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 Post subject: SP 303 Fix
PostPosted: Tue Feb 06, 2018 2:22 am 
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Joined: Tue Feb 06, 2018 2:05 am
Posts: 5
Very upset just bought a 303 and 2 of the knobs are not functioning. Would appreciate any advice on how to go about fixing, do i just have to resolder or to buy new knobs/potentiometers, and where would i find them?
Thank you in advance


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 Post subject: Re: SP 303 Fix
PostPosted: Sun Feb 11, 2018 5:34 am 
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Joined: Sat Dec 23, 2017 5:44 am
Posts: 114
It would be dependent on what knobs are not working and why. You are going to have to open that b*tch up like a virgin on prom night.
If the solder joints are broken then yes you can just reheat them (that problem plagues old korg products due to lead free solder).
If the pots are bad I believe the correct parts are as follows (this is from my research as I could not find a definitive answer and roland apparently will no longer help consumers with internal parts) (I am also posting this for my own record incase I need these parts again, so buy, try, and solder at your own risk).

Volume Pot:
Alps RK09K12C0A2s
Control Pot(s):
Alps RK09D1130C1B

These are the two part that I found closest to the originals for a 404 which should be the same for the 303. As for the control knobs, I have no idea what the Ohms (i believe originally 50k ohm, part number above 10k ohm), Taper, etc. should be.
Above is the best information that I have found from my research. If I end up replacing the control knobs with what is listed above I will post back.


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 Post subject: Re: SP 303 Fix
PostPosted: Mon Feb 12, 2018 5:54 pm 
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I see, so does it make a difference if you use lead free solder or not? Thanks


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 Post subject: Re: SP 303 Fix
PostPosted: Sun Feb 18, 2018 2:12 am 
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Joined: Sat Dec 23, 2017 5:44 am
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Lead free solder heats up quicker and flows better and supposedly makes a stronger bond. And gives you some sort of cancer, or metallic lung disease. I'm not even good enough to be called a novice when it comes to soldering so you will have to do your own research concerning chemical composition of solder if that's your jam.

As for the important question.

Both pot below work as they should with the sp-404
Volume Pot:
Alps RK09K12C0A2S (50k omhs)
Control Pot(s):
Alps RK09D1130C1B (10k omhs)


The pots for the Sp-202 should be:
Control: Alps RK09D1130A1N
Volume: Forgot to see if it was a three post pot when I had it cracked open.

The pots for the sp-303 should be:
Volume: Alps RK09K12C0A2S (50k omhs)
Control: Alps RK09D1130C1B (10k omhs) Should be 50k (according to the service manual but I can't find the equivilant). Edit: the 50k ohm pot is part number RK09K1130ACL but it has a shaft length of 15mm as opposed to 20mm.

haven't checked the EMX pots yet. If anyone wants to start a go fund me page for a proper soldering iron for me it would be appreciated and i will put this long searched for mystery for emx/esx replacement pots to a rest.


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 Post subject: Re: SP 303 Fix
PostPosted: Fri Mar 30, 2018 9:10 pm 
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Any soldering iron will do if you develop your Solder-Fu! :lol: Seriously, buy a cheapish one along with a desoldering pump, a $20ish spool of solder (lasts forever) a stand, and a metal work tray and practice removing/installing bits of junk boards (about $50-70 total investment). Aside from that there are a few basic principles you need to be aware of:

-discharge your body's static electricity on a metal tap before you work, maybe even ground yourself with a metal bracelet wired to your sink if conditions around you generate a lot of static.

-clean the tip of your iron with some new solder before you lay any down on your gear. It should look silvery, not crusty. Slather some new solder on it and carefully tap it off onto your workspace. Don't solder yourself doing this, dammit! You can also use a wet sponge to quickly wipe it too, but do the above as well.

-Prepare lengths of solder to work with by burning off a length and straightening it out so it's easier to work with when timing matters. Just remember you'll use a lot of that cleaning the iron.

-the idea is to touch the iron tip down into the existing solder until it rounds out (liquifies), then quickly remove the iron and have the solder-sucker ready to go at the very next instant; click the plunger down beforehand and just pop it up off the point. You'll know you did it if a crystalized-looking turd pops out of the pump when you re-plunge it...and obviously that point on the board should be cleared. If you didn't get it all, wait a moment before dabbing a bit more solder down and trying again. Using a little new solder is a good way to make an easier touching point for the iron in general, just don't overheat it.

-especially for finer components, don't keep the tip down in one place too long or you'll overheat it and cook the component! You'll have to learn to be steady and decisive as you run a line of solder onto the iron-tip+connection. Only a moment, like 1-3 seconds depending on the heat of your iron/the sensitivity of neighbouring stuff on the PCB. Move onto another solder far from that hot one to let it cool down a bit.

-get some VENTILATION! A running fan blowing the air out in front of your face to an open window is ideal. Don't inhale toxic shit!

-it requires steady hands. I don't exactly have a surgeon's touch but I can do basic jobs like I/O component repair/removal, etc., but I don't touch stuff like microprocessors or ICs for the most part because it's just too fine a job for my current -Fu (and you'd probably need to pay an order of magnitude more for a better iron). I've been tackling stuff closer to tiny surface components but it's always a challenge and a risk that has to be weighed.



~
Your thread helped me order a replacement for a dead SP-303 pot, so I thought I'd chime in.


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 Post subject: Re: SP 303 Fix
PostPosted: Fri Mar 30, 2018 9:58 pm 
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Joined: Sat Dec 23, 2017 5:44 am
Posts: 114
thehighesttree wrote:
Your thread helped me order a replacement for a dead SP-303 pot, so I thought I'd chime in.


Glad it helped. I think I'll just make a new thread entitled "Replacement Pots" so the info is easy to find.

And I can now verify that the part number for the 10kohm pots do work fine in the 303. If you get the 50kohm (15mm) pots the shorter length actually lets you use the moog style knobs that look great on the 303.

Great soldering "tips".


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