TDA8920bj mode switch

Discussion in 'The Projects Forum' started by tiggerlator, Jul 11, 2014.

  1. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    How do i mode switch a 8920bj using pin 23? i need to power on the module to operating mode.

    I know it is using pin 23 but don't what to connect to it.

    Here is a link to the service manual for the panasonic amp i am diy'ing. I am using the DAMP board and the SMPS power board. I have removed the reciever module board from it's slot in the DAMP board.

    I hope you guys can help, I want to use it for speaker power for my rotel rsp-960ax pre amp.

    http://diagramas.diagramasde.com/audio/SH-FX65P.pdf


    thx
     
  2. DickCappels

    Moderator

    Aug 21, 2008
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    Pin 23 of WHAT??????

    Also, in what part of the schematic are you looking?
     
  3. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    pin 23 of the tda8920bj !!!!!!!! think that would have been obvious, and page 40 of the service manual.
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    See page 6 and Fig 4 of the NXP datasheet for the TDA8920bj.
     
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  5. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    Thx Alec, it will be ok without the reciever board yes? it is really high quality made, all elna and nichicon caps.

    Ahh yes, what are the two components with R on them? resistors, but what value.
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Don't see why not (but I haven't ploughed through the service manual).
    I'd try both R=15k, C=47uF. The time constant should be at least 500mS to prevent switch-on pops.
     
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  7. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Looks like its a Mute pin, provided by Q1006 page 40 datasheet.
     
  8. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    It is, kind of, it seems to switch from mute, standby or operating. The actual panasonic unit does have a power switch for main power, but i am guessing the reciever board controlled mute/standby/operate via pin 23. It is pin 6 on the 8920bth which is smd mount. BJ version is mounted upright with pin through the hole.
     
  9. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Unless you want to add a switch or two to select mute and standby manually, I'd just connect a 47uF cap on pin 23 via a 10k resistor to the 5V line. The amp would then be muted at power-up and go into operational mode ~ 500mS later.
     
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  10. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    Oh thx, that is how i will do it.

    Like this?

    Really appreciate you taking your time to help me.

    Tiggerlator
     
  11. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Not like that. Check the datasheet (Fig 4). Note that the cap connects between pin 23 and ground. The R would go between pin 23 and +5V.
     
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  12. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    ok thanks for your help.
     
  13. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    it powers on after a second or so, but i'm not getting nothing from the input. I can hear a hiss from the speaker if i put my ear to it.

    I have tried the following input connections.

    pins 1 and 3 on cn1000 which is the socket the reciever board was in, and pins 2 and 22 on the 8920 module.
     
  14. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Why pins 1 and 3? According to the Service Manual, the L and R audio is on pins 2 and 4 of CN1000.

    Edit: BTW, the Manual shows the L and R surround speakers shorted together!. That can't be right.
     
    Last edited: Jul 14, 2014
  15. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    I have it connected to pins 2 and 4 of cn1000 meant to put 2 and 4, not 1 and 3, i have ground on pin 1 of cn1000. I did try pins 2 and 22 of the 8920 ic direct too but still no output. The input is coming from my rotel pre amps outputs.

    I'm not sure on the shorted outputs, but i do get a real low hiss from the speakers when it is powered up, so i'm sure it is powering up now.

    I appreciate the help.
     
  16. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I'm unclear as to your exact setup.
    If you're not using the receiver board, are you now supplying the Rotel pre-amp outputs directly to pins 2 and 22 of the 8920? Or are you using the 'High-pass filter and Pre-amp' section of the Sony system?
    Apart from the R and C discussed above, is anything else connected to pin 23 of the 8920?
    What is the voltage at pin 1 of the 8920?
     
    Last edited: Jul 14, 2014
  17. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    nothing, just the R and C. I don't have a multi tester to test voltage but i will try and borrow one today. I will also post a pic of the board with the connections i have done ok.
     
  18. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    sorry for delay.

    Pin 1 to ground with it powered on is 25.1v

    Nothing else connected to pin 23.

    I guess i don't need to use the receiver board, that is only for its original use.

    I have tried connecting directly to pins 2 and 22, and also to pins 2 and 4 of cn1000.

    I am connecting the input to the damp from the pre outputs of my rotel amp, these would normally go to the power amp.

    Thanks
     
  19. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Still waiting for the promised pic.
    Looking at the detailed schematic in the Manual, I see that pin 23 of the TDA IC already has an R and C connected (R1007, C5602), so you shouldn't need any additional components there. But if you don't have a receiver board plugged into CN1000 then you will need to make connections to certain pins of CN1000. Pin 7 needs to be pulled high (so could connect to pin 5 via a ~47k resistor), and pin 10 needs to be low (so could connect directly to pin 1).
     
  20. tiggerlator

    Thread Starter New Member

    Jun 7, 2014
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    I will get some pics up tomorrow ok. thanks again.

    So I can remove the R and C i added to pin 23, and connect to pins 7 and 10 of cn1000 as you have suggested?

    Cheers Alec.
     
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