3.3F 2.3V capacitor

[audiobeginne]

Used in Technics SUV85A amp in the led circuit. I think the function of the capacitor is to retain last memory set at the control panel. C702. The capacitance has become nano farads. I'M not good at reading the schematic. Can someone confirm?

I'm thinking of using not so expensive caps for this one.

 

[painttoad]

c702 is a 470pF non polar

the cap you have is a 3.3f polarized cap.

 

[painttoad]

c701



maybe something from this page

https://www.mouser.com/c/passive-components/capacitors/supercapacitors-ultracapacitors/?capacitance=3.3%20F&voltage%20rating%20dc=2.7%20VDC&instock=y

 

[tarior]

That's a super cap. 3.3 Farads @ 2.3 volts.

 

[tadawson]

Choose the 3.3F capacitance and best form factor with a *minimum* 2.3 volt rating. Higher is fine if it fits well.

 

[tarior]

Going up in voltage is fine. However, it's worth noting that they grow exponentially as voltage goes up. Gotta fit all those coulombs in there somehow.

 

[tadawson]

Yeah, but at least with older gear, often the same capacitamce and voltage is too small to fit the lead spacing on the board and goes on "ugly". Hence my addvice to check fit as a selection criteria as well.

 

[audiobeginne]

c702 is a 470pF non polar

the cap you have is a 3.3f polarized cap.

C701

 

[audiobeginne]

C701

 

[audiobeginne]

Ok the original panasonic C701 super capacitor is dead. I tried charging using a power supply set to 1.5 v and 0.148 A and watch the DMM. It climbed straight to 1.5V and when power supply is disconnected, it did not hold any charge and drops to miilivolts instantly. The new capacitor was able to hold its charge after charging with the same method and discharges slowly to zero volts.

I'm using CDA capacitor since its just to hold the memory of the selected LED on the front panel

 

[tarior]

The brand name really doesn't matter, so long as it's a quality brand, which CDE is.

 

[painttoad]

i wish i could get parts that fast

 

[tarior]

i wish i could get parts that fast

And lose the incentive to hoard massive quantities of parts? Certainly you jest!

 

[painttoad]

And lose the incentive to hoard massive quantities of parts? Certainly you jest!

you make a valid point sir.

 

[audiobeginne]

C=(I xT)/V where C is capacitance in Farad , I is current in Amperes, T is time in seconds and V is the voltage across the capacitor.

I adjusted the current to 0.07425 amp's and final voltage of the power supply to 2.7 volts and timed how long it took to fully charged it to 3.3 F. It took 120 seconds and the DMM reads 2.7 volts across the capacitor. So the capacitance is correct. I don't know how else to measure the capacitance of 3.3F