Bridgeport Series 1 Limit Switch

[kewl_cat]

Great News! The machine is up and running. I took the contactors apart and cleaned everything. I also changed another diode that was leaking a little. I guess a half bad diode .... Z still is not working. I have the cover off and the motor is trying but not going anywhere. I am going to recheck my voltages, current and transistors again and reclean it.
What is and where is the opto coupler?
I will keep working - still making progress...
thanks, -rob

[machintek]

I did haveone case where a Z axis on a BOSS 6 was giving me fits. The ZDI had a bad opto coupler (opto isolator). It does what it says. The signal becomes optical inside a device and is transmitted to a receiver. This isolates the signal and protects the board. With the Z axis; put it in step, take the belt off, try stepping it checking current and voltage. Then go to .01, then to .1, finally to continous. See if and how it runs. then put the belt back on and redo the trial. remember that the Z pulley extension with the dial cannot rub on the belt cover. Also flush the quill with kero.
Let us know the results. When you get done, you will answer all the posts on this topic!!

GTW

[HillBilly]

That is good news! Here is some links showing the opto couplers.

http://www.cnczone.com/forums/attach...tachmentid=958
http://www.cnczone.com/forums/attach...achmentid=2787
http://www.cnczone.com/forums/attach...achmentid=4794

Darek

[kewl_cat]

I checked the z-axis and it does 3 steps forward and one back and yep there was another blown transistor. This will be the third new one on this axis. The one that is blown was one that I replaced. I checked the static current and it is about 8.2. Any ideas what tends to prematurely blow these? I did not hit any limits while jogging...
-rob

[HillBilly]

I had a bad SMD board that was doing this. One channel out of the four was not working. There should always be two of the output transistors on at a time. When it got to the blown channel the ACC board forced the single transistor to carry the full 8.2 Amps which blew it every time. I reduced the current on this axis with the ACC adjustment to a minimum where I could trouble shoot it without blowing the transistor. After finding the problem and fixing it I walked the current back up. Make sure your machine is grounded good also.

Darek

[kewl_cat]

OK I just turned down the current. How do I check to see if two are working at a time? Grounded good? The only ground comes thru the 3 phase outlet?
-rob

[machintek]

Any part of the base machine should make a good ground. I believe I remember a small piece of aluminum angle at the bottom of the logic cabinet where a lot of ground wires are fastened.
There are a few ways to see what is going on with the transistors. Is the Z transistor block the one behind the SMD? If not you can measure the base voltage of each transistor to see which has forward bias (turned on). Then step the drive one step and see which is on again. Repeat untill you have a truth table.
If the Z transistor block is behind the SMD, then I would go to the terminal strip at the bottom of the door. You will see connections going out to the motors. I would check Z1 through Z4 to see which is on. Step the motor, and measure again. Repeat untill you have a truth table.
BTW, this is where all the dropped screws and washers end up when they fall. Usually creating a short that mimics a blown transistor. I have seen some also caught between the diodes just to the right of this terminal strip with the same symptoms. If you find that the transistors do not turn on and off crisply (stay on half way) then one of those diodes just mentioned is shorted. Been there.

George

[kewl_cat]

Hey, I am back. Been making a few chips which justifies this machine I am still having trouble with the z-axis. It keeps blowing the 3rd transistor down. I lowered the voltage as instructed but it immediately blows the transistor. I put another SMD board from another axis but with the same result. When I got the machine the z-axis would travel a little and then stall -- I noticed all the diodes on that board were disconnected so I soldered them back up. I have not had the z-axis back up working since. I do not know how or why the diodes would have become disconnected... Does anyone know what this would be indicative of?? Help... The z-axis is very helpful....
-rob

[machintek]

Look at the terminal strip below the SMD boards. Make sure all wires are tight and that there are no screws there that do not belong. They usally look like the screws that hold the transistor blocks. I wonder why.
If I was there, I would be comparing the Z to the other two axis. Checking every voltage that I can.
As a last resort, I would swap the Z motor with the X or Y. If the problem follows the motor, then you have an answer. There were two different motors used on these machines. Some were made by Sigma, others by Superior.

George