ktaylor@supernet.dallas.haus.com (Kurt Taylor) (02/23/91)
I have an old (broken :') tube amp with a pair 6L6GC's for the output tubes.t These tubes feed an output transformer which in turn drives the speakers. My questions are these : I have replaced all the defective parts that I can find. Even replaced all of the tubes with known good ones. All voltages are correct. Still there is a loud screech at the speakers when the amp is powered up. Could this mean that the output transformer is bad ? How can I test it ? Is there something else that I am overlooking ? Dang those output transformers are expensive ! Otherwise I would just replace it. Also is there a cheaper place to buy out. trans. ? I know, alot of questions. How about these simple questions oh great net wisdom...... :') Thanks in advance, Kurt Taylor
kludge@grissom.larc.nasa.gov ( Scott Dorsey) (02/25/91)
In article <1991Feb23.045313.29888@supernet.dallas.haus.com> ktaylor@supernet.dallas.haus.com (Kurt Taylor) writes: >I have replaced all the defective parts that I can find. Even replaced >all of the tubes with known good ones. All voltages are correct. Still >there is a loud screech at the speakers when the amp is powered up. Could >this mean that the output transformer is bad ? How can I test it ? Is there >something else that I am overlooking ? If there is a loud screech at the output, then there is something which is going into oscillation. Disconnect the input stage from the finals. If it continues to screech, then the finals are going into oscillation, otherwise it's probably the input stage. Check all components that are in the negative feedback loops... you'll probably find something open there. --scott