Partner 1 E Z Axis Drive Problem

[GP3 Racing]

Hello,

-I'm trying to buy a mill however it has a Z axis problem. I have used several pointers from other posts to try to pinpoint the problem. When I reset the drives right away the Z-axis drops until the brake comes back on. The display seems to be keeping track of where the Z is located though (ie. X and Y are still at home 0,0 but everytime the z drops it records more in the negative as it should).

-I tried changing the homing sequence and swapping drive boards with no success. The machine is a 1993 with a B serial number control. I have a monitor hooked up as the CRT just went out too. Very low hours on the machine as it has been used only at a school for a few hours a year. I did notice when plugging the Z axis wires back onto the drive board I got a little spark hooking one of the wires up. This scared me enough to quit working with the electronics for now. None of the other boards or axis connections did that. Breaker was off and machine powered down (careful to stay away from the capacitors).

-I have to let the machine sit with the breaker off for about 20 minutes for the Z axis to drop upon hitting the reset button. I get the normal 450 error and press ESC and then hit the reset button. Once the Z drifts down it trips out to a 409 error. I cancel that one out and try to go into HDW, MDI, or HOME and I get the 449 error.

-Someone else checked voltages to relays and tested them out, they are said to be fine. The limit and home switch were also tested for continuity and said to be fine as well.

-I did notice a wire broken on a diode connected to one of the capacitors but opted not fix that yet as I'm unsure exactly how to do so safely.

Any tips?







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[allen mullis]

try blocking the head the head so that it doesn't drop, then you can do a little experimenting without running the risk of bottoming the head out on anything in an uncontrolled manner. If you cant block the head, pull the top cover off of the Z housing by removing the 4 10-32 bolts from the corners, then you can see the top of the Z screw and the Z motor and you can concoct a way to hold the Z screw pulley after you take out the 4 1/4-20 SHCS's and tilt the Z motor enough to take the belt off. After doing either of these you will be able to play without running the risk of bottoming something out in a bad way on something you don't own. What is happening to cause this is the CR-1 relay is pulling in sending 24V to release the Z brake, but the drive is not catching the motor after the brake releases. Now you have to determine why without doing anything harmful to the machine.

[allen mullis]

try blocking the head the head so that it doesn't drop, then you can do a little experimenting without running the risk of bottoming the head out on anything in an uncontrolled manner. If you cant block the head, pull the top cover off of the Z housing by removing the 4 10-32 bolts from the corners, then you can see the top of the Z screw and the Z motor and you can concoct a way to hold the Z screw pulley after you take out the 4 1/4-20 SHCS's and tilt the Z motor enough to take the belt off. After doing either of these you will be able to play without running the risk of bottoming something out in a bad way on something you don't own. What is happening to cause this is the CR-1 relay is pulling in sending 24V to release the Z brake, but the drive is not catching the motor after the brake releases. Now you have to determine why without doing anything harmful to the machine.

[GP3 Racing]

Thank you for the reply. When I quit working on it yesterday I actually made a wooden fixture to hold the head up however I have not had time to play with it today. I will try this and look into the things you have mentioned.

[GP3 Racing]

Just an update. I was able to block the head from coming down which got rid of the one error however 449 still comes up not allowing me to move any axes.

[Brian L]

You need to replace that resistor (what you are calling a diode) that bridges the cap, it will prevent the machine from coming up. I rebuilt the computer on mine after having it dead for years and it still wouldn't run and found that resistor to be shorted out. Replaced it with parts from Radioshack (99 cents for two of them) and that's all it took for everything to power up. Just went thru my old emails, mine was beyond recognition, so Milltronics told me that is a 10 ohm, 10 watt resistor.

[GP3 Racing]

Okay I will replace it and see if anything changes. The computer boots up fine however it's obvious the resistor needs replacing either way. Any specific safety measures that need to be taken replacing the resistor on the capacitor?

[Brian L]

I did it on mine after the machine had been off since the previous day.... but I'm not an electrical guru and probably wouldn't have realized the danger if it was there. I used common sense and don't touch any terminals with bare hands or un-insulated tools. That resistor is detailed in the servo drive troubleshooting documents, so it will keep the drive system from coming up. I remember being a bit panicked after I had spent a decent amount of money rebuilding the computer to get it to fire up and then have the machine still not fire up.... figured I had really gotten myself into a can of worms.... and then was very happy it was a 99 cent part to fix it.

[GP3 Racing]

That's awesome. I will replace and or fix the connection and see what happens. That would be awesome if that was the fix. Thanks.

[GP3 Racing]

I reconnected that resistor however it did not fix or change anything. I'm going to track down an ohm meter here and test it as well as some other connections. It is labeled as a 10000ohm resistor.

[Brian L]

Well, not sure what your resistor was, and if a different machine had different resistors, mine is a Partner 4 from 92, so same vintage as yours.... this is directly from the email from Milltroincs:

I did find out what the resistor is, it is a 10 ohm, 10 watt resistor, our part number is RE-48. You are 100% correct that if it blows the resistor as soon as you try to reset it you have a 110 short.

[GP3 Racing]

I will see if there's a part number on it. I'm going to test the actual resistance of it too.

[allen mullis]

If you press and hold the reset button, will the drives then come up or does it stay in an error state? If the error goes away while holding the reset, try homing it while holding the reset. if you are sitting on an over travel switch it will prevent CR-1 from holding after reset and prevent any motion. Holding reset bypasses the "hold" side of CR-1 allowing you to come off an over travel. It could also be an over travel stuck open, this is particularly likely if you have the older plunger style switches. They are all normally closed, making any over travels "opens" the hold circuit that goes through CR-1 and the watchdog relays in the control. If this turns out not to be the case and you have a closed loop on the switches, then you might want to take the cover off of the black box and take a look at the 3 cards on the right, they should all have a green LED that should be lit when the power is on, this is to indicate that all the watchdog relays are in a non-error state.

[sportybob]

Some suggestions.
1. get the head blocked up and see if the machine will hold reset.
2. check the DC volts across the blue capacitors you should get ~160VDC
3. if you have voltage, try swapping the drives from X / Y into the Z axis. does the motor now have torque ? If yes replace / repair drive card. if no. them motor needs to be looked at.
If you do not have voltage, check the bridge rectifier (square black device near the caps) it should have 110VAC on one side when the reset is pressed ( ie "switched 110") coming from terminal block # 57 and #2 or thru CR1 and #2. the other side will output the DC voltage to the caps.
There is also fuse # 9 it is a 30amp glass fuse from CR1 or TB57 to the bridge rectifier. If this is blown the bridge rectifier is bad

This machine also has a CR1B relay, it is the relay to the lower left of the blue caps. This is also energized thru CR1 / TB57 on reset. This relay when not energized will bring the analog voltage to the drives to ground thru NC contacts stopping the voltage from reaching the drives. When it is energized it opens the contacts stopping the grounding of the analog voltage from the axis connector pin 11 to the drive cards J1 pin # 1.

PM Me if you need more info

Sportybob

[chipsinpan]

I have the same problem with my partner . I replaced the Caps , but did not fix the problem . Is there a possibility that the relay is "slow " to activate ?
I tried the swapping drive cards with no results . If I hold the reset button on start up or after an e stop , the head will still drop 1/2" or so , but it will remain latched .
Then I will have no problems for the rest of the day . I did E stop on top of a part once ( too heavy a cut ) luckily I was able to un clamp the part and slide it out from under the cutter . Otherwise I would have crunched a bunch of inserts .
Is there any way to diagnose the performance of this relay ?
I could focus a video cam and watch it from the front of the machine , if its a matter of observing a visual reaction of the relay .
Thank s
Bob

[sportybob]

Hi , Yes it could be a "slow" CR1B relay , try swapping the relay with the K8 ( flood pump) relay and see if it respond any better. CR1B and K8 should be the same relay,
The K1 contactor could be another source of "slow" response.

Sportybob

[chipsinpan]

Bob , I cannot find a relay labelled K8 but did find one MC2 . It is the same part # as the CR1B so I swapped them . Still no results - head still drops .
Where would I look for the K1 contactor ?
I see a MC5 , MC6 and CR1 but not a K1 . maybe they are labelled different on my machine .
I have 2 partners , so I could borrow one from my sister machine to test it out
Thanks
Bob

[sportybob]

CnPan use the CR1 MC6 and MC6 are the Tool changer Cw and CCW. have some one press the reset and watch and see if the CR1 latches slowly. might want to check the voltage on the contractor you should see 110 vac from L1, T1 and L3, T3 as soon as you press the reset. The Z brake releases and the motor should have "torque" at the same time. The brake seems to release but the drive is not powering the motor "in time" try swapping drives. If swapping drives does not help, I would suspect a motor problem, but I lean towards a drive. assuming the DC voltage across the blue caps is ~160VDC.

Sportybob

PM me if needed

[chipsinpan]

Bob , We did as you suggested . My helper observed the CR1 contactor ( it has a yellow indicator button )
When we press the reset button quickly , the coil will pull the contacts in , then they will pop back out . During this time the head is dropping a small amount -about 1/2"
BUT if we press in the reset on the front panel and hold it for a second or so , it will latch and hold , and the front panel will allow me to proceed to home . But the head will still drop during this event , as before , just 1/2".
I will call later in the day so you can instruct me how to proceed . There are sure a lot of wires going into this relay , and it appears there are actually 2 relays stacked , but pulled in by one coil .
Thanks
WI Bob

[chipsinpan]

So if the CR1 contactor assembly has the job of: a) releasing the mechanical brake on the Z drive motor and b) energizing the drive boards and sending power to the motor and inducing torque , then they would have to trigger both events at exactly the same time ? Or one would think in reality you'd want the boards energized a fraction of a second sooner .
Of the 2 contactor blocks in this assembly , I suspect the lower one that is larger , is the part that energizes the 3 drive boards . Possible oxidized contacts from a million cycles , is causing this situation ?
Thanks
WI Bob