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Yamaha T-60 Tuner

Discussion in 'Troubleshooting and Repair' started by SteveKnoblock, May 1, 2017.

  1. SteveKnoblock

    SteveKnoblock

    1
    0
    May 1, 2017
    I have an old Yamaha t-60 tuner from a thrift store. When I press the on button it does not light up. I found inside there is a small transformer, a switch and a power part of the PCB. There are two wire wrap posts that clearly provide AC power to the digital display. I checked the voltage and see 13v. In the power section I checked the output of the rectifier/diode IC and it puts out 15v DC. I am stuck at what I should check next.
     
  2. 73's de Edd

    73's de Edd

    2,644
    1,074
    Aug 21, 2015
    Sir SteveKnoblock . . . . .


    Thats upon a verge of unobtanium documentation, but thanks to an old colleague of mine well known in the antique radio restorations world . . . . Dave Wesserling . . . . has just provided me its schematic, from deeeeeep down within his archivial cobwebs.

    Your initial testing, up to the point where I marked as A and B , and then you pass to the left thru two regulators Q9 which should regulate and give you ~ 10 VDC at my mark on.

    The Q8 should do its regulation and give you ~5.6 at the other mark on.

    If you don't find that set of voltages, check to see if your zeners are not being shorted.
    You should also have the lamp at the bottom lit upon power up, if it is not burnt out.

    Le Schematique . . . . .

    Yamaha T-60 Tuner.png



    73's de Edd
     
    Last edited: May 3, 2017
    Dougnsalem and Dennis Wess like this.
  3. multimaxfm

    multimaxfm

    4
    0
    Sep 21, 2018
    Hello everyone! Maybe somebody has european vesrion of t-60? I bought yamaha tuner for american market but... i leave in europe. there is jumpers inside that can change region parametrs, if someone could make photo of tuner inside in good resoluton that would be really helpful for me =)
     
  4. multimaxfm

    multimaxfm

    4
    0
    Sep 21, 2018
    So i need to replace jumpers to make it work with european friequencies and deempasis 50us
     
  5. 73's de Edd

    73's de Edd

    2,644
    1,074
    Aug 21, 2015
    Sir multimaxfm . . . . .

    I'll just bet that you will wait for another 15 years . . .maybe ? . . . . for that specific photo request for that specific, somewhere rare vintage unit.

    Here goes . . .

    REFERENCING . . . . . .

    [​IMG]


    Top left corner is a block diagram of unit
    Bottom left corner is both the board foil pattern and the schematic snippet of the AC voltage switching.

    As you can see it suggests that next to the AC power input, is being switch SW17 that shifts the connection of AC line power to the proper primary winding on the power transformer, with its resultant operating continuously for 48 hours per day . . .ad infinitem..

    Top right corner is the related schematic for that unit with my PINK and YELLOW highlighting of the relevant deemphasis R and C time constants.

    If the unit is still wired Amerikanski or Canada . .oh my Canada . . . it purports 1100 pf caps and 68K
    resistors.

    Now if you fall under that BLUE star region, you would be using 390pf @100VDC and 120K resistors.

    The final right bottom corner info , is just being a full data sheet of the typical application of that LA3401 chip.

    Thaaaaaaaaaaaaaats-it . . . .

    73's de Edd
    .....
     
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  6. multimaxfm

    multimaxfm

    4
    0
    Sep 21, 2018
    hey! thank you so muuuch! realy really cool! but i can't get how to change frequency step =) i need to make it non USA to be able to tune and listen 87.5 87.6 87.7 87.8 and so on. What should i do to make it possible? =)
     
  7. 73's de Edd

    73's de Edd

    2,644
    1,074
    Aug 21, 2015
    Let's start with finding the audio R and L channel output jacks on the rear of the unit.
    Over to their side is a slide switch that I believe will transition between the present 10khz station separation to your needed 9khz interstation spacing for AM, and I believe that will coincidentally correct for the difference on the FM band also..
    Try it . . .you may like it . . . . .

    73's de Edd
    . . . . .
     
    Last edited: Oct 5, 2018
    Richard9025 likes this.
  8. multimaxfm

    multimaxfm

    4
    0
    Sep 21, 2018
    the problem is that my model does not have that switch on panel but thas the place on the board, where it is suppose to be. maybe usa model had no this switch?. i saw that is should be accordinary to scheme, but its doesnt in my model. i can make photo later.
     
  9. cASSetteMan

    cASSetteMan

    1
    0
    Nov 10, 2018
    Hello, I have a T-60 as well, and mine didn't light up upon pressing power so I went and tested all the points on the board that you've labeled and all of my voltages are correct.
    Upon a bit of prodding around I've found the lamp referred to on the schematic, and that does not light up when the power is pressed. Anyone have an idea what to do next?
     
  10. 73's de Edd

    73's de Edd

    2,644
    1,074
    Aug 21, 2015
    Sir cASSetteMan . . . . .

    Initially . . . . just like, as it was in the Duuuuurty Harry movie . . ." I GOTS to knows ! "
    Now . . . .would CassETTEmAN be your younger brother, older brother or fraternal twin ?


    You did not initially have the WHOLE inclusion of the pilot lamp wiring path.
    Looks like you need a wee bit more of the puzzle exposed, in order to ascertain your " lite bub " conundrum.

    That specific schematic snippet is now redrawn, and being shown below . . . for . . ."The Rest of the Story" . . . . .

    A LAMP CIRCUITRY WALK THRU . . . . .

    Being at the schema far righty center, is the T4 power transformer with only its low voltage secondary winding visible.
    Low voltage AC leaves the top of the winding and routes up to the tuner board above and goes in at the PS2 connection and then comes back down thru the PS1 connection . . IF . . . the power switch was being on, then AC passes down to the regulator board and the AC1 input and then a flow thru, over to the DF-02 Full Wave Bridge rectifier, and along with its C47 support capacitor, is being used to create the raw low voltage DC to power the receiver.
    Then there is the use of Q9 transistor for supplying the regulated 10 VDC, with its take off, being from its emitter.
    The Q8 transistor is supplying the regulated 5.6 VDC, with its take off point being from its emitter.

    The receiver should now have its DC power and typically be working with those voltages present.

    Back to the lamps AC supply at the AC input, the power routes down to the YELLOW BOX option area of then using the J7 jumper for a direct feed thru or, if left opened, the path is being thru a R58 dropping resistor . . . . as a "bub" saver . . . . if it is using that option. You analyze and figure what manner it uses.
    The AC then goes into and out of the lamp.

    THE LAMP . . . .

    Is being a 14.5 v @ 115ma lamp . . . . and only you can see if any specific mechanical conditions & connections are involved . That current consumption is being on the low end of expected norms, plus there may be heating restraints considerations , so that nothing in close proximity nearby gets scorched.
    Now, if you query YAMAHAULER supply , you will be finding an out of stock condition .and with their not knowing when ? if ? ever ? it is being available again.

    Sure, there is probably someone lurking on Ebay, with bated breath, that has an original New Old Stock lamp .that you can have for $50 plus $24.99 Pony Express shipping and handling fees.

    A CIRCUIT FLOW CONTINUANCE . . . . .

    The AC flow path out from the lamp passes up and over to the AC 2 terminal and then feeds up to the bottom of the transformer secondary winding, to have given a full power flow thru path.

    SOLUTION . . . . . .

    If all of the AC power supply path is complete and you merely have an open lamp.
    IF . . . . . being my puppy to groom . . . . . I would decide upon the desired lighting color, brightness and light beam spread that it has to create, along with mechanical mounting considerations and manner of wiring lead connectivity.

    The RED BOX area shows the utilization of a series 1/2 watt dropping resistor and a one way directional steering diode to utilize only the positive nodes of the AC supply and a LED for the illumination task .
    YOU . . . being able to observe the mechanical and mounting aspects . . . . lets you solve the associated electro mechanical aspects of using a LED for illumination instead of a limited time of use incandescent lamp, such as it was.

    The LED conversion should result in an expected half life of 3 eons.
    PLUS . . .the power transformer should just . . . . . L O V E . . . . you for the loading that you are additionally taking off from it.

    Thaaaaaaaaaaaaaaaasit . . . . .

    WORK REFERENCE . . . . . .

    upload_2018-11-13_14-23-55.png





    73's de Edd
    .....................

    I just love to go shopping, and while I am there, I love to freak out salespeople and totally mess with their minds.
    They always ask me if they can help me, and I say, "Have you got anything I'd like?"
    Then when they ask me what size I need, and I say, " Extra medium."


    .
     
    Last edited: Nov 13, 2018
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