Korg Forums

[FretProdigy]

I have this keyboard on my workbench for repair - the Korg X50. It's not outputting anywhere near the amount of volume it should be when you turn the volume up. I suspected it may be the potentiometer so I order one and it's here. I'm just now leary about taking it apart and installing it if someone else knows what this issue might be.

By potentiometer I mean the pot - or volume fader.

[xmlguy]

If the current volume fader adjusts the sound smoothly, despite the low audio level, then replacing the pot will likely do no good whatsoever. There are many things that could account for a low audio level. First of all, what makes you think the output is indeed low? Low by comparison to what? How are you testing the level? How are the cables hooked up? What kind of cables, exactly, are you using? What are you hooking it up to? Does it have a level/vu meter? Have you tried headphones?

[FretProdigy]

Im plugging a stereo cable into the right output. and plugging the other end in my Marshall 300watt stack and cranking the master volume, regular volume, and gain all the way to the max. it should be blaring but instead its very faint. like 10 decibels.

[xmlguy]

You're using the wrong cable and plugging it into the wrong place on the X50. You need to use a mono cable and plug it into the jack labeled "L/MONO". A regular instrument cable should work, as they have mono 1/4" TS plugs on both ends. There's another problem with your Marshall stack: it's for guitars, not keyboards, but that won't cause low valume. It will just make your synth sound suck, very loudly.

[FretProdigy]

That's what I meant - I was using an instrument cable. Fact is I own a music shop and this was brought to me so I can try and fix it. This keyboard is gigged very frequently and has been for a year I'm told. When I open it up theres a faint burnt smell. and the fader cuts out at certain points when youre pushing it up.

[xmlguy]

Ok, that's completely different info. It's good to get those kinds of details. Some of us are electronics engineers, but were not psychics, so we need the symptoms to give good advice.

Do you not have an electronics tech at the shop? Have an oscilloscope and know how to use it? That's what you usually need to fix these kinds of problems, especially if something has been fried, since there's usually multiple components that have been damaged and you'll never fix it by using the replace-a-part-and-test method. You have to trace the circuit part by part, and know what to look for all along the way to identify fried resistors, caps, IC's, and what have you. It may not be worth fixing at all, certainly not at regular billable shop time. But it very well could be fixable.

If the fader doesn't fade smoothly, then it probably should be replaced, but putting it on the scope will confirm it.

The big problem is the burnt smell. That is the smell of electronic death, as you probably know. Someone let the smoke out of some components. Someonly probably sent an overload into one of the jacks (phantom power, wrong AC adapter, powerful ground loop, power surge, shorted outputs together). The components and the PC board need to be closely inspected for any evidence of excessive heating, then all of the components around them are suspects until proven innocent. That needs a scope too, to do correctly, although some components may be obviously damaged, like blown capacitors and crispy, dark roasted resistors. Repairing a lot of fried components should be done only by a qualified tech or engineer, since further damage to the main board could occur if the repair isn't done right. A lot of music shops will only go so far as to replace full circuits or send the work out to a tech, so that may be a reasonable alternative if the damage looks bad. You might get lucky by replacing the pot alone, so that might be worth a try. Maybe someone spilled beer in it, which is a rather common form of gigging damage to keyboards.

[FretProdigy]

Thanks so much for the advice. You've been a huge help. Appreciate it much.

[xmlguy]

I guess that some of those years at engineering school, frying lots of circuits, has been helpful in this case. I've released the magic smoke from lots of stuff, but fortunately, I can usually recover the patient with surgery and my trusty soldering iron.