Im BAAAACK! Marathon amplifier question, won't work bridged mono!

[Perry Babin]

Run a 60-100Hz test tone into the amp and measure the AC voltage from pin 1 to pin 7 on the 8 pin op-amp that's in the center of the audio output section.

Also measure the AC voltage from each of those pins to the RCA shield (black lead on shield and red lead on each of the pins - 1 and 7).

Check it without a speaker connected and use enough signal level to get at least 1v on the individual pins of the op-amp.

If I'm not mistaken, you should get 2x the voltage when measuring across the terminals.



The secondary center-tap on this amp is where the windings go into the board just behind the two large filter capacitors. The trace goes over to the 4 center terminals on the vertical jumper board. All points connected to that trace should read 0 ohms to the shield ground.

[240z4u]

Perry, I am going to take some time tonight to set up a more functional test bench. I am working on the floor of my spare bedroom. I need more light and space now.

Ill also dig out my CD with test tones on it tonight. It may be tomorrow by the time I find it.

Evan

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