Falcon cap C6 incorrect polarity?

Post by **exxos** » 04 Dec 2022 13:37

Thing is just to measure the voltage on the capacitor. With probes the right way around and see what you have.

I did explain this already but cannot find the post now.

Problem with electronics is GND is generally the "default" for what everything is referenced to. But it's not so simple with split power rails.

I stole this image off the net to illustrate and added + and -

M47w4.png

At first glance it looks incorrect and the + on the cap is connected to GND. But it's actually correct.

+ and - on the top cap, no brainier.

However the bottom cap is NEGATIVE -4.5V in respect to GND which is 0V. So ZERO is MORE POSITIVE than NEGATIVE -4.5V.

So the positive of the cap goes to GND (0V) and the negative of the cap goes to NEGATIVE (-4.5v).

Another way to look at it is say you have 5V and GND (0v). Then take away "5" from each. So 5V becomes 0 (5V-5), and 0V becomes -5 (0V-5). So zero is 5V more positive than NEGATIVE -5V.

Steve · Post by **Steve** » 04 Dec 2022 13:57

@exxos Thanks for the electronics lesson, yes so in this case the ground/zero is more positive than -12 and therefore the positive of the cap will go to gnd/zero.

HigashiJun · Post by **HigashiJun** » 05 Dec 2022 10:19

Great, so no need to tinker my Falcon.

:D

T'PAU · Post by **T'PAU** » 10 Dec 2022 18:13

@HigashiJun if you want to leave C6 the wrong way... yes, no need for further action. ;)

@exxos Thanks for this very good explanation!

mikro · Post by **mikro** » 05 Mar 2025 14:44

HigashiJun wrote: 05 Dec 2022 10:19 Great, so no need to tinker my Falcon.

:D

T'PAU wrote: 10 Dec 2022 18:13 @HigashiJun if you want to leave C6 the wrong way... yes, no need for further action. ;)

@exxos Thanks for this very good explanation!

Just to clarify those confusing comments. As per @exxos's explanation, GND aka 0V is more positive. Therefore if the top pin of C6 is -12V and the bottom pin of C6 is GND, and since C6's negative leg is by factory mounted to the bottom, C6 clearly must be reversed. Its negative leg must be on top.

HigashiJun · Post by **HigashiJun** » 05 Mar 2025 23:17

Thanks @mikro !

frank.lukas · Post by **frank.lukas** » 06 Mar 2025 10:00

Bipolar ...?

Atari_NP_Elko.jpg

Steve · Post by **Steve** » 06 Mar 2025 11:36

I think they were normal, not bipolar.

sporniket · Post by **sporniket** » 06 Mar 2025 11:46

The left one, does "NP" stands for Non Polarized ?

Post by **exxos** » 06 Mar 2025 11:55

sporniket wrote: 06 Mar 2025 11:46 The left one, does "NP" stands for Non Polarized ?

Should be yes...

Though on my Falcon and others, they are not NP types.

https://exxosforum.co.uk/forum/viewtopi ... 310#p19310

Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Re: Falcon cap C6 incorrect polarity?

Who is online