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Old 13th Oct 2020, 12:37 pm   #101
G6ONEDave
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Default Re: EPE Electrolytic Capacitor Tester/Reformer Construction

Thanks, will try it out once I get some working space back on the bench. It's getting a bit clogged up at present, what with my first Ekco TMB272, coil winder and cap reformer along with various other odds and sods. It's a bit crazy at the moment, I have loads of storage space but am so full up there's nowhere to move anything to. Some of the stuff thats in the way is awaiting return/collection away from here and the rest needs a month of Sundays to even begin sorting it out!
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Old 29th Oct 2020, 5:24 am   #102
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Default Re: EPE Electrolytic Capacitor Tester/Reformer Construction

My box is coming along. I'm quite pleased with my first attempt at dovetails. I intend to cut it in two in order to create a lid and base now, then mount the top-plate. I've been quoted over £100 for engraving that SVG of my reworking of the Silicon Chip front plate, but a friend has divulged they have a screen-printing setup, so I'm going to try that...

As you can see, my girlfriend's losing interest halfway through dismantling her freewheel.
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Old 31st Oct 2020, 4:42 pm   #103
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Default Re: EPE Electrolytic Capacitor Tester/Reformer Construction

Now if my woodworking skills were that good, I would be doing a lot more of it. What a good bit of tongue and groove workmanship!

UB have you considered using a brass sheet for your control panel? I have a copy of the home workshop somewhere and it gives details on how to etch the surface using a wax coating, that is carefully scraped to reveal the areas to to etched. Then you apply the etchant to the exoposed areas, leave for a short while then rinse off. Another method might be to track down one of those companies that used to engrave out callsign badges at radio rallies (remember those?), obviously a bit more expensive than a name badge given the size of panel but just a thought.
Dave
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Old 1st Nov 2020, 7:38 pm   #104
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Default Re: EPE Electrolytic Capacitor Tester/Reformer Construction

Thank you for the kind words, Dave! It's one of those things I'd like to do more of, but there just isn't the space to have a proper workbench, though I have a reasonable number of good quality old tools and have been sharpening old saws recently. I'm pleased at the limited gaps in the dovetails considering the work's had to be done on a Workmate in the rain with a Screwfix tenon saw!

I've cut it in half now and managed to bodge the hinge alignment, so that's exercising me at the moment.

The £100 was from an engraving firm to do a CNC routing of the vector file posted previously. Brass is an interesting idea, though as I already have this black phenolic stuff I'm tempted to try printing that first so it's not hanging about awaiting some other use.

I've now realised that since I have a box, I could print the ESR table and mount it in the lid, rather than have all the faff of engraving/etching the tiny lines I had to do in order to get it to fit on the redesigned top-plate in the same way the Silicon Chip-supplied design does. I can have all the controls on the plate and just label them, pasting the instructions and table both inside the lid!

*Facepalm*
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Old 10th Nov 2020, 11:50 pm   #105
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Default Re: EPE Electrolytic Capacitor Tester/Reformer Construction

It runs! I'm testing the capacitors I've taken out of the Tektronix 2445 mentioned in the relevant section. A couple are way out of whack, with leakage of 6mA, though most seem fine, with ESR and value showing up correctly on my component tester.

I've made a hash of the front panel where I slipped with a file, and where I managed to drill the holes on my carefully constructed CAD templet before discovering some were in the wrong place. So I'll have to consider what to do about that, but fundamentally it's functional.

I'll post some pictures once I get the latches for the box lid, but here's one of it running. I've had to weigh down the lid of the test compartment as I can't find the magnets I'm intending to use to hold it shut, and otherwise the microswitch doesn't close.
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Old 11th Nov 2020, 1:48 pm   #106
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Default Re: EPE Electrolytic Capacitor Tester/Reformer Construction

Well done UB, it looks like you are beating me to the finish line with your impressive build. I must get back to my own version soon, although I have been somewhat sidetracked of late.
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Old 13th Nov 2020, 5:07 am   #107
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Default Re: EPE Electrolytic Capacitor Tester/Reformer Construction

Thank you, Dave - I did have quite a head start on you, though! It's hard to gee oneself up for projects where the tools and workspace are limited and the energy expended for success is greater than normal, and the chance for error is much increased.

I wonder if yours, or anyone else's works enough to tell me whether this is normal behaviour, or whether my transformer winding is at fault. When testing and leakage is high, the unit really struggles to get up to the working voltage. At the moment I'm on the 450V setting (off-load 468V) and with a leakage of 3.2mA it's hovering about 330V.
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Old 13th Nov 2020, 10:58 am   #108
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Default Re: EPE Electrolytic Capacitor Tester/Reformer Construction

Sorry not that far along yet UB, still sorting the coil winder. One thought though, what is the current rating of the supply. I realise that not much current should go into the capacitor being reformed but with that and the voltage generating oscillator, I would think that the supply psu probably needs a minimum 1A output and possibly more. I've not checked the magazine on this lately, just my thoughts. But by my rough reckoning if one has 468v at 1mA output a 12v psu would need 39mA for 100% efficiency, it's not a lot re 1A but then there is the other circuitry to allow for and the fact that the oscillator won't be 100% efficient. And of course as the output current goes up, the psu needs to be able to cope, as well as the oscillator. The other thought would be to do with the oscillator and it's operation frequency that might be drawing too much from the psu. I might be way off the mark here, it's just my initial thoughts and will need some further investigation to sort out.
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Old 13th Nov 2020, 8:25 pm   #109
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Default Re: EPE Electrolytic Capacitor Tester/Reformer Construction

I wouldn't worry about a winder - it works with my lashed up coil stuck on a few layers of rubber tape so it doesn't interfere with the transistor heatsinks! As I wasn't sure if the wire was duff or not I did it quite fast, without too much care to make sure the layers were lying completely flat to each other. It only takes a few minutes to get it working. When yours is, it will be interesting to see if it's more powerful and that my coil is at fault. As it's the only part that isn't 'stock', in other words the only part I could mess up, my suspicions fall on that naturally. My supply can do 1.5A at 12V - an old HomeHub switching plug.
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