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Repairing or Upgrading an Old Telephone Condenser

Started by Ktownphoneco, September 30, 2018, 03:19:02 PM

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Hi All  ....   I've done this a number of times, but usually forget to photograph the process in order to pass the information along to others.    What I'm talking about is repairing, or in some cases, altering the value of the older types of factory condensers found in the older sets.      Typically condensers were contained in rectangular metal cans, usually with 4 sides, a bottom piece and a metal cap.     Sizes vary based on capacitance and manufacturer.     Sometimes these condensers fail, and in some cases collectors may want to use an old condenser but require a larger or smaller capacitance value.    What I've done in the past, is remove the condenser's cap, and using a heat gun, remove the existing rolled paper by heating the tar like substance which usually surrounds the condenser components inside the can.     I normally place an old coffee can underneath to catch everything that is released from the condenser can as it's heated.
Once all the tar like material has finally dripped out, and the container is cool, I prepare small capacitors to be inserted into the can. 
At this point  the pictures I've included below , pretty much explain the process, but in addition to the information in the pictures,  may help in obtaining the parts.   I look for small metalized film capacitors which can usually be found every so often on eBay.    Some have seen previous service, but most often they're new old stock that have  been classified  as "surplus". 

In the pictures below, the original A.E. condenser is the correct size that I need for another telephone, but it  is, or was, a  0.5 mfd condenser, but I needed a condenser with a 1.0 mfd capacitance value.      So I "ganged" 2 mylar capacitors rated at 0.5 mfd each, and connected them in parallel.    That doubles the collective capacitance value.    Connecting them in series, reduces their collective value by a half.    If you needed a condenser or capacitor with a value of 0.5 mfd, and had two 1.0 mfd capacitors, connecting them in series will give you your required value of 0.5 mfd.

Once the capacitors are "ganged" together (wrapped together with black electrical tape) and inserted into the can with new cloth covered leads soldered in place,  I filled the can with black Silicon I picked up at Home Depot.      Lowes, Ace Hardeware, Rona and Home Hardware most likely carry it as well.      I positioned the cloth covered wires to more or less match the two openings in the condenser can cap.     Some condenser caps merely snap on and off the can, while others are soldered in place.

The end result is a perfect repair or capacitance value change, using an original factory condenser container, and no one will be the wiser that the condenser has a more modern upgrade or repair.

Jeff Lamb


Nice! Clever way to repair a phone and still keep it original looking. Thanks for sharing it.
Harry Smith
ATCA 4434

"There is no try,
there is only
do or do not"


It appears you may have had some experience with Vintage Radios or Televisions.


The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson


That is a great idea. I'll have to keep it in mind for future reference. Thanks for the tip.


Quote from: Dan/Panther on October 01, 2018, 12:19:08 PM
It appears you may have had some experience with Vintage Radios or Televisions.


Yes, I did play with old radios at one time.     Fun to tinker with and bring back to life.     They're great for waking one up in the morning too.    Just reach around and put a finger on the steel chassis, and your awake !   ;D




if you touch an aa5 chassis and it happens to be hot at the time you may never wake up again depending if you are touching ground with another part of your body that creates a path to ground through your heart. how do i know. i got a few shocks off of them. that is one reason for the rule when working around a live chassis keep one hand in your pocket.

what about the curtain burners. those radios could be dangerous.

nice job restuffing that condenser. you can also get good condensers online but im not sure if they are restuffed or origional.