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Thread: ARRGHHHHH!! Commodore electronics - so cheapskate...

  1. #11
    eslapion's Avatar
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    Quote Originally Posted by Merlin View Post
    I do wish Commodore had used slightly better electronics when they built their machines, but that's a whole new rant and is likely to stir up the natives, so let's not go there.
    It won't stir me... IMHO, you are perfectly right.

    The power supplies which come with Commodore 8 bit machines is especially questionable quality wise. It's one of the main reason for the destruction of these valuable antique machines.
    Last edited by Merlin; 12th August 2016 at 10:53. Reason: fixed a typo

  2. #12
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    OK, here's the circuit diagram for the C16 power supply, as far as I can make out it's nothing special, it's a pretty standard PSU that's non-regulated.


    I'll be getting the parts to try and repair the PSU later today.
    Edit: I've identified the rectifier bridge part No. now, so i've updated the diagram.
    Attached Thumbnails Attached Thumbnails C16 PSU Diagram.jpg.jpg  
    The future's so Retr0bright, I gotta wear shades.....

    As rkauer said:-
    "Retro computers seems like an orgasm: it is always better to have a real one than fake it".

  3. #13
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    OK, after a second trip to Maplins and a group huddle with then components nerd there, a 2A rectifier (slightly different design to the original and a tad bigger) and a 16v 4700uF electrolytic capacitor were purchased, along with some 1.25 20mm fuses. After some careful surgery, checking the tracks for damage and shoe-horning in of the rectifier, I can report that the PSU is now back in working order and Commodore C16 serial No. 483883 is reporting for duty

    The PSU actually outputs 14v with no load, with the centre pole of the plug to the C16 being negative. 14v is typical of an unregulated power supply and I'm surprised that Commodore didn't build a 10v regulator into the PSU (OK, I'm not really that surprised, as the regulator adds cost). The circuit diagram as drawn is correct.

    I did a quick test with a Strange Oddessy cartridge that came with the machine and it does appear to have survived. Now it's onto upping the memory in it, with some help from our resident uber-fixer.

    If I could find a 2-pin early VIC-20 lead to get that working, my C= 8-bit collection would be complete.

    Edit: I got off the phone with TheCorfiot earlier, who reminded me that I don't have a Commodore Pet. I did used to have a Pet 4016, however, I have it to a niece about 20 years ago and it was thrown away after a 'magic smoke' moment. I wish they had told me at the time, I could have repaired it.

    Time to hunt for another one, i reckon.
    The future's so Retr0bright, I gotta wear shades.....

    As rkauer said:-
    "Retro computers seems like an orgasm: it is always better to have a real one than fake it".

  4. #14
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    Good work Merlin!

    A little persistence payed off well this time and the story has a happy ending.

    P.S. I've spent more time and effort repairing switching PSUs with only mixed results to show for it.

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    I presume that any transformer that puts out 10 to 12v on the output at 2A before the rectifier will suffice for this PSU. I did assume that the transformer was 10v but checking the output under no load gave 14v, suggesting that it's a 12v transformer.
    The future's so Retr0bright, I gotta wear shades.....

    As rkauer said:-
    "Retro computers seems like an orgasm: it is always better to have a real one than fake it".

  6. #16
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    I hate stuff like this, its almost caught me out a couple of times,

    in the imported (converted to UK) vending machines the americans like to switch neutral not live, they think this would reduce arcing and interference on motors etc.

    what it does do on the tank heater circuit which is run off solid state relays (non moving part relay that switch current not voltage) so on an open circuit heater element or tripped over temp stat give you 230v all the time. only under load does it drop to 0 lol...

    now they do this in new coffetek machines,, knightmare to fault find a broken neutral ...pfft!!

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    Quote Originally Posted by Sardine View Post
    ... in the imported (converted to UK) vending machines the americans like to switch neutral not live, they think this would reduce arcing and interference on motors etc.
    Insurance companies and CSA/UL makes it mandatory. It's illegal in all of Canada and most american states to sell any electrical apparatus not configured like that.

    If you don't then the freewheeling current of electric motors can generate a spark of more than 1kV when stopping. Shooting back a surge of 1kV is not exactly good for other devices connected on the same electrical outlet or breaker circuit.

    Are you familiar with the concept of back EMF ?
    Last edited by eslapion; 14th August 2016 at 00:08.

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    Yup and such suppressor circuits are added (when in the uk) to said motors. but in vending machines the motors are so small they stop almost instantly anyway.

  9. #19
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    Quote Originally Posted by Sardine View Post
    ... in vending machines the motors are so small they stop almost instantly anyway.
    Even if it takes a blink of an eye to stop a motor, for a very brief period of time, it can be a source of current with nothing to limit the voltage, just like a spark plug in a car's engine. That's enough to send someone to the hospital, even cause heart attacks on older people.

    Many vending machines have refrigeration systems in them so the fans, compressor and pumps can all generate back EMF sufficient to start a fire, damage other equipment or injure people if not dealt with correctly.

    I strongly prefer machines that are safe to ones that lack important safety features to facilitate diagnostic. All suppressor circuits degrade over time.

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