MB Quart RAA2400 - Page 4

mike49504 · 9th February 2010, 01:31 AM

On the rectifiers i have 0.63 on legs 1 and 3 middle leg 0 volts

I should have my scope back this week its fixed all i need to do is buy some new probes.

My friend said hes comming over this week to set up my work stationn

So i have a sine wave generator, my scope, a amperge meter and all the good stuff So i should be back in business shortly

Perry Babin · 9th February 2010, 02:09 AM

Did you try placing the black probe on all of the points suggested?

mike49504 · 9th February 2010, 02:48 AM

yes on the center tap on the rca shield and on chasis ground still same readings

My friend testes the power supply in the amp and its working perfectly he said.

So the problem is in the output side somewhere

Perry Babin · 9th February 2010, 04:20 AM

What was the criteria used to determine that the power supply was working properly?

It's not producing any rail voltage.

mike49504 · 9th February 2010, 05:36 AM

we had the outputs out of the amp. And tested positive and negative rails, also tested the gates with my scope nice square waves on the gates and the rails both deflected the same

Perry Babin · 9th February 2010, 10:32 AM

Why are you getting ~0v of rail when you measure with your meter?

mike49504 · 9th February 2010, 04:13 PM

i dont understand this amp i get 0 volts of rail on outputs. Then i pulled the op-amp (kia393) and i got voltages at the outputs not what i need there but got like 7 volts to stay there so i replaced the kia393 with a lm393. Same thing 0 volts at outputs

Perry Babin · 9th February 2010, 08:26 PM

Post the voltages on the 393 and the 494.

494
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:

393
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:

mike49504 · 9th February 2010, 08:45 PM

It wont let me get the voltages off the 393

im gonna do somemore checking into the power supply of this amp and see what could be causing the no rail voltage issue.

Will it produce rail voltage without the driver board for the outputs in the amp?

Perry Babin · 9th February 2010, 08:50 PM

Having the output driver board out of the amp shouldn't cause the power supply to shut down.

What do you mean it won't let you measure the voltage on the 393?

9th February 2010, 02:09 AM	#32
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Did you try placing the black probe on all of the points suggested? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

9th February 2010, 04:20 AM	#34
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What was the criteria used to determine that the power supply was working properly? It's not producing any rail voltage. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

9th February 2010, 10:32 AM	#36
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Why are you getting ~0v of rail when you measure with your meter? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

9th February 2010, 08:26 PM	#38
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Post the voltages on the 393 and the 494. 494 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: 393 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

9th February 2010, 08:50 PM	#40
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Having the output driver board out of the amp shouldn't cause the power supply to shut down. What do you mean it won't let you measure the voltage on the 393? __________________ 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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9th February 2010, 01:31 AM	#31
mike49504 diyAudio Member Join Date: Sep 2006	On the rectifiers i have 0.63 on legs 1 and 3 middle leg 0 volts I should have my scope back this week its fixed all i need to do is buy some new probes. My friend said hes comming over this week to set up my work stationn So i have a sine wave generator, my scope, a amperge meter and all the good stuff So i should be back in business shortly

9th February 2010, 02:48 AM	#33
mike49504 diyAudio Member Join Date: Sep 2006	yes on the center tap on the rca shield and on chasis ground still same readings My friend testes the power supply in the amp and its working perfectly he said. So the problem is in the output side somewhere

9th February 2010, 05:36 AM	#35
mike49504 diyAudio Member Join Date: Sep 2006	we had the outputs out of the amp. And tested positive and negative rails, also tested the gates with my scope nice square waves on the gates and the rails both deflected the same

9th February 2010, 04:13 PM	#37
mike49504 diyAudio Member Join Date: Sep 2006	i dont understand this amp i get 0 volts of rail on outputs. Then i pulled the op-amp (kia393) and i got voltages at the outputs not what i need there but got like 7 volts to stay there so i replaced the kia393 with a lm393. Same thing 0 volts at outputs

9th February 2010, 08:45 PM	#39
mike49504 diyAudio Member Join Date: Sep 2006	It wont let me get the voltages off the 393 im gonna do somemore checking into the power supply of this amp and see what could be causing the no rail voltage issue. Will it produce rail voltage without the driver board for the outputs in the amp?

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