How do I know capacitor polarity with this marking on the circuit board?

[dj23tsi]

Hey guys

I'm recapping a Kenwood KR-5030 and ran into some confusion on the boards polarity marking. The cap that came out does not have the typical negative stripe and the board has the negative symbol right in the middle of the two holes. Please see pics to get a better understanding what I'm dealing with. Every other cap that I pulled from this receiver has been marked clearly on the outside of the holes. I have no idea whats going on with this one.

 

[avionic]

Thats a BP cap -- bi-polar/ non-polar

 

[avionic]

Nichicon muse series UES
https://www.mouser.com/datasheet/2/293/e-ues-1218987.pdf

https://www.mouser.com/ProductDetail/Nichicon/UES1A470MEM?qs=sGAEpiMZZMtZ1n0r9vR22e0BBN1kF1oiAyiVa%2biFYgo=

 

[dj23tsi]

Ah that was my first thought but the negative mark on the board threw me off... So that should not be replaced with a polarized cap then right?

 

[avionic]

Ah that was my first thought but the negative mark on the board threw me off... So that should not be replaced with a polarized cap then right?

Correct

 

[dj23tsi]

Thanks a bunch for your help!

 

[avionic]

Got your 6...

 

[dj23tsi]

Well I just ran into another cap with the same negative mark in the middle of the holes but the cap that came out was clearly labeled with a negative lead like normal. It was glued to the board so I think its safe to assume its an original cap. Out of the 20 or so caps I've replaced so far I've had 3 with this negative mark between the holes. I'm not sure if I should be concerned yet or just carry on as every other caps negative lead has been clearly labeled on the board.

 

[sregor]

Basic rule of thumb - stay with what is in there (unless its wrong....)
Check the manual and see what is in the schematic (unless its wrong, which does happen)
Check DC voltages - if everything is correct the + will be higher than the - side.
My2 cents

 

[dj23tsi]

CM34 was the one I was just talking about.

 

[avionic]

CM34 shows polar in the schematic. CM 33 shows non-polar in the schematic(47µf/10v)

 

[avionic]

Basic rule of thumb - stay with what is in there (unless its wrong....)

Ditto..