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amp problems blown transistor?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=110381
Printed Date: June 10, 2024 at 12:10 PM


Topic: amp problems blown transistor?

Posted By: bradlym
Subject: amp problems blown transistor?
Date Posted: January 05, 2009 at 11:15 PM

I have a 4ch Planet Audio Zentar ZR300.4. As I was driving today my amp went into protect mode. Restarted the car, light still on. I disassembled the amp, and tested the four different channels with a DMM. I have come to the conclusion that ch1 has gone bad. I have checked for continuity on one of the transistors labeled A1695 63 P. All three prongs tested positive for continuity. I tested the rest of the transistors on that ch and have found that some of them will read continuity with two of the prongs. The A1695 is the only one to have continuity among all three prongs. Would anyone know what I should do now? Is it fixable?

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MECP Basic certified



Replies:

Posted By: i am an idiot
Date Posted: January 06, 2009 at 2:10 AM
Yes it is repairable. Each channel has 2 output transistors. The 2SA1695 and also a 2SC4467?? May or not be a 4467 but I am pretty sure it is. One of them is a PNP transistor and the other is an NPN transistor. They are both rated at the same current. Only the 1695 may have failed, but they both went through the same abuse. In order to ensure that the 2SC device is not weakened from the same incident that took out the 1695, it needs to be replaced also. Some amplifiers will take out driver transistors and resistors when the output shorts. This amp usually takes out the output only. So if you replace both of them, it should be fine. MCM electronics has both of these parts in stock. When removing the original parts, do not use any desoldering braid until you get the parts removed. Put extra solder on each leg of the transistor and then heat up all 3 legs at once, by laying your soldering iron across the 3 pads. Once the solder is heated up on all legs, using a pair of pliers, (only so you do not burn your fingers) gently rock the part intil it comes out of the board. Then use desoldering braid to clean the holes to accept the new parts.




Posted By: bradlym
Date Posted: January 06, 2009 at 9:36 AM
Great thanks for the help I will try this, any reason why it may have gone bad?

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MECP Basic certified




Posted By: i am an idiot
Date Posted: January 06, 2009 at 4:48 PM
Trying to pull too much current through the device.  The amp was too hot.   Not sure about the current rating on those particular transistors, but a transistor rated at 15 amps at 75 degrees F.  the same tranny is capable of producing about 5 amps at 200 degrees.  So basically the hotter the amp gets the more vulnerable the parts are.




Posted By: bradlym
Date Posted: January 06, 2009 at 6:03 PM
Ok one last thing MCM has the 2SC4468 on backorder for like three months. Would there be a comparable model to this transistor?

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MECP Basic certified




Posted By: i am an idiot
Date Posted: January 06, 2009 at 6:14 PM

I have no experience with this company.  They do have both in stock.  They have a 15 dollar minimum order.  Order enough of each to make the minimum. 

https://www.bdent.com/search/part.jsp?partnum=2SC4468






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