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Author Topic: MP-2 Bad pots  (Read 5079 times)

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chipdougal

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MP-2 Bad pots
« on: Time Format »

I bought replacement pots off of ebay for the room eq and the volume.  I took off the cover to see that access to the pots is blocked by a circuit board.

How can I remove the pots and put in the replacement ones, I am afraid to just start unsoldering stuff or trying to pull that board off I can't tell how it is connected.
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MarshallJMP

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Re: MP-2 Bad pots
« Reply #1 on: Time Format »

Actually the pots are soldered to that pcb. So you need to unscrew both pots from the front panel, then you can remove the small pcb and desolder the pots. Put the new ones on and put it all back.
BTW it's connected by wires going to different places on the main pcb.(with connectors)
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chipdougal

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Re: MP-2 Bad pots
« Reply #2 on: Time Format »

Thanks appreciate it.
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rnolan

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Re: MP-2 Bad pots
« Reply #3 on: Time Format »

Don't forget to draw a picture of what wires go where  O:-)
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MarshallJMP

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Re: MP-2 Bad pots
« Reply #4 on: Time Format »

Well you can desolder the pots without removing the connectors if you like.
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chipdougal

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Re: MP-2 Bad pots
« Reply #5 on: Time Format »

How the hell do you get these things out of here.  I started desoldering it sucking up the solder with a desoldering tool from the back side of the PCB but it seems impossible to remove still.
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MarshallJMP

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Re: MP-2 Bad pots
« Reply #6 on: Time Format »

Since this is a double sided PCB,so soldered on both sides, it takes a bit of skill to remove it. Make sure you don't damage the PCB by applying to much heat. Best thing is if it doesn't come loose after you sucked out the solder, resolder it again and try again. Don't try to suck up some remainder because it won't work.
What are you using to remove the solder?
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rnolan

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Re: MP-2 Bad pots
« Reply #7 on: Time Format »

Also worth getting some desolder wick/braid.  I've found 3mm (wide, it comes in various widths) works well for that sort of job.  Mike used it when he did his MP1 pots (much the same job) and it worked well, seemed to me better than a solder sucker for that kind of desolder (ie fair bit of solder and flat wide lugs).  So you put the end of the braid on the solder and heat it from on top of the braid (also dissipates a bit of heat into the braid which will help not to overheat the join).  When the solder melts it gets sucked into the braid (you'll see it). Try each flat side of the lug using fresh braid (cut the used end off the braid)
And as MJMP said, if it's being problematic, resolder and then go again (pause to cool down in between so you don't wreck a pad).
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