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    Weber WZ68 now NOT recommended on Weber website!

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    sKiZo

    Posts : 1312
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by sKiZo on Sun Sep 27, 2015 12:55 pm

    arledgsc wrote:
    If B+ has increased closer to 550V I will wire up my unused ST120 rectifier heater winding as a bucker with the incoming line voltage to effectively reduce the AC coming in about 5V.  This should reflect to 15-20V less HV AC at the rectifier input.  

    Hadn't thought of that ... I made an external bucker instead, using a transformer that's good for 6a. Will that spare winding handle the current?

    Wonder if you could wire up that extra heater winding for hot switching? Turn it on when needed, or not. I know my line voltage was at 124+vac when I first got going here due to a recent upgrade in the grid for a new housing development down the road. Power company has since got things back to normal, and the bucker is out of the loop ... for now anyway.

    Kentley

    Posts : 335
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by Kentley on Sun Sep 27, 2015 5:24 pm

    Today I switched out rectification in my VTA ST-120. I replaced my trusty Mullard GZ-37 with the Weber WS1. The sound is comparable. One caveat -- lower your bias adjustments to minimum before you switch to the WS1. What used to be spot-on .54 VDC with the tube when the pots were at 2 o'clock became dramatically different with the Weber and now .54 VDC is achieved with the pots at 10 o'clock. Caveat rector!
    I've run it at moderate volume for an hour now and the temp. on the copper-cap reads at 156F. Way cooler than the WZ-68 which I melted down several months ago!
    DON'T TRY THE WS1 if you don't have the time-delay relay installed -- unless you wish to be blowing output tubes left and right. Bad pun intended. It blasts B+ voltage instantaneously -- no delay whatsoever.
    The WS1 is less than $20 from Weber Speaker Co. That is a good thing.

    arledgsc

    Posts : 340
    Join date : 2012-11-30
    Location : SF Bay CA

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by arledgsc on Sun Sep 27, 2015 6:47 pm

    Good job Kentley!  I probably need some form of inrush current reduction with the straight diode replacement.  I will work on that.  The lights dim a little for a second when the delay relay kicks in - more than usual.

    Skizo I wish the bucker idea with the main transformer was mine as that is a brilliant solution.   I got the notion from our forum member "peterh".   I'm sure a in/out switch would work on the bucker but would recommend only changing with power off and recheck bias afterward.
    http://dynacotubeaudio.forumotion.com/t2403-howto-cut-5v-from-the-mains-line?highlight=line+voltage

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