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Repair and disassembly guides for electronic keyboards.

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The volume output is very low

I have a Yamaha DGX-220 and the volume output is very low. Can I fix that, or must I refer ta specialist?

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To laurel, are you the first owner of the keyboard? Does it has the same volume level, the first time you use it? Or does it happen only lately?

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Hi,

As @ruggb suggests this requires testing the circuit as the audio outputs are supplied by a single audio amplifier IC, which may be the problem

It could also be the master volume potentiometer VR551 that is the problem though.

Here’s the service manual for the keyboard.

Go to p.8 to see the block diagram and find the Power amp IC551 and next to it is the master volume control VR551. This is just to give context as to how the audio is supplied to the speakers. There is no detailed wiring schematic for the board, only a board layout so this will have to be worked out if wanting to test the volume control.

On p.29 and p.30 Test #13 it shows what equipment is needed to test the volume and what audio levels are expected.

You may have to contact a reputable, professional electronics repair service (perhaps specializing in electronic piano or keyboard may be best) and ask for a quote.

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Hi, I'm a technician, also have dgx 220, I don't think it's the circuit or ic, because the sound is not distorted in any way, or the potentiomer for its not intermittent, its functioning good. It just not the sound level as other model of yamaha. I just want to know if there's a setting or function that is not right. Or the sound level is its normal design. I can boost it up by adding an op amp circuit, I have use it in my other keyboard that has a defective op amp ic, I think it will work, I just need to know if it its normal design to have low volume.

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@josephx

I shouldn't think that low volume would be normal.

Have you tried to reset the keyboard to its factory default condition and check if that resolves the issue.

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I have resolved the issue. I replaced 4 resistors in the amplifier stage, located at the input ic of the amp. 2pc, 4.7k ohm, located at the front of the ic, replaced by 100 ohm, and 2pc 10k ohm located near the ribbon wire, replaced by 1k ohm. I have notice some difference in diagram design that I've search from the Web to actual design in the keyboard.

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I think yamaha replace the original design board with other model board. So it doesn't match the input resistors from the mother board to the amplifier board.

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just a guess, but it is likely a component failure in the audio amp circuit.

Some serious troubleshooting must be done.

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I don't think so, I have the same problem, same dgx 220, low volume out, if their is a problem in the circuit I would notice some anomaly or distortion or noise. Even at 127 sound level, the sound is good, clear, no distortion, just low volume. Maybe only 50% of other model.

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@josephx distortion would not necessarily accompany a low volume. Preamp volume may pass thru the final amp with no amplification or distortion. However, if you have another with the same issue, then it may be design intent.

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I have already resolve the issue. I have replaced 4 resistor from the amplifier input stage, 2pc, 4.7k replaced by 100ohm, and 2pc 10k replaced by 1k. Now working better.

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Laurel, you could ask your technician to replace 4 resistors at the amplifier board. 2pc 4.7k just infront od the amplifier ic, replace 100ohm. And 2pc 10k replace by 1k, under the ribbon wire.

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