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Repair and disassembly guides for Casio electronic keyboards.

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Do I have a ghost in the piano?

All my life I sighed, after the piano I left behind, when we had to change our residence. At the age of 60, I gave myself a present: a Casio piano PX160. I was very happy when I bought it. Exactly one month after the warranty expired, it broke. From the official Service they told me that it is an old model and they can no longer find parts. When I bought it, the sellers told me it was the last model. Who should I believe?

The symptom is very strange, I haven't found anything similar on the net.

A note sings by itself, without touching the key. After singing alone, the key becomes non-functional (it no longer makes any sound). The service changed the 3 boards with contacts under the keys. It cost me a quarter of the piano`s price. It lasted half a year and broke down again: the same symptom. And after another month, the key didn't work at all. That note is dead.

Maybe for many people $500 is not a big amount. For me it is huge.

Does anyone have any ideas?

Thanks in advance...

P.S. I cleaned the contacts under the key. The simptom persisted.

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The last model means the newest model.

da

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Hi

I’m not too familiar with casio keyboards but I have worked on Roland’s and a couple other brands and here’s what I usually find works:

When you say you cleaned the contacts that usually work but only if it has gold plated contacts

If they are black that means that they are carbon contacts and to help them work you need to clean them then get a pencil and draw some carbon dust back onto it to help it become more responsive

If that doesn’t work I would start looking towards the main board and have a look for anything off looking (for example burned or blown components or corrosion) as it could be a dodgy or faulty component on the board that may need replacing or you could just replace the whole board and sell the old one for parts

If the above doesn’t work please let me know and we can further look into your issue

Hopefully this helps

Any questions please ask

Thanks:-)

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Thank you for your prompt response and for your willingness to help me.

I cleaned the contacts on the board (even if they looked flawless under the magnifying glass) with isopropyl alcohol. I think they are golden.

I also cleaned the rubber contacts with isopropyl, very carefully (I know about the carbon film underneath).

After this operation, the keyboard worked perfectly for a while without problems (so I didn't destroy the carbon film), until the note was heard again without pressing the key, after which the key became useless (it didn't make any sound). I closed the piano, turned it on again, it started working without problems and after a few hours the defect occurred again.

This happened before taking the piano to Casio service. At the service they replaced the 3 boards with contacts under the keys. It ran for a few months without problems, after which the defect reappeared and a few months later that note died completely. Only now I can think that the contact is no longer made under the flap. These days I am busy with other things, but next week I want to open the piano again.

Another specialist consulted by phone told me that there is no way it could be from the main processor. If it were from the processor, all E notes from all 7 ranges should have the same problems. That may be so?

While writing these lines, I checked the piano. Now it works!! I don't know until when.

It is very difficult to detect a defect that appears randomly. I don't know which working method to use. It is clear that the repair should be started only after the symptom appears.

Thanks for any ideas.

Dan Miles

da

@danmiles

If the issue reappears I would have a look at the main boards and check for any broken traces or any corrosion

But for now I am glad your keyboard is working ok for now

But please let me know if the issue reappears and we can look into it further

Thanks:-)

da

Hello again,

and thank you again

I am sure that at some time the defect will appear again. He did so many times. Every time I turn it off, it somehow resets and after I turn it on again, it works ok until the ghost appears. Sometimes after two hours, sometimes after two weeks. But it appears.

Next week I will take it apart and look carefully and with a magnifying glass after you said: broken traces or corrosion.

However, thinking logically, I wonder: it is normal for the piano to produce a sound by itself, in the case of a broken track? Have you encountered such a defect so far?

Next week I will write again, here, what I found.

Until then, all good thoughts!

And thanks!

Dan Miles

da

@danmiles

I have seen it a couple times and I can be cause by thing’s disconnecting and reconnecting randomly:-)

da

OK, disconnecting and reconnecting could also be from false soldering (not only from broken traces); which means that I should redo all the solders. This will only happen after I remove the motherboard.

I forgot to mention an aspect (it could be useful):

when that note (generated by the ghost) is heard, it is heard at maximum volume, it does not matter that the piano volume is at 30%.

Thank you again for your patience!

Dan Miles

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I will do that again. The man from service told me that he find a short circuit in the cable and he changed the cable. I am not so shure about that.

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@danmiles

Sounds like a plan

Good luck and if you don’t find anything we can have a look at other stuff:-)

da

Thanks for encouragement.

I still have a problem: from the point of view of reliability, the first parts of an electronic assembly to be destroyed are in order: the capacitors, the fuses, then the semiconductors (including integrated circuits), then the resistors... the cables are in last place. Am I so unlucky that a cable breaks right at me? These days I'm opening it and I'll see... after I finish what I started last week... I haven't finished the work yet and I don't like to tackle several things at once.

As soon as I have new information I will post it here.

I wish you all the best

Dan Miles

da

@danmiles

Sounds good

Absolutely no rush,please take your time and do it when ever you feel up to it or have the time

Il be here when you come back

Just make sure to reply to me to get my attention;-)

Thanks:-)

da

HelloMacOS

I'm sorry it took so long. Here, we have a saying: "the calculation at home is different in the market". In the end I solved everything.

Back to the piano issues:

I've been measuring for a few days untill now and instead of having a clearer situation, it's getting more complicated.

The connecting ribbon between the keyboard and the motherboard no longer makes noise. I abandoned the ribbon topic.

I moved on to the next step: I started measuring voltages on the keys contacts; at those two keys with problems, in direct current, the voltage was lower. I also measured in alternating current: the white key (tone) had lower voltage; the black key (semitone) had an almost ok voltage, a little lower (10%).

Next, I measured in direct current to the ground: on the keys with the problem the voltage was lower, but at the same time it was also lower on the other two keys, between the two with the problem. So I had 4 keys with lower voltage.

I will continue on the next page. The limit is 1000 characters.

da

Page 2

I measured in alternating current: the same, 4 keys with lower voltages. To be clear, I number the keys in order 1, 2, 3, 4. 1 and 4 are the keys with problems that break. All 4 contacts are underpowered. However, now, 2 and 3 work perfectly. (!!!)

Next, I saw in an older diagram of an PX130 (I couldn't find a service book for my, PX160), that on the motherboard, where the keyboard contacts enters, there are some capacitors and resistors, placed in a matrix. I started measuring the voltages on the capacitors there: In continuous voltages: almost all capacitors had the same voltage at the terminals, except for two. I imagined that I had found the defect and in that moment I checked the keyboard: the two keys with problems were working!!!!

From this moment I don't know what to do. The defect will probably appear again. I am waiting for him.

However, I don't know which method to approach next. I don't have a diagram and that processor seems very complicated to me.

Any ideea?

Thank you

Dan Miles

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HelloMacOS

Sorry for the inconvenience.

I post a message for you, 3 days ago. Do you receive it?

Thank you,

Dan Miles

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Dan Milesman sarà eternamente grato.
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