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Standby switch (Read 1656 times)
MattG
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Standby switch
07/03/12 at 22:15:33
 
Hello,
I'm hoping someone can help me out- I'd like to add a Standby switch and was staring at the board thinking of how I could add in a switch before the 1st filter cap. After looking at other schemes, would it work if I  instead put the Center Tap for the 300V (black/red wire on the Edcor XPWR107-120) on a switch, going from grounded (ON) to floating (STANDBY)??

Thanks
Matt
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MattG
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Re: Standby switch
Reply #1 - 07/05/12 at 18:35:06
 
After some more googling, I wired it up as Center Tap ground/open. Apparently there are pros & cons to the methods, but this was fairly easy.
I will report back on results when I finally power up...
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mboxler
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Re: Standby switch
Reply #2 - 07/06/12 at 15:42:10
 
Matt...

I'll be interested how this turns out!  If it seems to work, I'll order a switch similar to this

http://site.tubedepot.com/pdf/p-dpst-3way.pdf

Good luck!

Mike
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MattG
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Re: Standby switch
Reply #3 - 07/06/12 at 17:20:14
 
Oooh, all-in-one, nice! Cool

I'm using up spare parts, thus my 2 separate switches Smiley Plus it looks pretty cool from the front, the 2 switches with the volume knob in the middle...

yeah, notice the wiring pic at the bottom of the link - shows "HV B+" - to implement that method, I'm pretty sure you'll need to cut a trace on the PCB to "open" the power rail and insert those 2 wires...if the CT method works without obnoxious popping or somesuch, then you could wire it up using the CT wire and then just another wire tied to circuit (or chassis?) ground. No scraping at copper traces...

-Matt
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MattG
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Re: Standby switch
Reply #4 - 07/10/12 at 18:50:19
 
just a quick update - I powered up, am getting sound!

the CT ground/lift standby does NOT work as I thought - the music plays regardless. I haven't quite wrapped my head around it, I *think* it might have something to do with this being a 2 diode rectifier ckt, and not a full wave 4 diode bridge ?? Regardless of the CT being grounded or not, the red wires still show 300VAC going to the diodes...

oh well, standby was just a nice to have, not necessary - hey the production amp doesn't have one, right?!   Roll Eyes
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MattG
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Re: Standby switch
Reply #5 - 07/16/12 at 20:52:24
 
well the saga continues...since my initial attempt at CT-lift standby "failed", I turned that switch into a 2nd power switch for my 2-amps-in-1-box...I swap the wires over and plug in the power cord, both switches in OFF position...and the tubes for the amp with the 'new' power switch light up! WTF?! Get out the meter and lo and behold, the damn switch had shorted!! it was always ON!

Of course, when wiring the switch up for power, I'd cut back the CT wires and grounded them to the chassis, well away from the switch. So I'd have to re-extend those wires to try the CT-lift standby again, which I decided I wasn't going to bother with...

SOOO, what this means is that CT-lift standby may in fact work, I (for the 1st time ever) had a bum switch!

If anyone else is brave enough to give it a shot (MikeB?!), I'll bet they'll have better results! Smiley

Again, it's a real easy way to implement standby, just the CT wire and a wire to ground, on a (working) switch...no PCB trace scraping!

Anyway, thought I'd report this find, I'd hate to spread mis-information...if someone tries it, pls let us know!

-Matt
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mboxler
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Re: Standby switch
Reply #6 - 12/08/12 at 00:56:08
 
Better late than never.

Finally got one of my amps finished, and yes, used the standby switch I mentioned above.  Works Great!  Matt...you were correct.  Wired the CT wire thru the B+ side of the switch.  Flip the switch up half way...tubes glow.  After 30 seconds, flip swith all the wasy up...music.

Still don't know if this is worth it, but sure is cool!

Mike
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MattG
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Re: Standby switch
Reply #7 - 12/08/12 at 03:07:53
 
Sweet!
I'd been off the forum for a while since I finished up my amp, but decided to check in this evening and lo and behold I saw your post!
Really glad to hear it worked out, Mike...and congrats on getting yours up and running!
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