power amplifier DB audio

View previous topic View next topic Go down

power amplifier DB audio

Post by triac on Thu Oct 05, 2017 10:02 am

Good Day Mga Sis,

Please help me with my power amplifier.When i turn the volume up,output transistor always gets busted,including transistor 2n5551 and resistors.Fuses are okay.May problema po ba ang power supply at ang pre-amp?Thank you all. Question

Things that i did:

i replace all the resistor,transistor na 2n5551,output transsitor.When i turn the volume up sunog na naman ang resistor at sira na rin yung output transistor.Kung 1/4 lang volume ko di naman masisira yung unit.  Question
avatar
triac
D Battery
D Battery

Posts : 697
Join date : 2011-04-28

Back to top Go down

Re: power amplifier DB audio

Post by ultrasonic™ on Sat Oct 07, 2017 12:27 am

pwede siguro sis sira ang spkr.. na try mo na e check baka sobrang mabigat na ang reading (very low resistance almost short).. or minsan naman sumasayad na voice coil... 

or else out bias iyan.. kaya nasusunog

_________________
6th member of STTM
former 2nd member


im always walking on the rain so that no one could see me crying
avatar
ultrasonic™
D Battery
D Battery

Posts : 4362
Join date : 2010-08-19
Age : 31
Location : Davao City

Back to top Go down

Re: power amplifier DB audio

Post by triac on Sat Oct 07, 2017 11:22 am

sis ultrasonic okay naman po yung speaker..tama ang resistance niya at hindi rin sumasayad ang voice coil niya..check ko po yung biasing na sinasabi mo..thank sa info sir..
avatar
triac
D Battery
D Battery

Posts : 697
Join date : 2011-04-28

Back to top Go down

Re: power amplifier DB audio

Post by danny on Fri Oct 13, 2017 2:25 pm

ilan ang idling current /bias current mo?
avatar
danny
D Battery
D Battery

Posts : 406
Join date : 2012-04-16
Location : Seattle, Washington

http://www.washingtonelec.com

Back to top Go down

Re: power amplifier DB audio

Post by triac on Wed Oct 18, 2017 5:24 pm

@sir danny,sir ano po yung idling at bias current?paano e measure yan sa analog tester?sorry po sir danny baguhan pa lang po ako.salamat.
avatar
triac
D Battery
D Battery

Posts : 697
Join date : 2011-04-28

Back to top Go down

Re: power amplifier DB audio

Post by Hertz on Wed Oct 18, 2017 10:48 pm

Getting Bias Current of an Output Transistor of an Amplifier Circuit

In this article, we will be focused on getting the bias current of an output transistor of an amplifier circuit. According to wikipedia:
Biasing in electronics is the method of establishing predetermined voltages or currents at various points of an electronic circuit to set an appropriate operating point. The operating point of a device, also known as bias point, quiescent point, or Q-point, is the steady-state operating condition of an active device (a transistor or vacuum tube) with no input signal applied.
This is the method shared by ricdelros, one of the Elab Forum member, based on the topic about how to get the bias current of an output transistor” Bias voltage can be simply check by following situations that will serve as a guide.
 
1. Power-up the amplifier circuit without Output Transistor.
Having a driver transistors can provide a few hundred milliwatts of power without the Output Transistor which should be enough to tell if an amplifier operation is correct. If it’s going right so far, turn of power and connect the output transistors, turn the bias trimmer to max resistance, connect 8 Ohms load and apply power again.
Example: If you have 60w amp, connect a DC Voltmeter across either of Output Emitter Resistor and adjust Bias Trimmer and adjust trimmer for a reading of slightly less than 20mv, this will set an Idle Current of around “50mA” which is close to specs of 60w. Watch your multimeter while testing. If at anytime the reading jumps when you have no input, “”STOP”” and check quickly for circuit oscillation, if you are not lucky, such condition may blow fuse, amplifier with this kind of problem can cause heartburn and lots of ulcer and stress. Recheck the circuits..


2. Another way is to check Both Emitter Resistor voltage of the output transistor. Connect a Positive lead to Point M and a negative lead to Point N and advance the idle by trimmer until you get a voltage reading of 20 millivolts below.


3. Other very simplest way is to connect a Milliammeter between the Power Supply Source and to either Positive or Negative Rail Terminal (must have a firm connection or else a little loose can blow the opposite fuse). You can see the the idle current here of 50mA as registered in step 1. This method is the one we used in testing the idle current taught by our instructor while I’m studying electronics.


ilabas lang natin ito Sir Danny

_________________
3rd member of STTM
former 4th member
avatar
Hertz
Admin
Admin

Posts : 1520
Join date : 2010-08-12
Age : 37
Location : Cagayan De Oro City

Back to top Go down

Re: power amplifier DB audio

Post by triac on Thu Oct 19, 2017 4:27 pm

@Hertz,thank you po dito sir,+1 po sa iyo.dagdag kaalaman po.
avatar
triac
D Battery
D Battery

Posts : 697
Join date : 2011-04-28

Back to top Go down

Re: power amplifier DB audio

Post by triac on Wed Nov 22, 2017 11:31 am

mga sis next week pa ako maka update nito.salamat.
avatar
triac
D Battery
D Battery

Posts : 697
Join date : 2011-04-28

Back to top Go down

Re: power amplifier DB audio

Post by Electro on Sat Dec 02, 2017 9:31 pm

musta ito master triac?
avatar
Electro
D Battery
D Battery

Posts : 1475
Join date : 2010-08-26
Age : 28
Location : Calinan Davao City

Back to top Go down

Re: power amplifier DB audio

Post by triac on Thu Dec 07, 2017 11:07 am

update ko lang ito mga sis..okay na po ang unit..

defective parts A940 & C2073 leaky po ito mga sis..at isa pa sa bangongot ko,nakabili ako ng mga transistor na leaky rin pala.Thanks master electro..sir hertz,sir ultra,at sir danny +1 po sa inyong lahat cheers
avatar
triac
D Battery
D Battery

Posts : 697
Join date : 2011-04-28

Back to top Go down

Re: power amplifier DB audio

Post by alvinquimbo on Thu Dec 07, 2017 3:51 pm

congratulation congratulation congratulation
avatar
alvinquimbo
D Battery
D Battery

Posts : 773
Join date : 2014-03-29
Age : 29
Location : Davao City

Back to top Go down

Re: power amplifier DB audio

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum