High value capacitor between Hot and Neutral at AC inlet?

diymixer · 01:39 AM

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?

neutron7 · 02:00 AM

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.

diymixer · 16th November 2010, 02:08 AM

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

SY · 16th November 2010, 02:39 AM

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.

Cristi · 16th November 2010, 02:56 AM

Motor starter capacitor

power factor correction, in the old fashion. anyway, 200uF should take half on the space inside the case.

metalsculptor · 16th November 2010, 08:26 AM

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.

AndrewT · 16th November 2010, 09:34 AM

no knowledge is dangerous.

Go and get help.

analog_sa · 16th November 2010, 09:57 AM

Quote:

Originally Posted by diymixer

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

pjp · 16th November 2010, 12:47 PM

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.

wwenze · 16th November 2010, 01:23 PM

"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.

16th November 2010, 01:39 AM	#1
diymixer diyAudio Member Join Date: Jun 2010	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

16th November 2010, 01:57 AM	#2
neutron7 diyAudio Member Join Date: Dec 2003 Location: Toronto Canada	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.

16th November 2010, 02:39 AM	#4
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	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. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

16th November 2010, 02:56 AM	#5
Cristi diyAudio Member Join Date: Dec 2008 Location: Shenzhen	Motor starter capacitor power factor correction, in the old fashion. anyway, 200uF should take half on the space inside the case. __________________ www.connexelectronic.com complete assembled amplifier and SMPS

16th November 2010, 09:34 AM	#7
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	no knowledge is dangerous. Go and get help. __________________ regards Andrew T.


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16th November 2010, 02:08 AM	#3
diymixer diyAudio Member Join Date: Jun 2010	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

16th November 2010, 08:26 AM	#6
metalsculptor diyAudio Member Join Date: Sep 2010 Location: Melbourne	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.

16th November 2010, 12:47 PM	#9
pjp diyAudio Member Join Date: Nov 2006 Location: under the rainclouds	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.

16th November 2010, 01:23 PM	#10
wwenze diyAudio Member Join Date: Mar 2008	"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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