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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 29th Sep 2009, 5:03 pm   #1
Diabolical Artificer
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Default Bush RP 60-paper caps?

Looking to service said record player amp,as well as replacing the Erie power can,theres 3 dodgy looking paper/wax caps.One is between the earth wire of the power lead and ground(strange).its 1" x1" x 3/16 (CP3P-0.01 uf BS415) brown in colour,with a red dot to one side on top.The other two are
CP3E also 0.01uf,these on the tone pots,all made by Erie.
Ive been told its standard to replace paper caps,whilst the CP3E,s look pretty straight forward,the cap on the earth (ground really)has me flumexed.What do I replace with? As it has a polarity?
Its a nice little amp with a UY85 (rectifier?) and UCL82 valves.Sorry no pics
Any ideas? M
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Old 29th Sep 2009, 5:10 pm   #2
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Default Re: Bush RP 60-paper caps?

Quote:
Originally Posted by magnetic View Post
One is between the earth wire of the power lead and ground(strange).its 1" x1" x 3/16 (CP3P-0.01 uf BS415) brown in colour,with a red dot to one side on top.... the cap on the earth (ground really)has me flumexed.What do I replace with? As it has a polarity?
Its a nice little amp with a UY85 (rectifier?) and UCL82 valves.
Be careful here!

U-series valves usually indicate a "live chassis" design with no mains isolating transformer!

That strange capacitor you mention sounds like a safety isolation cap (hence the BS marking) and must be replaced with a special-grade type for safety reasons.

I'll let the experts tell you more.

Nick.
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Old 29th Sep 2009, 5:14 pm   #3
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Default Re: Bush RP 60-paper caps?

The capacitor between neutral and earth should be a 10nF, Y-rated type (which never fail short-circuit). It's not actually polarised.

This record player uses a non-isolated, transformerless power supply (not AC/DC though, due to the motor), but has a tape recording output taken from downstream of the speaker transformer. It's also new enough to have a stereo-capable cartridge. It was still being made into the 1970s (later examples use a C1xx changer with manual record size selector), after other manufacturers had started using those IC amplifiers with the "hedgehog" heatsink; seems Bush must have had a few crates of UCL82s lying about!
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Old 29th Sep 2009, 5:29 pm   #4
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Default Re: Bush RP 60-paper caps?

If I wanted to turn the amp into a small guitar practice amp,how would I go about it?Would it need some pre-amp stage on the input?The turn-tables kaput,using the amp to learn about valve amps,M
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Old 29th Sep 2009, 5:31 pm   #5
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Default Re: Bush RP 60-paper caps?

You would need to buy a 1:1 mains isolating transformer to make it safe. This is probably uneconomic.

Fix the record player, sell it, then buy something more suitable. Sorry.

Nick.
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Old 30th Sep 2009, 10:21 am   #6
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Default Re: Bush RP 60-paper caps?

I'll second what Nick says.

Probably the best thing to use to make into a practice amp is a tape recorder. They all have isolated chassis, due to the need to connect to external equipment including hand-held microphones; they can be obtained for not much, especially if they have mechanical problems; and nobody's going to miss a common one.

Oh, and magic eye indicator tubes are space-age cool
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Old 30th Sep 2009, 10:23 am   #7
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Default Re: Bush RP 60-paper caps?

And record players are generally more collectable, even if non-working, so you may be able to get a tape recorder for less than you can sell the Bush for.

As a general rule, anything with valves whose codes start with an E will be suitable; those with U-series valves will use a live-chassis design and be potentially lethal if modified.

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