What type of capacitor is this? - UK Vintage Radio Repair and Restoration Discussion Forum

WaveyDipole · 14th Dec 2015, 6:10 pm

Is this a ceramic single or multilayer type? Does 'M47' have any meaning? The application is a mid 70s power amplifier module and the board also has a standard round ceramic on it. Its counterpart on the second board is broken and I was wondering what to replace it with?

HamishBoxer · 14th Dec 2015, 6:14 pm

Can you check the value with a cap meter?

WaveyDipole · 14th Dec 2015, 7:50 pm

Yes I was intending to do that anyway because although it appears to be marked 56n, the only cap in the circuit with a value of 56 is a 56pf cap. My query though is more about whether the replacement needs to be a specific type bearing in mind that it forms part of the audio circuit?

joebog1 · 14th Dec 2015, 11:18 pm

With any cap of 56 pF I would be using NPO
cheap and stable, Voltage should be OK as its sand and even if the module is a monster, wont be over 100 volts.

Joe

WaveyDipole · 16th Dec 2015, 11:01 am

Thanks. I will add a couple of 56pf NPO's to my next order. As you say, its not going to ever have over 100v applied to it. The max that could ever appear across it would be around 70v but its not likely to get anywhere near that in the signal path.

I haven't seen one like that before and just wondered what type it is. Given that this piece of equipment was at the time (circa 1975) apparently 'of advanced technological status' (as described in the makers marketing materials), I wondered whether this part might have been of a specific high quality type for audio purposes and perhaps ought to be replaced with something of equivalent grade to maintain the original audio quality.

Station X · 16th Dec 2015, 11:13 am

Looks like a silvered mica cap to me. They used to be flat, but nowadays they have a sort of dog bone shape.

14th Dec 2015, 6:10 pm	#1
WaveyDipole Nonode Join Date: Mar 2013 Location: Leicester, UK Posts: 2,535	What type of capacitor is this? Is this a ceramic single or multilayer type? Does 'M47' have any meaning? The application is a mid 70s power amplifier module and the board also has a standard round ceramic on it. Its counterpart on the second board is broken and I was wondering what to replace it with? Attached Thumbnails

14th Dec 2015, 6:14 pm	#2
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: What type of capacitor is this? Can you check the value with a cap meter? __________________ G8JET BVWS Archivist and Member V.M.A.R.S

14th Dec 2015, 7:50 pm	#3
WaveyDipole Nonode Join Date: Mar 2013 Location: Leicester, UK Posts: 2,535	Re: What type of capacitor is this? Yes I was intending to do that anyway because although it appears to be marked 56n, the only cap in the circuit with a value of 56 is a 56pf cap. My query though is more about whether the replacement needs to be a specific type bearing in mind that it forms part of the audio circuit?

14th Dec 2015, 11:18 pm	#4
joebog1 Banned Join Date: Jun 2015 Location: Mareeba, North Queensland, Australia Posts: 2,704	Re: What type of capacitor is this? With any cap of 56 pF I would be using NPO cheap and stable, Voltage should be OK as its sand and even if the module is a monster, wont be over 100 volts. Joe

16th Dec 2015, 11:01 am	#5
WaveyDipole Nonode Join Date: Mar 2013 Location: Leicester, UK Posts: 2,535	Re: What type of capacitor is this? Thanks. I will add a couple of 56pf NPO's to my next order. As you say, its not going to ever have over 100v applied to it. The max that could ever appear across it would be around 70v but its not likely to get anywhere near that in the signal path. I haven't seen one like that before and just wondered what type it is. Given that this piece of equipment was at the time (circa 1975) apparently 'of advanced technological status' (as described in the makers marketing materials), I wondered whether this part might have been of a specific high quality type for audio purposes and perhaps ought to be replaced with something of equivalent grade to maintain the original audio quality.

16th Dec 2015, 11:13 am	#6
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: What type of capacitor is this? Looks like a silvered mica cap to me. They used to be flat, but nowadays they have a sort of dog bone shape. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.