Author Topic: PCB Repair (lost SMC cap)  (Read 491 times)

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Offline skymontTopic starter

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PCB Repair (lost SMC cap)
« on: February 04, 2025, 10:40:42 pm »
I accidentally knocked off a capacitor while plugging the power cable back in, my hand slipped and the tool smacked off the cap, Im not too familiar with sourcing new parts, I know its a 603 size, 150uf ceramic capacitor, and the battery is 7.74v. the capacitor is right after the battery cable so its definitely getting 7.74v.
can anyone help me find a replacement capacitor? dont care if I have to spend $50 on a book for smcs
 

Online ataradov

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Re: PCB Repair (lost SMC cap)
« Reply #1 on: February 05, 2025, 12:49:31 am »
150 uF capacitors don't exist in 0603 package. And how do you know the value? It is typically not printed on the ceramic capacitors.
Alex
 
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Offline skymontTopic starter

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Re: PCB Repair (lost SMC cap)
« Reply #2 on: February 05, 2025, 03:33:22 am »
thats what the muiltimeter read, fluke 87. I just double checked like 10 of them, they all read 148-152 uf.
after double checking the sizes, micrometer measured .074 by .037 inches, which is imerial 603 or metric or metric 1608
 

Online ataradov

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Re: PCB Repair (lost SMC cap)
« Reply #3 on: February 05, 2025, 04:07:08 am »
Are you measuring in-circuit? That measurement is meaningless.
Alex
 

Offline gamerpaddy

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Re: PCB Repair (lost SMC cap)
« Reply #4 on: February 05, 2025, 10:31:39 am »
probably just a decoupling cap, slap in a 100nF 0603 in there and call it good.
you can even fit a 0805 in a 0603 footprint.

ive repaired multiple wifi routers with 100nF caps on the dc-dc converters that failed until i had the idea to measure a good one to see if its even the right value .. it should be 2.2uF...oops
but nevermind it still worked just fine on all of them..   

Offline skymontTopic starter

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Re: PCB Repair (lost SMC cap)
« Reply #5 on: February 05, 2025, 09:34:57 pm »
I found out the problem, its a me problem, clearly ive lost my mind. obviously is possible to have them wired in parallel on a circuit board, dont know why I thought I could get an accurate measurement off the board lol.
aaaaanyways, any recommendations on where to buy the part after I un**** my brain and get around to pulling one off for proper a measurement?
also, does voltage rating matter a lot? is it safe to go over but not under? do I need to at least be close but above?
also how far off my measurement capacitance wise is accaptable?
 

Online ataradov

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Re: PCB Repair (lost SMC cap)
« Reply #6 on: February 05, 2025, 10:17:55 pm »
There is a good chance you don't need that cap at all. But generally pick anything with a higher voltage and basically any capacitance in a 1-10 uF range if that makes you feel better.
Alex
 


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