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Help Yamaha psr e343 won't stay on

Discussion in 'General Electronics Discussion' started by samuel phillips, Oct 30, 2017.

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  1. samuel phillips

    samuel phillips

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    Jul 3, 2017
    Hello i have Yamaha psr e343 problem is when i press the switch the lcd light comes on and as i let go the button it turn off and wont stay on. If I hold down the power button same thing i'm not locating the service manual any help would be nice.
     
  2. kellys_eye

    kellys_eye

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    Jun 25, 2010
    We need to see more of the instrument - clear, in-focus images of the electronics.

    Is the power button 'mechanical' or 'soft'? for example?

    How are you powering it? Batteries or power pack? Is the battery/power pack ok?
     
  3. samuel phillips

    samuel phillips

    41
    1
    Jul 3, 2017
    I think i found the problem there is a transistor that not giving out power and its receiving voltage from the main supply I will change it and let you all know.
     
  4. samuel phillips

    samuel phillips

    41
    1
    Jul 3, 2017
    The transistor number is 2N5551C K435 can anyone help me find a data sheet thank you.
     
  5. kellys_eye

    kellys_eye

    4,275
    1,146
    Jun 25, 2010
  6. samuel phillips

    samuel phillips

    41
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    Jul 3, 2017
    i'm not deep into electronics there is voltage at the collector base is on ground and i'm not getting anything from the emitter so i suspected that its bad i feel like a mad scientist right now.
     
  7. 73's de Edd

    73's de Edd

    2,943
    1,246
    Aug 21, 2015
    Sir Samuel Phillips . . . . .


    Hmmmmmm . . .we've done great and wonderful things to equipment before, . . .haven't we ?

    Check out both with the AC supply and with HOT batteries, to see if the situation is being duplicated the same with both.

    Referring to below, you can see that the "electronic power switch" is being the TR201 and the two ancillary transistors.

    We might initially expect your problem to either be with the equipment pulling too much current, like a bad audio output stage and the shut down info comes down D205 or D207 and turning off the unit by unlatching TR201.

    UNDER THAT CONSIDERATION . . . .


    I have BLUE X'd in three points to "micro" cut the foil, to open that power path and then see if the unit remains turned on. Initially test at A to see if the voltage remains constantly on after turn on.
    If so, then you solder drop bridge the cleaned gap to restore the connection.
    Then you move on down to sub supplies B and C if needed . . . to see exactly where the excess current pull is being from.

    Standing by . . . . .

    WORK AREA REFERENCING . . . . .

    YAMAHA E343 Keyboard.jpg

    73's de Edd




     
  8. samuel phillips

    samuel phillips

    41
    1
    Jul 3, 2017
    @73's de Edd good to see you man i'm unable to test with hot batteries at the moment. just to be clear am i cutting the copper on pcb where the blue x is.
     
  9. samuel phillips

    samuel phillips

    41
    1
    Jul 3, 2017
    PCB EDIT.jpg
    This is a picture of the pcb with transistor 2n5551c removed as you can its different from the schematic you have what i'm getting when its off is that the orange and blue mark 12vdc and no power at the green mark or center pin but with it on (meaning i have to hold down the power button to keep it on) i get power at orange and green mark but 1.2vdc at blue mark which goes to the transistor as the main supply.
    IC201 is is labeled as IC501 on this board and its working not exact 5vdc but like 4.7vdc.

    i'm giving you this info cause your schematic is different from what it have on board here and its the same model.
     
  10. 73's de Edd

    73's de Edd

    2,943
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    Aug 21, 2015
    I have another schema that uses "500" numbering of those parts in that area but it looks like you have pulled TR501 while mine shows TR502 as being the MAIN power switching transistor, which is a TO-220 cased PNP transistor.
    Do you have that TR502 part being located / used on your board ?

    I will prep that schema snippet tomorrow and submit.

    Is your AUDIO power amp being a BLACK cased BA5417 . . . . numerical identified as assigned as IC502 and is having 15 leads SIP style.
    I'm suspecting that as likely being your problem . . . . pulling excess current.

    73's de Edd
     
    Last edited: Nov 1, 2017
  11. samuel phillips

    samuel phillips

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    Jul 3, 2017
    no i don't have that part TR502 on board.
    but question how much voltage should i get at pin 8 of IC502 that is the standby pin.
     
  12. samuel phillips

    samuel phillips

    41
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    Jul 3, 2017
    @73's de Edd i took out the part labled on board FT501 the number on it TJ20A10M3 its a Field Effect Transistor Silicon P Channel MOS i tested it with my digital meter and with the positive lead on drain and negative on source i should not not be getting a reading but i'm get a diode reading and in opposite no reading and according to the data sheet i'm testing the correct pin outs let me now what you think.
     
  13. samuel phillips

    samuel phillips

    41
    1
    Jul 3, 2017
    @73's de Edd I changed IC502 BA5417 and problem still exist.
     
  14. 73's de Edd

    73's de Edd

    2,943
    1,246
    Aug 21, 2015
    Woe is me . . . . ., any and all of those units, that I find data on do not seem to have a single " 500 " assigned designator that is being used for the units "electronic power switch" function.
    What is the period of time that you are now getting the unit to stay turned on, and is that being a long enought time to be able to see a display working, or a LED lighting or any sound coming from the unit ?
     
  15. samuel phillips

    samuel phillips

    41
    1
    Jul 3, 2017
    @73's de Edd yes it was working like normal but now i tried back again this morning holding down the button untill it turns on and it wont work now. lol like i was lucky yesterday.
    so what i found is that i working condition there's 5v dc present at stand by pin on ic502 in none working condition there 1.5vdc and lower at that same pin.
    also there's voltage drop at ic501 in 11vdc and present at ic501 is about 8vdc.

    this ones a head killer. lol
     
  16. olavvejbaek

    olavvejbaek

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    Jul 17, 2020
    did you ever find a solution to the problem?
    - Olav
     
  17. Striker105

    Striker105

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    Oct 29, 2020
    I suppose he should have, I had or have rather the same problem with the same model. Through your reviews and ideas,i was able to find a solution
     
  18. Striker105

    Striker105

    2
    0
    Oct 29, 2020
    Found out that since the keyboard won't stay ON, it had to be the transistor (the one acting as switch) that's the 2N5551c.
    Well I got the faulty one removed and replaced,AND my keyboard came back to life.
     
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