hallicrafters s 40 b bites back

Discussion in '"Boat Anchor" & Classic Equipment' started by KB2WVO, Oct 5, 2018.

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  1. KB2WVO

    KB2WVO Ham Member QRZ Page

    ok to know if iam on rite track..
    when you hook antenna to ground on the RX. it bites back if your touchin chassie.
    iam guessing caps. mind you 70 year old radio orig cond. never been touched. it does work..

    but iam 98% sure recaping is in the future of this RXer..
  2. K3UJ

    K3UJ Ham Member QRZ Page

    Two prong AC plug? Try reversing it in the wall outlet.
    KB2WVO likes this.
  3. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    Even reversing a 2-prong plug will not usually eliminate the "tickle". The radio was designed to be used with an external ground connected to the 3rd terminal on the antenna terminal strip.

    The tickle is caused by the bypass capacitors on the AC line. The proper thing to do is to replace the 2-wire cord with a 3-wire cord and add a fuse (the receiver did not have a fuse from the factory.

    The 3-wire cord needs to be wired as follows:

    Black wire: First to the fuse and then to the off / on switch.

    White wire: To the "other side" of the original 2-wire cord.

    Green wire: Connect directly to the chassis.

    Then, you really need to replace all of the paper capacitors in the receiver. Most, if not all, of those capacitors are going to be leaky. Also, before turning the receiver on again, replace the electrolytic capacitors. Those are certainly going to be leaky and, when they go full short, they are going to damage a LOT of components and some of those are going to be expensive to replace.

    New capacitors are inexpensive from places like Mouser.

    After doing these changes, there will not be a "tickle" on the cabinet and the receiver will definitely work better.

    My restored S-40B is at the bottom at the following URL:


    Glen, K9STH
    KC8YLT and N2EY like this.
  4. WD0GOF

    WD0GOF Ham Member QRZ Page

    The S-40 has a power transformer. The line is isolated from the chassis. If you are getting bit by the chassis then:
    >> C56 is leaky.
    >> The transformer has a short.
    >> Some one has improperly installed a three wire power cord.
    >> Your station gnd is not.
    >> Your antenna system gnd is not.
    N2EY likes this.
  5. KB2WVO

    KB2WVO Ham Member QRZ Page

    sounds like a good thing to do for sure... and that s 40 looks good.. sort of figured a full cap job. that will be a very very slow thing ... the one site just radios... seems he has all caps ... i figure 2 or 3 a month . 30 plus caps. then the resistors. by this time next year all good lol ..

    in the images below.. is the redish orng paint orig ?? i think it is... not 100% tho .

    looks orig plug 2 wire.
    yeah ground what is that lol ... i been wanting to run a line from breakers. 25ft under me. but not goin to happin to soon..
    the antennas are grounded. think the cap bleed thru pushed thru to antenna.. there for the bite. ??? askin as iam not sure. it made a curcit.?

    few pix of it... its all orig. the pins for the cover and the holes for the pins are there and tight as new. cover isnt bent . paino hing isnt bent. nor rusty.
    there isnt no rust at all.. heck still has some of the label under it.. 70 year old. to me wow... i know its not top end. but its sooo cool to have this.. love the old stuff..

    Attached Files:

  6. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page


    Even if C-56 is not really leaky, there still will be enough voltage on the chassis to produce a slight tickle. Not enough current to do any real damage, but, remember, a capacitor passes AC but rejects DC. Therefore, there will still be a little AC voltage passed by the capacitor.

    However, even when new, the old paper type capacitors had a lot more leakage than modern poly type capacitors. As such, there was the tickle on the cabinet when the radio was new if someone got between the cabinet and ground. Of course, when the receiver was designed, 3-wire systems were not present in homes, floors were made of wood, and unless the receiver was operated near a water faucet, or outside, no one got between the cabinet and ground. Therefore, no one even thought about the tickle on the cabinet.

    Glen, K9STH
    N2EY, KB2WVO and WA7PRC like this.
  7. K0OKS

    K0OKS Premium Subscriber QRZ Page

    Of course any cap from line to ground must be replaced with a Y rated safety cap which are designed to fail open, rather than short. These cannot my ordinary film capacitors, etc., but rather need to be Y rated. Otherwise, when your cap fails, old or new, you are going to get more than a tickle.
  8. KB2WVO

    KB2WVO Ham Member QRZ Page

    will its goin to take me a few on that one.. iam still tryin to remember mmf is pf or uf and uf is pf and nf and mmf and my hair my hair. lol

    i thought i had a little bit of handle on it.. but its still a bit cornfusing. i remember numbers like 1 2 3 4 5 6 so much easier then .022uf or 22pf or .0018uf so on o my lol or where to use metel film or replace some fo the caps in this with what orange dips and fire safe .. then i got one cap thats 30-10-10. so if not able to find i guess its a 3 part build. no idea yet. if its a can big enough to rebuild orig can.

    not even sure if the old caps are guttable. so i can use the casings. to keep as orig look as i can. lots to learn ..
  9. K0OKS

    K0OKS Premium Subscriber QRZ Page

    mmf is Micro-Micro Farads... which is the same as picoFarads


    That company also sells caps and talks about the Y and X rated safety caps as well.


    You can often gut those paper caps and stick the metal film or polymer caps inside them if you want to go hard core on the original look. Looks like a nice radio. Good luck with it.
    N2EY and KB2WVO like this.
  10. KB2WVO

    KB2WVO Ham Member QRZ Page

    yep thats the site i was looking at...
    there some ceramics i dont think he had. not sure.. i know aslong as the volts is above whats called for is ok... so call for 200v. 1600v cap is fine. unless in the electrolicy.and the meltel film or mica caps so on... mr C has a video on caps .. ill have to rewatch it.

    ty for info tho... and ty on radio comment.. yeah its in great shape at least it powers up and works.. so worth working on...
    i have a s22r. but that is in rough shape ... in case is repaint . side moldigs beat up.. and inside is rust free. but its a total rebuild. wires and all..
    and no tube tester so sort of didnt want to work on it till i know there ok. still able to get them. but total cap price was 30 bucks. resistors was in the 20 buck area. tubes was in the 40ish area for all.. that will be when i hit the lotto jackpot lol ..
    tho it does have the big VC and 6sk7s. could build a tube regen.. mmmmmm

    ty on the good luck.. ill need it lol

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