Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: LHPcope on August 29, 2013, 10:09:51 pm

Title: Need help locating 50 k ohm L center tapped pot.
Post by: LHPcope on August 29, 2013, 10:09:51 pm

Hello all,

Hopefully someone on the forum can point me in the right direction on this.  I have a Vox 125 Lead amp in for repairs.  The immediate problem is broken shafts on three 50k L center tapped pots which are used in a multi-pole E.Q. circuit in this thing. 

I have searched the Internet and can't find too many folks who even know what a center tapped pot is let alone have any of the little beasts in stock.

Help! 

Title: Re: Need help locating 50 k ohm L center tapped pot.
Post by: John on August 30, 2013, 05:55:57 am

http://www.ebay.com/sch/i.html?_trksid=p2053587.m570.l1313.TR9.TRC1.A0.Xcenter+tapped+pot&_nkw=center+tapped+pot&_sacat=0&_from=R40 (http://www.ebay.com/sch/i.html?_trksid=p2053587.m570.l1313.TR9.TRC1.A0.Xcenter+tapped+pot&_nkw=center+tapped+pot&_sacat=0&_from=R40)

http://www.oldradioparts.net/ (http://www.oldradioparts.net/)

You have probably seen both of those already. From what I gather, you can contact Mark at ORP if you don't see something listed. HTH!

http://www.ebay.com/sch/i.html?_odkw=center+tapped+pot&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR11.TRC1.A0.XPot+with+center+tap&_nkw=Pot+with+center+tap&_sacat=0 (http://www.ebay.com/sch/i.html?_odkw=center+tapped+pot&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR11.TRC1.A0.XPot+with+center+tap&_nkw=Pot+with+center+tap&_sacat=0)

Worded the query differently, came up with a few more options. I *think* you can parallel a resistor across the pot to get a closer value.

Title: Re: Need help locating 50 k ohm L center tapped pot.
Post by: kagliostro on August 30, 2013, 07:44:30 am

if you didn't find what you need

my council is to use some rotary switch and resistors

as to emulate the center tapped pot you require

K

Title: Re: Need help locating 50 k ohm L center tapped pot.
Post by: LHPcope on August 30, 2013, 08:06:09 am

Let me check out the ebay listings; the last time I looked that I came up with nothing, but as you say it all depends on how you word the query. 

As to the resistor(s) across a pot I looked at using a 100k pot with 2 50k resistors in series & across the pot #1 & #3 terminals that works if you are only looking at the Pot #1 & #3 terminals and somewhat simulates the CT but fails when you look at the pot wiper to the CT which should go to 0 ohms when the wiper is centered; with the resistors its @ 50k.

Let me also noodle about on the rotary switch idea, although more costly that might get me to where I need to be electrically.

Thanks all!