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Thread: MCS2000 Excessive Standby Current Draw

  1. #1
    maxkelley No Longer Registered

    Default MCS2000 Excessive Standby Current Draw

    Hello all,

    Wondering if anybody has had this happen.. I've got an MCS2000 900MHz Model III which draws 1/4amp when it's off. What gives? Does anyone know the cause of this?

    Thanks!
    Max


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    Do you have the ignition sense line tied into the B+ line? In a mobile enviroment, the radio is supposed to be installed so the ignition sense is on when the vehicle is running, because when the radio is off, it is still on (standby) if it senses 12 volts on the ignition sense line.

    The current draw is within specs. If you want the radio to turn off completly, don't connect the ignition sense to the battery.

  3. #3
    maxkelley No Longer Registered

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    Within specs? My CDM1550LS+ barely draws anything when it's off completely. And no, this one is not tied to ignition sense. I use the power button to turn it on and off. When it's on and backlight is full-brightness (not receiving) current draw is ~450mA, when I then push the power button and turn the radio off (screen goes blank, backlight off, etc.) the current draw is 250mA. That's *way* more than the CDM's and most others I've seen.

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    Hmm. That does sound weird. Is it only on the ignition control line, or is it on the PA power leads? Isolate by pulling the ignition wire and see if the drain persists.

    Maybe the reverse protection diode has taken a spike and is partially punched-through. This is usually a large pill-shaped diode near the power entry of the PA. I'm not that familiar with the CDM's so I can tell you exactly where it is, but it's a giant diode across the power input leads, and it's meant to pop the fuse if the radio is installed reversed-polarity. Maybe that diode is leaky? If the problem is isolated to the ignition wire (drain goes away when wire is pulled) then try looking for leaky devices (diodes, transistors) on that line. There is very likely some kind of protection diode or EM filtering on that line that also might be punched.

    I have seen this problem with the static protection zener diodes in portables as well. Frequently a static zap will partially punch them through, so they get a low resistance to them but aren't quite shorted completely, but they will mess with whatever signal they were installed to protect. These usually are on pins going into/out of processors, like programming ports, speaker/mic connections, etc.

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    cyrus's Avatar
    cyrus is offline Trailer Park Superintendent
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    My old MCS2000 always drew a lot of standby current. Seems to be the nature of these beasts.

    I just made sure to pull the power to the radio if the vehicle was to sit more than a couple of days.
    Cyrus

    Bubbles: I'd like to see that Red Blue Green c***sucker put one of those together, duct-tapin' it.

  6. #6
    maxkelley No Longer Registered

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    Quote Originally Posted by Alpha View Post
    Hmm. That does sound weird. Is it only on the ignition control line, or is it on the PA power leads? Isolate by pulling the ignition wire and see if the drain persists.

    Maybe the reverse protection diode has taken a spike and is partially punched-through. This is usually a large pill-shaped diode near the power entry of the PA. I'm not that familiar with the CDM's so I can tell you exactly where it is, but it's a giant diode across the power input leads, and it's meant to pop the fuse if the radio is installed reversed-polarity. Maybe that diode is leaky? If the problem is isolated to the ignition wire (drain goes away when wire is pulled) then try looking for leaky devices (diodes, transistors) on that line. There is very likely some kind of protection diode or EM filtering on that line that also might be punched.

    I have seen this problem with the static protection zener diodes in portables as well. Frequently a static zap will partially punch them through, so they get a low resistance to them but aren't quite shorted completely, but they will mess with whatever signal they were installed to protect. These usually are on pins going into/out of processors, like programming ports, speaker/mic connections, etc.
    Hi Alpha... I don't use the ignition sense line on this radio (although I might now, once I put it in the vehicle again.) I will check that diode... that's not a bad idea. I just find it hard to believe that this radio *should* be drawing that much current in standby. I've heard, cyrus, that many of them seem to do it, but I can't bring myself to believe that they designed them to work that way originally...

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    It is the diode a lot of the time. Sometimes the car gets jump started and it damages that diode.

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    Quote Originally Posted by maxkelley View Post
    Hi Alpha... I don't use the ignition sense line on this radio (although I might now, once I put it in the vehicle again.) I will check that diode... that's not a bad idea. I just find it hard to believe that this radio *should* be drawing that much current in standby. I've heard, cyrus, that many of them seem to do it, but I can't bring myself to believe that they designed them to work that way originally...
    That is why they have an ignition sense line. They don't draw that current unless the vehicle is running. Specs for an Astro Spectra list standby current at 750mA, so 250mA is nothing.

  9. #9
    maxkelley No Longer Registered

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    I don't know if I was clear or not... What I'm calling standby is "off". I.E., somebody pressed the power button, the screen turned off, the radio is "off" waiting for somebody to press the power button again, or for ignition sense to go high. In this state, a CDM I was measuring the other day was drawing 70mA (ish). If my Astro Spectra drew 750mA when it was off, my car battery would have been dead long ago!

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    TECHNICAL INFORMATION CENTER
    8000 W. SUNRISE BLVD. FT.LAUDERDALE,FL 33322

    SRN: 1211
    APC: 722
    Date: December 18, 1996
    Deadline Date: Not Applicable
    Memo To: SRN Mailing List
    From: MCS2000 Product Group/Product Services,Plantation


    Subject: Ignition Sense Set up on the MCS2000 - Informational Bulletin

    Symptoms:
    Unexpected Battery Discharge, the radio continues to draw approximately 300mA, even though the radio control head display is off.


    Potential Problem Radios:
    MCS2000 mobiles with firmware version R04.00.00 which have Ignition Sense set to BLANK in the RSS programming.

    Cause:
    The Radio firmware R04.00 functions slightly differently than firmware release R03.13 or earlier.

    Corrective Action:
    With firmware release R04.00, if the ignition sense cable is connected to the vehicle battery power, it is necessary that Ignition Sense be programmed to Soft Power Off (instead of BLANK) using the Radio Service Software (RSS).

    1. Using RSS, program the ignition sense to Soft Power Off, even if you do not plan to use the ignition sense feature;

    ---------or---------

    2. Do not connect the ignition sense cable to the radio.
    To determine firmware version: Immediately after pressing the test mode entry button five times, observe the display. The radio will scroll automatically and sequentially through the following displays:


    • SERVICE
    • Radio Software version (firmware)
    • Control Head version
    • Model Number
    • Serial Number
    • FLSHCD, 2-3 screens of flashcode information
    • RF TEST

    This bulletin is for information only, no warranty is implied or offered.


  11. #11
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    What firmware version is in the radio, maxkelley?

    If you need an update to fix this issue, and are unable to find anyone else to perform it, I can do it. See my ad in my signature.

    Or send a message to Magnus; he's in the USA and can likely do it, too.

  12. #12
    maxkelley No Longer Registered

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    I'll have to check and see what firmware is in this radio... I can't honestly remember off the top of my head, and it's in pieces on my bench at the moment (along with a decent amount of other things.... :P) So, if it is before 4.00, it shouldn't be doing it... If it *is* 4.00, I have to correct that setting. If it's after 4.00, I'm screwed. Did I get that right?