I’m working on a Yamaha YDP 161 keyboard I got used for my daughter to practice on. Unit powers on fine, all the buttons seem to work. Sound from headphone jack to a Roland keyboard amp works fine, all keys produce sound and have equal weight. Only one of the two headphone jacks supplies signal to amp. Should I suspect the other jack switch is tripped and preventing speaker circuit from operating?
Other details: local control appropriately toggles signal to amp on and off, but does nothing when amp isn’t plugged in, so I know it isn’t just a matter of toggling local control. Factory reset operates but doesn’t recover sound.
I found a copy of service manual online, and replacement of the HP control board seems fairly straight forward. I see stereo phone jack w switch part avail from Syntaur. Buy that and solder into existing board, or try and find new board too? Thanks for any help.
Can you actually push a jack into both headphone sockets? I have encountered instances where 6 1/4 to 3 1/2 mm adapter break and the tip bit getting stuck inside the jack socket - that would prevent the main speakers from working.
Yes. Jack will go into both sockets. In one, the amp produces sound, in the other nothing. Have looked up in there and can’t see anything. Am thinking about ordering a couple new jacks from Syntaur and then digging into keyboard to get at the board the jacks are attached to. Doesn’t look crazy difficult to get there. I’m a little intimidated by soldering in the new jacks but have done a little board work a long time ago.
Correction. Order new sockets from Syntaur. From discussion elsewhere, it sounds like socket connections to the board are fragile and may just need connections re-soldered.
I don’t think soldering will do the trick but worth a look and try. These jack sockets can get damaged when plugs are shoved in hard or headphones plugged in and then walk away tearing the cable/jack sideward out.
You could also remove the suspect jack socket and jumper the required signal - not hard.
First thing to check are the speakers. Could be open voice coil. Just get a 1.5v battery and solder or hold wires to each terminal then apply to dealer terminals. If you don’t hear “cracking” then replace speaker(s)
Two speakers dead … unlikely.
I have even seen many speakers in YAMAHA keyboards with surrounds completely perished and they still worked; sounded not really good through. Additionally, in over 25 years doing that sort of work I have never seen one of these amp chips gone dead … and I have had hundreds of these going through the shop.
I think given that one of the headphone jacks works with an external amp plugged into it, and the other headphone jack right next to it doesn’t work with external amp plugged into it, that I’m going to focus on the jacks and HP board. Wernersaurus, in your circuit diagram, I see HP1 and HP2 which must be the jacks. And I see your blue arrows, presumably meaning current comes into the HP board on 5 and back out on 4. So jumper 4 and 5 together to bypass the jack switches?
PCM-tech, I hear you about the speakers, and once I’m into the guts of the keyboard, checking them should be fairly easy. Also going to order a solder sucker so I can get the suspect jack out, and do a little practice on an old board I have in my soldering kit, before I get to the real patient. I’ll report back once I’ve done some more diagnostics. Thanks all for the responses.
HP1 and HP2 are the phone jacks.
It’s a GND (ground) level coming in on pin5 of CN1 going to pins 4 & 7 on HP2 then out of pins 5 & 8 on HP2 to pins 4 & 7 on HP1 and again out of pins 5 & 8 on HP1 back to pin4 on CN1. That GND is sensed by the CPU chip on the DM board. If any of the jacks is inserted that GND is lost forcing a +3.3V via a pull-up resistor on the DM board to that respective CPU pin calling for the speakers to be silenced.
Since there is no signal on HP2 I think we can assume that the socket is faulty/broken somehow.
Remove that socket and jumper 4 - 5 or 7 - 8 will make it go through.
You could as well go to DM board CN8 connector and shorten pin 4 & 5 (speaker should then work) to prove the point - that is easy to access from above with the top cover off.
