Capacitors

[greenhorn]

one more doubt - this one has a couple of .1uF electrolytics. I wonder why they were used instead of ceramics/film caps. Can I replace them with non polarized ones ?

 

[Robert Bose]

Nichion Caps, value upto 33000 MFD 80V rating having size 63 by 100

80 Deg C is advertised in a DIY UK site Hi Fi collective

I have Yamaha M80 which is very very similar to M85 with same caps

Price is listed at 38 pound sterling , this site sells genuine Stuff and ships

by postal service so customs is not an issue, 47000 is not advertised here

47000 is made by Mundorf Germany , 63, 80 V but size is

90mm dia 75mm height and price would be atrocious

my M80 is still working touch wood, you need to check one fast switching

power diode on the rectifier PCB to which the caps are wired

this should be Shottkey 50A fast rectfier as M80 and 85 are class G

rail switching amps, the voltage at the speaker is sum of the voltage

across 47000 and 33000 caps, the transformers weigh a ton and

are designed for high harmonic current , hope you have the circuit

Robert Bose

 

[linuxguru]

one more doubt - this one has a couple of .1uF electrolytics. I wonder why they were used instead of ceramics/film caps. Can I replace them with non polarized ones ?

They were probably used just for economics - I've seen this even in some Denon amps - 0.15 and 0.22 uF, Nippon Chemicon SMH or similar. A few of them had also developed high leakage current with age.

The choice of the best substitute for small electrolytics depends on the function, but in almost all cases they can be replaced by a metalised polyester film cap of similar value and voltage rating.

The most easily-available compact film caps to replace these kinds of caps are box-type film caps like Wima MKS2, Evox/Rifa MMK, ERO KT1826 or similar in 5 mm pitch. Wima also made compact PPS film caps like the MKI2 in 5 mm pitch, but they're no longer available. Evox/Rifa makes (or made) compact 5mm pitch PPS film caps in the SMK and SMR series, which are still available online from places like Digikey, etc. A few MKP types are also available in 5 mm pitch, like Wima MKP2, Evox/Rifa PHE426, etc.

If they're in the signal path, I also use a 22nF to 100 nF Panasonic ECHU SMD stacked PPS film cap on the underside of the board, to bypass the polyester. This may not be necessary in most cases, as the polyesters are already much better than almost all electrolytics (except maybe Black Gate, Cerafine, Pureism and a few others, most of which are no longer available in small values. There's also a sub-miniature Nichicon MUSE SW which is useful to replace caps in the 4.7 to 22uF ranges - it's very transparent sounding, like most MUSE caps).

Don't use a Sanyo Oscon for DC blocking unless the blocking voltage is very low, say 100s of millivolts or lower. Oscons have relatively high DC leakage currents. They're great for supply rail bypassing, especially in digital sections.