A little help

Discussion in 'General Electronics Chat' started by R!f@@, Sep 30, 2012.

  1. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
    see the attached.

    I think it's a SOT-89 package.
    number marking is 37 & 89

    The second picture says 1.6 & MF

    I got to know what they are doing..or what they are. Marking indicates an IC. I am thinking it's a regulator of some sort.

    Any one any ideas ?
    Last edited: Sep 30, 2012
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    After 5851 posts, I would think that you would come up with a meaningful title for a thread. ;)

    SgtWookie likes this.
  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    I'm surprised you are asking, with your repair experience. It's marked IC. It's obviously a power device so that rules out 3pin voltage supervisors etc, so 99% probability is a regulator.

    Check it for standard regulator pinout for that package and if one pin is ground and the right pins go to caps (which appears to be true looking at the photo) the only question remaining is what voltage is it?

    1.6 marking is likely a 1.6v regulator. Powering it up should answer that too. ;)
  4. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
    Don't mind me asking, what's tht suppose to mean.?
    I think th title was meaningful. I need a little nudge on the right direction ;).

    Come to think of it, you need title for ur posts. :cool:

    Hey...I am banging my head 24/7. Isn't it obvious I might miss some things. Besides I got u guys for friends. What good are u if u do not advice. :D.

    Now tht u said it, it makes sense. I will get back at it after finishing the current job.
  5. BSomer


    Dec 28, 2011
    I have nothing for you on the "1.6 MF". However, the "37 89" could be a UTC81XX which is a power reset switch. The problem though is that the datasheet does not show how the markings are for the SOT-89 pacakge.
  6. t06afre

    AAC Fanatic!

    May 11, 2009
    The Turuta databook say so. But if it was that chip. The markings would have been different. R!f@@ are you able to trace how this chip is connected to other ICs. That may be of some help. If it is not a regulator it may be a Zener. The often come in SOT-89 package
  7. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
    The two buggers are located around two power PNP's. One PNP collector gives me around 5V but the other zip. The first picture is the one I am having trouble. The PNP connected to it does not have any base voltage.

    The item is a kenwood DVD car stereo. It is dead no display power up what's so ever. The LCD itself is OK, I checked. the worked the back-lit separately to see if the thing powers up for a sec or two but nada.

    I believe a low voltage used for the μC is missing. At the instant of connecting the 12V the set whines a low level tone for a few ms and it dies, no display flicker, no mechanism initiation. But I can get some voltage at the second PNP and after the whine it dies.

    Could them be 3.7V and 1.6V reference generators or regulators