In the Garage - coil condenser tester

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TheGeneral
Posts: 12
Joined: Mon Jun 13, 2022 3:38 pm

In the Garage - coil condenser tester

Post by TheGeneral »

There isn't a category for garage tools & equipment so I've posted this here - Mods please move if it's in the wrong category.
Found this coil condenser tester on Ebay, probably paid too much for it but I'd been looking for one for ages.
This seems to be a holy grail of Sun testers, I don't think many were sold & they seem to be rare even in the USA. This one is an export 240V model which has to be even more rare. The serial number tells me that it was built in late 1973.
It tests ignition coil output which is displayed on the scope, it also checks condenser leakage, capacitance & series resistance. Plus an ohmmeter feature. Sun get full marks for a clear easy to read meter scale & the whole unit seems rugged & well made.
I want to use this so so I needed to check it out & repair any faults. The whole kit seems in good condition, most importantly the coil test cable with its voltage divider was included, the DC test lead was missing but it was a simple job to make one up with some figure of 8 cable & croc clips. The two pole connector on the other end is an Amphenol microphone connector which I found on Ebay.
Opening it up everything was in good order & fortunately unmolested. I found the operating instructions on the internet but as for a schematic, forget it. So as it was a piece of gear with which I was completely unfamiliar I decided to reverse engineer it & sketch one out. That kept me occupied for a while as the switches were pretty complex.
Well once I'd figured out how the thing worked it turns out to be very basic; there's the bare bones of a CDI ignition there to drive your coil, the output is displayed on the scope screen. The unit measures condenser capacity by repeatedly charging & discharging it with a fast acting relay & there's a single valve there which is part of the condenser resistance measurement bit.
So, little needed to be done in terms of restoration, the main thing to check on vintage electronic test kit are the capacitors, those are the blue cylinders in the photos. They were tired so I replaced them. One wire was resoldered onto a switch tag & I found a knob to replace the missing one on the calibration control. Then it was time to test.
I found an old coil to try & it worked very well, in the photo it's outputting a healthy 20 kilovolts. The capacitance range was unreliable as the relay wouldn't activate reliably, this turned out to be a faulty semiconductor diode which I replaced, the relay then buzzed away happily & the capacitance range is surprisingly accurate.
A new power cable & a good clean completed the job.
So it's pretty simple, almost crude in fact but it performs its intended function very well & is accurate enough for its intended purpose. Simplicity implies reliability & ruggedness.
It will be used mainly for checking magnetos on small engines
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cct10 rhs.jpg (90.06 KiB) Viewed 10708 times
TheGeneral
Posts: 12
Joined: Mon Jun 13, 2022 3:38 pm

Re: In the Garage - coil condenser tester

Post by TheGeneral »

More pix
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cct10 top.jpg
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cct10 scope.jpg
cct10 scope.jpg (101.86 KiB) Viewed 10707 times
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