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Audio and Video Talk
Valves / Vacuum Tubes
Please help identify rectifier
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<blockquote data-quote="handsome" data-source="post: 829504" data-attributes="member: 772"><p>Directly heated rectifiers conduct almost immediately, indirectly heated rectifiers take longer to warm up and only then conduct. A choke input PSU must have a minimum current drawn through it otherwise its output voltage will rise some 50% or more. The resulting high voltage could destroy or stress some components. Because the amplifier tubes (EL84s and drivers) are indirectly heated they will take a while to start drawing current from switch-on. If your rectifier is directly heated and it is a choke input power supply you will get said over-voltage condition at every start-up.</p><p></p><p>So make sure it really is a choke input power supply - check exactly what is connected to pin 8 of the rectifier socket. The choke will be connected to it but if there is also a capacitor connected from there to ground you have a capacitor input power supply. </p><p></p><p>Be careful with a 5U4 in that amp: it will try draw 3A and could burn out the transformer if the transformer is only rated for a 2A rectifier. Its probably a GZ34 you are after: it has the correct pin-out, it can handle the current of 4x EL84s, it only requires 2A of heater current and they are still being manufactured.</p></blockquote><p></p>
[QUOTE="handsome, post: 829504, member: 772"] Directly heated rectifiers conduct almost immediately, indirectly heated rectifiers take longer to warm up and only then conduct. A choke input PSU must have a minimum current drawn through it otherwise its output voltage will rise some 50% or more. The resulting high voltage could destroy or stress some components. Because the amplifier tubes (EL84s and drivers) are indirectly heated they will take a while to start drawing current from switch-on. If your rectifier is directly heated and it is a choke input power supply you will get said over-voltage condition at every start-up. So make sure it really is a choke input power supply - check exactly what is connected to pin 8 of the rectifier socket. The choke will be connected to it but if there is also a capacitor connected from there to ground you have a capacitor input power supply. Be careful with a 5U4 in that amp: it will try draw 3A and could burn out the transformer if the transformer is only rated for a 2A rectifier. Its probably a GZ34 you are after: it has the correct pin-out, it can handle the current of 4x EL84s, it only requires 2A of heater current and they are still being manufactured. [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
Please help identify rectifier
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