Just built a JLH96 using this schematic:
I built it on a breadboard, point-to-point. Everything started out fine... I set my power supply for 0.2 amps and 0 volts. Attached the power supply, turned it on and rolled the voltage up to 2 volts. So far so good. I increased the voltage to 5 volts. All good. Then I went to 10, 15 and finally 22 volts. No smoke!
I have an 8 ohm 35 watt resistor attached to the output terminals. The dc offset was ~76 millivolts so I used VR1 to reduce it to 0 volts. Everything still seems good.
Next I increase the current to 1 amp. After which something must have blown. I didn't hear or smell anything but I could't read any voltage on the output terminals any longer. I turned the power supply off and waited a few minutes. Turned it back on and tried to change the dc offset with VR1 but it had no effect. The output transistors never got warm.
I have no idea where to start or how to begin troubleshooting this thing. Could anyone give me an idea of what to check or where to start??
Thanks much for your help -
Bruce
I built it on a breadboard, point-to-point. Everything started out fine... I set my power supply for 0.2 amps and 0 volts. Attached the power supply, turned it on and rolled the voltage up to 2 volts. So far so good. I increased the voltage to 5 volts. All good. Then I went to 10, 15 and finally 22 volts. No smoke!
I have an 8 ohm 35 watt resistor attached to the output terminals. The dc offset was ~76 millivolts so I used VR1 to reduce it to 0 volts. Everything still seems good.
Next I increase the current to 1 amp. After which something must have blown. I didn't hear or smell anything but I could't read any voltage on the output terminals any longer. I turned the power supply off and waited a few minutes. Turned it back on and tried to change the dc offset with VR1 but it had no effect. The output transistors never got warm.
I have no idea where to start or how to begin troubleshooting this thing. Could anyone give me an idea of what to check or where to start??
Thanks much for your help -
Bruce
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Thank you for your reply sreten, I'm using this one:
An externally hosted image should be here but it was not working when we last tested it.
Hi abpea,
Frustrating! Look there is a very large thread here (over 3,000 posts) on this amp/circuit at "JLH 10 Watt class A amplifier" (use search function). That is where all the JLH aficionados/gurus hang out. I think you'll get a quicker response from them if you post your question there. And that thread is also frequented by very civilized and helpful people.
Cheers,
Jonathan
Frustrating! Look there is a very large thread here (over 3,000 posts) on this amp/circuit at "JLH 10 Watt class A amplifier" (use search function). That is where all the JLH aficionados/gurus hang out. I think you'll get a quicker response from them if you post your question there. And that thread is also frequented by very civilized and helpful people.
Cheers,
Jonathan
Abpea now now moved to the JLH Thread
http://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier-156.html#post4448622
Could we now close this Thread?
http://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier-156.html#post4448622
Could we now close this Thread?
Continued here,
http://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier.html#post4448410
Thread closed.
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