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  1. #321
    Can you take a resistance measurement at the coil that you do not have continuity? If you put your multimeter at continuity scale you get a bazing sound of a reading only if resistance is low,I think up to 10 ohm but I am not sure if it is a little higher or change between the brands of the meters,if resistance is higher you have to take a measurement with the ohmmeter.

  2. #322
    Quote Originally Posted by Nickhofen View Post
    Can you take a resistance measurement at the coil that you do not have continuity? If you put your multimeter at continuity scale you get a bazing sound of a reading only if resistance is low,I think up to 10 ohm but I am not sure if it is a little higher or change between the brands of the meters,if resistance is higher you have to take a measurement with the ohmmeter.
    I've ordered another transformer, will check the existing transformer though

    https://www.maplin.co.uk/p/2x50v-100...nsformer-a74qj

    It's 50v per output core

    I hope there's no issue going oversized with a 1000va transformer but I didn't realise they had 625va one and this was 1/2 price same make as rapid.

    Saved enough cash on the transformer that I just managed to buy a new AM882 as well with fast shipping.

    Normal version not am882h.

    One good bit of news the new parallel port card came I fitted it and parport recognises it so linuxcnc should at least work and I bet mach 3 does to.


    Click image for larger version. 

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    I got it wrong before there's no continuity between blue and grey OR violet and brown but there is continuity between grey and violet I guess this means both thermal fuses are blown.

    One question about the new transformer I know I wire on the input side the brown and blue to the mains, the grey and violet together as before. On the output I wire the orange to the black and the yellow to the red then wire them to the the rectifier is that correct?

    Would wiring a 5amp plug fuse to the PSU input give some protection to without tripping out in normal usage?
    Last edited by Desertboy; 09-11-2017 at 05:01 PM.
    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

  3. #323
    Omg that's some low price transformers :D
    Good find and I'm happy that you are back on track!

    Wish they delivered to Sweden ;)

    Skickat från min SM-N910C via Tapatalk

  4. #324
    For the fuse question.. think it might blow when charging the caps..

    Skickat från min SM-N910C via Tapatalk

  5. #325
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 12 Hours Ago Has been a member for 5-6 years. Has a total post count of 1,162. Received thanks 209 times, giving thanks to others 5 times.
    Quote Originally Posted by Desertboy View Post

    Would wiring a 5amp plug fuse to the PSU input give some protection to without tripping out in normal usage?
    I suspect that 5A might be a bit small and might blow on switch-on, although you will probably get away with it. Typically, a standard fuse will blow within 10sec with a 2x overload, so that might be OK. For normal running, you are unlikely to be drawing anything like 1000VA (which is a touch over 4A in practice) most of the time, if ever, so that's well within the fuse rating. I use a 10A MCB on my own machine feeding all the PSUs (although the stepper driver PSU is the most power-hungry) and I haven't had it trip yet.

    Unfortunately, the fuse is very unlikely to protect the equipment and that's not really why it's there. In practice, the fuse blows just after the equipment fails! It's really there so that in the event of a serious fault that draws excess current, the wiring isn't going to burst into flames. In the case of elecronic components, it's well-known that the transistor is the fastest fuse on three legs...

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  7. #326
    Right I'll get 1 of these mcb's tomorrow to wire the PSU through
    https://www.toolstation.com/shop/p26107

    and 2 10 amp ones, one for the spindle and one for the twin 3 pin wall sockets.

    I am going to wire 32amp to the junction box soon so might as well plan for the future.
    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

  8. #327
    Quote Originally Posted by Desertboy View Post
    Right I'll get 1 of these mcb's tomorrow to wire the PSU through
    https://www.toolstation.com/shop/p26107

    and 2 10 amp ones, one for the spindle and one for the twin 3 pin wall sockets.

    I am going to wire 32amp to the junction box soon so might as well plan for the future.
    I think you might want a D rated one with that big transformer
    ..Clive
    The more you know, The better you know, How little you know

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  10. #328
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 12 Hours Ago Has been a member for 5-6 years. Has a total post count of 1,162. Received thanks 209 times, giving thanks to others 5 times.
    I think I use a C type MCB - more surge-resistant than a B (the usual domestic type) but trips a little more easily than a D. But that's with a 650VA transformer. However, without analysing in too much detail, I doubt that the transformer difference is that significant and it's the size of the capacitors that matters more. I would tend to go with C type, I think.

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  12. #329
    Just an observation - are you running the primaries in series (240v) or parallel (115v) ??

    If series the you need to connect supply to blue and brown with grey/violet joined.

    If parallel then connect blue/violet and grey/brown then connect supply to to those pairs.

    Just an observation as said but easy to ignore those little dots on the transformer winding pictures ;)

  13. #330
    Quote Originally Posted by Davek0974 View Post
    Just an observation - are you running the primaries in series (240v) or parallel (115v) ??

    If series the you need to connect supply to blue and brown with grey/violet joined.

    If parallel then connect blue/violet and grey/brown then connect supply to to those pairs.

    Just an observation as said but easy to ignore those little dots on the transformer winding pictures ;)
    I had it wired blue and brown to mains 240v, grey and violet joined on the input side. On the output side orange and red to the rectifier, yellow and black joined. This was a dual 25v output core.

    This time with the 1kva transformer I'm going to wire the input the same (it's a dual core 115v input). The output I will join the orange and black and then wire to rectifier, join the yellow and red and to rectifier. (Dual core 50v output, I want 50v out to feed into the rectifier so I get my 68-70v out for my drivers.)
    Click image for larger version. 

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    Last edited by Desertboy; 10-11-2017 at 11:10 AM.
    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

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