Ocilloscope Issue

[coreAngel]

Hello,everyone i have an issue i really need your help, i bought an ocilloscope on ebay one of those DIY kits,

DSO138 2.4" TFT Digital Oscilloscope Kit DIY parts ( 1Msps ) with probe


and the electrolytic caps that came with it 4 of them, 2 have the bung pushed out when i look at the manufacturer it's Cheng craps.

So i wanted to ask i wanted to choose other caps or poly's they are very small caps
would general purpose caps work, low impedance caps ,or very low esr?

thanks for your help

[stj]

Re: Ocilloscope Issue

size of the can, distance between the wires, rating of the caps please.

[coreAngel]

Re: Ocilloscope Issue

size of the can, distance between the wires, rating of the caps please.

Sorry i thought i posted the specs, the caps are small 16v 100 microfarad Cheng fakes i believe..it says Chng


distance between leads is 2mm
And the cap is 6mm high

[coreAngel]

Re: Ocilloscope Issue

Any help would be appreciated.. i just don't know what would be good, low esr, caps..etc

these are my choices

http://www.mouser.com/ProductDetail/...%2fXYbMkdFI%3d

http://www.mouser.com/ProductDetail/...MWtkd2mWibI%3d

[stj]

Re: Ocilloscope Issue

without more info on the fakes or a schematic, it's hard to help
personally i'd just stuff it full of panasonic FR - but i do that with everything!

[coreAngel]

Re: Ocilloscope Issue

without more info on the fakes or a schematic, it's hard to help
personally i'd just stuff it full of panasonic FR - but i do that with everything!

thanks i might go fr, or all poly's

[momaka]

Re: Ocilloscope Issue

I doubt you need low ESR caps in there. General purpose 105C should be fine. But given that there is little difference in price between low ESR and general purpose, you might as well go low ESR.

How "low" ESR?
- Doesn't matter. If the original caps were intended to be Cheng/Chang/Chong crap, the scope was probably never designed to care anyways.

That said, I would *avoid* aluminum polymer caps - they have much higher leakage than regular electrolytic caps (about 10x higher), and that can cause drifting and DC biasing issues with sensitive amplifier inputs. So it is best NOT to use polymer caps.
On that note, general purpose 105C electrolytic caps usually have lower leakage current than low ESR caps.

So again, I would just do the whole thing with quality Japanese GP and maybe low ESR caps if the latter is cheaper.