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Considerations when replacing GZ34 with 1N4007's

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  • Pixel
    replied
    How about pushing a long lead octal socket into the existing socket?

    Leave a comment:


  • g1
    replied
    I guess it's a different socket than the ones for the 6SL7's ?
    I had wondered if maybe there was one of those repair bases on the 5AR4, that are used when the locator pin breaks off.

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  • Mr_bibbles
    replied
    Originally posted by nevetslab View Post
    One thing that will occur making this change, is 5AR4/GZ34 rectifier tube has a 10 sec or so warmup, and the DC supplies slowly ramp up to nominal supply voltage, while the heater supply warms up the tubes. With the 1N4007 rectifiers in place of the rectifier tube, the HV will be applied immediately.

    You might want to consider replacing the tube socket, or, if feasible, re-tension the tube sockets.
    Thanks Nevetslab, it's hard to explain but I tried describing it in my first post; the tube pins barely even REACH the sockets, much less fit snugly. There is no way to re-tension them. It has never worked while my customer had it. I wish I could take a picture to explain how funky this thing truly is, but a new phone is in the US mail service at the moment... My next move usually would be to replace the socket, but it's mounted in such a way that the non-standard chassis mount points function as part of the circuit's ground, so I would have to rewire half of the power supply to get a new standardized socket in there IF It would fit in the mount.

    I never like altering a circuit when I could repair the existing one, but in this case it seems like the least aggressive course of action.

    As for the warm up times, I saw someone in a different forum suggest adding a thermistor to help with the warmups.. the issue here is that B+ would hit the rest of the tubes before the heater can make them comfortable with the voltages?
    Last edited by Mr_bibbles; 07-03-2021, 11:46 PM.

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  • nevetslab
    replied
    One thing that will occur making this change, is 5AR4/GZ34 rectifier tube has a 10 sec or so warmup, and the DC supplies slowly ramp up to nominal supply voltage, while the heater supply warms up the tubes. With the 1N4007 rectifiers in place of the rectifier tube, the HV will be applied immediately.

    You might want to consider replacing the tube socket, or, if feasible, re-tension the tube sockets.

    Leave a comment:


  • Mr_bibbles
    started a topic Considerations when replacing GZ34 with 1N4007's

    Considerations when replacing GZ34 with 1N4007's

    Hey Y'all,

    I normally wouldn't do something like this, but I have a very nicely made Lumley HIFI that has a goofy socket for it's rectifier; long story short, the pins of any rectifier are not long enough to fit into the tension sockets... At the very bottom of their travel they barely even touch the contacts, so even a spring retainer might not be reliable: When the amplifier is on, any tiny bump will disconnect a pin of the rectifier, making it far less than ideal. I tried looking underneath to see if I could tighten the socket pins, considered adding solder to the leads, etc etc, but there's simply no way to get this tube (or any others) to fit snugly.

    So if I were to replace the gz34 with a hard wired full-wave 1N4007, I know the voltage would go up by about 50v so I would need to ensure that the B+ line is rated high enough, and that the filaments are off their own transformer taps so that they'd be unaffected.

    My question is, am I missing some important variable here? Would this be safe assuming I don't exceed component values? If not, could I add a simple dropping resistor to pad the voltage down?

    Thanks!

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