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Author Topic: Srange Chorus problem  (Read 158 times)

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Pete66

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Srange Chorus problem
« on: Time Format »

Hello Everyone,

I'm having some strange issues with the Chorus effect on my MP-1. 
I traced the signal and the chorus effect goes from BBD out to NE570 and in and out of U11 and eventually to U10.  So it is making it way through the circuit but only in Line mode

In Line mode Chorus is working on outputs A and B.
In Instrument mode Chorus is not working on A or B
Chorus is always working in headphones output.
Chorus never works on Send / Receive loop.

Im not sure what to think of this.  Maybe bad Line switch?  But why no chorus on send / receive then?

Not sure where to check next.  Any ideas would be appreciated.

« Last Edit: Time Format by Pete66 »
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MarshallJMP

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Re: Srange Chorus problem
« Reply #1 on: Time Format »

No chorus in the loop is normal because the chorus is placed after the loop.

About the no chorus in instrument setting, my "guess" is that channel A and B is shorted together somehow in instrument setting, this way the original signal gets through, but since the chorus A and B is out of phase by 180° the chorus signal is canceled out. Best is to either replace the switch or just bridge it in line mode.
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Pete66

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Re: Srange Chorus problem
« Reply #2 on: Time Format »

No chorus in the loop is normal because the chorus is placed after the loop.

About the no chorus in instrument setting, my "guess" is that channel A and B is shorted together somehow in instrument setting, this way the original signal gets through, but since the chorus A and B is out of phase by 180° the chorus signal is canceled out. Best is to either replace the switch or just bridge it in line mode.

Well that was a great "guess".  I decided to check the switch and 2 of the pins are shorted together.  Upon further inspection, whoever soldered that switch put too much solder on those 2 pins and it flowed through the holes to the other side bridging the pins together.  There is no solder mask on this board.  I removed the switch resoldered it and everything works now.

Thanks!
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