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Author Topic: MP-1 A channel much quieter than B  (Read 15083 times)

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Mxzx

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Re: MP-1 A channel much quieter than B
« Reply #15 on: Time Format »

Thanks, I'm guessing by master volume you mean master gain?

I did put that on 9 with with output level full open, and it still is quiet.

Thanks
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MarshallJMP

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Re: MP-1 A channel much quieter than B
« Reply #16 on: Time Format »

Try replacing U10,it's a NE5532,very common opamp.Maybe a tip,when you replace put a ic socket first.
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Mxzx

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Re: MP-1 A channel much quieter than B
« Reply #17 on: Time Format »

Will do, where exactly is it and where would I get a new one?

Thanks
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MarshallJMP

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Re: MP-1 A channel much quieter than B
« Reply #18 on: Time Format »

U10 is just behind the vol pot,it's a 8 pin ic,there is NE5532 printed on the top.Normally you can get it in any electronics store.
Where are you from?
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Mxzx

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Re: MP-1 A channel much quieter than B
« Reply #19 on: Time Format »

Thanks I'll check it out.

I live just outside of Louisville KY.
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MarshallJMP

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Re: MP-1 A channel much quieter than B
« Reply #20 on: Time Format »

Well in your case mouser does carry these.Or check out the local electronics store if there is one in your neighborhood.
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Mxzx

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Re: MP-1 A channel much quieter than B
« Reply #21 on: Time Format »

I called electronics store and no one seems to have it.  I don't mind ordering one, but Mouser lists a bunch of them.  Is there one in particular I should get?  Also if you could recommend a IC socket too that would be great.

Just so I am sure, is this the correct opamp?



Thanks again!
« Last Edit: Time Format by Mxzx »
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MarshallJMP

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Re: MP-1 A channel much quieter than B
« Reply #22 on: Time Format »

NE5532   http://mouser.com/ProductDetail/Texas-Instruments/NE5532P/?qs=sGAEpiMZZMtCHixnSjNA6Araa3jp4DVBKprmLw7OjBo%3d

socket  http://mouser.com/ProductDetail/3M-Electronic-Solutions-Division/4808-3000-CP/?qs=sGAEpiMZZMs%2fSh%2fkjph1tvt1%2fmEPT%2fXoueZQAPgo6HQ%3d
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Mxzx

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Re: MP-1 A channel much quieter than B
« Reply #23 on: Time Format »

Got it, thanks!

Just ordered them. 

I'll let you know how the install goes.
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MarshallJMP

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Re: MP-1 A channel much quieter than B
« Reply #24 on: Time Format »

BTW that's the correct opamp,so lets hope this is the problem.
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Mxzx

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Re: MP-1 A channel much quieter than B
« Reply #25 on: Time Format »

Update:

Just replaced the opamp with new socket and opamp, no difference.  One side still much quieter, when I swap the red plug around, it switches sides like before.

Any other ideas?
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MarshallJMP

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Re: MP-1 A channel much quieter than B
« Reply #26 on: Time Format »

-The top switch.
-Caps C56 or C49
-The front pot.
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Mxzx

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Re: MP-1 A channel much quieter than B
« Reply #27 on: Time Format »

Okay, thanks.

What do I need to do to test these?  The front volume knob works correctly when the red plug is switched back and forth, so would that eliminate it as a potential problem?

Do I need to replace the switch or is there a way to test.

Where are the caps on the board and can I test them installed with a meter?

Thanks again for your help on this.
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Sparker

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Re: MP-1 A channel much quieter than B
« Reply #28 on: Time Format »

You could try shorting C56 (connecting both pins together) then C49 and see if any difference to the volume.
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Mxzx

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Re: MP-1 A channel much quieter than B
« Reply #29 on: Time Format »

It was the switch!!  Started jiggling it around when plugged into a little practice amp and the volume came up.  Sprayed it with contact cleaner and worked switch back and forth, seems okay now.

Guess I'll be doing the switch mod to get it out of there and replace switch!!

Thanks all who helped!!
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