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Studebaker M15A-20 "Mr. Potato Head"

Friday, February 10, 2017

Condenser

I finally perfected the assembly of the ignition condenser. I got tired of replacing the condenser because of terrible manufacturing so I decided to "can" a high quality capacitor. Here is a list of materials:

1. Capacitor, .22 uF, 850 VDC, https://www.digikey.com/product-detail/en/illinois-capacitor/224PPA850K/1572-1374-ND/5411480
2. Brass tube, 21/32" OD, 0.628" ID, https://www.mcmaster.com/#8859K338
3. Brass Sheet, 0.032", 260, https://www.mcmaster.com/#9758K11
4. Rubber sheet, 1/8", Buna-N, https://www.mcmaster.com/#1861T24
5. Wire, Black, stranded, 22 AWG
6. Terminal, Spade, Side entry
7. Flat copper braid

 Start by cutting the tube to proper length

 De-burr the inside edge

 Using a small socket as a guide, mark brass sheet for end cap

 Cut end cap out


 End cap cut out

Round up the end cap to fit into the tube end
 
 Test fir end cap

 Using template, mark out the mounting tab

 Cut out the mounting tab

 Mounting tab cut out

 Shaping mounting tab

  Using an automatic center punch mark where holes are to be drilled

 Mounting tab drilled, test fitting in a distributor

Rounding edge of mounting tab to conform to tube
 
 Setup ready for brazing mounting tab to tube

Mounting tab brazed to tube using silver brazing rod
 
 Brazing ground smooth

 Preparing plumbers lead free solder

Solder ring installed in tube and slathered with flux

 End cap installed

 View of solder ring ready to be heated

 View in the tube showing the solder flow

 Tube ready for assembly

 Capacitor ready for leads to be trimmed

 Attaching ground strap

 Ground strap soldered

 Attaching hot lead

 Hot lead soldered

 Soldering the ground strap inside of the tube

 Cutting the end seal

 End seal cut

Drilling lead hole in end seal
 
 Test fitting end seal

 Masking external surfaces and applying weatherstrip sealant to inside both ends of the tube

 Assembled capacitor and end seal

  Comparing spade lug width. Could not purchase correct side lugs so I had to trim them in the belt sander

 
Capacitance test and HV leakage test

 
 All done!!





Thursday, December 1, 2016

Condenser Solution

After experiencing a condenser failure I decided to investigate why these guys failed and why so often. Here is a link where someone else investigated:


http://www.nonlintec.com/sprite/cap_failure/


https://www.smokstak.com/articles/capacitors.html 

So here are some pictures of the condenser that failed:

I ground the edge off the condenser can to pull out the guts.


 What can be seen here is evidence of arcing on the top of the condenser end where the lead contacts the foil.

 Other end of the condenser there is no arcing.

 Lead end show evidence of arcing. I also noticed that the lead is soldered to a disc that contacts the foil. This lead was not bent over completely and appears to have protruded into the foil maybe shorting out the condenser.


This construction design is substandard in my book. My issue is mainly with how the foil is connected to can and lead. These are just pressure connections and of different metals. Additionally, the unit is not hermetically sealed so that corrosion can compromise these poor connections.

My solution is to make my own condenser using a high quality capacitor.

Parts needed:
1. Recovered lead from old condenser
2. Recovered end cap from old condenser
3. Brass tube, 21/32" x 0.014" (8144)
4. Capacitor, 0.22 µF, 1,000 VDC (940C10P22K-F)
5. Brass shim stock
6. RTV


 Brass tube to house the capacitor.

 Checking fit of the capacitor in the tube and tube in the holder.

 Cutting the tube.

 Made a end cap and soldered into place with 50'/50 solder.

 Tube housing cleaned up.

 Because the capacitor fits so tightly in the tube I used thin sheet brass to bring the internal lead to the other end.

 Inserting capacitor into the prepared tube.


 Soldering the internal connection to the inside of the tube.

 Soldering the lead to the capacitor.

 Applying RTV to the end of the assembly.

 Inserting the rubber end cap into the the tube.
 Checking correct capacitance to be ~0.22 µF.

 Hi-POTing the capacitor. My capacitance tester only goes to 600 volts, oh well.

 Completed unit ready for assembly into the distributor.

 Testing fit.