Quick recapping question please - identifyin polarity

[hearingisbelieving]

I want to replace the two big gold axial electrolytic caps pictured. Problem is their polarity isnt clearly marked - well not in a way I am used to...
Just to check I have this right, the cap has some + symbols on it that are closer to one end of the cap than the other - does that make that closer end the positive end? sounds stupid but just want to check its right.

[chris217]

Can you switch the equipment on and measure the voltage to confirm?

[JPG]

The safest way is to trace the circuit around the caps.

If you look at the diode bridge supplying the capacitors, it appears that the positive is to the left in that photo.



The lines on the symbols represent the lines on the diodes, so they are towards the positive.

As a result, the sealed end with the plastic disc and the terminal in the middle is the +ve: to the left on the lower cap.

However, I'd like to see a photo with the caps removed before fully committing to that...

[hearingisbelieving]

Thanks James and Chris. no power to circuit at the mo and caps already removed so have provided another pic with caps out:

[alexh]

Polarised electrolytic have the + nearest the dimple so the bottom cap has the + facing to the LH side.

Cheerz, Alex.

[sq225917]

1st picture, top cap right positive, lower cap left positive.
Same on next picture but image has been rotated 90 CW

[hearingisbelieving]

awesome, as I thought but always great to have someone confirm. thanks for your help guys. everyone repped

[reddish75]

Clean the crap off the board before putting new ones in.

[hearingisbelieving]

Clean the crap off the board before putting new ones in.

any suggestions for what I should use?

[reddish75]

Methylated spirits, cheap and readily available, just apply with a cotton bud and allow to dry for a few minutes, give the new capacitor legs a quick clean with it as well.

[hearingisbelieving]

ok thanks chris.

[earlofsodbury]

Methylated spirits, cheap and readily available, just apply with a cotton bud and allow to dry for a few minutes, give the new capacitor legs a quick clean with it as well.

Wot?

That'll just redistribute the resin.

Solder residue comprises organic and inorganic components which if left can degrade solder joints; use a proprietary flux remover, couple of quid for a spray can from RS/Farnell/Maplin.

[hearingisbelieving]

Thanks Paul. I have some meths at home so will try using that by applying it then wiping it and the flux away whilst still wet. If that dont work will get me some proper stuff as you have recommended.
The PCB Im working on is of the Active T+A's you fancied at Bob's bakeoff. Will let you know how they sound after!

[earlofsodbury]

Thanks Paul. I have some meths at home so will try using that by applying it then wiping it and the flux away whilst still wet. If that dont work will get me some proper stuff as you have recommended.
The PCB Im working on is of the Active T+A's you fancied at Bob's bakeoff. Will let you know how they sound after!

Just don't break 'em - I might want them!

[reddish75]

Wot?

That'll just redistribute the resin.

Solder residue comprises organic and inorganic components which if left can degrade solder joints; use a proprietary flux remover, couple of quid for a spray can from RS/Farnell/Maplin.

That is great if your doing a large area but a one off where you need to quickly clean the area meths and a cotton bud will work just fine.

[earlofsodbury]

That is great if your doing a large area but a one off where you need to quickly clean the area meths and a cotton bud will work just fine.

I'm OK with the meths (drink a lot myself, too), but your instruction is basically to dab it on and let it dry, which will of course do nothing without the vital "Dab It Off" stage as we in Rocket Science call it in the technical literature.

I've no doubt that isn't what you intended, and I'm sure Chris ain't so dim as to follow the instruction verbatim, but in any case meths will only remove organic residues, leaving the mix of salts and acids which are a byproduct of flux-based soldering. So, knowing he's a bit of a tinkerer I thought I'd offer the advice I wish someone had offered me when I started tinkering aeons ago: do it right, do it thoroughly, first time, every time.

[stewartwen]

"do it right, do it thoroughly, first time, every time."
Rep added Sodders.

[reddish75]

I'm OK with the meths (drink a lot myself, too), but your instruction is basically to dab it on and let it dry, which will of course do nothing without the vital "Dab It Off" stage as we in Rocket Science call it in the technical literature.

I've no doubt that isn't what you intended, and I'm sure Chris ain't so dim as to follow the instruction verbatim, but in any case meths will only remove organic residues, leaving the mix of salts and acids which are a byproduct of flux-based soldering. So, knowing he's a bit of a tinkerer I thought I'd offer the advice I wish someone had offered me when I started tinkering aeons ago: do it right, do it thoroughly, first time, every time.

Must proof read my posts, but all i can think of at the moment is kenwoods twatting thermistor controled bias circuit, anyhow i agree with sodders common sence advise.

[earlofsodbury]

Must proof read my posts, but all i can think of at the moment is kenwoods twatting thermistor controled bias circuit, anyhow i agree with sodders common sence advise.

That sounds a 'mare!

[Sir_Franc]

Most flux residue will easily flick off if scratched with a fingernail.