Author Topic: Sun Motor Tester - 1950s vintage refurbish  (Read 113 times)

Online goodfellow

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Sun Motor Tester - 1950s vintage refurbish
« on: October 10, 2020, 11:58:00 AM »
Note: These threads are old. I managed to restore these Sun Automotive Equipment threads from backups that I had made several years ago.
Hope you like them -


Had a day to myself and decided to tackle the old Sun Motor Tester. First thing I saw was a date stamp on all the modules (they all were built between March and Oct. of 1948). So this unit is pretty old.

Here's what i started with



Except for some rodent crap and dead insects, the back of the unit was pretty clean. But the wires were total trash --





The first module out was the emissions unit. Like the cars of the time, All the modules run on 6V DC, so I used a 6V battery charger to power test the unit. It was intermittent -- lights flickered and the wiring was brittle. Time to disassemble the electrics and trouble shoot --







Lights Flicker -- continuously





Pretty rough -- but it can be cleaned up with lacquer thinner and some elbow grease



Here's the cover plate after a good cleaning (I don't want to paint these silk screened parts because the lettering is so delicate)



Time to separate the electronics from the frame, and throw some paint on the frame! 






Turns out that the big problem with the flicker was just a few cracked wires -- they were replaced and all is OK.



The gauges were cleaned and polished with lacquer thinner and WD-40 -- they look great!!



The frame came out nice --



Time to wire wheel the brass acorn nuts -- details are important





Bulbs were desoldered, cleaned and rewired with good quality 14ga wire.



The emission tester used a 6V impeller vac pump to draw exhaust gases into the spec tube. That black hump is the motor for the pump. It was rewired and cleaned up nice



Everything put back in palce and "buttoned up"





Lights, pump and impeller work flawlessly



The emission pump impeller resides in this housing - Knobs are polished with WD-40 and reinstalled (one knob was missing, so I'll have to hunt one up)



This one is done and workin' --  :blob1:

Online goodfellow

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #1 on: October 10, 2020, 11:58:29 AM »
Time for " Phase II"

The next module was "a bear" -- the broken coil testing module. This thing was banged up pretty good, and a lot of dirt and corrosion managed to accumulate in the meter housing. To make matters worse, all the wires and leads were shot -- so I'll have to replace and do a heck of a lot of soldering





This was a pleasant surprise. The battery compartments still had batteries in them. They have to be at least 50 years old, because I haven't seen a Ballard battery since that time. What's amazing, is that the darn things didn't leak -- way too cool



I tested the large caps and they still were OK - surprised myself.



The bid "hump" is the coil breaker motor -- (nothing more than a condenser and a set of breaker points that are electrically driven by that motor). This tests the coil output to see if its output is within specs.



Well, the meter is shot and so is the glass.





What happened next is amazing. The meter bezel was exposed to the elements for so long, when I tried to clean it with some Windex, the oxidized paint just flaked off. This is the first time that's happened while cleaning a bezel. It's a shame, but I know a guy that has some spares -- so it's not a lost cause.



The meter "zero" adjuster was broken, so I scavanged another from an old Simpson gauge in the junk drawer. I was also able to readjust the movemnt and bend the needle straight so that the meter is working again -- that was a chore.







Done!!

Next I turnned my attention to new leads. Just a whole lot of de-soldering and re-soldering -- for over two hours (boring!!!)



I try to use shrink tubing when ever possible on these projects since the solder joints are so close together and could short.







Next, I gutted the frame and checked the rest of the electronics --



The cover plate was pretty bad, but it came out nice with some cleaning and elbow grease (before/after)





When she's all gutted, it's easier to check for bad capacitors -- this one was shot!!!

I didn't post any pics from painting the frame -- it's pretty much the same porcedure as all the previous modules



This old wax capacitor is a "monster" -- it's totally toast!!!



Sun used the best components of the time -- all caps are Cornell-Dubilier
It helps to have a good stash of capacitors and resistors on hand -- LOL



A more modern replacement -- about the 1/3 the size of that 1940's monster and also Cornell-Dubilier



Here's a tip when installing grommets in tight openings. Take the heat gun to it (or immerse in hot water for a minute) and the stiff grommet will become nice and pliable for about 30 seconds -- this makes installation of tight grommets a breeze



All new leads, wires, grommets, test clips and boots installed --





Here is the completed module back in the frame





It looks good, but hopefully I can replace the faded bezel soon.

Online goodfellow

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #2 on: October 10, 2020, 11:58:55 AM »
Next comes the frame:


Here are the castings -- rough!! But after an hour with some cleaner and 150 grit sandpaper they were ready for paint. Long story short, here are the before/after pics.






This is the back cover panel -- it came out very nice, but i did have to hammer and dolly out some dents to make it look decent.



The just completed emissions module installed --



Next module on to fix was the vacuum and capacitor tester unit







The dial face will clean up as well as the other unit -- no large areas of corrosion.



Although it looks ominous, this is basic 1940's technology that handles the capacitor tester. It's amazing, today we can reduce all this electronic mess into the size of a matchbook --  :toothy9:

The electronics simply steps up 6V battery voltage to test circuit capacitance in the distributor condenser (aka capacitor). To do that it uses vacuum tubes as the amplifier circuit. My problem is that this sucker has a bad choke/transformer. That's bad, it's pretty rare -- because it has quite a few taps. So I'm hunting for a choke transformer. Also, the two vacuum tubes were shot -- so I'm going hunting for those as well.



Better view of the tube amp circuit --



When doing a resto on these things -- I replace old wax and paper capacitors as a matter of course. However, since it'll take some time to hunt down the tubes and transformer, I'm going to leave it as is for now, and just replace shoddy wires and clean up the electronics with denatured alcohol and contact cleaner.





Long story short, just as in the previous module I separated the electronics from the frame and put a nice paint job on the frame before reassemply. For reassembly, the vacuum gauge just needed a new neoprene vacuum line -- everything else looked great. Again, as before, the knobs were polished with WD-40. There was one knob missing, but the rest turned out pretty well.

So this is how far I got today -- completed two modules and the tester frame. I also painted the top art deco sign and will hand letter the reliefs with red paint when the entire unit is completed





I'm a bit tired from standing all day -- so it's time for an adult beverage and a good cigar!!!! :occasion14:



Online goodfellow

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #3 on: October 10, 2020, 11:59:15 AM »
Went to Radio Shack and bought a few switches and spare bulbs (just in case I blow a few)  :toothy5:

Wired in the switches and hooked up a 6V battery charger to test the unit -- while crossing my fingers that I hadn't forgotten to do something important  :thumbsup:

Turned it on and it lit up like a Christmas Tree (In a good way)!





One thing to note on all this old testing equipment:
In keeping with the automotive DC electrical convention of the time, everything is based on "positive ground" circuits. So the battery charger and/or battery leads needs to be reversed -




Online goodfellow

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #4 on: October 10, 2020, 11:59:55 AM »
I just finished refurbishing this new addition to the garage -- the 1940's Art Deco look is real cool!





Finished painting the cast sign:









Offline Heiny57

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #5 on: October 10, 2020, 08:04:47 PM »
That is a hell of a project. Nice job. :bravo_2:  But what is this place you called Radio Shack?   :lol_hitting: :lol_hitting: I didnít know any were still open.
MAGA

If you canít fix it with a hammer, it must be electrical.

Offline DeadNutz

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #6 on: October 10, 2020, 09:21:50 PM »
Thanks for getting these back up and we need a sticky with all the Sun threads. :great:

Offline john k

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #7 on: October 11, 2020, 04:00:30 AM »
That was a pile of work, tedious, standing at the bench all day stuff.  I can imagine the feeling when all the dials jumped, and the lights came on.  Have on occasion seen old test equipment, but the owners still thought there was gold in them, and had to pass them by. 

Offline stokester

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #8 on: October 11, 2020, 04:06:03 PM »
Nice  :bravo_2:
Nick
Yorktown, VA

Offline coolmercury

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #9 on: October 11, 2020, 07:03:11 PM »
I'm impressed with your restorations. :bravo_2:

Offline skfarmer

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Re: Sun Motor Tester - 1950s vintage refurbish
« Reply #10 on: October 12, 2020, 09:50:28 PM »
Looks good. Always impressed with your turd polishing skills.
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