Dead amp..nothing burnt, but visible orange crust.

marcello7x · 2nd October 2006, 06:25 AM

My amp died about 3 months ago and i finally got around to taking it apart to look at the board. I am not very experienced with working on board, but am studiing electrical engineering in school and know a little about this stuff.

None of the caps seem to be bulging, and all the transistors look in good shape, haven't tested them yet. Could the crust be because of early faliure from the caps? And the system when before they could buldge.

Also what is the best way to test the mosfets without removing them from the board.

Attached is a pic of the amp. its an audiobahn a2300hct.

singa · 2nd October 2006, 06:34 AM

Hi,
The orange crust is leftover flux residue.(Not thoroughly cleaned).Check mosfet pins with multimeter probably shorted.

Power off!

marcello7x · 2nd October 2006, 02:55 PM

Which pins should i check? I did a quick test not sure what i was looking for and found some mosfets having a resistance of 0. Are those the shorted ones? A whole row of 4 on each side had this. I would have to replace all four on each side correct?

TO-3 · 2nd October 2006, 04:39 PM

Quote:

Originally posted by marcello7x
Which pins should i check? I did a quick test not sure what i was looking for and found some mosfets having a resistance of 0. Are those the shorted ones? A whole row of 4 on each side had this. I would have to replace all four on each side correct?

A 0 ohm resistance would indicate that one ore all four of the devices has shorted. You must replace them all as if one goes, the other try to pick up the rest but it only stresses out the other remaining parts. You may be able to just swap the parts and be done with it or there may be another problem that caused the parts to fail. I did not look at the pic but I am assuming that they are power supply mosfets. Either they had inadequate heat-sinking or there may be a problem in the audio section.

marcello7x · 2nd October 2006, 05:25 PM

The amp worked fine till i had run the subs to 1ohm or less. They were theoretically at one ohm, if the speakers were rated correctly, which i found out they almost never are. I am going to check the mosfets when i get home from school tonite and give an update then.

Bose(o) · 10th October 2006, 02:12 AM

Why don't we run our speakers at lowly resistances? So we don't blow our amplifiers!

10th October 2006, 02:12 AM	#6
Bose(o) diyAudio Member Join Date: Dec 2001 Location: Ottawa, Ontario, Canada	Why don't we run our speakers at lowly resistances? So we don't blow our amplifiers! __________________ ERTW 4 life! "the day has 24hours. If that is not enough take the night."-Roemhild

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Difference between Analogue and Digital made visible. Not	Netlist	Everything Else	37	2nd October 2006 11:54 AM
Hidden clipping made visible.	Netlist	Digital Source	9	30th January 2006 08:11 AM
Careers, or: What do you do for a crust?	SHiFTY	Everything Else	24	29th January 2003 03:08 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

2nd October 2006, 06:34 AM	#2
singa diyAudio Member Join Date: Apr 2004 Location: near	Hi, The orange crust is leftover flux residue.(Not thoroughly cleaned).Check mosfet pins with multimeter probably shorted. Power off!

2nd October 2006, 02:55 PM	#3
marcello7x diyAudio Member Join Date: Sep 2006	Which pins should i check? I did a quick test not sure what i was looking for and found some mosfets having a resistance of 0. Are those the shorted ones? A whole row of 4 on each side had this. I would have to replace all four on each side correct?

2nd October 2006, 05:25 PM	#5
marcello7x diyAudio Member Join Date: Sep 2006	The amp worked fine till i had run the subs to 1ohm or less. They were theoretically at one ohm, if the speakers were rated correctly, which i found out they almost never are. I am going to check the mosfets when i get home from school tonite and give an update then.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)