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#2144858 - 09/05/13 09:02 PM Help! serious hum from Casio PX-130
Cranson Snord Online   content
Junior Member

Registered: 09/05/13
Posts: 6
I just purchased a used PX-130 with CS-67 stand and an SP-32 pedal bar. It's had little or no use, just basically sitting for the past 3 years. Only a couple marks and a fair amount of dust, now removed.

At the previous owner's house, it was played for about 20 minutes at various volumes, different tones, no issues. Removed the KB from the stand, wrapped in a blanket and put in our car for the ride home. Dusted KB on the way through garage by hand and with a little compressed air. Tightened up the stand screws, brought it inside and set it up. Plugged in, turned it on and starting about 25-33% volume setting, there was a very obnoxious AC hum type noise coming from both speakers. My wife the pianist, didn't have her "ears in", but it was loud enough she could hear it easily. There is no way it was doing that at the previous owner's house. It was very quiet in the house and I'd have heard it 20-30ft away. The higher the volume, the worse it gets. Both external speakers and headphone jacks sound the same. No other audio equipment/TV in our house is affected by AC hum noise. Even so, I turned off all breakers except for the one the keyboard was on, which also had a table lamp plugged in. No change. I turned on a different breaker and turned off the other. No change.
Based on the fact that nothing else in the house is affected by this type of hum, I'm guessing the problem is either the AC adapter, or one of the boards inside the piano. There were no loose connections or suspicious solder joints inside. If the AC adapter plug was more standard, I'd rig up the KB to run on battery as I have several 12V UPS batteries that would work fine for testing purposes.

I've looked for related problems on the web, but nothing found yet. I'd appreciate any help you can give for this as I'm scratching my head at the moment, not to mention sputtering and fuming about a potential 'waste' of $350. Everything works, but the hum is really obnoxious.

Thanks to all for reading.

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#2144878 - 09/05/13 09:35 PM Re: Help! serious hum from Casio PX-130 [Re: Cranson Snord]
Morodiene Offline
Yikes! 10000 Post Club Member

Registered: 04/06/07
Posts: 11422
Loc: Boynton Beach, FL
I'm not really sure what the problem might be. I would advise against using compressed air to remove dust in the future, often it just wedges the dust further in where you don't want it.

Does the adapter sit snugly in the port? Or does it have a lot of wiggle room? Does fiddling with the adapter near the port (wiggling it, turning it) change the static level or sound at all?

You may need to get a replacement AC adapter. I'm sure you can purchase them from any Casio dealer. If it's someone local then perhaps you can return the adapter for a refund if the problem persists after trying it.
private piano/voice teacher - full time
MTNA member
Petrof 9'2 Concert, Yamaha G3, Roland FP-7, Yamaha MOX6, Kawai MP11

#2144890 - 09/05/13 09:57 PM Re: Help! serious hum from Casio PX-130 [Re: Morodiene]
Cranson Snord Online   content
Junior Member

Registered: 09/05/13
Posts: 6
Thanks for your note; I was however careful to use low pressure and shield the areas where it shouldn't go. The dust was mostly in the gaps around the stand and indent lines in the plastic pieces and quite a bit underneath as it had sat over a floor register probably its entire life in that home. I think it hasn't been used hardly at all based on the condition of the keys. (The husband jabbed the wife a little as we were leaving, "Wow; she played that thing longer testing it out than you have since we bought it!") Despite a 1/2" x 3/4" scrape on the front rail, and a couple tiny nicks or scratches on the pedal bar, it's in very nice shape.

The adapter fits very snugly and it doesn't matter the orientation or whether it's fiddled with. I will probably run over to a local Guitar Center tomorrow or Saturday. I was thinking I may take the keyboard/adapter with me to get their impression, and also ask if I could use one of their display adapters for a moment just to try it out. Based on that, perhaps purchase a new one.


#2144896 - 09/05/13 10:06 PM Re: Help! serious hum from Casio PX-130 [Re: Cranson Snord]
SoundThumb Offline
Full Member

Registered: 03/28/10
Posts: 334
Loc: San Diego, CA
Sounds to me like a filter capacitor has become disconnected. Really shouldn't have happened as you took reasonable care bringing it home, but sometimes a manufacturing defect doesn't become apparent for a time. Especially if the previous owner never moved the board around. It might be something you can find yourself if you know what you are doing. Otherwise, take it somewhere to be repaired, shouldn't be too expensive.

Edited by SoundThumb (09/05/13 10:07 PM)

#2144909 - 09/05/13 10:26 PM Re: Help! serious hum from Casio PX-130 [Re: Cranson Snord]
Kawai James Offline
8000 Post Club Member

Registered: 09/06/07
Posts: 8854
Loc: Hamamatsu, Japan
Yes, give Casio a call and ask for information about servicing centres. With any luck, it should be a quick and simple fix.

Employed by Kawai Japan, however the opinions I express are my own.
Nord Electro 3 fan & occasional rare groove player.

"Richard, none of us could forget you have a CLP-990." - EssBrace, 2014

#2144912 - 09/05/13 10:35 PM Re: Help! serious hum from Casio PX-130 [Re: Kawai James]
Cranson Snord Online   content
Junior Member

Registered: 09/05/13
Posts: 6
SoundThumb & Kawai James -
Thanks! I didn't see any swollen caps nor were there any that appeared "loose" or badly soldered. I did wiggle them when powered on, but no change. I may have missed one or just not wiggled it the right direction.

I've written an email to Casio tonight, and will check out the AC adapter next since that's an easy one. Now that I've gone through the disassemble routine, it will go much faster next time, and if the adapter does no good, will look a little closer at the power supply board.

#2145987 - 09/07/13 08:05 PM Re: Help! serious hum from Casio PX-130 [Re: Cranson Snord]
Cranson Snord Online   content
Junior Member

Registered: 09/05/13
Posts: 6
Update on the Casio; I tried moving it to different rooms, took it across the street away from the noisy transformer in our front yard and no change. Then took it for a ride in the car using an inverter; no change. So it's off to Guitar Center. frown No one with any keyboard expertise at G.C. tonight, but I tried the AC adapter in 3 different Casio keyboards, and no hum. So I guess I'll be calling a Casio service center and exploring other options.

Edited by Cranson Snord (09/07/13 10:11 PM)

#2272121 - 05/07/14 12:00 AM Re: Help! serious hum from Casio PX-130 [Re: Cranson Snord]
Cranson Snord Online   content
Junior Member

Registered: 09/05/13
Posts: 6
So it's been some time, but after a fashion, I've made some progress. I checked into a Casio authorized repair facility and immediately dismissed that idea. $70 bench charge, clearly not a lot of in depth PX-130 knowledge at that place, and was told that they would likely replace 'a board'. The power supply/amplifier board would run $225, plus another $70 in labor, for a tentative total of $365, more than we paid for the keyboard.

Although he's an old time radio guy and NOT familiar with solid state circuitry, my dad suggested using a signal tracer. I finally received it a couple months ago. Using a PX-130 service manual as a reference and getting the basic logic flow of the board [I know just enough to be dangerous with electronics...] I began checking various components, specifically filter capacitors. By the way, the hum is ~82Hz, a poorly tuned E2. There weren't many places I could touch that didn't make a comparable noise to what was coming from the speakers. However, by far the loudest component was the voltage regulator, particularly the Vout terminal [the supply of 5V to the whole system]. It was several times louder, possibly an order of magnitude louder than anything else. After some discussion with dad, it seemed like a good possibility. It was making such a 'racket', it was easy to imagine it 'backfeeding' into the 12V side of the the board. So I've located a replacement voltage regulator at an Amazon vendor of all places, and hope to have them [it wasn't a lot more expensive to order 10 than it was for 1] within a week or so.
So if anyone comes across the post and has an annoying hum problem with their PX-130 or CPD-200 [uses the same voltage regulator], I'll have some extras and will post the results within a week or two.

#2307153 - 51 minutes 45 seconds ago Re: Help! serious hum from Casio PX-130 [Re: Cranson Snord]
Cranson Snord Online   content
Junior Member

Registered: 09/05/13
Posts: 6
Another bit of time later...

It turns out the Amazon vendor did NOT have any of the voltage regulators in stock; "they had gone missing and couldn't be found." ??? I searched and searched and found nothing in the US other than a few large wholesale houses requiring minimum orders of $100-$200. I was about to order some from a vendor on AliExpress in China, but the shipping was pretty high. So I checked one more time in a few likely places and a place that had been out of stock for months finally had some again! I ordered them on Wednesday and they came in the mail today. So either tonight or tomorrow, I'll swap out the voltage regulator and see if there's any change. If you're in need of a voltage regulator for your PX-130 or CPD-200 piano, let me know.


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