NOSValves Posted November 11, 2005 Share Posted November 11, 2005 BTW, explain what the drawings are supposed to tell me. The 5U4 is a directly heated rectifier basically instant on, The 5AR4 is an indirectly heated rectifier so it conducts nothing for a short period while the heater warm all the tubes in the amp. By the way is a Stock Mark III with no in rush current litmiter the 5AR4 still can not slow down the voltage spike enough and still spikes at 575V or more. It is tamed very well with the use of the proper inrush current limiter. The 5U4 the limitier does not solve the voltage spike. Quote Link to comment Share on other sites More sharing options...
Marvel Posted November 11, 2005 Share Posted November 11, 2005 I understand turns ratios quite well thank you. I guess I was missing that the 5AR4 is not directly heated. I hope you understand I am not trying to argue, but to understand where you're coming from in this. Bruce Quote Link to comment Share on other sites More sharing options...
3dzapper Posted November 11, 2005 Share Posted November 11, 2005 I'll translate into technobable for you Craig. The current and voltage are inversely and linearly variable. At a turns ratio of 2:1 with 120VAC and 1A the secondary would see 240V and .5A. With a 6.3V filament transformer nominally 1:20 120 VAC @.5A would produce 6V @ 5A on the secondary. The primary winding at say 3:1 @1A would produce 360V @ 330mA. The two windings and their connected circuits are totaly seperate and must be considered separately. Craig's point Shawn is that the IRC will not protect the power supply input capacitor from the high voltage present before current can begin to flow through the output tubes. A Mark III Power tranny can produce an unloaded voltage of about 565V without current flowing through the circuit that voltage is expressed across the capacitor. Much has been written about the weak link in the Dynaco Mark III, the under spec'ed PS capacitor. Even the original 525V unit was not adequate in the Mark III's circuit. A 500V Ruby cap manufactured on former East German equipment surely will be inadequate. IMO it is far better to deviate from the original, unsafe, design of a Mark III by using series caps than to meet or even go below the meager OE specs. Shawn, You don't face the same situation with your Mark IV's lower voltage peak. Rick Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 11, 2005 Share Posted November 11, 2005 Marvel, Please understand I realize your trying to understand. Some others here are not trying understand there trying to undermind big difference. If you undestand turn ratio's I have to ask you then why the questions? KT88's in a Mark III translated into 1.5 amps each at the wall then how the heck could the amp not blow its 3 amp fuse? Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted November 11, 2005 Share Posted November 11, 2005 KT88's in a Mark III translated into 1.5 amps each at the wall then how the heck could the amp not blow its 3 amp fuse? Ever heard about a slow blow fuse? Or that's techno babble... Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 11, 2005 Share Posted November 11, 2005 Oh now your going to join the ridicules! Thats great! A slow blo fuse is not going to protect against the kind of current Shawn is suggesting beside I have tested this theory and its just plain wrong. The amp spikes for a split bit of a second to 1.5 amps and then drops instantly all the way back too 300mA at the wall socket sitting 300mA for over a minute while a 5U4 bakes the power supply can. What do you 3 people suggest I'm lying now??? Craig Quote Link to comment Share on other sites More sharing options...
Parrot Posted November 11, 2005 Share Posted November 11, 2005 This would be even more fun if Ryan popped in. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 11, 2005 Share Posted November 11, 2005 Maybe for you! Quote Link to comment Share on other sites More sharing options...
D-MAN Posted November 11, 2005 Share Posted November 11, 2005 Are we there yet? DM Quote Link to comment Share on other sites More sharing options...
edwinr Posted November 11, 2005 Share Posted November 11, 2005 Hey, Craig! I just jumped on this thread. Are you getting hammered again? I can't leave you alone for 5 minutes without you getting into more trouble! [:@] Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 11, 2005 Author Share Posted November 11, 2005 Rick: "Erik, The ICL goes in either leg of the AC line in. With an IEC input the easiest place to install it is between the IEC and the fuse in the switch side." I appreciate that advice, Rick. I guess I was the one who (sort of unfortunately) brought up the use of current limiters in this thread. I did mention it's installed on the primary side of the PT at that time. Craig's description of it has been the reverse of how this particular type of IRC functions. I thought maybe I was misunderstanding something, and wanted his clarification of where it's installed in the circuit (HE) is discussing. Not sidestepping (or name calling for that matter), just asking for clarification of the position in the circuit. Erik Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 11, 2005 Share Posted November 11, 2005 Edwin, Yup. But I'm not the cause just the cure. By the way you should carefully reread the thread. Your post should read "I see this same few are trying hammer you but once again there efforts are in vain" Cheers Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 11, 2005 Share Posted November 11, 2005 Rick: "Erik, The ICL goes in either leg of the AC line in. With an IEC input the easiest place to install it is between the IEC and the fuse in the switch side." I appreciate that advice, Rick. I guess I was the one who (sort of unfortunately) brought up the use of current limiters in this thread. I did mention it's installed on the primary side of the PT at that time. Craig's description of it has been the reverse of how this particular type of IRC functions. I thought maybe I was misunderstanding something, and wanted his clarification of where it's installed in the circuit (HE) is discussing. Not sidestepping (or name calling for that matter), just asking for clarification of the position in the circuit. Erik cough cough bullsh!t Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 11, 2005 Share Posted November 11, 2005 I'll translate into technobable for you Craig. The current and voltage are inversely and linearly variable. At a turns ratio of 2:1 with 120VAC and 1A the secondary would see 240V and .5A. With a 6.3V filament transformer nominally 1:20 120 VAC @.5A would produce 6V @ 5A on the secondary. The primary winding at say 3:1 @1A would produce 360V @ 330mA. The two windings and their connected circuits are totally separate and must be considered separately. Craig's point Shawn is that the IRC will not protect the power supply input capacitor from the high voltage present before current can begin to flow through the output tubes. A Mark III Power tranny can produce an unloaded voltage of about 565V without current flowing through the circuit that voltage is expressed across the capacitor. Much has been written about the weak link in the Dynaco Mark III, the under spec'ed PS capacitor. Even the original 525V unit was not adequate in the Mark III's circuit. A 500V Ruby cap manufactured on former East German equipment surely will be inadequate. IMO it is far better to deviate from the original, unsafe, design of a Mark III by using series caps than to meet or even go below the meager OE specs. Shawn, You don't face the same situation with your Mark IV's lower voltage peak. Rick Thank you Rick! I agree with it all except this IMO it is far better to deviate from the original, unsafe, design of a Mark III by using series caps than to meet or even go below the meager OE specs. If an inrush current limiter of the proper value is installed with a 5AR4 rectifier all problems are gone. The can will never experience more the about 480V and this comes up slow and easy. this is a reasonable safety margin. If space was more readily available under the chassis I would 100% agree with your post. Real estate is very valuable in there. Thanks again Craig Quote Link to comment Share on other sites More sharing options...
edwinr Posted November 11, 2005 Share Posted November 11, 2005 Craig, You remember that guy who said the world was round? And everyone else thought the world was flat. Of course that one guy was wrong... wasn't he? Quote Link to comment Share on other sites More sharing options...
3dzapper Posted November 11, 2005 Share Posted November 11, 2005 The world isn't flat? Oh, the humanity. Rick Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted November 11, 2005 Share Posted November 11, 2005 Craig, You remember that guy who said the world was round? And everyone else thought the world was flat. Of course that one guy was wrong... wasn't he? Well be it a flat earth or a round earth, V = RI is hard to ignore in the electronic world. Be it in a stationary regime or a transitional regime. Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 11, 2005 Author Share Posted November 11, 2005 Craig: "cough cough bullsh!t" Indeed, that has been and continues to be your M.O. Do you still want clarification on the anode and cathode orientations for a solid state bridge rectifier? You thanked me at the time I gave you the advice, but I wasn't sure if you understood or not. I suspect you probably did, it's not very difficult. Erik Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 11, 2005 Author Share Posted November 11, 2005 Here's the initial bit I wrote: "... A couple of things that can be done at not too great an expense (just a little work) involve the installation of standby mode, which could be as simple as a switch installed on the center tap of the of the high voltage winding of the power supply transformer. IOW, B+ isn't applied to the plates (manually, by making the switch) until the fiilaments have warmed the tube. The correct thermistor can also be used on the power transformer primary winding, which will provide something of a soft-start feature. These are actually very effective, and are inexpensive. And Craig, here's your initial response: "Sure the things you mention would help and can be done!" This of course was followed up with statements about people being cheap and doing things wrong, but if I don't know anything, why would you both agree with and reconfirm the statement I made? Erik PS: Sorry for the delay, I'm not very good at copying and pasting multiple bits of information! Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 11, 2005 Author Share Posted November 11, 2005 ...and Marvel: Thanks again for the important reminder of the resistor used with the standby switch on the high voltage CT. Erik Quote Link to comment Share on other sites More sharing options...
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