Resistance between the following points?
Q115 to Q119 center legs?
Q115 center leg to L+ speaker terminal?
Q119 center leg to L+ speaker terminal?
Q115 to Q119 center legs?
Q115 center leg to L+ speaker terminal?
Q119 center leg to L+ speaker terminal?
How can that be true if you have 0v across the speaker terminals but have the voltages you gave in post #336?
http://www.diyaudio.com/forums/car-audio/293482-rockford-301s-wont-power-up-34.html#post4803013
http://www.diyaudio.com/forums/car-audio/293482-rockford-301s-wont-power-up-34.html#post4803013
Well, I have no idea. I thought there wasn't supposed to be DC across the speaker terminals? I just remeasured.
Black lead on the L - speaker terminal. Red lead on the
Gate (leg 1) of the 9540 (Q119) 11.8VDC
Drain (center leg) 30.7VDC
Source (Leg 3) 30.7VDC
Both leads across the speaker terminals 0.00VDC
Black lead on the L - speaker terminal. Red lead on the
Gate (leg 1) of the 9540 (Q119) 11.8VDC
Drain (center leg) 30.7VDC
Source (Leg 3) 30.7VDC
Both leads across the speaker terminals 0.00VDC
Measure the DC voltage on the left + speaker terminal with the black probe on the primary ground.
Then with the black probe on the left+ speaker terminal.
Then with the black probe on the left+ speaker terminal.
0 Volts in both cases. I confirmed the meter was working by checking the gate of the IRF3205 in each case and had proper voltage. 5.5V
Something doesn't make sense. You have voltage on the drains of the outputs which appear to be directly connected to the speaker terminals but you have no voltage across the speaker terminals for that channel.
Well for giggles, I hooked up the other 301s and performed the measurements you just asked for. They were identical except, there was indeed 30.8 VDC across the speaker terminals of the left channel.
I'm confused though. I thought you said there should be less than 0.05VDC across the speaker outputs?
There should be very nearly 0.000v DC across the terminals. What's confusing on the original amp is that you have 30v on the output transistors but no DC on the speaker terminals.
Somewhere you are losing me in this one. You say, there should be nearly 0vDC across the terminals. Then you say, you have 30V on the output transistors but, no DC on the terminals.
Are you saying the DC should be there during testing when the output transistor is turned on but, shouldn't be there when there is actually audio being driven into the amp?
There should be no DC on the speaker terminals nor on the drains of the output FETs. The drains of the FETs are what drive signal to the speaker terminals. How do you have 30v on the drains but not on the speaker terminals if the drains are directly connected to the speaker terminals?
That clears it up. Shouldn't I then be looking for what is allowing DC to get to the output FETs?
Fortunately, I did get fed up a week and a half ago and ordered that Class D sub amp I previously linked you to. I've installed it so this 301 is an extra now.
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