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 Post subject: In search for a volume pot...
PostPosted: Wed Sep 26, 2012 12:46 pm 
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Joined: Wed Nov 17, 2010 6:17 am
Posts: 97
Location: Vilnius, Lithuania
Hi,

once i had a volume knob problem on 303, which was simply solved by resoldering mounting points of a pot. Recently a friend of mine asked me to look at his 404, as the volume was stuck on one value and turning the knob didn't do anything (i know it's a common problem). And simple resoldering didn't help. I assume that the pot itself died and tried searching for a replacement. I've searched the forums but didn't find any specific solution... Contacting Roland is not really an option in my country (unavailable), I assume it takes a lot of time too compared to just resoldering one part on a circuit board... So i tried searching for the information on where can I get the pot that would fit. Numbers on the pot on the board weren't of any help. I found a service manual (http://elektrotanya.com/roland_sp404.pdf/download.html) in which I found the part number for the pot (RK09K12C0A8H) and started searching for that part, but i got no results. After trying to understand what those numbers mean and searching other parts from that list I found that the potentiometers were made by ALPS. I tried searching their catalogue for RK09K12C0A8H - nu success. Then I found a document explaining the meaning of those symbols and discovered, that the part I should have been looking for was RK09K12C0A8K which is possible to find and buy. I'm not 100% sure (could be some special part made for roland or 404), but I think there is an error in service manual. I'm deffinately going to order a couple of those (just in case) and try. Will update when have news.
Hope this helps anyone experiencing same problems =]

p.s. for FX pots, the part number is RK09D1130C5B, but I haven't checked those...

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 Post subject: Re: In search for a volume pot...
PostPosted: Thu Sep 27, 2012 9:47 am 
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Joined: Thu Nov 22, 2007 9:09 pm
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Location: Berlin
thanx for the service manual link... shit might be helpful one day.. spi?

speaking for the poti i'd suggest to figure out how much "kΩ" and "W" the original poti ...uhmm... 'took' or 'needed' ... once you got the right specs and size then any other non-roland poti should do it as well...

please let us know, once you figured out which poti works...
resoldering did the trick for me; until now...


try to contact roland nevertheless... i wanted to buy new pads but they are moving the warehouse (germany) where the spare sparts are sold a.t.m. ... gotta wait some weeks...

i'm pretty sure you could order that stuff even from latvia, if not they could at least tell you which poti specs are needed... they always have been helpful to me...


i guess the community would greatly appreciate if you could do some photos of the process, since it's a big issue for all 404 users....

good luck and thanx!


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 Post subject: Re: In search for a volume pot...
PostPosted: Thu Sep 27, 2012 3:03 pm 
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Joined: Fri Jun 22, 2007 4:37 pm
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Location: Adelaide
It looks like RK09K12C0A8K will be correct. it shouldn't really be an issue anyhow - you could technically put any pot in and it would work to some level, you just might not get the full volume range from 0 to max or it might be very touchy to control, or the opposite - not enough control range. But it will work.

All you need to do is attach those 5 pins. You might find it easier to get the old ones out if you cut the pot off the pins, then use pliers + soldering iron to heat up one pin, pull it out, then heat up the next, pull it out - its hard to get all 5 hot at once using only home tools.

Did just have one thought though - i hope you got the correct pin arrangement (pictured on this page are the different types)

http://www.datasheetdir.com/RK09K12C0A8K+Resistors

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 Post subject: Re: In search for a volume pot...
PostPosted: Mon Dec 17, 2012 9:56 am 
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Joined: Wed Nov 17, 2010 6:17 am
Posts: 97
Location: Vilnius, Lithuania
The quest is complete after waiting for a couple of months for those potentiometers to arrive :) I didn't find those to buy anywhere (except mouser, which ships at very high rates to my country), so I wrote to Roland, and they replied that those pots could be shipped at a fair price (something ~20$ for two potentiometer incl. shipping), but it had to be done through a local distributor. The hard part was waiting for those parts to arrive as it took about 2 months.
I forgot to take pictures and only remembered about this thread today (sorry), so I'll just explain what I did and what I did wrong:
first thing -
remove the caps from potentiometers.
unscrew 6 bolts from the back of the sp.
unplug 2 battery power wires from the pcb.
unplug two ribbon connectors to remove the pcb.
unscrew the bolts that hold the remaining pcb. <- that's the easy part and it's hardly possible to eff something up till that stage. the process needs to be done in reverse when assembling the unit. I'd also advice to clean the casing and buttons while you have your unit disassembled, it'll have time to dry while you do the fix and it will feel and look fresh after the repair :)
I had two sp-404's to repair with the same problem and I've made some mistakes with the first one.
The problem is - removing the potentiometer. It has 7 legs to hold it in it's position, so when you unsolder one leg and move on to another, the first one gets cold and doesn't move anywhere. I only had one soldering iron and tried applying heat to all the pins at the same time and also applying force. Also tried the same, but with only half the pins at the time. The result was messy and I screwed up one pin - the contact trace went off with a pot (later i fixed it by soldering the wire to one pin and the ribbon connector). I know there are certain tools and techniques for that, but they were not available at the time. Here's what I did with the second 404: I've cut all the legs of a pot (it was broken anyway and i wouldn't need it. why didn't i think of that before :) and then removed the pins one by one unsoldering them. Worked like a charm.
The next step was to prepare the spot for a new pot. When the old pot was removed, the holes got filled with solder. Again, I don't know the techniques for clearing those holes, so i had to play with some needles, wires and iron to clear them.
After that - just inserted the new pot in it's place and soldered it.
A few more tips - after work was done, there were a lot of burned flux marks on the soldering points. I found that acetone or white spirit do the job of cleaning those marks pretty well.
When assembling the unit, check if all the elements fit properly in their place (i didn't fit the threshold light indicator in it's spot and couldn't close the unit).
Hope this will be usefull. Cheers

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 Post subject: Re: In search for a volume pot...
PostPosted: Mon Jan 28, 2013 12:05 pm 
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Joined: Wed Oct 17, 2007 6:51 am
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Location: PA
THANK YOU!!!
i have a sp 404 i replaced but kept w a broken volume pot.. def going to fix it now

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 Post subject: Does anyone have the service manual for the SP-404SX?
PostPosted: Sat Sep 21, 2013 7:48 pm 
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Joined: Sat Sep 21, 2013 7:17 pm
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I guess the potentiometers for the SP-404SX are the same as the pots for the SP-404? I've been having the same problem with the volume pot on my sp-404sx and never got around to fixing it.

Does anyone have the service manual for the SP-404SX?

And I didn't see any RoHS sticker on it so I guess I can use 62/36/2 solder on it and not that lead-free non-sense? (even though it would work either way, it's just an OCD about what solder I use)


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 Post subject: Re: In search for a volume pot...
PostPosted: Sun Sep 22, 2013 2:29 pm 
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I found a SP404sx service manual, I'll upload it!

Super interesting read.

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 Post subject: Re: In search for a volume pot...
PostPosted: Mon Sep 23, 2013 1:16 pm 
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Joined: Sat Jan 31, 2009 9:42 pm
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Location: Hartford
I had the same problem (volume level stuck on my 404) until a few weeks ago when I was fiddling with the volume knob and the sound went out completely.. I am not confident about opening the device up so I will be bringing it in to be serviced...


I just wanted to ask if this has happened to anyone else or if someone can explain what the problem is so I don't sound like a complete idiot when I bring my 404 in to be serviced


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 Post subject: Re: In search for a volume pot...
PostPosted: Mon Sep 23, 2013 6:03 pm 
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Rabot wrote:
I found a SP404sx service manual, I'll upload it!

Super interesting read.


Dewd, awesome! Where its at?
Thx,
C

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SP-202, SP-404SX (main one I use), SP-505, SP-555, ES-1, ESX-1, RS7000, etc.


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 Post subject: Re: In search for a volume pot...
PostPosted: Tue Jun 17, 2014 9:34 pm 
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Joined: Wed Dec 12, 2007 6:18 am
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Rabot wrote:
I found a SP404sx service manual, I'll upload it!

Super interesting read.

can you please upload the 404sx service manual? My vol pot just died and would be very helpful- thanks.
C

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SP-202, SP-404SX (main one I use), SP-505, SP-555, ES-1, ESX-1, RS7000, etc.


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 Post subject: Re: In search for a volume pot...
PostPosted: Sat Jan 19, 2019 4:39 am 
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Joined: Sat Jan 19, 2019 4:36 am
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Necroing but I just found a supplier and purchased a bunch of these pots new. If anyone needs the Volume or FX Pots shoot me a message and I'll get them to you.


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