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.
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.
These are rather modern transistors.an old amp that has 14 toshiba 2sa1943 and 14 toshiba 2sc5200
Are you sure they are originally in this amp? Or maybe omeone simply swapped output transistors with newer ones without readjusting idle current?
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 web/lsa2000.htm
any ideas
http://www.legionsound.com/legion web/lsa2000.htm
any ideas
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?
Attachments
adlaic said: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 web/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?
adlaic said: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.
Huh?
Huh?????
adlaic said: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.
Huh?????
That amplifier (like most others) appears to have low voltage auxiliary rail supplies, probably +-15V. Since the fault appears in form of distortion equally in both channels, one of the first things that should be checked is whether these auxiliary supplies are working properly. The capacitor board appears to have a few smaller capacitors and heatsinks where +-15V regulators are probably located.
I have unsoldered the transistors off of one board when I check them with a ohm meter what reading should I get. On the NPN I am going from base to emitter and then base to collector. Same with the PNP but with the leads reversed. On the NPN I get readings and when I reverse the leads I get OL same with the PNP. But each transistor does not have the same reading.
When testing the transistors this way (B-E and B-C), the multimeter should read between 500 and 700 in one direction and OL in the other. Also, testing between E-C should produce OL in both directions. A few milivolts of difference between devices is normal. By the way, when mounting the transistors back try to place the ones with similar B-E readings together in the same bank.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Solid State
- distortion in amp Please help