[ARC5] Reviving squealing "command" receivers (re-capping)

[Lenox Carruth]

-----Original Message-----

 

Subject: Re: [ARC5] Reviving squealing "command" receivers (re-capping)

 

On 6 Mar 2011 at 7:41, David Stinson wrote:

 

> It's worth the effort to be sure which caps are bad, rather than just 

> "shotgunning" them.

 

 

 

I am not sure that I agree with that.  There are few caps in ARC-5 receivers
that I have not found bad.  Not in the same receiver but, they are about 70
years old.  If you are going to replace some of them, it is not that
difficult to do them all.

 

Note that this is the first time that I have ever not agreed with Dave as
his knowledge about these radios is legendary.

 

It is not that difficult to recap the ARC-5s.  The first couple of cans that
you do will take a while but, after that, it gets routine and fairly fast.

 

Here's how:

 

1.  Remove the cans.  Leave the wires as nearly in place as you can as this
makes it easier to reconnect them.

 

2.  Carefully take an Xacto knife (Use the triangular blade.  I think it is
an 11) and go around the mica insulator where it joins the can.  Don't try
to cut all the way through in one pass.  Make several passes until you can
remove the insulator.

 

3.  Cut the wires to the individual (in the case of the cans that have more
than one cap) and remove the insulator.

 

4.  Heat the terminals and pull the wires out of them.  Lay this aside.

 

5.  Take a small screwdriver and dig most of the wax out of the can.

 

6.  Heat the solder on the back of the can and pull the caps out or just cut
the wires short at the back of the can.

 

7.  Drill a small hole in the center of the back of the can and stick the
ground side of the new caps through it.  Solder and clip the excess leads
off.

 

8.  Push the cap leads through the appropriate holes in the terminals on the
insulator,  put the insulator in place on the can (Observe proper
orientation), solder the leads and clip the excess.

 

9.  Mix some clear epoxy and run a small bead around the joint between the
insulator and the can.  Wipe off the excess epoxy trying to make a flat
joint.

 

10. Let the epoxy harden and reinstall the can.

 

Sounds harder than it is.  After you have finished, it will be almost
impossible to tell that you ever did it.  

 

Note that the new capacitors are all much smaller than the old ones.  I used
Orange Drop capacitors.

 

The electrolytic will be harder to remove from the cans but it can be done.

 

Once you have finished, you will have a radio that will last for years to
come - buy a set of spare tubes!

 

With one Saturday in the workshop, you can do three or four receivers.

 

Good luck!

 

Lenox