Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting Audio Equipment
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 02-26-2020, 04:11 AM   #1
ComputerGeek
Badcaps Veteran
 
Join Date: Oct 2011
City & State: San Diego, CA
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist
Posts: 217
Default Yamaha YPG-635 Keyboard with No Sound

I have a Yamaha YPG-635 that will not make any sound either thru the headphones or the speakers, I'm thinking that the amplifier/power PCB is no good. I've tried to go thru and reset all the menu settings as well. Does anyone have recommendations on what I can troubleshoot on the board?

Also, if there is a better place to post this related to circuit repair please let me know. Thanks!

Here are a few photos of the board. I can pull it and get a photo of the traces tomorrow.
https://imgur.com/V7neazz
https://imgur.com/bLLDQ3h
ComputerGeek is offline   Reply With Quote
Old 02-26-2020, 10:43 AM   #2
R_J
Badcaps Veteran
 
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 5,724
Default Re: Yamaha YPG-635 Keyboard with No Sound

The first thing to do would be remove the amp board and check for poor solder connections, I have seen this before on other keyboards, If the connections are ok, check the voltage going to the board.

Also if you can Attach the pictures to the post would be best.

Last edited by R_J; 02-26-2020 at 10:44 AM..
R_J is offline   Reply With Quote
Old 02-26-2020, 07:24 PM   #3
ComputerGeek
Badcaps Veteran
 
Join Date: Oct 2011
City & State: San Diego, CA
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist
Posts: 217
Default Re: Yamaha YPG-635 Keyboard with No Sound

Here are some photos and an update,

I built myself a little signal tracer with a headphone amplifier. And found out I have sound on Pins 1 and 6 of the LA4625. I have 11.75 on Pin 14. What else can I check? I'm assuming as of now that LA4625 is dead?
Attached Images
File Type: jpg 1 - 3AanOUn.jpg (554.0 KB, 4 views)
File Type: jpg 2 - L3miTLQ.jpg (527.1 KB, 4 views)
File Type: jpg 3 - 0ltR1Gf.jpg (733.7 KB, 5 views)
ComputerGeek is offline   Reply With Quote
Old 02-26-2020, 07:39 PM   #4
ComputerGeek
Badcaps Veteran
 
Join Date: Oct 2011
City & State: San Diego, CA
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist
Posts: 217
Default Re: Yamaha YPG-635 Keyboard with No Sound

Here is the board labeled as well.
Attached Images
File Type: jpg 1 - 3AanOUn.jpg (576.4 KB, 4 views)
ComputerGeek is offline   Reply With Quote
Old 02-26-2020, 09:39 PM   #5
R_J
Badcaps Veteran
 
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 5,724
Default Re: Yamaha YPG-635 Keyboard with No Sound

Check the voltage on pin#4 this is the standby pin and needs to be at +5 volts, It looks like R214 connects pin 14 to pin4 to supply the standby on. Check the voltage on pin 5, (+2.3v) and pin 7 (+2.0v)
Also check the voltage on the speaker pins, or the output pins of the ic, They should be about +5 voltes each. It could be the ic is bad. It has protection so it could be internally shut down

Last edited by R_J; 02-26-2020 at 10:19 PM..
R_J is offline   Reply With Quote
Old 02-27-2020, 01:06 AM   #6
ComputerGeek
Badcaps Veteran
 
Join Date: Oct 2011
City & State: San Diego, CA
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist
Posts: 217
Default Re: Yamaha YPG-635 Keyboard with No Sound

Pin 4 has just below 5 volts, I'm thinking you meant R205 which seems to be correct. Voltage on Pin5 is Present and Pin 7. Voltage is between 4-4.5v on the speaker pins.

I'm assuming that this means LA 4625 is dead?

Also the ribbon cable pictured pretty much feel apart, the plastic tabs just feel off, I bent the pins back and superglued it back together but I'm not counting on it surviving me taking it out and replacing it again when I solder the new parts in. How can I find a replacement for this? Can it be cut from a larger pin one? And would I be able to use some Cat5 or something just to solder a jumper, or would this cause issues with noise or interference?
Attached Images
File Type: jpg 87445412_569052600364118_1447759683648487424_n.jpg (810.9 KB, 6 views)
ComputerGeek is offline   Reply With Quote
Old 02-27-2020, 04:44 AM   #7
ComputerGeek
Badcaps Veteran
 
Join Date: Oct 2011
City & State: San Diego, CA
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist
Posts: 217
Default Re: Yamaha YPG-635 Keyboard with No Sound

How does Pin 2 work?
ComputerGeek is offline   Reply With Quote
Old 03-02-2020, 01:34 AM   #8
ComputerGeek
Badcaps Veteran
 
Join Date: Oct 2011
City & State: San Diego, CA
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist
Posts: 217
Default Re: Yamaha YPG-635 Keyboard with No Sound

Just checking back. Thanks!
ComputerGeek is offline   Reply With Quote
Old 03-02-2020, 11:28 AM   #9
R_J
Badcaps Veteran
 
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 5,724
Default Re: Yamaha YPG-635 Keyboard with No Sound

Quote:
Originally Posted by ComputerGeek View Post
How does Pin 2 work?
It is just a filter, it smooths the bias voltage.
The TWO connectors pictured look ok, What is broken? how did you break them? The cable pulls straight out and pushes straight in. You will need to search the internet for them, search for FPC or FFC connectors, you will need to know the pin pitch (distance between conductors on the flat cable) There is nothing to the circuit, so if you can confirm you have a good audio level on the ic's input, it is likely the ic is bad.

Last edited by R_J; 03-02-2020 at 11:33 AM..
R_J is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2020
Powered by vBulletin ®
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 09:10 AM.
Did you find this forum helpful?