Casio Privia - Schematic?

[techineer]

Does anyone have a service manual/schematic for a Casio Privia?

A customer brought in a Casio Privia slab piano with a wierd symptom. At normal power-up, it works OK. but if you plug in to the line out jacks, the output signal to the external amp pops rythmically 3-4 pulses/sec. If you then pull out the plugs from the line out jacks, the output in the speakers has a tremolo effect.

I've tried to check out the power supply and looked for bad solder connections on the jacks, with no success.

Has anyone seen a symptom like this before?

[samas11]

chek out here casio cz-101

[techineer]

How is that helpful? It appears to be totally unrelated to my question.

[Jazz P Bass]

Exactly which model Privia is it?
This is a digital keyboard, is it not.
Casio may or may not have used a buffer ic (opamp) on the line out.
If they did, I would check it.
Maybe monitor the ic power rails before & after inserting the jack.

[techineer]

It's a PX130BK.

I had to hunt for the model number.... it's molded into the case bottom, and difficult to see. No sticker except the serial number.

I had checked the power supply lines. +5 out of the switching regulator is fine, but it drops to around 3.6v to what looks like an SMD op-amp. The number (3547) is one that I can't find any data on. If it has the same pinouts as other op amps, pin 8 has the 3.6 v and there is a pulse riding on the DC that could well be related. Voltages on pins 1,2&3 don't make any kind of sense for a linear op-amp circuit.

If the phones/line outs are fed to an amp input, it results in a relatively loud rythmic popping in the output. The internal power amp is disabled, but with nothing plugged into the line outs the internal speakers have the tremolo effect instead of the popping.

[doctor]

It's a PX130BK.

I had to hunt for the model number.... it's molded into the case bottom, and difficult to see. No sticker except the serial number.

I had checked the power supply lines. +5 out of the switching regulator is fine, but it drops to around 3.6v to what looks like an SMD op-amp. The number (3547) is one that I can't find any data on. If it has the same pinouts as other op amps, pin 8 has the 3.6 v and there is a pulse riding on the DC that could well be related. Voltages on pins 1,2&3 don't make any kind of sense for a linear op-amp circuit.

If the phones/line outs are fed to an amp input, it results in a relatively loud rythmic popping in the output. The internal power amp is disabled, but with nothing plugged into the line outs the internal speakers have the tremolo effect instead of the popping.

The aforementioned chip is BH3547 headphone amplifier
manufactured by Rohm.

Please see attentively the application circuit.
I am sure that Casio designer exactly copied this schematic.

And most probably line outputs are connected to the BH3547
outputs using resistor dividers (as for example Line 6 often does).

[techineer]

Thanks... that puts me on the right track. Too bad Casio is so difficult to get data from. Their stuff seems to be built fairly well.

[techineer]

Now, can anyone tell me where I can get the BH3547 chip? None of my usual sources seem to carry it.

[Jazz P Bass]

Find BH3547 Stock and Compare Prices Across the Most Reputable Distributors in the Industry.
Looks as if Newark Electronics is the one.

[techineer]

Thanks for the link, although all the ones listed with stock are overseas with large minimum orders.

The Newark entry is a link to Farnell Europe.

Anyone have a source in the US?

[Jazz P Bass]

Try the Farnell link.
I do not believe that they have a minimum.
If they do, order other things to meet it.
One week shipping from the UK.

[kurtdaniel]

Does anyone have a service manual/schematic for a Casio Privia?

A customer brought in a Casio Privia slab piano with a wierd symptom. At normal power-up, it works OK. but if you plug in to the line out jacks, the output signal to the external amp pops rythmically 3-4 pulses/sec. If you then pull out the plugs from the line out jacks, the output in the speakers has a tremolo effect.

I've tried to check out the power supply and looked for bad solder connections on the jacks, with no success.

Has anyone seen a symptom like this before?

Casio Keyboards have always been popular for its affordable range of prices and they have managed to remain the top choice for beginners who play a piano over so many users. But now I wonder why there have been many reports of issues in the new Casios both in the Privia and Celviano line pianos.