I've removed a capacitor, but like the n00b I am, have forgotten which way round it went.

From this picture can you deduce the polarity? It was removed from the board in the circle with the two holes.

There is a plus + sign there, but that might be related to a much smaller blob to the side of it, and the circle is marked slightly thicker black on one side.

enter image description here

Any ideas?


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Added pic of other capacitor. Yes - it does follow the pattern. Thick black signifies neg.

I will proceed.... wish me luck!


It worked... my first cap. replacement...

enter image description here

Old dreambox PSU back from the dead.

  • 3
    \$\begingroup\$ Does the pattern match any other capacitors on the board? (Thicken circle on one side) It kind of looks like the other two Caps shown have it. \$\endgroup\$ – Tyler Dec 26 '17 at 21:37
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    \$\begingroup\$ It appears the cap next to this one is installed with negative pin on the left, and it appears the dark band is next to the negative. In this case, same would apply to this cap: dark band for negative, tiny "+" symbol for positive. Can you confirm this for any others? \$\endgroup\$ – Ryan Griggs Dec 26 '17 at 21:51
  • \$\begingroup\$ i agree with @RyanGriggs. please post a picture of the other side of the board (same area). \$\endgroup\$ – jsotola Dec 26 '17 at 22:34
  • \$\begingroup\$ Looks toasty. Is it running hot? \$\endgroup\$ – winny Dec 28 '17 at 17:07

The polarity of electrolytic capacitors is marked on the body with an arrow with an embedded - sign pointing to the base. The lead closest to the arrow is the negative pin for the cap.

As shown on the electrolytic cap immediately to the right of the removed part location, the thickened part of the outline is where the negative lead of the cap goes. The + mark on the legend is indeed for the + lead of the removed capacitor. So the decal has two markings to indicate polarity.


You cannot do wrong it as it shows a bold round line for the negative leg on the right. If you check the other three caps on the right and the cap on the botton left they are mounted in the opposite sense but all according to this bold round mark.


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