.15
leg2= 13.08
leg3=0

on all of the power supply fets

7812 reads

leg1= -39.34
leg2=0
leg3=0

Perry Babin · 8th February 2010, 09:43 PM

What do you have on the 3 legs of the rectifiers? Place the black meter probe on the center tap of the power transformers, on the RCA shield and on the chassis ground if you don't initially see any rail voltage.

The 7812 is generally only rated for 35v. It may have gone into protection. Can you lower the 12v power supply voltage so the voltage feeding it drops to 35v to see if it will produce output?

If it doesn't, pull leg 3 and insert a low value resistor (1 ohm - 5 ohms) to see if it will produce output. Measure the voltage across the resistor to determine if it's producing any current.

mike49504 · 8th February 2010, 10:48 PM

Which one are the rectifiers in this amp i have one that says d600k

And some fmg part numbers

Perry Babin · 8th February 2010, 10:59 PM

FMG are typically rectifiers. The D600K is likely an NPN transistor.

8th February 2010, 03:45 AM	#22
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	That would be the first thing you need to do. Does it go into protect with the audio driver board out of the amp? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

8th February 2010, 01:09 PM	#24
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	0.1uF, not pF. Virtually any type would work. The original was likely a ceramic capacitor. A mylar/film capacitor would also be OK. Post the voltages on the power supply IC. IC# Pin 1: Pin 2: Pin 3: Pin 4: Pin 5: Pin 6: Pin 7: Pin 8: Pin 9: Pin 10: Pin 11: Pin 12: Pin 13: Pin 14: Pin 15: Pin 16: __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

8th February 2010, 08:51 PM	#26
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If it doesn't have rail voltage, the power supply FETs have failed or the rectifiers have failed. Do you have 5, 12 and 0v (G, D, S) on each of the power supply FETs? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

8th February 2010, 09:43 PM	#28
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What do you have on the 3 legs of the rectifiers? Place the black meter probe on the center tap of the power transformers, on the RCA shield and on the chassis ground if you don't initially see any rail voltage. The 7812 is generally only rated for 35v. It may have gone into protection. Can you lower the 12v power supply voltage so the voltage feeding it drops to 35v to see if it will produce output? If it doesn't, pull leg 3 and insert a low value resistor (1 ohm - 5 ohms) to see if it will produce output. Measure the voltage across the resistor to determine if it's producing any current. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

8th February 2010, 10:59 PM	#30
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	FMG are typically rectifiers. The D600K is likely an NPN transistor. __________________ 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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7th February 2010, 11:43 PM	#21
mike49504 diyAudio Member Join Date: Sep 2006	never got it to produce rail voltage yet

8th February 2010, 11:22 AM	#23
mike49504 diyAudio Member Join Date: Sep 2006	it doesnt go into prtection at all with the audio board in or out of the amp. Thye 7812 is connected to the 0.1 pico farad caps then goes to the driver board. Can i raplace the resistor looking caps with any 0.1 pico farad cap since i accidently broke the lead off one of them?

8th February 2010, 08:47 PM	#25
mike49504 diyAudio Member Join Date: Sep 2006	They are using a Sg3525ap on the power supply driver board pin1=0 pin2=5.16 pin3=0.2 pin4=0.24 pin5=2.06 pin6=3.69 pin7=2.04 pin8=4.91 pin9=5.70 pin10=.07 pin11=5.17 pin12=.01 pin13=12.31 pin14=5.14 pin15=12.31 pin16=5.16

8th February 2010, 09:32 PM	#27
mike49504 diyAudio Member Join Date: Sep 2006	leg 1= 5.15 leg2= 13.08 leg3=0 on all of the power supply fets 7812 reads leg1= -39.34 leg2=0 leg3=0

8th February 2010, 10:48 PM	#29
mike49504 diyAudio Member Join Date: Sep 2006	Which one are the rectifiers in this amp i have one that says d600k And some fmg part numbers

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