# How to simulate a capacitor's value ?

Joined Oct 21, 2016
34
Okay now the title may sound a bit strange so to make it more straight forward which is better putting two capacitors in series or in parallel
Now my problem is an old monitor of mine gave up a couple of days ago and as expected the power circuitry's capacitors were faulty (I don't blame them for blowing after 11 years of service) and from the blown up capacitors are a couple of 680uF 25V which aren't available at my local electronics shop
I determined that to have a simulated 680uF I would either need to put a 2200uF and 1000uF capacitors in series or I can put a 470uF and 220uF capacitors in parallel which according to the math should produce 687.5uF and 690uF respectively which I think is still within the accuracy of the original capacitor
Now how does they behave when in either configuration in terms of the voltage aspect ?

Thanks a lot

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#### Kjeldgaard

Joined Apr 7, 2016
381
I would use 1000 uF / 25V alone.

Joined Oct 21, 2016
34
I would use 1000 uF / 25V alone.
Wouldn't that disrupt some sort of refresh rate / cycle frequency ?

#### Kjeldgaard

Joined Apr 7, 2016
381
If the capacitor is in the input of the power supply, a slightly higher value should only yield a smaller ripple voltage.

I'd guess that 680 uF is just enough for the monitor's design.

Joined Oct 21, 2016
34
Here are a couple of pictures of the PCB
I assume because they are close to the power plug they are related
Though I also not sure because they are also close to the high voltage outputs

#### MrChips

Joined Oct 2, 2009
19,730
As Kjeldgaard suggests, if the capacitor is from the power supply section, you don't need to match the value exactly. The other requirement you need to consider is the physical dimension and lead configuration, i.e. radial or axial. In other words, does the replacement fit in that location?

If the original is 680μF/25V your next best replacement is 680μF/63V. That is, it is acceptable and even better to go for a higher voltage rating.
Failing that, you can get 1000μF/63V if it fits physically.

This gives you a wider selection.