mojo2000

timwebb · 16th January 2011, 02:56 AM

i just got this amp and this part has blown.looks to be part of the current sensing in the amp.all i can read is hmr?

Perry Babin · 16th January 2011, 03:01 PM

If I'm not mistaken, the P-channel FETs use a 0.04 ohm resistor and the N-channel FETs use a 0.02 ohm resistor. There should be enough readable ones to confirm this.

timwebb · 17th January 2011, 02:41 PM

i looked up the part number but didnt get any where.

Perry Babin · 17th January 2011, 02:52 PM

This should get you closer. You'll have to measure them to get the correct size.
current sense resistor 0.04

timwebb · 17th January 2011, 08:43 PM

ok i got the amp to function but it has a ground issue every time i touch a gain nob or a rca jack it goes into protection.

Perry Babin · 17th January 2011, 08:47 PM

Assuming that there is no significant DC on the RCA jacks or across the speaker terminals... Does the amp produce clean audio when you connect a signal source and speakers?

Is the body of the pot loose (does the body wiggle more than the other pots when you touch it)?

Have you checked the RCA shield ground?

timwebb · 17th January 2011, 09:14 PM

ok there is 4vdc on the rca. 0vdc on the speaker terminals, all the pots are firm and in place. but does not produce audio.

Perry Babin · 17th January 2011, 09:25 PM

Do you have both positive and negative regulated voltage on the op-amp power supply pins?

timwebb · 17th January 2011, 09:54 PM

all TL072 op amps have 23.v and the 4559 have 11.5v

Perry Babin · 17th January 2011, 09:57 PM

Do all of them have negative voltage as well?

16th January 2011, 03:01 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If I'm not mistaken, the P-channel FETs use a 0.04 ohm resistor and the N-channel FETs use a 0.02 ohm resistor. There should be enough readable ones to confirm this. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

17th January 2011, 02:52 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	This should get you closer. You'll have to measure them to get the correct size. current sense resistor 0.04 __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

17th January 2011, 08:47 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Assuming that there is no significant DC on the RCA jacks or across the speaker terminals... Does the amp produce clean audio when you connect a signal source and speakers? Is the body of the pot loose (does the body wiggle more than the other pots when you touch it)? Have you checked the RCA shield ground? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

17th January 2011, 09:25 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have both positive and negative regulated voltage on the op-amp power supply pins? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

17th January 2011, 09:57 PM	#10
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do all of them have negative voltage as well? __________________ 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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17th January 2011, 02:41 PM	#3
timwebb diyAudio Member Join Date: Jan 2010 Location: memphis tn	i looked up the part number but didnt get any where.

17th January 2011, 08:43 PM	#5
timwebb diyAudio Member Join Date: Jan 2010 Location: memphis tn	ok i got the amp to function but it has a ground issue every time i touch a gain nob or a rca jack it goes into protection.

17th January 2011, 09:14 PM	#7
timwebb diyAudio Member Join Date: Jan 2010 Location: memphis tn	ok there is 4vdc on the rca. 0vdc on the speaker terminals, all the pots are firm and in place. but does not produce audio.

17th January 2011, 09:54 PM	#9
timwebb diyAudio Member Join Date: Jan 2010 Location: memphis tn	all TL072 op amps have 23.v and the 4559 have 11.5v

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