Power Supply parts

[Arcticfox46]

This was bastardized at some time in the past and one of the little white blocks had just a nub left on it. It appears to be part of the power supply - and the wires go off and supply power to the parallel port board.

I accidentally knocked off the connection. I was able to re-solder it back together. The nub was no more than 1/8 long.

These white blocks get hot when the machine is turned on.

To do the job right I should replace them with new ones.

How do I know what they are or how to get replacement parts. One of them - the one with just a nub - no longer has any markings on it. I don't know if I should just assume they are both the same.

[Crevice Reamer]

Hi AF.

That looks to be a Voltage divider setup. The one with markings appears to be a 33 Ohm 5W resistor. If both are the same, then this will provide 1/2 the Voltage of the power supply to whatever circuit it is wired to.

For example, if your PSU puts out 50V, then the Voltage measured from the center junction of the resistors to ground would be 25V more or less. The corrosion at the junction may add resistance and cut that 25V some.

CR.

[Al_The_Man]

I see you have a Toroidal transformer, If the 'tapped' supply is fairly low current for auxiliary supply purposes, which I imagine it would be if both resistors are the same value.
I would look at a much more efficient method, that is to add an overwind on the Toroid, it is relatively easy to do and would not be a power waster or vary with load like the resistive divider.
You could reckon on ~2turns/volt on average.
Al.

[Arcticfox46]

Thanks guys - I am NOT in any way shape or form - electronics minded.

I have no idea what terroids are or how to rewire anything. Sounds like hemaroi...... oh, never mind....

I do have easy access to the Electronics Engineering department at work. I am going to take that assembly apart and give to to one of the engineers there. He will rebuild it for me.

I "think" I am all set with that one.

Thanks.

[Al_The_Man]

If you have access to that kind of help, I would pass on the mention of adding the overwind, he should know exactly what to do.
If not,get him to visit here.
Done this many, many times.
Al.

[Larken]

Where do the black and red wires run to ? The fan ?
Maybe someone put a lower voltage fan in and made a voltage divider.

The normal PS voltage is about 45 volts on that controller.

Larry

[Arcticfox46]

Where do the black and red wires run to ? The fan ?
Maybe someone put a lower voltage fan in and made a voltage divider.

The normal PS voltage is about 45 volts on that controller.

Larry

Larry,

The three sets of black and red, wires directly connected to the terminals go directly to the axis drive boards

The one set of black and red wires coming from the resistors - go directly to the AC plug on the starcam board

Leo