It's possible that the signal is passing through a resistor to the inverting input of an op-amp. The normal operation of the op-amp would cancel all signal on that resistor (assuming that the non-inverting input of the same op-amp had no signal or was connected to a ground/reference).
If this is the case and you connect another resistor (1k ohm?) in series with it, you should be able to see signal on one end of the resistor when you reconnect the jumper wire. You could also follow the trace back to see if you can find the resistor that's already in the circuit. It would have signal on one of its terminals.
If this is the case and you connect another resistor (1k ohm?) in series with it, you should be able to see signal on one end of the resistor when you reconnect the jumper wire. You could also follow the trace back to see if you can find the resistor that's already in the circuit. It would have signal on one of its terminals.
Yep, I followed to a resistor on the bottom board and can see the signal when I use my meter on the other side of the resistor.
I also started tracing the origins of pin 1 on the input board. it seems like after the inputs for RF,LF,RR,LR pass through some resistors, then a buffer, then each one goes through a 39 k resistor and all of them connect to pin 1.
I also started tracing the origins of pin 1 on the input board. it seems like after the inputs for RF,LF,RR,LR pass through some resistors, then a buffer, then each one goes through a 39 k resistor and all of them connect to pin 1.
The signal on the resistor is passing through terminal 1. It may not seem like it's passing through but it is. The signal into the inverting input of the op-amp is effectively a current instead of a voltage.
This circuit sounds like a mixer for the 4 channels. They probably use the inverting input so that the voltage from the other channels cannot bleed back into the other channels. This saves them from having to insert a buffer op-amp for each channel.
This circuit sounds like a mixer for the 4 channels. They probably use the inverting input so that the voltage from the other channels cannot bleed back into the other channels. This saves them from having to insert a buffer op-amp for each channel.
Yeah, it looks like the resistor on the bottom board connects to the output of of an op-amp, there is a cap that connects that output to the inverting input, not sure if anything connects to the non-inverting side. Does this accomplish the same thing?
do you think this where my problem lies, with the fronts leaking onto the lp rear signal?
do you think this where my problem lies, with the fronts leaking onto the lp rear signal?
I don't quite understand the circuit you described.
I don't think you're getting the leakage here. It's not mixing the low pass and high pass from what you described.
Are you producing a schematic of this circuit? If so, after you have a bit more of it, post it or email it to me and I'll see if I can find where you're getting the leakage.
Does your circuit seem to be similar to the one I sent you?
I don't think you're getting the leakage here. It's not mixing the low pass and high pass from what you described.
Are you producing a schematic of this circuit? If so, after you have a bit more of it, post it or email it to me and I'll see if I can find where you're getting the leakage.
Does your circuit seem to be similar to the one I sent you?
okay, I'll work more on making a proper schematic.
Parts of the circuit you sent me seem similar. But it seems like that amp had inputs for the sub channels and the other channels were all hp? I was trying to find some that that made a summed lp signal for the rear channels but didn't see anything similar.
Parts of the circuit you sent me seem similar. But it seems like that amp had inputs for the sub channels and the other channels were all hp? I was trying to find some that that made a summed lp signal for the rear channels but didn't see anything similar.
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