TM-731a CMOS Reseting Itself

Discussion in 'Mobile Radio Systems' started by W5CNW, Nov 25, 2012.

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  1. W5CNW

    W5CNW Ham Member QRZ Page

    You're right about the battery voltage dropping. I should have remembered that. I'll check my power supply with my scope to see if I can detect a spike. I'll also watch the radio closely over the next month to see what it does installed mobile.
  2. KA9MOT

    KA9MOT Ham Member QRZ Page

    Your local radio club is working surveillance at the mall? Why would you need your rig in your car? Why would the radio club be working surveillance?
  3. K0BG

    K0BG Ham Member QRZ Page

    Steve, it is sort of like Halloween prankster watches. I personally don't believe in it, but there it is!
  4. W5CNW

    W5CNW Ham Member QRZ Page

    We just drive around the parking lots and report anything that looks suspicious to our net control, who then relay it to the mall's security.

    Anyway, it still hasn't reset since I installed it mobile (about a week and a half ago). Here's a picture of the power up curve of my power supply:


    This is 5 volts/div on the vertical, and 20 ms/div on the horizontal.

    Here's a video of the power down curve (a little more interesting, if you ask me):

    Last edited: Dec 11, 2012
  5. KA9MOT

    KA9MOT Ham Member QRZ Page

    Playing Paul Blart Mall Cop? Is using amateur radio to provide back up security for a private business legal? Is that with-in the definition of the Amateur Spirit? Your bio says you are 16... Is this something a teenage kid should be doing? Shouldn't you be dating or something? Why would you need an HF rig for this? What club? And lastly, do you and your club aspire to wackerdom?

    If I were your dad, I'd insist you find a new club and a girlfriend, and then I'd go have a long conversation with the unbalanced individual who is misleading you.
  6. KA9MOT

    KA9MOT Ham Member QRZ Page

    Somebody is certainly putting this kid in harms way, if nothing else.
  7. KG4CGC

    KG4CGC Ham Member QRZ Page

    Even in America, some people still want to play SS.
  8. W5CNW

    W5CNW Ham Member QRZ Page

    First of all, we don't get involved in anything. We all have specific orders not to get involved in any situation. We simply report what we see to the security and, if necessary, the local police (who are working directly with us). As far as any of the public can tell, we're just normal vehicles (save the antennas) driving around the parking lot. I highly doubt that anyone even notices our presence. My dad knows full well what risks are involved, and has allowed me to participate. In many ways we are actually safer than a member of the normal public shopping at the mall, because we have a direct radio link to security and police.

    Secondly, I started this thread to discus the problem of a TM-731a (a dual-band 144/440 mobile, not an HF mobile) losing it's memory, and I'd appreciate it if we can stay on-topic. :)

    Ok, having said that, do y'all see anything weird going on with my power supply that could cause problems?


    P.S. I just got a new call sign this morning. It's now W5CNW, formerly KF5IYL.
  9. KJ3N

    KJ3N Ham Member QRZ Page

    It's probably been close to 18 years since I've had a 731a and it had the same problem back then. The following is all going by memory, so it might not be exactly correct.

    What I think you're looking for is a bad electrolytic capacitor buried in the front panel. When I took mine apart, I remember seeing a very small electrolytic capacitor that showed signs of leakage. It was either tied to, or very close to a 6 or 8VDC source. Once I replaced that cap, the problem never came back.

    Looking at the service manual and schematic online, there is a C107 (100uF @ 10 WVDC) tied to the output of IC102, which is a 6 volt regulator tied to the IC103 CPU chip.

    That might be the cap I replaced, but I'm not entirely sure. I simply remember that it was very small and it was an electrolytic capacitor of some sort. The 10WVDC rating seems to be familiar to me.
  10. KC2UGV

    KC2UGV Ham Member QRZ Page

    Why doesn't the mall just hire more security?
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