Sounds like the volume knob has a dirty pot? (EMX/ESX)

bog · Post by **bog** » Wed Dec 15, 2010 4:48 pm

So I just got an EMX off Craigslist from this guy who said it was "like new" and "literally used twice" but when I got it, it was obvious even just from the appearance that it had been used for a while with a bunch of deep scratches you couldn't see from the photo.

Anyway, the only problem I've noticed so far is that when I turn the main volume knob all the way up, when it gets to about 95% of the way up, I start hearing what sounds like a dirty pot, until it's all the way up. When it does that, it also seems to affect panning of the EMX's signal by going in and out of the left and right speaker. When the volume knob is all the way up and I leave it like that, it sounds fine.

Anyone else experience this or have a guess what the problem could be? Any easy solutions to fix this?

bog · Post by **bog** » Tue Jan 04, 2011 3:45 am

Damn. It's getting worse. I just turned it on and only the left stereo signal was coming out. Turning the volume knob up and down made the right signal start working again but now the right channel is coming out much lower than the left. It used to be that if I turn the volume knob all the way up, I had full left and right audio coming out but now it's mostly just the left.

Has anyone else experienced something like this or have any idea what might be causing this?

tim from texas · Post by **tim from texas** » Tue Jan 04, 2011 4:49 pm

youre using the volume knob and not the tube gain right? have you messed with the pan knob?

if its left and right weirdness and static it might be the tubes.. does one look crooked or different than the other?

Griffin Avid · Post by **Griffin Avid** » Tue Jan 04, 2011 6:42 pm

Hell the guy might have Replaced the tubes. Might be that they need to be balanced or that one is loose or simply going.

I would:

1. Check mixer/soundcard to make sure it's not anywhere else in the signal chain.

2. Check with Head phones directly from each channel (Left and Right) to make sure it's definitely the audio outs.

3. Check headphone jack to see if it's the ports or the electribe itself.

4. Open the back panel and wiggle the tubes to make sure they haven't become loosened in transit.

5. Check the tubes model number to see if the tubes have been replaced.

6. Swap the tubes (there's a step by step somewhere on this forum) to see if the problem switches channels.

7. If so, replace tubes with a call to KORG tech support.

8. If not, there is a small white dial(s) on the back that may need adjusting. It balances the left and right side output volume. See #6

9. If it's been determined that the UNIT ITSELF is failing, then RETURN IT.

10. If all else fails and you're simply S- out-of-luck, then the Headphone jack might have to be split and be used as your Main Outs instead. I would try doing this anyway- until parts show up -if that's the case.

bog · Post by **bog** » Tue Jan 04, 2011 7:29 pm

tim from texas wrote:youre using the volume knob and not the tube gain right? have you messed with the pan knob?

Yes, the volume knob. I haven't touched the tube gain since I just leave it at a sweet spot. The pan knob is fine and has been doing what it's supposed to do.

tim from texas wrote:if its left and right weirdness and static it might be the tubes.. does one look crooked or different than the other?

Wow, you may be onto something here. One thing I've noticed is that the tube on the left seemed to be put on crooked when it arrived in that it was slightly misaligned compared to the one on the right. I didn't think too much of it. So what does the tube have to do with left or right weirdness?

Griffin Avid wrote:Hell the guy might have Replaced the tubes. Might be that they need to be balanced or that one is loose or simply going.

They look like the stock EH tubes. The fact that both of you mention the tubes is encouraging. I'm beginning to think one of the tubes that is crooked is just loose?

Griffin Avid wrote: 1. Check mixer/soundcard to make sure it's not anywhere else in the signal chain.

Yup. Checked.

Griffin Avid wrote: 2. Check with Head phones directly from each channel (Left and Right) to make sure it's definitely the audio outs.

Ok, the headphones are working fine on both left and right.

Griffin Avid wrote: 4. Open the back panel and wiggle the tubes to make sure they haven't become loosened in transit.

I think this might be it. It was packed really half-assed.

Griffin Avid wrote:8. If not, there is a small white dial(s) on the back that may need adjusting. It balances the left and right side output volume.

That's good to know. Thanks.

tim from texas · Post by **tim from texas** » Wed Jan 05, 2011 5:18 am

crap! i thought i had backup for you and i dont... i thought i read somewhere that the audio doesnt run through the tubes for the headphone jack but thats not true.. i just went and checked on my own esx. i swear i read that but i guess not. that would have totally made sense but no.

mess with the tubes yet? and news?

bog · Post by **bog** » Wed Jan 05, 2011 6:03 am

well, it's not as crooked as I thought it was and they're both in there all the way. Not loose or anything. What's strange is that after I used the headphone jack, the main audio ouput was working better again whereas yesterday it was stuck at coming out mostly on the left.

tim from texas · Post by **tim from texas** » Thu Jan 06, 2011 5:43 pm

sometimes my audio has a slight amount of fuzz in it until the machine warms up but i never have the audio up past 40% maybe? maybe not even that high. and call me crazy but i always have tube gain turned completely off unless im recording a song.

was the song you were listening to a stock song? i know its a stupid question but the left and right panning wasnt a motion sequence was it? if you can return it i would maybe?

bog · Post by **bog** » Thu Jan 06, 2011 8:08 pm

tim from texas wrote:was the song you were listening to a stock song? i know its a stupid question but the left and right panning wasnt a motion sequence was it?

No, it's a completely new pattern. No motion sequence.

tim from texas wrote:if you can return it i would maybe?

I don't know if I can. I found it on craigslist in another city, and paid it via paypal. I don't know if I have any recourse through paypal if you purchase outside of ebay. Perhaps I should have been more suspicious that he was willing to let it go for much cheaper ($200) than the going rate.

I've been playing around some more and there's definitely something up with the volume knob. If I don't touch it and leave it all the way up, it might go back to working mostly normal (the left side only so slightly higher than the right). But as soon as I start turning the volume knob, it easily loses the right side almost completely, even if I turn the knob back to all the way up and leave it there. It's more like a crap shoot in that I have to keep doing that until I can get both left and right levels to be working when I turn the volume know all the way up and just leave it there.

tim from texas · Post by **tim from texas** » Fri Jan 07, 2011 6:00 am

youre running it through a mixer? its odd to me that youre able to work with it at such a high volume... i have no other suggestions other than trying to take the face off and cleaning out the volume pot. whats odd is that you always hear of the main selection knob going out and having jitter and needing replacement but you never hear about the volume knob because you wouldnt think that knob sees much action. CLEAN it...maybe something got spilled on it or theres gum or dog poo wedged in there.. its bugging me that the headphone jack doesnt do it... youve tested the headphone jack a good amount or just a little?

bog · Post by **bog** » Sat Jan 08, 2011 7:11 pm

tim from texas wrote:youre running it through a mixer? its odd to me that youre able to work with it at such a high volume...

Yeah, I'm going through a mixer.

tim from texas wrote:its bugging me that the headphone jack doesnt do it... youve tested the headphone jack a good amount or just a little?

You're right. I tested the headphone out again and I can confirm that it's affected in exactly the same way by the volume knob.

tim from texas wrote:i have no other suggestions other than trying to take the face off and cleaning out the volume pot. whats odd is that you always hear of the main selection knob going out and having jitter and needing replacement but you never hear about the volume knob because you wouldnt think that knob sees much action. CLEAN it...maybe something got spilled on it or theres gum or dog poo wedged in there..

Alright, I'm down to try that out. Is it fairly straightforward to clean the pots on the EMX/ESX? Is it just a matter of taking off the face, or is it more complicated than that?

bog · Post by **bog** » Tue Jan 11, 2011 8:55 pm

Ok. I did some more tests. I just put some drops of Deoxit Faderlube around the volume knob pot without taking the face off and thought it had improved it a bit.

But upon further testing I have discovered that I can make the right channel go out completely just by tapping on the side of the volume knob! The volume knob, as with all the other knobs on the Electribe seems to have a little bit of give. All I have to do is to just tap it very lightly to one direction and the right side will go out. Tapping it in the other direction makes it come back.

So, what does this mean? It doesn't seem like it's a dirty pot issue anymore. I guess the pot is worn out and needs to be re-soldered and/or replaced?

Anyone know where I can get potentionmeters for the EMX?

Laxiton · Post by **Laxiton** » Tue Sep 06, 2011 9:00 pm

@ bog Looking for the same thing! You've found some?

bog · Post by **bog** » Tue Sep 06, 2011 10:31 pm

Laxiton wrote:@ bog Looking for the same thing! You've found some?

I haven't gotten around to it yet but I think these will work:
http://www.mouser.com/Search/Refine.asp ... rns+PTV112

Laxiton · Post by **Laxiton** » Wed Sep 07, 2011 12:16 pm

Well I actually opened it op a few days ago and although the number PVT112 B103 etc seems correct there must be, or a error in the picture or even another type because I believe the potentiometer inside had 6 small mounting points nest to the two large ones on the side.