[kenshi]

hello,
I have a Bridgeport J-Head vertical mill, but I can't use the cross and long feed system because the drive of the DC motors is burnt out. the problem is in the SCR abd Diode wiring.

I'm looking for the circuit diagram for the motor DC drive. if any one can help me I will be grateful.

Thanks,
Sami

[gus]

Let me guess, it is a 1951 with gearbox x axis power feed and a yang shen brand y power feed circa 1997..........................

[kenshi]

NO, it's a 1968 I think with long & cross feed powerd by 1/2 HP DC motors, one feed control circuit and two change over relay for the DC motors.

my problem is with the feed control circuit ...

[Al_The_Man]

I just converted one to a Baldor BC-140, I used the existing SCR's and heatsinks.
I could not find a complete schematic, this is for the 90v 12amp 1 HP motor.
If yours is only 1/2 hp, there should be no need to use the bigger SCR's.
Al.

[lakeside53]

I have the board level and wiring schematics for the 6f/8f BP drives... Send me your email address.

[kenshi]

hi,

about the feed motor, I have a 110v DC motor, my problem is not Witch SCR to use. it's how to wire the two SCR with the three Diode's in the circuit board controller.

[Al_The_Man]

I am not sure what you want exactly.
If you want the SCR bridge diagram, I can describe how it is wired and how the connections can be identified.
Is there is a 6 pin plug connecting the SCR/Diode bridge to the Pct?
Al.

[lakeside53]

Kenshi - check your email. The 6F schematics have been sent.

[kenshi]

Thanks "Lakeside" for the schematics. I am not sure if this is the correct diagram of my controller, But I will check it.

the controler came with 12 pin plug. that conected to change over relay circuit.

I have analyze my circuit controler board and came with this scheme. I post it.
but I think there is something Wrong with this circuit. I don't know how to conect the SCR with the Diode's.
maybe someone can help.


note:

sorry for my bad english.

[Al_The_Man]

To me it appears that you have the three diodes reversed.
The version I have, all three diodes on the heatsink have the cathode's to the heat sink, not the anode's as you show it.
Two complete the bridge, and the third is the back emf diode, which in your case is shown normally forward biased.
One heatsink is DC+ the other DC- and are hot, so they should not be connected to ground accidentally.
I can draw up the bridge as it should be and post it for you, by tomorrow.
Al.

[Al_The_Man]

Here is the connections I have for the bridge, hope this helps.
The DC+- from the heats sink are the motor connections.
Al.

[kenshi]

the problem that I can't reverse the Diode's or the SCR's, because the heatsinks is made of one piece of aluminium each one.
if I send you a photo of the controller board, maybe this will help.
also if you can draw up to me the bridge I will be grateful.

[Al_The_Man]

I am not sure I follow? Commonly, SCR's have the Stud = anode, which will mount directly onto the Neg H.S.
The three diodes require Cathode stud mount.
This enables the SCR's to mount on one HS (-) and the three diodes on the other H.S. (+).
Otherwise you would need to use mica insulators to mount them.
I have drawn up the bridge above, as it applies to the one I have modified.
Al.

[kenshi]

hi,

I wasn't here for some time. I had a lot of works. I wanted to thanks you guys for your help. and thanks to you "Al" for the Bridge Scheme.

Finally I found the problem in the bridge. One of the diodes has inverted polarity.

I need only to obtain one new and to substitute it. and I hope that this will work.

[Al_The_Man]

Diodes with a anode on the stud, usually have an R (reverse) in the part number, the ones you need are Cathode to stud.
Check the ones you have to replace and if an R is present, remove the R and this is most likely the correct number.
Al.