Yamaha psr s710 - No Sound no led lights from buttons.

[samuel phillips]

Hi everyone I have a Yamaha psr S710 keyboard to fix. The problem is that it turns on fine but no sound no lights on the nobs there Is stuff showing on the lcd screen but no response from controls pads to screen nobs that should change stuff on the lcd does not work. I know is not the amp cause there is static and even when you turn the volume button up you hear scratch sound like if its dirty. Any help would be appreciated to solve this problem thanks. Here is a link to the service manual:

https://elektrotanya.com/yamaha_psr-s710_psr-s910_sm.pdf/download.html

 

[kellys_eye]

Check all the supply rails. Report on any missing or incorrect voltages.

 

[samuel phillips]

Hi @kellys_eye all rails checked out good there is power going to the keys and there is power going to led driver that's on the connections.

 

[73's de Edd]

Sir Samuel Phillips . . . . . .

If you can confirm amplified wiper noise from the master volume, then proceed backwards in the signal flow, to the two preamp stages within IC43 which feed into the volume control.
Their inputs are pins 5 and 10 . . . to see if an injected test tone will pass from that point to the speakers.
If not, then . . . . we move even further backwards, to their feeds, coming from the outputs from the DAC . . .IC401, that exit from connector CN400 (9P) of the DML board.
STANDING by . . . .

IN REFERENCING TO:



73's de Edd
.....

 

[samuel phillips]

@73's de Edd injecting tone works both ways I get sound coming out. let me say as I said before the problem is that nothing moves on LCD screen, the control pads have leds on them they don't light up when they should be lit up and there is power present on the connectors of each board there is no response from keys or control pad there is options on the LCD screen but that's all nothing moves there. so it not just a sound problem somthings affecting both the controls and keys for sound. hope this info helps you to help me lol.

 

[samuel phillips]

@73's de Edd @kellys_eye what you guys think anything else i can check on. from the schematic which IC controls the lcd information and the sound creation for the keys. this is tough one my head hurts lol.

 

[kellys_eye]

Check that the processor clock is running properly - the 11.2MHz crystal, X300.

Check the supplies and decoupling capacitors on the processor board.

Check the connections to the board.

 

[samuel phillips]

@kellys_eye all supplies and caps check out. On the x300 crystal there is voltage present 1.4v i don't have tool to check the frequency. was looking the flow chart and it looks like a its an IC bad sine all the supply checked out what do you suggest I do.

 

[kellys_eye]

Top left corner of the block diagram (page 153) is the EIF board. This interfaces the LEDs via the E-Bus1 signal(s) which look to be based on the I2C data bus.

Check the supplies to and at this board (looking for 5V and 3.3V) first - if the supplies are ok you'll need to check the data to/from that board. You 'might' get a determination from a static DC check but a DSO is the basic minimum test equipment required to process the fault finding any further.

 

[samuel phillips]

@kellys_eye I found a dead cap by IC303 that's C303 i will change it and see what happens but what you could this IC303 not functioning be the cause its a low voltage translator.

 

[kellys_eye]

I found a dead cap by IC303 that's C303

How do you know it's 'dead'? It's a 100pF device. Not easy to test (although a dead short would be very apparent) and you'd normally have to check it 'out-of-circuit'.

If you are testing components at random then good luck - you may eventually stumble across a defective one.... but there's an awful lot of them!

Checking that all the relevant supplies are 'there' on each board would be an obvious place to start. Some boards have a 5V basic input supply but onboard regulation that creates 'sub-supplies' on those boards which can be anything from 1.8V to ... whatever.

The circuit schematic is very comprehensive - you should be able to find all the supplies mentioned and test them. Report back on any supplies that are widely out of spec/missing.

 

[73's de Edd]

Sir samuel phillips . . . . .

I found a dead cap by IC303 that's C303

That's a mere 100 picofarad hf bypass function . . . . unless it's found being dead shorted.
I was expecting your " find " to be a 100 ufd electrolytic, which had decreased down to 1 ufd or so of capacitance .
Is there being any meaningful graphics on the display . . .or just gibberish ?
Do you confirm that Zero of the LEDs light up ?
Also as was mentioned . . . . . do you have an Old - silly-scope and know how to shoot it ?

73's de Edd
.....

 

[samuel phillips]

How do you know it's 'dead'? It's a 100pF device. Not easy to test (although a dead short would be very apparent) and you'd normally have to check it 'out-of-circuit'.

If you are testing components at random then good luck - you may eventually stumble across a defective one.... but there's an awful lot of them!

Checking that all the relevant supplies are 'there' on each board would be an obvious place to start. Some boards have a 5V basic input supply but onboard regulation that creates 'sub-supplies' on those boards which can be anything from 1.8V to ... whatever.

The circuit schematic is very comprehensive - you should be able to find all the supplies mentioned and test them. Report back on any supplies that are widely out of spec/missing.

ok from those that i've check thus far like for example i checked the VCC for the cpu which is 1.8v I get like 1.72V so am not getting the flat 1.8 and same goes for those other supplies in that area 5v reading as 4.6 ect, i will check those that you told me about before. I have digital meter i used and di a resistance test from ground to positive side and i got a high read of 1.250 and I did a and put the meter on 2k ohm setting and did another resistance test and got no reading not even a flash which indicated to me that its bad I may be wrong so i'll leave that so but i will do what you told me test the supplies on the EFI Board.

 

[samuel phillips]

Sir samuel phillips . . . . .

I found a dead cap by IC303 that's C303

That's a mere 100 picofarad hf bypass function . . . . unless it's found being dead shorted.
I was expecting your " find " to be a 100 ufd electrolytic, which had decreased down to 1 ufd or so of capacitance .
Is there being any meaningful graphics on the display . . .or just gibberish ?
Do you confirm that Zero of the LEDs light up ?
Also as was mentioned . . . . . do you have an Old - silly-scope and know how to shoot it ?

73's de Edd
.....

The only testing tool i have a my meter so here is a picture of the problem. so no lights no sound from keys when pressed. been try to activate the test program that ain't working either there is voltage present on the key area. as for the screen upon turning on the the keyboard it boots showing the Yamaha logo, the model number of the keyboard, the owner and the the screen your seeing in the picture. Pressing the buttons for the menu and other stuff does not work and does not change anything on the screen the only thing working the contrast nub.

 

[kellys_eye]

Supply voltages are ok when within 5 or 10% of the stated values - they don't have to be spot-on!

Resistance checks are not reliable when measuring in-circuit. You would normally have to remove the components to get a true reading. The capacitor is ok.

Another potential fault could be a sticky button. If one is stuck down it may lock out all others.

Since the machine 'boots' and otherwise seems to work I suggest there is a problem with the data bus between modules. If one has a fault it may be stopping all other functions. Starting with the switch modules, disconnect them individually whilst trying to activate a music function. If/ when you disconnect the dodgy module the system should burst into life.

This assumes the dodgy module isn't a system module..... Which would stop you trying this.

.

 

[Kimnet]

Hi guys,I am stuck on the same problem. Did anyone find a solution to this??