I'm trying to figure out why this echo board has a PA and PA+ connection, what are they and why are they there? I'm retrofitting a different echo board and not sure what to do with these PA wires. I have my suspicions.
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Galaxy DX33hml echo pinout question
- Thread starter Cable Guy
- Start date
This type of echo board is inline with the mic and the audio IC in PA mode and inline with the mic and mic gain knob in AM mode.
PA is just that, the public adress system which I'm sure you already may know. To retain the PA mode just connect PA+ and PA wires together or leave it alone if you don't care about using the PA.
Correct me if I'm wrong
PA is just that, the public adress system which I'm sure you already may know. To retain the PA mode just connect PA+ and PA wires together or leave it alone if you don't care about using the PA.
Correct me if I'm wrong
Thanks, that's what I was kinda thinking, just not sure why echo board needs to know when pa is on or off unless it solely handles the PA function.This type of echo board is inline with the mic and the audio IC in PA mode and inline with the mic and mic gain knob in AM mode.
PA is just that, the public adress system which I'm sure you already may know. To retain the PA mode just connect PA+ and PA wires together or leave it alone if you don't care about using the PA.
Correct me if I'm wrong
View attachment 71668
After looking at the schemo, pa+ is just for switching a transistor on.
Not sure why it takes mic output and feeds it to amp input, pin4 of ta7222ap. Seems like it would create a loop. Maybe I'm not looking at it right.
Edit: I figured it out. I was thinking mic audio was already passed thru the audio ic (brain fart), then remembered the 4558...
Not sure why it takes mic output and feeds it to amp input, pin4 of ta7222ap. Seems like it would create a loop. Maybe I'm not looking at it right.
Edit: I figured it out. I was thinking mic audio was already passed thru the audio ic (brain fart), then remembered the 4558...
Last edited:
Okay, PA+ is an 8v source switched from the mode selector. It turns on a transistor on the echo board. That transistor takes some mic audio and pipes it out the PA pin into the ta7222ap input.
The ta72222ap normally amps up Rx audio only, unless in PA mode, and feeds it to the speaker or jack and is NOT connected with the modulator (my confusion). The 4558 mic amp/tr switch is connected to the modulator/AM regulator and handles tx audio.
With the retrofitted echo board installed, PA isn't going to work. I think with a relay and resistor, or a transistor and a few resistors, PA can be made to work again. No biggie.