Capacitor polarity WG7400 25" P538

[Slippyblade]

Hi folks.  Trying to cap a monitor here.  I know how to solder, got my caps all nice and laid out.  Got all the board caps listed in a chart for reference...  Now looking at the board I realize that NONE of the caps on the board have polarity on them.  The silkscreening doesn't have polarity either.  Soooo, silly question.  How do I tell how to insert the new caps?  Does the neg always go to ground?  Or will I need to break down and resort to schematics?

Thanks in advance,
Slippy

[grantspain]

marked with a black dot or line on the circuit board?

[Slippyblade]

Caps in question are all 10uf 25v caps on a P538 board.  WG7400 25".  There's no polarity marked on the schematic for these guys either.  It does say NP next to the notation on the schematic, but the caps themselves look like standard polarized electrolytics.  I'm looking at C4, C5, and C6.  They also all connect from an IC leg straight to ground through resistors.

Any ideas?

Thanks again.

[lilshawn]

It does say NP next to the notation on the schematic, but the caps themselves look like standard polarized electrolytics.

you should have some replacements there that are labeled NP or Bipolar. you might have inavertantly placed them in another spot. double check. the look identical to regular caps except the np mark.

does the neg always go to ground?

not on a negative voltage rail it doesnt.

There's no polarity marked on the schematic for these guys either.

if they are non-polarized they wont have markings saying + or -, sometimes a designer gets lazy and just throws a regular cap marker on the silkscreen image so best to do them 1 at a time to avoid mixups.

I'm looking at C4, C5, and C6.  They also all connect from an IC leg straight to ground through resistors.

i don't know what schematic you are looking at since most WG including the 7400 series use a 3 digit component id # (C101, D806, U701, etc.)
http://www.wellsgardner.com/pdf/Schematics/K7400_25_inch.pdf

[Slippyblade]

Seems I must have the K7000 then.  Either way, the PCB says P538 and schematic is here. http://www.wellsgardner.com/pdf/Schematics/K7000_25_27_inch.pdf

Cap kit that I have seems very substandard.  Not enough caps to do the job, a couple of extras that are not needed and no chart/list.  It's from Syracuse Semiconductors if that makes any difference.  Well, I'm going on the assumption that neg to ground.  Worse case scenario I guess is popped caps.  I think they are simply acting as filters.  We'll see.

[Ken Layton]

A "P538" main board means you have a 25" K7000 (probably a 7191) and NOT a 7400 (different family altogether).

[Slippyblade]

Figured it out thanks to the Mouser Cap thread.  The little buggers in question are "Bi-Polar" caps.  They are indeed polarized caps, but are designed so that either lead can be either polarity.  How messed up is that.  I wonder how the hell I hook those up now???

Lilshawn was right as well...  Guess I should read posts more carefully.  Oops.