Sunbeam S7 Deluxe - Oil Pressure Switch

 The oil pressure light has not been extinguishing on the Sunbeam S7 Deluxe.  I removed the switch and put some pressure to it, which did not open the contacts.  The stamp mark on the body of the switch is 10psi.  I was well above 10psi air pressure and the switch did still not open.

Figuring that there are replacement switches available, it would not hurt to try to take this one apart to see if it was repairable.  The switch was not leaking oil, so it seemed reasonable it may be just something with the contacts preventing it from opening at the correct pressure.

The adjustment pin has a slotted head inside the electrical contact stud and would not move.

There is a pressed sheet metal collar around the switch body.  I put it in the vice and began prying at the collar.  It eventually slipped up over the switch body and exposed two cutouts with a view of the contacts.  The diaphragm pushes against the outer contact which lifts it from the fixed contact.  The fixed contact was initially factory set at 10psi, and then fixed in place with a center punch mark.  This explained why the adjustment would not move.

After cleaning the inside of the contact chamber with contact cleaner, I was able to see it operate.  Using two small flat bladed instrument screwdrivers, I could hold the fixed contact against the adjustment pin and slightly bend the profile of the contact.  A few iterations of this yielded a nearly perfect contact break point just around 10psi.

The tool I'm using in the video is a continuity tester.  It has a small buzzer and battery in series.  The pointer end is connected to the buzzer and the other side of the battery is connected to the wire clip lead coming out the back.  I built this long ago for general electrical testing.

(Forgive the state of the workbench, I usually don't leave it that dirty.)

If it continues to act up, I will probably order a new pressure switch.  For now at least I know how the original switch works.

I fitted a tee to get the oil pressure switch out into a little bit of cool air.  I'm told that will lengthen the life of the switch.

Keyswitch overhaul

I wasn't happy with the broken light switch handle on my Sunbeam S7 Deluxe. I managed to score a pretty beat up electrical box from an S7 on ebay, which included a switch. The switch was worse shape than I thought when it arrived. Apparently the early models used steel setscrews, which rusted in place. This meant I had to drill them out and re-create some brass ones.

Disassembly was easy. First the back retaining stud for the tumblers had to be released from its fastening nut. This was easily done, by snapping the stud accidentally. *whoopsie* The front bezel turns and then comes off through some slots. This allows everything to come apart.

Making a key was easy.  I just inserted the blank into the tumblers and then marked each tumbler position.  Then I estimated the depth of each notch in the key, and began cutting with a dremel grinding disc.

The hard part was drilling out the setscrews.  I only buggered up one thread by accidentally drilling crooked, the others came out without a problem.

The contacts were cleaned up and new setscrews fashioned.  The original spring was shot, so a new one had to be made.  This allowed the lamp switch to operate smoothly, but with enough pressure to make contact with the position detents.  This picture was taken before the brass contacts were cleaned up and polished.

I had to drill out the fitting that the tumbler snaps into, and put a tap new stud in it.  I made it long enough to fit two jam nuts on the end.

The switch assembles as easy as it came apart.  The tumbler can actually snap in last.  This makes the assembly MUCH easier.