identify coupling capacitor in Rotel RA-820BX2

[zog666]

Hi,
I've just been looking into an old amp of mine (now sold to a friend) to replace the capacitors as the electroytics would be getting pretty old now.

I was able to find the service manual from:
http://www.bwgroup-support.com/rotelservicemanuals.html
which is very handy!

Tracing the circuit I can see 2 coupling capacitors where the line level inputs go in, 1uF rated.. but the type is not mentioned and they aren't familiar to me (but I'm a bit of a newby at this). These are C602 and C601 in the diagram by the way

Anyone know what these kind of capacitors are? -



(the blocky silver one in the middle)

.. and the follow on question, how good are they (should I bother replacing them)

[jackand08]

These capacitors are multilayer type capacitors with an open construction (not sealed in resin or anything like that). They are an older type of capacitor and if you are replacing the rest of the caps, you may as well do these too. Although they probably won't have gone out of tolerance and will be fine, its best to replace them anyway. Multilayer type capacitors are dirt cheap these days and shouldn't be hard to find.

[alexcp]

This cap looks like a Metallized Polyester Film (MKT), e.g. Epcos B3256x (see http://www.epcos.com/inf/20/20/db/fc...B32560_564.pdf). Should be replaceable with any good MKT or better MKP cap.

[zog666]

ok, thanks.. got a bag of red WIMA MKP10 0.47uF caps here, 2 of those (= 0.94uF) should make a nice replacement.

for what it's worth, heres a peep inside the amp (leaving off the phono stage which is 1/4 of the PCB but I'm not interested in)