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what happens lower voltage cap. connected instead of higher voltage

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adnan_merter

adnan_merter

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hi, i just realized i connected 6.3v 0603 case 10uF capasitor instead of 16v(which is in datasheet design) and this capasitor is a boost converter capasitor for oled screen's internal DC-DC converter. oled requires 7.5 volt VCC and this capasitor is 6.3v. of course my screen doesnt work.

i wanna know "is this the real reason why it doesnt work? if so, is my oled damaged?"
 

i wanna know "is this the real reason why it doesnt work?
Click to expand...
The only way to know is check the signals with an oscilloscope...
 

shaiko said:
The only way to know is check the signals with an oscilloscope...
Click to expand...

thanks for reply

unfortunately i don't have a scope, can you tell me what happens a lower voltage capacitor is connected instead of higher voltage capacitor. does this blow the capacitor or the capacitor can not charge more than the specified limit and survive anyway.
 

I accidentally applied 16V to a 10V electrolytic, causing it to explode. The metal container detached and flew across the room. Bits of brown paper were scattered.

Even if it had not exploded, it would no doubt have its dielectric ruined.

Test the capacitor by itself, to find out its condition.

An easy test is to connect an ohmmeter set to a high range. The needle should swing immediately to a low value (to the right), then go back slowly to infinity (to the left). Do this a few times, at one polarity, then the other.

When done, do not leave the capacitor charged to the wrong polarity.
 

i have ceramic smd capasitors, actually i havent seen any explosion or burn mark on capasitor, but the screen is not responding, i think the only way to understand is to use 16v capasitor and check the oled screen.

thanks for reply
 

I think that ceramic capacitors usually fail shorted under over voltage conditions and they tend to not show any external damage unless the over voltage was large enough that it basically explodes.

Look at the following study.
 

A 6.3V ceramic capacitor will unlikely fail with only 20% overvoltage. Capacitance will be however reduced to a value between e.g. 15 and 50 % of the nominal value which might affect circuit operation.

In practice you would replace the capacitor and check if this solves the problem. Of course you can also check for short circuit.
 

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