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Old 16th November 2010, 01:39 AM   #1
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Default High value capacitor between Hot and Neutral at AC inlet?

hey all-

I was dissecting my old Laserdisc player for parts when I saw a massive 200 uF 200V electrolytic connecting Active and Neutral right after the connection between the AC plug and the power supply board. What is the capacitor for and is it a good idea to implement it into a mixer's power supply?

Last edited by diymixer; 16th November 2010 at 01:39 AM. Reason: improper punctuation
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Old 16th November 2010, 01:57 AM   #2
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DO NOT DO THAT!

there are special grade capacitors for AC, and you must use those. are you sure it is not 200nf? i think 200uF would explode.

check more closely, i cant see them doing that.

Last edited by neutron7; 16th November 2010 at 02:00 AM.
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Old 16th November 2010, 02:08 AM   #3
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I'm positive that it's 200 uF; it's been in the player for the past 15 years and it still appears brand new
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Old 16th November 2010, 02:39 AM   #4
SY is offline SY  United States
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If there's 200uF of electrolytic across the line, what you have is an explosion. So... either it's not 200uF or it's not across the line.
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Old 16th November 2010, 02:56 AM   #5
Cristi is offline Cristi  Europe
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Motor starter capacitor power factor correction, in the old fashion. anyway, 200uF should take half on the space inside the case.
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Old 16th November 2010, 08:26 AM   #6
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If it was 200uF it would be about a as big as small soft drink can for 120VAC operation, it would not be electolytic as it would explode even motor starter capacitors can only run for a short time before exploding. Motor run capacitors are fine for continuous use. FWIW I have 100 uF in a small 240V welder for partial power factor correction and I have 60uF across the 575V tap of another welder for the same reason.

Are you sure it is not a type of mains filter? I have seen these look like capacitors.

If it was a capacitor connected as such it would draw 9A with a 120V 60Hz supply.

Alternatively there might be a bridge rectifier hiding in there somewhere to get a DC supply for an SMPS.
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Old 16th November 2010, 09:34 AM   #7
AndrewT is offline AndrewT  Scotland
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no knowledge is dangerous.

Go and get help.
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Old 16th November 2010, 09:57 AM   #8
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Quote:
Originally Posted by diymixer View Post
I'm positive that it's 200 uF; it's been in the player for the past 15 years and it still appears brand new

It is so unpolite to argue with people. Why discourage him if he is so positive? Nevermind the cap is after a rectifier in an SMPS - how different can this be to what he's saying
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Old 16th November 2010, 12:47 PM   #9
pjp is offline pjp  India
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were SMPSes in use in the days when LaserDisc players were being built ? I thought all of those day's electronics had linear power supplies.
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Old 16th November 2010, 01:23 PM   #10
wwenze is offline wwenze  Singapore
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"right after the connection between the AC plug and the power supply board"

I interpret it as the capacitor is on the power supply board, and after a rectifier.
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