Several PX-160 Keys Sound Strange

[LitCactus]

Hello,

 

Every few months my PX-160 plays these strange sounds over some of the keys. This glitch comes and goes for months at a time and I have no idea what causes it or why it sometimes stops. 

Here is a video of the glitch.

If anyone has an idea of how it can be fixed, I would be grateful.

[John M]

I don't have sound right now so I'll have to check the video when I get off work, but I remember several other threads where there was dust preventing the sensors from working properly. The quick fix is to blow compressed air between the keys to clear the dust out. I can't guarentee that will fix it, but it's worth a shot!

[LitCactus]

I blew between the keys with compressed air and had no luck. 

 

Investigating further, I've learned that pressing (just above middle C) C#, D, D#, or E also plays the minor sixth above that key. 

For example: C# plays A; D plays A#

If I play that same A, it plays the C# below. This is true for all 4 of the lower keys and all 4 of the higher keys (A, A#, B, C).

 

If I try to play both notes which correspond to each other, only the first pressed down makes a sound. 

 

This does not work for all octaves, only the specific keys mentioned with respect to middle C. 

 

If anything I wrote was unclear please say so.

[Brad Saucier]

Unfortunately, I think you'll need to have it serviced.  If you're under warranty, I would definitely go that route.  Opening it up yourself would void any warranty.

[LitCactus]

Unfortunately it's no longer under warranty. Today I lifted the keys, inspected the boards. Several screws were rusted and there was a small sticky stain. (I suspect juice was spilled on the keyboard.) The affected area was the board, though seemingly away from any components. After a thorough cleaning & dusting, I reassembled the piano. No dice. 

 

The worst of the matter is that the glitch disappears for months at a time and returns without any obvious reason. And it is always the same exact keys in the same exact way.

 

 

[Jokeyman123]

Rusted screws? wow, that's not good. An IC board can become contaminated, even if it looks OK, unfortunately from any kind of damage. if it was juice or soda, the acid might have effected the conductivity of the traces, or even contaminated components nearby. What did you use the clean the board? Sometimes a plain water/mild alcohol or white vinegar solution might remove any contamination, but you are taking a risk and have to be very careful. Might be a difference in temperature or humidity that is causing the intermittent problem. something marginally functioning could stop working or conducting-even a solder joint, if there is a change in temperature or humidity. Sorry I couldn't help further-but if someone spilled something-this is one of the toughest problems to solve-if you can get a replacement board, I would try that, if the keyboard is worth it to you. 

[Jokeyman123]

On 2nd hearing-/viewing your video-I would bet there is contamination under several rubber boots that make and break the key electrical contacts., especially since you say there is evidence of a spill inside. 

 

if you are willing and are adept at fine repairs-you need to lift those rubber boots in that area-carefully inspect for any type of contamination-and again, carefully clean the carbon contacts within the rubber boots, and the contacts on the IC board in the area of the problem keys. Do not clean this carbon material with anything stronger than plain water and a lint-free cloth-distilled water if you have it. Even minerals in your tap water might cause the carbon to no longer conduct properly. This is a difficult repair, but i think this might be the problem. And i think again because it is happening in such a strange way-some humidity or temperature might be causing these marginal contacts to malfunction in such a peculiar way. If these rubber boots and the contacts inside are not perfect-your keys will double trigger-trigger adjacent notes, or fail to trigger at all. Post back if you have any success with this. i think you might b able to repair this if you are willing to do the work. 

[LitCactus]

I cleaned with alcohol. The contacts appeared clear so I didn't touch them. The greater part of my confusion lies in the keys which are double-playing: not adjacent, but 8 semitones apart. Unsurprisingly, the spill was more or less underneath of these keys. I wish I had have taken pictures.

 

Tomorrow I will give it another go. It took a long time to pull apart so I am not eager to be disappointed again.

[AteS]

Check the board for possible shorts between tracks. Looking at the keymatrix ( see the file). This is from the servicemanual of a  CDP200, but I think most Casio 88 key keybeds are more or less the same. The keys you mention are on the adjacent connections.