Broken CMOS Battery Holder ML1220

Discussion in 'Hardware Components and Aftermarket Upgrades' started by nrvinh, Nov 4, 2020.

  1. nrvinh

    nrvinh Notebook Enthusiast

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    I accidentally broke the CMOS Battery Holder. :(

    Here's with the battery:

    Acer1400_withBattery.jpg

    Here's with the broken + (positive) contact side:

    Acer1400_BatteryHolder1.jpg

    Here's with the + (positive) contact side removed to reveal a black pad(?) underneath. Is it a contact pad? There's no glob of solder holding it down, like on the - (negative) side. (See first picture with battery to see the - side solder.) I'm just wondering how the contact is made.

    Acer1400_BatteryHolder2.jpg

    I found the exact replacement here:

    https://www.digikey.com/en/products/detail/keystone-electronics/1072/9921820

    and schematics here:

    http://www.keystoneelectronics.net/ENG._DEPT/WEB_ORACLE/PDF/PDF CAT NO DRAWINGS/1000-1999/1072.PDF

    I can't tell from the schematics how the battery holder is attached to the motherboard. Is it two solder joints? One on each side of the battery holder? Do I just put a dab of solder underneath the + side?

    Anyone familiar with this type of battery holder?

    Motherboard is an Acer Aspire 1410 (1810T) netbook.
     
  2. Shin Falcon

    Shin Falcon Notebook Guru

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    Hello,

    It seems like a part of the PCB track is brocken too.
    If i was you i'll replace it with a vertical CR2032 holder and solder 2 wires (one for the + and one for the -)
    Have a look at this with this kind of holder you just have to cut the white connector, and solder + and - and use some electronic tape to cover the visible part of the CR2032.
    With this is place, you'll just have to remove the tape from CR2032, change it and take back the tape.

    If you're not familiar with soldering, you may ask an electronic part repair, it doesn't seems to be very hard. I think it's way easier to solder 2 wires than the same holder that was on the board. Plus as i said PCB track seems brocken.
     
  3. nrvinh

    nrvinh Notebook Enthusiast

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    Thanks for the response!

    The original battery is an ML1220 Rechargeable, so to introduce a CR2032, I would need to add a diode to prevent the recharging. Since this is inside a small netbook and the motherboard is multilayered, I don't think I can easily do that. However, if I can find a similar holder for the ML1220, that might do it.

    The first question is whether the black pad underneath the + side is the conductive contact point and I need to expose the metal underneath? I'd rather not scrape something off that should be there. The - side has some solder to hold it down, but the + side didn't appear to have any and the bottom of the broken part just has a square metal pad.

    Currently, the black pad doesn't appear to be conductive at all.

    Black pad in question:

    Acer1410_BatteryHolder3.jpg

    Bottom of broken + side. It's just a square metal pad that is conductive: (Was it just held in place with some kind of conductive glue, whereas the - side uses solder?)

    Acer1410_BatteryHolder4.jpg
     
  4. nrvinh

    nrvinh Notebook Enthusiast

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    Here are the two sides of the replacement part:

    The + (positive) side doesn't have much clearance for soldering down a bead of solder. Maybe put some solder on the contact pad and heat up from above to make the connection?

    [​IMG]

    The - (negative) side has plenty of space for solder:

    [​IMG]
     
  5. Shin Falcon

    Shin Falcon Notebook Guru

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    Hello,

    CR2032 and ML1220 have same voltage, ML1220 is rechargeable you're right and ML1220 is indeed smaller.
    Seeing your last photo of post #3, you can see the copper from the track still soldered to the part of the holder. That's why you see the black/metal plate you circled in red with an arrow. What remain of the track is on the right of your red rectangle.
    There are soldered ML1220 with wires already protected with protective tape like this and it'll be a lot easier to solder.
    If you're not sure on what to do or not familiar with soldering, you may ask an eletronic part repair. It seems to be more difficult since one of the track is brocken.
     
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  6. Mr. Fox

    Mr. Fox BGA Filth-Hating Elitist

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    The design of that socket looks inherently weak and subject to the breakage you experienced. Rather than trying to replace the socket, perhaps the easiest way to fix it might be to solder the female side of one of these pigtails to the motherboard:
    https://www.ebay.com/itm/10-PCS-Micro-JST-PH-1-25-2-PIN-MALE-FEMALE-PLUG-CONNECTOR-WITH-WIRE-CABLE-M578/233719768767?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
    ...and use this type of CMOS battery:
    https://www.ebay.com/itm/Yellow-Res...906053?hash=item3d524ee085:g:gX0AAOSwM3hfg9fU
     
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  7. Shin Falcon

    Shin Falcon Notebook Guru

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    Hey @Mr. Fox Thank for confirming my idea is good.
    So @nrvinh your best bet is to find an ML1220 like me and @Mr. Fox said and solder it.
    Do not try to remove what remain of the - part without a soldering iron and for the + you must remove it to have a better access to the - track.
    I recommand you a very thin 10-15w soldering iron and a multimeter to check cuitinuity of your soldering. Also you must be very carefull with nearby component.

    EDIT : Or you can try to break the big black round part and keep what remain of the + side, and use what did contact to the ML1220 as a soldering plt for the + wire of your new ML1220 part.
    Hope you'll understand, it's hard to explain in english.
     
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  8. nrvinh

    nrvinh Notebook Enthusiast

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    @Shin Falcon I think you're right about the trace being broken and the contact pad being ripped off the motherboard by the broken half of the battery holder. I took some more pictures... Thanks again for the observation and advice!

    @Mr. Fox Thanks for the advice and link to the pigtails. I hope I can find an ML1220 Rechangeable that has the connector, to make for easy future replacement.

    The black pad should probably stay to prevent electrical contact with what's below it. It seems there's only a sliver of the trace from the motherboard going to the missing contact pad that used to be over the black pad. I was able to test electrical continuity between the left and right side of the sliver. I guess I'll need to scrape off some of the green motherboard coating on the sliver to provide more surface area to solder to:

    Acer1410_BatteryHolder5.jpg

    Here's the ragged edge of the square pad:

    Acer1410_BatteryHolder11.jpg

    The battery side of the broken part, showing some solder:

    Acer1410_BatteryHolder8.jpg

    A little lower angle:

    Acer1410_BatteryHolder9.jpg

    Opposite side of battery of battery holder. The original contact pad is super thin!

    Acer1410_BatteryHolder10.jpg
     
  9. nrvinh

    nrvinh Notebook Enthusiast

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    Well, here's my attempt at the repair... first, the easy part, prepping the battery...

    Acer1410_BatteryReplacement12.jpg

    Positive and negative contacts taped down with foil tape, which contours very well around the wires. The adhesive prevents the charge from passing through, so although metal...

    Acer1410_BatteryReplacement13.jpg

    Wrapped with non-conductive electrical tape...

    Acer1410_BatteryReplacement14.jpg

    Shrink wrapped to make sure it stays together...

    Acer1410_BatteryReplacement15.jpg
     
  10. nrvinh

    nrvinh Notebook Enthusiast

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    Now the motherboard... which I can't be sure worked...

    The battery holder removed... missing positive pad on left, negative pad on right with some residual solder...

    Acer1410_BatteryReplacement16.jpg

    Some of the coating scrapped away to expose the trace to the missing positive pad. Negative pad cleaned of solder with desolder braided wick...

    Acer1410_BatteryReplacement17.jpg

    Battery connector soldered...

    Acer1410_BatteryReplacement18.jpg

    Since there wasn't much metal to solder to and the solder joint is weak, I decided to reinforce with non-conductive electrical tape to hold it in place...

    Acer1410_BatteryReplacement19.jpg

    Wider view with battery connected...

    Acer1410_BatteryReplacement20.jpg
     
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