Puzzled about Kenwood KR-7050 power supply cap

[turbotee]

I posted before about trimmer pots and appreciated the help. NOW, I'm puzzled about this capacitor:

Kenwood KR-7050 service manual downloaded from HiFi Engine:
Power supply Board (X00-2050-10) shows

C18 : "Electro 4.7uf 25WV"

All caps on board are polarized EXCEPT this one it seems. Usually I see "NP" when a cap is bipolar. There is no "+" sign to determine orientation of the cap when replacing (as I saw with all other caps on the board) so I soldered in a polarized cap same value. I doubled checked an extra power board and same cap installed.

My question: Is the manual wrong? Am I wrong? Does it make a difference in terms of sound, overall performance or any variable I'm not aware of?

To my ears, it sounds a bit "brighter", not bad but differing from the Kenwood sound that attracted me to receiver in the 1st place.
So reinstalled old cap and order new ones just in case.
Thanks folks

 

[llwhtt]

Looks like C18 may have a positive voltage on it until Q11, relay driver, turns on. After Q11 turns on the voltage on C18 goes negative as indicated on the schematic. Probably why there's NP capacitor in that location. Has NOTHING to do with the audio signal.

Craig

 

[EchoWars]

The circle around the symbol on the schematic ID's it as a non-polar cap.

 

[turbotee]

The circle around the symbol on the schematic ID's it as a non-polar cap.

Thanks. The change in sound is probably in mind like you said ... thanks Craig and Echowars for another lesson. I installed a new cap anyway )