Connect with us

Yamaha PSR530 Keyboard, No Display

Discussion in 'Troubleshooting and Repair' started by Rickedafied, Aug 15, 2014.

Scroll to continue with content
  1. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    Ok I'll try that
     
  2. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    IC701 is back to 2.98v and the others are still the same as the first readings also.
    I'm gonna start disconnecting the connectors one by one now
     
  3. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    Ok. When CN602 LCD bottom right DSCN0186.JPG is disconnected, IC701 keeps moving around weird from 4.40 to 4.80 non stop. Should I flip the board now and check for more components?
     
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,267
    Nov 28, 2011
    OK, CN602 is the connection from the 5V rail on the main board to the LCD board. It most likely powers the backlight. But there is no information on the LCD assembly in the service manual. Can you take some photos of it please? Especially the place where the two wires from CN602 come into the board, and anything they connect to on either side.

    Yes you can take the board out and check for tantalum capacitors and anything getting hot on the underside. Use a folded up towel under the board when you've flipped it over, so nothing can touch the metal chassis. You can test it with everything unplugged (except CN701).
     
  5. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    Circled in red is the CN602 LCD connection. DSCN0192.JPG DSCN0190.JPG DSCN0192.JPG DSCN0190.JPG DSCN0191.JPG DSCN0192.JPG DSCN0190.JPG DSCN0191.JPG DSCN0187.JPG
     

    Attached Files:

  6. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    Where CN602 LCD wires are coming from DSCN0193.JPG
     
  7. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,267
    Nov 28, 2011
    OK, I'm only interested in the LCD end of the CN602 wire. It looks like it goes into a small extra PCB at the top of the photo in post #26, which has some backlighting LEDs on it, I guess. Have a good look at that board and see if there's anything visibly wrong with it. Can you unscrew that board and take a photo of each side as well.

    Looks like there are no tantalum capacitors on the underside of the main board, just a number of ICs. Are any of them getting hot?
     
  8. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    Just a light bulb under that board DSCN0198.JPG
     
  9. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    Nothing under the main board getting hot either
     
  10. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,267
    Nov 28, 2011
    OK. I think you'll have to try to follow the current around the board to find the fault.

    Unplug all the connectors except CN701, turn the board over, turn it on, and find the section of the board that I've marked up in this picture. It's underneath the regulators. Set your multimeter to volts (if it has a very-low-voltage range, use that), and hold the red probe on the point marked 1. This is the 5V output from IC701.

    Move the black probe to each of the other numbered points, and write down the voltage you measure. Then post a list. This may or may not tell us which way the fault current is flowing.

    To go any further than that, I think we'll have to Skype. PM me your Skype username and I'll contact you. But post that list of voltages first.

    Edit: Oops, forgot to include the picture!

    5V measurement points.jpg
     
  11. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    2 reads .000
    3 reads .000
    4 reads .000
    5 reads .001
    6 reads .002
     
  12. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    What if I were to pull out IC701 to see if its bad? Or do we already know its bad for sure? I can't just replace it with a new one? Or is the new one gonna get shorted out?
     
  13. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,267
    Nov 28, 2011
    It is possible that IC701 is bad, but not definite. But the original part, Sharp PQ05RA1, is obsolete. You could replace it with a standard 7805 voltage regulator but it is not a drop-in replacement. The pins won't line up, because the 7805 has three pins not four, and two of them need to be crossed over.

    If you want to try replacing it, go ahead. Radio Shack have the 7805 for two bucks: http://www.radioshack.com/product/index.jsp?productId=2062599. I'll post a diagram showing how you need to install it.
     
  14. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    I figured it was obsolete since I couldn't find it in a parts catalog lol. I thought maybe I was gonna have to say goodbye to it. Sounds like its gonna be fun installing the new one though, I really wanna try it.
    How do I test the IC701 after I pull it out? I saw a few videos on testing it, but they weren't 4 pins like mine.
     
  15. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,267
    Nov 28, 2011
    It's simplest just to try replacing it. If the replacement works, the old one was faulty. If it doesn't, the old one is probably OK.

    u701 replace with 7805.jpg

    Here's how to connect a 7805 into that position. You need to cross over two of the leads. This will be tricky because they're flat metal, not wires, and they're not flexible that way. You will also need to make sure they can't touch together where they cross - either by bending one up and one down, and making sure that when the leads are soldered into the board, they are rigid enough that they can't move and make contact, or by putting some insulating sleeving (taken from some insulated wire) on one or both leads.

    The fourth hole is not used with the 7805.

    Here's how to remove the old IC701. Unscrew the mounting screw and bend the device gently until it's easy to grab onto. If possible, avoid getting the white goop on your skin. Clean it off the IC with a rag or cotton swabs.

    Turn the board over and find the four connection points. You need to melt the solder on these, one at a time, and add plenty of extra solder on them to join them together (temporarily). Don't hold the soldering iron on the board for more than 4~5 seconds at a time, and then allow time for everything to cool down enough that you can hold your finger against them. Once you have plenty of new solder and it's flowed onto all the old solder, let it all cool down again, then use the side of the bit to heat up all four pads at once, and with your other hand, pull the IC out of the board.

    Let it all cool down, then remove the solder from each pad using either a solder sucker or a solder blower ("desoldering bulb"). Printed circuit boards vary in quality but are not really designed for rework and repeated high temperatures. Always be careful to minimise the duration of contact between the soldering iron and the circuit board, and try not to slide the iron around on the copper pad. Heat up the pad, get the sucker or blower ready, move the iron away, move the sucker or blower onto the pad and push the button or squeeze the bulb.

    Desoldering bulb (USD 6): http://www.radioshack.com/product/index.jsp?productId=2062742
    Solder sucker (USD 10): http://www.radioshack.com/product/index.jsp?productId=2062745
    Solder sucker (USD 20): http://www.radioshack.com/product/index.jsp?productId=17241906

    You may want to initially solder the 7805 just loosely onto the board and leave it standing up, so you can find out whether it fixes the problem or not. Then you have the opportunity to install it properly, or remove it and reinstall the original.
     
  16. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    Wow, thanks for all your detailed instructions! I'm real excited to get started on this. Ive been up all night with this so I need to get some sleep lol. I'm real curious if this IC is bad though before going out and getting the 7805. I have one of those DC power supply boxes. Its has a regulated 13.8V / 3Amp output.
     
  17. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,267
    Nov 28, 2011
    You need a load, such as a resistor between 4.7Ω and 10Ω with a power rating of 5W or higher. If you find one of those, and remove the device from the board, I'll describe how to test it.
     
  18. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    Ok nevermind, I'm just gonna go get a new one like you said lol. I gotta get some sleep though. When I get the part in, I'll let you know if it works.
     
  19. Rickedafied

    Rickedafied

    126
    0
    Aug 3, 2014
    Could i use this PQO5RD11 IC to replace the PQO5RA1 IC on the Yamaha PSR 530? It figure it would be easier to modify the IC for this Yamaha because how its standing. This one is a PSR 275 DSCN0199.JPG
     
  20. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,267
    Nov 28, 2011
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-