Alpine MRV-1002

m4ick · 05:03 PM

This amp had 2 shorted outputs and one blown power supply. The other power supply is still in tact. The power supply that was still in tact is being regulated and the one that I am using the 3205s in has a wider pulse width indicating to me that that power supply is working harder to maintain voltage.

When I power the amp on I get -46V on the secondary CT and on the RCA shields. I'm not sure what is causing it, any help would be appreciated.

m4ick · 22nd February 2012, 05:06 PM

As a side note, the secondary CT starts at -18 volts and moments later jumps to -46.

Perry Babin · 22nd February 2012, 05:25 PM

Do you have both positive and negative rail voltage on the output transistors?

m4ick · 22nd February 2012, 05:56 PM

Referenced from secondary CT I have +- rail voltage.

Referenced from amplifier ground I have approximately +1.8 and -96.

m4ick · 07:21 PM

Just for your information this amp uses 2 494Cs, one for each power supply. Each power supply generates separate rail voltage for each channel. + rail on one channel is not directly connected to + rail on the other.

Each of the 494s has .25vdc on pin 4 yet each one is showing different dead times.

m4ick · 22nd February 2012, 07:55 PM

Nevermind the different dead times, there's a pot for each 494 that feeds pin 1. Is there a certain pulse width I should set this to?

Other than setting the dead time, the only issue I have now is the -46v on the secondary CT. Referenced from secondary CT I have about +-48v. Both sets of rails are having the same symptoms, -46V at secondary ground.

Perry Babin · 22nd February 2012, 08:07 PM

Is one of the rectifiers or outputs shorted to the heatsink?

m4ick · 22nd February 2012, 08:16 PM

The rectifiers are in plastic cases and I don't get continuity between the center leg of any outputs and the metal plate.

Also, from a cold start the sec CT is at -18V, as soon as I turn off my power supply it jumps to the -40s and begins to discharge. Each time I start it after that without allowing it to fully discharge it goes directly to -46v.

Perry Babin · 22nd February 2012, 08:40 PM

Email me.

babin_perry@yahoo.com

22nd February 2012, 05:01 PM	#1
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Alpine MRV-1002 This amp had 2 shorted outputs and one blown power supply. The other power supply is still in tact. The power supply that was still in tact is being regulated and the one that I am using the 3205s in has a wider pulse width indicating to me that that power supply is working harder to maintain voltage. When I power the amp on I get -46V on the secondary CT and on the RCA shields. I'm not sure what is causing it, any help would be appreciated. __________________ Scope - DMM - 460W Computer PSU - Tutorial Last edited by m4ick; 22nd February 2012 at 05:03 PM.

22nd February 2012, 05:06 PM	#2
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	As a side note, the secondary CT starts at -18 volts and moments later jumps to -46. __________________ Scope - DMM - 460W Computer PSU - Tutorial

22nd February 2012, 05:25 PM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have both positive and negative rail voltage on the output transistors? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

22nd February 2012, 05:56 PM	#4
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Referenced from secondary CT I have +- rail voltage. Referenced from amplifier ground I have approximately +1.8 and -96. __________________ Scope - DMM - 460W Computer PSU - Tutorial

22nd February 2012, 07:03 PM	#5
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Just for your information this amp uses 2 494Cs, one for each power supply. Each power supply generates separate rail voltage for each channel. + rail on one channel is not directly connected to + rail on the other. Each of the 494s has .25vdc on pin 4 yet each one is showing different dead times. __________________ Scope - DMM - 460W Computer PSU - Tutorial Last edited by m4ick; 22nd February 2012 at 07:21 PM.


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22nd February 2012, 07:55 PM	#6
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Nevermind the different dead times, there's a pot for each 494 that feeds pin 1. Is there a certain pulse width I should set this to? Other than setting the dead time, the only issue I have now is the -46v on the secondary CT. Referenced from secondary CT I have about +-48v. Both sets of rails are having the same symptoms, -46V at secondary ground. __________________ Scope - DMM - 460W Computer PSU - Tutorial

22nd February 2012, 08:07 PM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Is one of the rectifiers or outputs shorted to the heatsink? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

22nd February 2012, 08:16 PM	#8
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	The rectifiers are in plastic cases and I don't get continuity between the center leg of any outputs and the metal plate. Also, from a cold start the sec CT is at -18V, as soon as I turn off my power supply it jumps to the -40s and begins to discharge. Each time I start it after that without allowing it to fully discharge it goes directly to -46v. __________________ Scope - DMM - 460W Computer PSU - Tutorial

22nd February 2012, 08:40 PM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Email me. babin_perry@yahoo.com __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

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