Quick Amp Question

audiobahnkid592 · 9th November 2007, 01:00 AM

I just got this amp today with two blown IRFZ44N's in it replaced all 12 just to get smoke in the restistior next to the yellow box thing..not sure what that is. Took the yellow thing out amp functioned fine on my subs for ~30 min at full power with no problems. My question is Why was the resistor smoking and how bad is it to run the amp without that yellow thing in it? Sorry for the bad pics camera isnt that great.
PS yellow thing appears to be stamped either 7470nK 63 or T470nK 63

http://i227.photobucket.com/albums/d...P/DCP_3436.jpg

http://i227.photobucket.com/albums/d...P/DCP_3433.jpg

Perry Babin · 9th November 2007, 02:02 AM

The capacitor is a 470 nanoFarad 63 volt film capacitor with a ±10% tolerance. The 'T' is probably the manufacturer.

It appears that the capacitor is the wrong value. In all similar amps, the capacitor is a 47nF capacitor. A 470nF capacitor would allow much more of the square wave on the primary windings to pass through the resistor (instead of only passing the higher frequency ringing waveforms). This could cause the resistor to overheat. If you look at the other 3 snubber capacitors, you'll see that they're marked 473k 63.

audiobahnkid592 · 9th November 2007, 03:06 AM

Yes Perry they are marked 473k 63 this amp I know has been repaired(hack job) before I bought it and I aslo thought that was the wrong piece. Were Can I purchase this piece? would a store IE radioshack carry one or could order one? and What else will work in that spot? just that one number?

Perry Babin · 9th November 2007, 03:21 AM

Virtually any film capacitor of the same value will work in that application.

47nF = 0.047uF

This should work well. Confirm that they're the correct size (physically) before ordering.

http://www.mouser.com/search/refine....7%2f100%2f5%09

audiobahnkid592 · 12th November 2007, 05:30 PM

http://www.radioshack.com/product/in...entPage=family

Perry, Would these work for the application or no?

Perry Babin · 12th November 2007, 07:11 PM

Yes. The lead spacing may be wider than the others but other than that, they will work.

9th November 2007, 01:00 AM	#1
audiobahnkid592 diyAudio Member Join Date: Mar 2007	Quick Amp Question I just got this amp today with two blown IRFZ44N's in it replaced all 12 just to get smoke in the restistior next to the yellow box thing..not sure what that is. Took the yellow thing out amp functioned fine on my subs for ~30 min at full power with no problems. My question is Why was the resistor smoking and how bad is it to run the amp without that yellow thing in it? Sorry for the bad pics camera isnt that great. PS yellow thing appears to be stamped either 7470nK 63 or T470nK 63 http://i227.photobucket.com/albums/d...P/DCP_3436.jpg http://i227.photobucket.com/albums/d...P/DCP_3433.jpg

9th November 2007, 02:02 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The capacitor is a 470 nanoFarad 63 volt film capacitor with a ±10% tolerance. The 'T' is probably the manufacturer. It appears that the capacitor is the wrong value. In all similar amps, the capacitor is a 47nF capacitor. A 470nF capacitor would allow much more of the square wave on the primary windings to pass through the resistor (instead of only passing the higher frequency ringing waveforms). This could cause the resistor to overheat. If you look at the other 3 snubber capacitors, you'll see that they're marked 473k 63. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

9th November 2007, 03:21 AM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Virtually any film capacitor of the same value will work in that application. 47nF = 0.047uF This should work well. Confirm that they're the correct size (physically) before ordering. http://www.mouser.com/search/refine....7%2f100%2f5%09 __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

12th November 2007, 07:11 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Yes. The lead spacing may be wider than the others but other than that, they will work. __________________ 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 November 2007, 03:06 AM	#3
audiobahnkid592 diyAudio Member Join Date: Mar 2007	Yes Perry they are marked 473k 63 this amp I know has been repaired(hack job) before I bought it and I aslo thought that was the wrong piece. Were Can I purchase this piece? would a store IE radioshack carry one or could order one? and What else will work in that spot? just that one number?

12th November 2007, 05:30 PM	#5
audiobahnkid592 diyAudio Member Join Date: Mar 2007	http://www.radioshack.com/product/in...entPage=family Perry, Would these work for the application or no?

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