distortion in amp Please help

adlaic · 16th March 2006, 10:34 PM

I just bought an old amp that has 14 toshiba 2sa1943 and 14 toshiba 2sc5200 the amp plays but it has distortion at all volumes.

Any idea what could be wrong with it? It is a two channel amp has 7 2sa1943 and 7 2sc5200 for each channel it also has fault and clip lights on the amp. The fault and clip lights are not on.

darkfenriz · 16th March 2006, 10:47 PM

Quote:

an old amp that has 14 toshiba 2sa1943 and 14 toshiba 2sc5200

These are rather modern transistors.
Are you sure they are originally in this amp? Or maybe omeone simply swapped output transistors with newer ones without readjusting idle current?

adlaic · 16th March 2006, 11:58 PM

I don't guess its that old of a amp the amp is a legion by madison model no LSA-2700 does anyone know anything about this amp. The louder you turn it up the less distorition you get. it is similer to this amp

http://www.legionsound.com/legion%20web/lsa2000.htm

any ideas

adlaic · 17th March 2006, 12:21 AM

here is a picture of the amp

adlaic · 17th March 2006, 01:23 PM

can a bad transister cause it to have distortion or would it not work at all if it had a bad transister. I bypassed the build in crossover and vol. knobs and it has the same distortion. So I know its not the crossover or the vol. knobs. could a bad resistor cause this? Both channels are doing the same thing. what should the rail voltage be? the rail voltage is around 130v is that to high or about right?

adlaic · 17th March 2006, 01:29 PM

it has some ceramic resistors .22 ohm 5w and the ceramic is comming off of a couple of them. What would cause this?

adlaic · 17th March 2006, 01:35 PM

picture

http://www.diyaudio.com/forums/attac...&postid=871707

ilimzn · 17th March 2006, 02:01 PM

Quote:

Originally posted by adlaic
I don't guess its that old of a amp the amp is a legion by madison model no LSA-2700 does anyone know anything about this amp. The louder you turn it up the less distorition you get. it is similer to this amp

http://www.legionsound.com/legion%20web/lsa2000.htm

any ideas

You seem to write a lot more than you read!

It sounds like a missing bias problem. Do you know how to measure it?

Elso Kwak · 17th March 2006, 02:08 PM

Quote:

Originally posted by adlaic
it has some ceramic resistors .22 ohm 5w and the ceramic is comming off of a couple of them. What would cause this?

The resistors could have been overheated causing them to open. Check with Ohm-meter. In that case I would not trust drivers and output transistors either.

adlaic · 17th March 2006, 06:55 PM

I'm sorry that I have reading on this site for over 24 hours and havent found anything that is helping me so I am asking questions for someone that might know how to help me.

16th March 2006, 10:34 PM	#1
adlaic diyAudio Member Join Date: Feb 2006 Location: united states	distortion in amp Please help I just bought an old amp that has 14 toshiba 2sa1943 and 14 toshiba 2sc5200 the amp plays but it has distortion at all volumes. Any idea what could be wrong with it? It is a two channel amp has 7 2sa1943 and 7 2sc5200 for each channel it also has fault and clip lights on the amp. The fault and clip lights are not on.

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16th March 2006, 11:58 PM	#3
adlaic diyAudio Member Join Date: Feb 2006 Location: united states	I don't guess its that old of a amp the amp is a legion by madison model no LSA-2700 does anyone know anything about this amp. The louder you turn it up the less distorition you get. it is similer to this amp http://www.legionsound.com/legion%20web/lsa2000.htm any ideas

17th March 2006, 01:23 PM	#5
adlaic diyAudio Member Join Date: Feb 2006 Location: united states	can a bad transister cause it to have distortion or would it not work at all if it had a bad transister. I bypassed the build in crossover and vol. knobs and it has the same distortion. So I know its not the crossover or the vol. knobs. could a bad resistor cause this? Both channels are doing the same thing. what should the rail voltage be? the rail voltage is around 130v is that to high or about right?

17th March 2006, 01:29 PM	#6
adlaic diyAudio Member Join Date: Feb 2006 Location: united states	it has some ceramic resistors .22 ohm 5w and the ceramic is comming off of a couple of them. What would cause this?

17th March 2006, 06:55 PM	#10
adlaic diyAudio Member Join Date: Feb 2006 Location: united states	I'm sorry that I have reading on this site for over 24 hours and havent found anything that is helping me so I am asking questions for someone that might know how to help me.

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