Re: [CAD_CAM_EDM_DRO] I just bought a robot controller

Eric Keller wrote:

> The nice thing about it is that once you take the cover off, it was two
> pieces,
> an outdated computer and six never go out of date H-bridges. The bad thing
> is
> that it is H-bridges, not a chopper amp, and the chopper part is up in the
> controller.
> It has a monster unregulated supply. The H-bridges have 5 inputs, A,B,C,D
> and EN.
> I assume A,B,C,and D are the legs of the H-bridge, and EN is Japanese for
> Enable.
>
> I have 2 questions:
> 1 -- does it make sense to have all 4 transistors independently driven?

Maybe, but it is dangerous.

>
> 2 -- is it likely that if I turn it on to check the power supply that I will
> smoke a H-bridge? There is a bleeder resistor across the main filter
> cap, so that part is relatively safe.

Quite possible. it depends on the polarity of the A-D drive signals. Most
likely, only an idiot would make them default to on with no signal. But, you
never know. Best would be an opto-coupled input, with LED on=transistor on.
I think you'll have to dig into it to figure out what it is doing. If there is
a
fuse in the DC supply at the H-bridge, then you might be able to put a light
bulb or some other current limiter in place of the fuse, and have it light up
if there is a short (all transistors on at once).

Jon