New member...need guidance on IC CHIP

Discussion in 'The Projects Forum' started by robismod, Sep 22, 2015.

  1. robismod

    Thread Starter New Member

    Sep 22, 2015
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    Hello all:
    I am trying to repair an AEQ BC300 radio broadcast mixer. Six of 12 channels have a problem with distortion on input signal, and a couple have fader issues too. There are only three IC chips on each channel: LF 351N, LM 833N, and T9734.
    I have found the 351 and 833, but cannot find the T9734 ANYWHERE. Mfg. has an office in Florida, and the kind tech guy there sent me a service manual. It IDs the T9734 as an SSM 2018. I find great difficulty in finding that one too, or any text on something that might replace it. Another email to the tech guy and he says he has only ONE, and it's 30 bucks.
    The two small chips are a single, and dual op amp. But this bigger T9734 seems to control many different things I think (rookie here).
    Can anyone shed any light on it for me?

    Thanks much,
    Tim
    LOVRadio.com (please check my site out)
     
  2. absf

    Senior Member

    Dec 29, 2010
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  3. robismod

    Thread Starter New Member

    Sep 22, 2015
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    Thanks much Allen...
    I found out a bit more a few minutes ago...talked with a great fellow from AnalogDevices about their SSM2018. Chip is obsolete now, but
    they still have one of the versions of it.
    The 2018PZ receives trimming from an external circuit (I THINK this is what I need, as there is a variable/adjustable component tied to it in the schematic, as well as I can see if physically on the board)

    The 2018TPZ is factory trimmed; does not require external circuit.
    AnalogDevices does have in stock the TPZ versions, but no PZ, but did say their distributor Rochester Electronics has oodles of them.

    I'm going to check on them.
    (I've seen a few on Ebay yes, but I don't like to order from China or else if I don't have to--last time it took about three weeks to get something, and I'm sure impatient..haha)
     
  4. robismod

    Thread Starter New Member

    Sep 22, 2015
    10
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    Found this on the Analog Devices site:

    The SSM2018T represents the continuing evolution of the Frey Operational Voltage Controlled Element (OVCE) topology that permits flexibility in the design of high performance volume control systems. The SSM2018T offers voltage output and is laser-trimmed for gain core symmetry and offset. As a result, the SSM2018T is the first professional audio quality VCA to offer trimless operation.

    Due to careful gain core layout, the SSM2018T combines the low noise of Class AB topologies with the low distortion of Class A circuits to offer an unprecedented level of sonic transparency. Additional features include differential inputs, a 140 dB gain range, and a high impedance control port. The SSM2018T provides an internal current-to-voltage converter; thus no external active components are required.

    This device is offered in a 16-pin plastic DIP package and guaranteed for operation over the extended industrial temperature range of -40°C to +85°C.

    Show Less..
     
  5. robismod

    Thread Starter New Member

    Sep 22, 2015
    10
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    Dang! Rochester Electronics site shows to have the P version (AD said ok), over 8000 in stock at about 5.58 each. BUT they want a minimum order of 250 dollars, or agree to pay a "service charge" of the difference...(less than 40 dollars of parts still would cost 250 dollars! Yikes)
    Sooooo close...but yet so far......(sigh)
     
  6. absf

    Senior Member

    Dec 29, 2010
    1,492
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    Glad you found the chip finally.

    But there are lots of chips that are obsolete when I was repairing musical keyboards and Technics digital piano, I always use eBay as my last resort when I run out of choices.

    Allen
     
  7. robismod

    Thread Starter New Member

    Sep 22, 2015
    10
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    Looks like that is where I'll have to go Allen...lol...guess I'll be waiting awhile--means parts laying all over the place for some time to come...haha
     
  8. robismod

    Thread Starter New Member

    Sep 22, 2015
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    AEQ Circuit.JPG
     
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  9. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    absf likes this.
  10. absf

    Senior Member

    Dec 29, 2010
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    Yes, I have ordered from these guys too. Same impression as yours though slightly more expensive than the other guys from China. I think this company is based in HK.

    Allen
     
  11. robismod

    Thread Starter New Member

    Sep 22, 2015
    10
    1
    Thanks again guys...just ordered six of the chips from UTsource, and used the Express shipping...anxious to get them and proceed...
     
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