Pictorial: forgetful Zumo slows down, loses settings -> replacing internal GPS backup battery

Discussion in 'Mapping & Navigation' started by rdwalker, Dec 7, 2015.

  1. rdwalker

    rdwalker Long timer Supporter

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    Is your Zumo 550 becoming senile? Forgetting where it was and what it was doing last time you used it?

    Well, you may be surprised to find that there is an internal battery in the 400/500 Zumo series, in addition to the large external main battery. The removable main battery provides power only for the operation of the receiver, but not the real time clock.

    The non-removable internal battery maintains device memory. The symptoms of failing internal battery are:
    • Excessively long time to lock onto GPS satellites after power up.
    • Loss of time-of-day.
    • Powering up in wrong daytime/nighttime display mode.
    • Reverting to XM-radio preview channel instead of last-used channel with the GXM30 sat radio puck.
    These GPS receivers are becoming old by now; it is likely that your Zumo is having this problem.

    Note: I believe that this post should pertain to the whole Zumo 400-450-500-550 series. I only performed the operation on my own 550 - open your device to confirm the location and type of the internal battery.

    You should be able to replace the internal battery if you have some elementary electronic tools and skills. I purchased the replacement battery from www.palmdr.com for just under $10; they also offer repair service if this is beyond your abilities.

    Here is the procedure.

    1. Your problem: the Zumo 400, 450, 500 or 550 receiver loses its memory of last-used state, including time-of-day. This causes very long GPS resync times.

    [​IMG]

    2. Remove the external "backpack" battery. Depending on model and date of production, you may have to unscrew a T-10 Torx security, an Allen-head or a Philips-head screw.

    [​IMG]

    3. You may be able to defeat the Torx security by jamming a small flat screwdriver into the fastener and using pliers to turn it.

    [​IMG]

    4. Pop off the top cover ('cap’) by twisting a coin or flat screwdriver in the slot; remove the T-6 screws from the hinge of the bottom cover.

    [​IMG]

    5. Unscrew the 4 fasteners from back cover of the receiver - most likely T-6, though I have seen Philips-head as well. Open the receiver. Gently! There are some wires in the way. Do not disconnect anything.

    6. The battery is under this shield. Remove it.

    [​IMG]

    7. Now de-solder the internal battery.

    [​IMG]

    8. These are the solder pads, once the battery is removed.

    [​IMG]

    Make sure to correctly place the replacement battery on the pads, avoiding short-circuiting it or applying reverse polarity to the circuit.

    Dab a little silicon caulk or RTV onto the battery after soldering, to glue it to the circuit board, to prevent vibration from ripping it off the pads.

    From now on, follow the process in reverse to reassemble the receiver.


    Good luck!
    #1
  2. 06motorradman

    06motorradman Been here awhile

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    I wonder if this would work on my BMW branded Garmin unit.

    Sent from my XT1254 using Tapatalk
    #2
  3. rdwalker

    rdwalker Long timer Supporter

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    The difference between BMW-branded Navigators and original Garmin receivers is mostly in software. If you have the Navigator II and Navigator III, you will find that these are the equivalent units to the Zumo 400/500 series. The earlier Navigator units also supported the special BMW cradle, with additional pushbuttons on the left side.

    But:

    The proof is in the pudding. Simply, take your receiver apart and check if you have the battery shown in my pictorial. Not a big effort.

    Regards, Robert.
    #3
  4. Guy Young

    Guy Young Long timer

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    I know this is an old post, and others have probably found this out already, but Item 6 is incorrect. The battery is actually on the flip side of the main PCB on the opposite side of that picture. You need to remove the PCB from the rear housing to access the battery. Found this out when I had mine apart to replace the crumbling button key pads. Figured I'd replace the weak/dead internal battery at the same time.
    .
    #4
  5. Guy Young

    Guy Young Long timer

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    If I might beg the indulgence of the original poster, I FINALLY had a chance to take the time to replace the keypads on my Zumo 550. Removal and replacement of the pads was pretty straight forward. The old ones were mostly removed with my thumbnails; they just crumbled away. The remainder was removed with an X-acto blade and Scotchbright pads. From a procedure I’d received from the keypad vendor, I used the recommended Sil-Net silicone sealer to secure the new pads in place.

    While I had it apart, I replaced the internal battery since it had died a number of years ago. The original pictures are a little misleading as this freakin’ thing is small and it can be a little difficult to manipulate into place with correct contact alignment without shorting it out. Aged, fumbling fingers don’t help in the process either.

    To avoid any drama and risk shorting out the new battery, I cut a 1/4” to 3/8” wide strip from a Post-It note in the sticky area, and stuck it over the two battery contact pads on the PCB. This, of course, was after the bad battery was removed. I used a magic marker to mark over the 2 areas of the pads to show their exact location. After that, I put a small dab of silicone sealer on the back of the new battery and put it in place, carefully aligning the battery’s two contact fingers over the marks I’d made on the Post-It note strip.

    After a couple of days to insure the sealer had cured, I tried to wiggle the battery to make sure it was stuck in place and wouldn’t move. Satisfied all was good, I pulled the Note’s strip out from under the contacts and carefully soldered each in place with a small, pencil tipped iron.

    Everything was reassembled in short order, and I had a new, old unit that now keeps track of the time (without satellite intervention) and acquires satellites in pretty short order.
    #5