[inertialabs]

I just picked up a Bridgeport Series II with the 4 hp head and I am concerned about witch tap the 220 stinger leg goes on T1 T2 or T3?

I have read it does not matter but I'm Leary.....

[john-100]

with the machines single phase transformers being connected across the machines T1 and T2 supply terminals
I would connect the stinger / wild leg to T3





that way you have 120V between each end of the transformer primary and ground
not 120 V on one end and 208V on the other (with respect to earth)
in both cases you will have 240V across the transformer primary but I prefer the symmetry you have connecting L1 and L2 to the transformer

Attachment 300570

with respect to earth / neutral
L1 = 120V , L2 = 120V , L3 = 208V

voltage between any two phases = 240V





John

[inertialabs]

Thanks I will give it a shot

[inertialabs]

Progress report
That seemed to work and we have a spindle turning now !
The next issue is that the X and Y power feed is turning but very slow and when I get below half speed there is no movement . I have a feeling that something is not getting full power but aside from checking for loose wires and fuses I'm a bit lost....
Any thoughts?

[mactec54]

inertialabs

Just make sure that the wild leg is not powering any of the low voltage,stuff the wild leg is only for the spindle 4 hp motor, so check all the outputs from your transformer, to see if you have the correct voltage out to the axes drives, is this CNC or Manual

[inertialabs]

It's a manual mill
I will check the transformer to see what it is putting out later
The axis drives say 90v and I and not sure if that is ac or dc it looks like there are drive cards with rectifiers but I can't tell

[mactec54]

It's a manual mill
I will check the transformer to see what it is putting out later
The axis drives say 90v and I and not sure if that is ac or dc it looks like there are drive cards with rectifiers but I can't tell

They are DC, check the motors you will see were the brushes holders are, this will tell you that they are DC type motors

[inertialabs]

So the X and Y motor turns when I turn the power feed on but it moves very slow
When I back the speed down below half the motor stops turning all together
I checked voltage to the motor and it ranges from 60-90 volts
The rapid traverse does nothing at all and the Knee power feed does not move either
I am guessing that the drive board is not producing enough current to make the motors go but this is just a guess....
Another clue is I found two new electronic parts in the bottom of the cabinet and I see them on the X and Y board it has a threaded end that I'm guessing is a way to sinc heat and the other end has two electrical connections on it I am considering replacing them to see if it makes something happen
Trouble shooting in the dark

[magnadave]

You may have a bad speed pot. The electrical schematic shows that they used a 2K ohm pot on enclosure serial number D001 - D101 and a 5k ohm on D102 & up. That also depends if you are using the original Bridgeport SCR drive. The range of voltage you should have is 0 - 90 VDC. Also the heat sinks on the original SCR are what are called HOT or LIVE. Which means they have electrical current running through them. If you have loose connections at the heat sinks that could be your problem.