Yamaha NP-30, no sound - Page 1
Forum section: electronics / repair

author: pyroesp
author_rank: Regular Contributor
timestamp: June 19, 2022, 10:04:34 pm
content: Hi all,I got a Yamaha NP-30 with no sound.Power LED lights up when pushing the on button, but pressing any key doesn't produce audio on the speakers.I tried plugging in headphones, but no luck there either.Voltages seem fine. Input is 12VDC, goes down to 5VDC, then 3.3VDC and 2.5VDC. There's no obvious damage on the PCBs, nor bad caps that I can see.I've looked at the opamps in IC402, but there's no signal on the output when pressing keys.So I looked at the output of the DAC, but there's nothing there either.Then I looked at the input of the DAC and it does look like some data is being written to it from the CPU SDO pin.The DAC has a master clock (pin 1), which looks like this:Looks like a sawtooth between 1V and 2V.But looking at the datasheet it seems like the DAC wants a TTL clock:So if my scope measurement is right, the clock sent by the main CPU has the wrong voltage.It's lower than VIH and higher than VIL...I tried injecting a 3V 11MHz square wave to the master clock with a 3325A, but that didn't do anything.If anyone here has a Yamaha NP-30, that's willing to measure the master clock so I can be sure mine is f'ed or not that would be neat.I've attached the schematic, but you can find the full service manual (with PCBs) online.Any help is appreciated.PS: I don't know the history of this yamaha keyboard. The guy I got it from said he bought amplifiers and that came with the lot.

author: Uunoctium
author_rank: Frequent Contributor
timestamp: June 20, 2022, 05:30:16 am
content: What do you measure at pin 5 (PDN)? If zero, DAC is in power-down mode

author: pyroesp
author_rank: Regular Contributor
timestamp: June 20, 2022, 05:43:46 am
content: It's logic high, sorry forgot to mention that.

author: lugaw
author_rank: Regular Contributor
timestamp: June 20, 2022, 07:25:03 am
content: If pressing the PLAY button to play the demo doesn't produce sound then there's something wrong with the CPU. Also try connecting to it via MIDI port if you can.

author: pyroesp
author_rank: Regular Contributor
timestamp: June 20, 2022, 01:06:01 pm
content: I've tried all the buttons but still no sound.I only measured the SDO of the CPU when pressing the keys, not the voice/song button so I'm not sure if the SDO line changes.Connecting to MIDI was something I planned to do, but haven't had the time yet.

author: pyroesp
author_rank: Regular Contributor
timestamp: July 10, 2022, 02:52:02 pm
content: Looking through the microcontrollers I have at home, I saw I still had a couple 16F18325.This one has a reference clock output which, not looking at I/O slew rate, can output the internal clock.As it looks like, at least to me, that the master clock to the DAC is wrong, I've connected the PIC to the CPU clock and thanks to the internal PLL I could generate the 33MHz or so clock. Although not a square wave, it seemed like the Vmin and Vmax would be acceptable for TTL levels.But still no luck.I didn't check if my clock is synced with the CPU master clock, but as the PIC is fed from the same clock, I'd think it is. Maybe something to double check.I have bought a MIDI to PC cable and will try that whenever I get it, but would prefer to have audio on the keyboard itself instead of relying on a PC.I also bought a new DAC from aliexpress to try a "new" one out, just in case.As I didn't see any signal out of the DAC I haven't tested the pre-amp and amp yet, so I might try injecting a sine wave to see if the main amp still works.To test the pre-amp I think I need to remove the DAC though so that might be something I do when I get the new DAC.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: July 12, 2022, 09:22:47 pm
content: The piano has a built in "Demo" function that will play songs without having to use MIDI or the keyboard.You should only be using this to troubleshoot, as this is the only way of guaranteeing the CPU will output data to the DAC.You're going to feel a bit silly if it turns out the keys are disabled via the "local off" function for example.And forget the PC to MIDI thing, there are way too many variables you have to get right before this will work.You need to test stuff with something you know works.The only thing you know will work is the Demo songs.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: July 12, 2022, 10:10:46 pm
content: That also applies to buying a DAC off Ali Express instead of a real DAC from a reputable source.You don't know if that device will work.So when you fit it and the keyboard still doesn't work you are none the wiser, and probably more inclined to think it's not the DAC when it might have been all along.

author: pyroesp
author_rank: Regular Contributor
timestamp: July 13, 2022, 12:14:08 pm
content: Quote from: Audiorepair on July 12, 2022, 09:22:47 pmI did a factory reset, or whatever it's called on these keyboards, and I also tried turning "on" or "off" that local mode you mentioned.I'm pretty sure I mentioned data being sent to the DAC whenever I press the keys, so I know the CPU does something.I didn't check validity of the data, but both data clock and left/right clock are sent. Just the master clock seemed off to me.The MIDI to USB cable was cheap. I would prefer having sound on the keyboard itself, but if not then this is the next option.Quote from: Audiorepair on July 12, 2022, 10:10:46 pmI get that buying from aliexpress can be dubious, but this DAC isn't available anymore from reputable sources.And even if it was, just the shipping alone adds 20EUR to the bill which I don't want to pay for.

author: abraxa
author_rank: Frequent Contributor
timestamp: March 23, 2023, 05:46:35 pm
content: Were you able to make any progress on this?I have a PSR-E223 and the schematics match its output section exactly. My master clock is also 32.768MHz but with a 3.3V peak, so that's correct. However, the DAC produces no output despite the I2S signals being correct. I can see the data changing when I play a key.

author: abraxa
author_rank: Frequent Contributor
timestamp: March 24, 2023, 09:25:58 pm
content: For those encountering this thread looking for an answer: in my case it was the 100uF/16V cap connected to the FILTER pin (6) of the amplifier IC BA5417. It shorted to ground and since that filter pin also acts as a mute input, it effectively muted the amplifier. Replacing it brought my YPT 220 (PSR-E223) back to life.Judging fromhttps://www.keyboardforums.com/threads/yamaha-ypt-220-no-sound-from-speakers-or-headphones.29665/,https://www.keyboardforums.com/threads/yamaha-ypt-220-psr-e223-no-sound-powers-on.32417/andhttps://www.keyboardforums.com/threads/yamaha-e333-with-no-sound.31298/it appears to be a common issue with this series.

author: pyroesp
author_rank: Regular Contributor
timestamp: March 26, 2023, 01:49:20 pm
content: Quote from: abraxa on March 23, 2023, 05:46:35 pmNo I haven't figured out what the issue is yet.I did replace the main amplifier as for some reason sometimes it would draw close to 1A and heat up, but that didn't fix it.Quote from: abraxa on March 24, 2023, 09:25:58 pmGlad you got yours fixed with replacing that cap. It's weird that the DAC didn't output anything even though the muting was done on the amplifier...I know the NP-30 has a similar feature through the STANDBY pin of the LA4625 amplifier as you can see in the image below:But on my board I don't have TR103. Just the pull-up resistor R111 to 12V.Even if the SPOFF line were to go high (which it isn't) it wouldn't do anything.Anyways, still stuck with this thing :/EDIT: Forgot to add, I did change the DAC with the one from aliexpress but it still doesn't work and I'm suspecting it's fake anyways.

author: frabas
author_rank: Newbie
timestamp: June 07, 2025, 01:46:18 am
content: Hi there,I have a similar problem with a Yamaha NP12 from a customer: nothing out of the DAC (an AK4430ET).Yamaha NP32 Service manual:https://drive.google.com/file/d/15Wu0lo_TxgesZm921Jze3JCbhLv4y2Lu/view?usp=sharingIt has been replaced (don't know the source; purchased by the cutomer). I also replaced C363, a 1uF cap used for charge pump on pins 1 and 2 of the DAC. The datasheet doesn't provide any info on the expected voltage between pins 1 and 2; I have 0.7V, not sure if it's correct or not, but my guess is it should be OK.AK4430ET datasheet:https://drive.google.com/file/d/1lOR-jf0O6Sl-fPJ1pxlvrpKxWEv-Tnvt/view?usp=sharingAs Pyroesp, the master clock signal (pin 4) is dubious; it's square-ish, but it could be my due to my probe.Measure on DAC pin 4 (master clock):https://drive.google.com/file/d/1UQDkB4fdbyH6ZExhyBFlGGUTIX73w1rr/view?usp=sharingThe other signals seems correct:Measure on DAC pin 5 (Audio serial data clock):https://drive.google.com/file/d/197UP8XNqi7PmxYsk60HZ8Apub9JeLfH3/view?usp=sharingpin 6 (Audio serial data in):https://drive.google.com/file/d/1JdLJRcA-atnJgwQouYCusTOUklLGtUUU/view?usp=sharingpin 7 (Ledt/right clock)):https://drive.google.com/file/d/1WEliXsGKGzMwShnjPg5z0R02oWSvPfRd/view?usp=sharingMy concern is about the MUTE signal (pin 4); I find 146mV out of TR361. Is this low enough?I forgot to say I did all the reset procedures from the Service Manual, but no luck obviously.