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Temp "Time Format" issue Fix in Discussions

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Author Topic: New MP-2, need some help!  (Read 26148 times)

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rickeb1

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Re: New MP-2, need some help!
« Reply #15 on: Time Format »

Well, I got the new SSM2120 chip today and was able to replace the old one without too much difficulty.  The chip is actually just to the left of the one pointed to in the photo from SC, and was a little tricky because it is almost completely covered by a circuit board above it.  Anyway, I put in the new chip, fired it up, and ... I still have the same problem: no sound at all from the unit with the compressor engaged.  :(  On top of that, I've discovered that the wah does not seem to work, either.  If I switch the wah in, no matter what I set it to, when I pick a note, all I get is a low buzzing noise.  So, no compressor and no wah.

I'm not sure what to do with this.  Part of me wants to make an issue of this with the eBay seller and try to return it for a refund.  On the other hand, it sounds good, I most likely wouldn't use the wah feature anyway, and I can probably live without the compressor.  But then if I ever sell it, I'll have to sell it for a lot less than I paid for it as I'd have to sell it as damaged goods to a degree.  I'll have to think about this...
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MarshallJMP

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Re: New MP-2, need some help!
« Reply #16 on: Time Format »

It seems U207 is busted since both the compressor and wah don't work.So i would try to replace it,use only the same opamp,the OPA2604AP,these are the only opamps that can handle +-24V!!!Since you're going to replace U207 i would also order an extra one for U205 because when one usually goes the other one goes too.
U207 is located just above the SSM2120 (U210)(a little on the left).See attached pdf.And U205 is located just above U207.Both opamps are in a socket so easy to replace.
« Last Edit: Time Format by MarshallJMP »
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rickeb1

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Re: New MP-2, need some help!
« Reply #17 on: Time Format »

Thank you very much for all the info, I guess I'll give it one more try!  Are U207 and U205 the same chip?
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Systematic Chaos

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Re: New MP-2, need some help!
« Reply #18 on: Time Format »

Sorry to hear you still got problems.....
But yap, both U205 and U207 are OPA2604AP.

Aaand....since it sure as hell happened/happens to all of f us  :facepalm: Watch the orientation of the ICs when replacing them  ;D
« Last Edit: Time Format by Systematic Chaos »
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rickeb1

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Re: New MP-2, need some help!
« Reply #19 on: Time Format »

Ok, I received the new op amps and replaced U207, and if anything, it's gotten worse.  Not only did it not fix the issues with the compressor and wah, the volume seems to have dropped, and using any voices other than clean results in a lot of low hum, noise and feedback.  I think I give up on this thing, and will try to force the seller to take it back.  Very disappointing, as I was really hoping this unit would work out.
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RobbHell

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Re: New MP-2, need some help!
« Reply #20 on: Time Format »

Did you have good solder joints?  It has traces on both sides.
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rickeb1

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Re: New MP-2, need some help!
« Reply #21 on: Time Format »

It was in a socket, so I just pulled the old one and put in the new one, being careful to keep the same orientation as SC pointed out.
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MarshallJMP

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Re: New MP-2, need some help!
« Reply #22 on: Time Format »

Do you also have this hum with the comp and wah switched off?Did you replace them both?
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rickeb1

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Re: New MP-2, need some help!
« Reply #23 on: Time Format »

Yes, the hum is with both the comp and wah switched off.  I only replaced U207, but I did buy an extra IC, so I could replace U205 as well.  Would that be worth trying?
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MarshallJMP

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Re: New MP-2, need some help!
« Reply #24 on: Time Format »

You can try it to see if it will work but with the comp and wah off these are not in the signal chain,so i doubt this will be the cause of the hum.Did you check R913?

First try to measure the high voltage.Look at the pdf i attached,you will see the HV test point,measure between the chassis and this test point,it should read 190Vdc,if it's higher like more then 200V you should desolder one end of R913 and measure the resistance,this should be 240k,if not replace it with a 1/2W 240k metal film resistor.This usually gets rid of the hum.

So keep me updated.
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rickeb1

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Re: New MP-2, need some help!
« Reply #25 on: Time Format »

Ok, I worked out the volume problem - totally my error, as I had it hooked up incorrectly in the back (there are a lot of jacks back there!).  So, the issue now is just the comp and the wah.  I will try replacing U205 and see if that helps.
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Systematic Chaos

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Re: New MP-2, need some help!
« Reply #26 on: Time Format »

Good to hear!! While you´re at it, do as MJMP suggested and replace R913...the MP-2 will be quieter in terms of hum/noise
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MarshallJMP

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Re: New MP-2, need some help!
« Reply #27 on: Time Format »

Like SC says try it out anyway,do those measurements,if they are good,fine,if not replace the R913.

Ok keep us updated
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rickeb1

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Re: New MP-2, need some help!
« Reply #28 on: Time Format »

Well, I replaced U205, and if anything, I think it made it worse.  :(  As far as taking measurements and replacing soldered components, it's way beyond my abilities, I'm afraid.  I think at this point I need to have someone much more competent than I take a look at this thing.  MarshallJMP is The Man, but since I'm in the States, is there anyone closer to home who could look at it?  RobbHell maybe?

Thanks again to all of you for your continuing help with these problems, I am very grateful!

~ Rick
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Systematic Chaos

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Re: New MP-2, need some help!
« Reply #29 on: Time Format »

Trullmon (Matt Trull) still around here??? IIRC he fixed Dante's and Adam's MP-2...he's in the US, so you might wanna get in touch with him...
I don't have his ctc-details but I think Dante has....
« Last Edit: Time Format by Systematic Chaos »
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