[Milsurplus] PP-109 Dead Vibrators

[mac]

The technique described in detail by Robert (see attached) works quite  
well and has been around for some time.  For years I had been opening  
the cans and grinding the coating off the contacts with abrasive  
paper.  That works very well but is a lot of work takes a while  
because the coating is HARD!  Because of this I was skeptical about  
the electrical burn-off technique but finally tried it and  
surprisingly (to me) got very good results.  Have now built up a  
"rejuvenator board" with multiple sockets, light bulbs and switches to  
accommodate all the various vibrator  types found in my (and my  
friends) radios.

Dennis D.  W7QHO
Glendale, CA

***************
On Dec 3, 2013, at 12:27 PM, WA5CAB at cs.com wrote:

> Somehow, I missed the original post.  In my experience, the most  
> common
> failure mode for vibrators that haven't been used in decades  
> (whether NOSB or
> Used) is that the tungsten contacts react with sulfer outgassed from  
> the foam
> rubber sleeve and become non-conductive.  The details of the fix  
> method
> I've always used varies depending upon whether the vibrator is a  
> Series or
> Shunt type.  But basically you apply the 120 VAC line across each  
> contact in
> series with a 15 to 40 watt 120 V incandescent lamp.  One lamp is  
> put in series
> with the coil to pull the armature to one side and close half the  
> contacts.
> In the series type, this also puts it in series with the actual  
> vibrator
> contact.  Additional lamps are put in series with the remaining  
> contact(s).
> The armature is common to all circuits.
>
> Lamp sizes that I use are as follows:
>
> For the lamp in series with the coil
> < 6V   40W
> 6V 40W or 25W
> 12V   25W
> 24V   12/15W
>
> All other contacts, 12/15W.
>
> For shunt type, one lamp is put in series with the coil only (see *  
> below).
> Tie the two contacts, one of which is used as the shunt contact,  
> together
> and put a second lamp in series with them.  Run the setup until the  
> second
> lamp lights.  disconnect the two contacts and determine which is  
> working.
> Connect it as the shunt contact and put the second lamp on the other  
> contact.
> If you have enough lamps, connect additional ones to the other  
> contacts.
> Run the setup until all lamps light or flash.  May take several hours.
> Dropping a diode (1N4008) in series with the coil may speed things up.
>
> *  If the shunt contact is internally connected to the coil you  
> can't use a
> separate lamp on it and if repair is successful it may take many  
> hours.
>
> Also, the procedure will not work with a VB-5 because it has a 470 ohm
> resistor across the vibrator contact internally.  And to add insult  
> to injury,
> the aluminum cans on every VB-5 I have ever fixed are the only ones  
> i've
> encountered that consistantly crack when you try to open them up.   
> You'll have
> to have a non-VB-5 organ donor to supply a replacement can.
>
> In a message dated >  
> --------------------------------------------------
>> From: "David Stinson" <arc5 at ix.netcom.com>
>> Sent: Tuesday, December 03, 2013 7:24 AM
>> To: <milsurplus at mailman.qth.net>
>> Subject: [Milsurplus] PP-109 Dead Vibrators
>>
>>> I know this has been covered before, but I can't find it.
>>>
>>> Anyone have a good, non-destructive procedure for
>>> reviving dead 6-volt, 7-pin vibrators from the PP-109
>>> power supply?  This one is recapped and waiting to
>>> power some bench projects if I can "wake it up."
>>> 73 Dave S.
>
> Robert & Susan Downs - Houston
> wa5cab dot com (Web Store)
> MVPA 9480
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