therocket290
Member
I was helping my buddy clean up and adust the DC offset and idle current on his Optonica SA-5606. We set the DC offset first and that was fine. When setting the idle current, our goal was 10mv between two test points. The left channel had zero voltage between the test points, regardless of where the variable resistor was set. The highest we could get the voltage on the right channel was about 0.5mv. I am by no means an expert, but I have adjusted dc offset and bias on other receicers. So I am pretty sure I am using my multmeter correctly and measuring at the correct points.
When we set it back up, it sounded fine. However, the heatsink for the transistors on the right channel heated up very quickly while the other heatsink stayed cool. I'm talking over 160 degrees F in under 10 minutes. I'm pretty sure that is not normal for this type of amplifier. We didn't notice any difference in how the left and right channels sounded and they sounded fine.
I'm wondering if anyone has any ideas about
1) Why there is less than 0.5mv at the test points for idle current when there should be 10mv?
and
2) Why one heatsink is getting very hot while the other is barely warm? The one getting hot is the only channel showing significant voltage (but still less than 0.5mv) at the test points for idle current.
Thanks.
When we set it back up, it sounded fine. However, the heatsink for the transistors on the right channel heated up very quickly while the other heatsink stayed cool. I'm talking over 160 degrees F in under 10 minutes. I'm pretty sure that is not normal for this type of amplifier. We didn't notice any difference in how the left and right channels sounded and they sounded fine.
I'm wondering if anyone has any ideas about
1) Why there is less than 0.5mv at the test points for idle current when there should be 10mv?
and
2) Why one heatsink is getting very hot while the other is barely warm? The one getting hot is the only channel showing significant voltage (but still less than 0.5mv) at the test points for idle current.
Thanks.