Overvolting e-lyts - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th January 2004, 08:03 PM   #1
Ryssen is offline Ryssen  Sweden
diyAudio Member
 
Ryssen's Avatar
 
Join Date: Dec 2003
Location: Sweden--> Here
Default Overvolting e-lyts

I have an e-lyt in my tube headphone amp that is rated for 400VDC the voltage on it is now 407-415Volt, is this safe or not?
  Reply With Quote
Old 19th January 2004, 08:27 PM   #2
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
It's not safe anywhere, least of all in a headphone amp. You should use elcos at least at 20% below rated voltage.
  Reply With Quote
Old 19th January 2004, 08:31 PM   #3
316a is offline 316a  England
diyAudio Member
 
316a's Avatar
 
Join Date: Dec 2002
Location: West London
Default Re: Overvolting e-lyts

Quote:
Originally posted by ryssen
I have an e-lyt in my tube headphone amp that is rated for 400VDC the voltage on it is now 407-415Volt, is this safe or not?
It may help if you can post a schematic . What is the correct HT voltage ? Does the cap have a bleeder resistor across it ? Is the 400V reading off load or with the headphone amp circuitry attached ? Really electrolytics should be conservatively rated to allow for fluctuations in mains voltage

316a
  Reply With Quote
Old 19th January 2004, 08:39 PM   #4
Ryssen is offline Ryssen  Sweden
diyAudio Member
 
Ryssen's Avatar
 
Join Date: Dec 2003
Location: Sweden--> Here
Quote:
What is the correct HT voltage ? Does the cap have a bleeder resistor across it ? Is the 400V reading off load
I am trying another trafo,thats why the HT voltage is too high,
It has no bleeder resistor,what´s it for?400V reading is on load.
  Reply With Quote
Old 19th January 2004, 09:12 PM   #5
316a is offline 316a  England
diyAudio Member
 
316a's Avatar
 
Join Date: Dec 2002
Location: West London
Default New Trafo

Quote:
Originally posted by ryssen

I am trying another trafo,thats why the HT voltage is too high,
It has no bleeder resistor,what´s it for?400V reading is on load.
Hello ,
Ok , I see , it is a new build . Why don't you try using psud2 to model your power supply before implementing it ?

psud2

316a
  Reply With Quote
Old 19th January 2004, 09:17 PM   #6
Morse is offline Morse  United States
diyAudio Member
 
Join Date: Jan 2003
Location: US for now.....
Hi Ryssen;

>>>...400VDC the voltage on it is now 407-415Volt, is this safe or not?...<<<

>>>... am trying another trafo,thats why the HT voltage is too high, It has no bleeder resistor,what´s it for?400V reading is on load...<<<<

Aaaaargh!!!

Ahem, sorry Ryssen, but it was VERY frustrating reading that.

Please take no offence, but there are some things you MUST fix if you want to be safe!!

1. Bleeder resistors are there to SAFELY discharge capacitors. A cap charged to over 400V will give a NASTY shock if it's discharged THROUGH YOU.

2. NEVER run caps over their rated voltage. Frankly, 20-30% margin of safety is required for reliable, SAFE operation. Remember, that when the amp is first turned on and the valves are not conducting, the B+ voltage will climb well over what it is during normal operation. I've built amps that when loaded run 100 or more volts below this "unloaded voltage". BTW, that 20-30% safety margin should be OVER THE PEAK VOLTAGE EVER ENCOUNTERED ON THE UNLOADED AMP. That way you can expect many years of SAFE and RELIABLE operation.

Please be safe. Either lower the voltage on those caps or put in higher rated caps. And PLEASE put in a bleeder resistor AFTER you have SAFELY discharged your PS caps.

Good luck and all the best,
Morse
  Reply With Quote
Old 19th January 2004, 09:31 PM   #7
Ryssen is offline Ryssen  Sweden
diyAudio Member
 
Ryssen's Avatar
 
Join Date: Dec 2003
Location: Sweden--> Here
Quote:
Bleeder resistors are there to SAFELY discharge capacitors. A cap charged to over 400V will give a NASTY shock if it's discharged THROUGH YOU.
Ok,TROUGH MEEE!! What Wattage Ohm´s should they be?
  Reply With Quote
Old 19th January 2004, 09:41 PM   #8
dhaen is offline dhaen  Europe
diyAudio Moderator Emeritus
 
dhaen's Avatar
 
Join Date: Jun 2002
Location: U.K.
I normally use 220K 2W bleeders. Beware of the maximum voltage rating of resistors. It is often better to use 2 in series.
  Reply With Quote
Old 19th January 2004, 10:42 PM   #9
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

Quote:
I normally use 220K 2W bleeders.
Bleeder resistors also prevent overvoltage on the caps and should be calculated accordingly.

They also provide for a discharge path when the gear is turned off.

IOW, if you don't use them you risk overvoltage on the caps at switch on and you risk an electrical shock (possibly lethal) when working on your gear before the caps had the time to discharge through the bleeder.

Thirdly and not unimportant, they can force a constant current draw from the PS.

There's a formula to keep things safe but I'll let you all google for it...I won't.

Cheers,
__________________
Frank
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 05:20 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2