Wed May 04 2022

Super Cap Post

Can anybody help me how to replace the super capacitor on a Medfusion 3500 properly. I have blown out one mainboard already. It seems there is a proper way to do it. Is it like replacing a backup battery? must leave the unit on somehow? Or use jumpers to feed 5volts while removing Capacitor? Need Helpful advice please.

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Thu May 05 2022Reply from T-Lobato
T-Lobato

You do not want any power attached to the device.  Also, be sure to discharge the capacitor before you remove it.  Capacitors hold a charge by nature and you do not want it to discharge by accident and take out other components.

Just me.

T.


TJ Lobato | MedWrench Guru
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Thu May 05 2022Reply from T-Lobato
T-Lobato

By the way, my post is merely around replacing capacitors in general.  I am not sure about this specific repair whether it's soldered in to the mainboard, another board, etc.


TJ Lobato | MedWrench Guru
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Mon May 09 2022Reply from JD Medical
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Use good soldering iron with a solder sucker. Make sur polarity is right when you place new one on.


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Mon May 09 2022Reply from Clin Eng
Clin Eng

Not sure how you have blown out the motherboard in attempting to replace the supercap.

It is fairly straight forward.  Just cut the 4 dabs of hot glue that should be around the edges of the cap being careful to not gouge the board tracings.

Then just unsolder the cap from the opposite side.  If you do not have good soldering skills do not attempt it.  You should apply some fresh solder to the connections to make it easier to desolder then use a solder sucker to remove.

I have performed over 25 of these with no issues and always corrects the supercap alerts at great savings over factory repair or board replacement.costs.


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Mon May 09 2022Reply from James1784
avatar placemark

Hi Clin Eng, was those SuperCaps you changed from a Medfusion 3500 mainborad?

I am hesitant to try again I though it was staright forward desolder/remove and replace with new Super Cap (the Mainboard lost all functions) 

I talked to an experienced tech from another facility and the said you have to continiously maintain voltage while removing and installing a SuperCap otherwise you will lose everything and/or damage the mainboard. But he declinded to tell me how.

I figure to attached aux power (5volts) to the capacitor ternimals during removal/installing. 

I will give it try.


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Tue May 10 2022Reply from Clin Eng
Clin Eng

Yes, We only have the Medfusion 3500 model and I have done many as mentioned with no problems.  I did not need to discharge the cap. or keep a voltage on the board.

You may have damaged surounding components or caused an electrostatic shock to the board.  Make sure you are grounded before handling the board.


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Tue May 10 2022Reply from T-Lobato
T-Lobato

Clarification: If the cap is bad, then it should not hold a charge.  In general though, I always discharge a cap before I handle it as they can hold a charge. 

I personally would not work on a live circuit.  

Let us know how it comes out James1784.


TJ Lobato | MedWrench Guru
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