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My FP2 just stopped

MarkTr

Plastic
Joined
Sep 29, 2022
After 30 years of ownership and two moves, my FP2 stopped in the middle of milling a part. The serial number is 2870 which I cannot find on any list. It looks like a 60's model with a separate power cabinet.

I was finishing up a 2" vertical light skim cut with a 1" mill end when I heard a pop and it went dead. Checked my rotary on my Monarch and it is putting out 220. So I checked the four fuses in the cabinet---all showing 0 resistance. The transformer was warm-but when I applied power to the cabinet I do not feel it buzzing like I believe it should.

Performed a search and found mostly threads about converting to a different motor and driver- not much on how the OEM German box works and what goes wrong in these old boxes. I have a manual-but it mostly covers all of the attachments-no electrical. I downloaded a manual in German but the wiring diagram appears to be covering a different generation FP2.

Anyone here has kept the OEM box and had it shut down power to the mill- and found a solution? I rotated the sprung switch on the side of the box, and cycled all of the switches inside the box.

Do transformers go down with a small pop? If it is the transformer am I on the path to a complete power conversion?

I am in the middle of a job so this did not come at a great time-never does.

Any thoughts or check paths would be great.
 

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Get your VOM out and begin tracing the voltages from the input buss all the way to the motor.....No electronics here just straight ahead electrical paths.... With power off you can ohm all the critical lines from input buss to contactor to motor,,,,then power up and test for needed voltages

Transformer provides low voltage to run the accessories like the optical rotary table and the centering scope. Low power is also used to pull in the relays (contactors) through the off/on push buttons that control the main motor...Check the input to the transformer and its outputs....
Cheers Ross
 
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Thank you for getting back to me Ross-

I did just what you suggested early today and traced the main power leads---all read the correct voltage.

For some reason, after going through the tracing process and from time to time pushing the on-button-- she started running---but then the relay would drop out after a few minutes. So dirty contacts on the relay and/or the on-button came to mind.

I dressed the relay contacts and it now intermittently drops out. It began running for longer and longer time periods before dropping out. Also,it is not a sure thing that the relay will pull in when I push the on-button.

I do not have a schematic for my particular machine but from your description- I am assuming that the on-switch is a latching contact switch that directs power from the transformer to pull in the relay for the three contacts. If the on-switch contacts are dirty the relay would drop out.

Can you pull the on/off switches out from the front face in order to inspect and clean them? I do not want to begin prying if that is not the way to get to them.

I was able to keep her running long enough to finish the rough-out of the piece that I am milling which took a load off.

Thank you again- please correct me if I am going down the wrong path.
 
From memory.....the "ON" button is a momentary contact switch....they are often less than 100% at starting the machine, butt won't cause it to stop once started.
Once the on button is pushed power is supplied to the main contactor and it pulls in. There is a latching circuit that goes through the "OFF" switch.
Once energized the relay stays pulled (on) till the latch is broken via the "OFF" switch. (Normally Closed switch)
As i recall, the "ON/OFF" push buttons are retained via threaded rings from behind (inside the panel) Its been some time since i have been in there on my early FP2, sorry ,so maybe someone here can give a more exact answer.
Removal of the side panel is not a trivial matter. ...You should be able to jumper the off button circuit at the relay to verify that is where your issue lies before needing to get to the buttons (panel removal).
You must remove the speed and feed selector handles to get the panel off, as well as removing the "Y" axis hand wheel ,micrometer dial, rapid feed lever, and "Y" power feed lever/coolant on off handle.
There are Allen bolts that hold the panel on that double as the feed/speed small crank hand wheel spring pin seats ..Allen key center hole,they unscrew.
There is also a bolt from inside behind the sheet metal plate that holds the oil guns. (open the non operators side door, remove the sheet metal cover piece)
The speed/feed handles are retained via taper pins...often troublesome to remove.....Good Luck!
Cheers Ross
 
Thanks Ross-- so the on-switch is just a momentary contact switch and the off-button circuit is latching and goes to ground when you push it cutting the power to the relay--I think I have that correct.

I am finding a firm push again will start the machine- never had to before. Sounds like a bit of a job to get to the switches- and they are probably enclosed so I cannot clean the contacts anyway. I will trace the off button circuit to the relay-but it appears that all of three legs of power to the motor are power-- then I have my choice of red solid wires. I attached the only power schematic I have- but I do not know what generation FP2 it covers.

After I dressed the contacts on the relay it looks like a bit of pinpoint welding is occurring. I must have left debris behind- or gone through the thin silver contact plating-I hope not. Not sure if I will be able to replace these points if I have.
 

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Don't think that schematic is correct.....think that is for a later two motor FP2 ...The motor shown on the print is the feed motor which you don't have.
Some transfer on the main contactor contacts is normal i think.
Don't think the "Off" switch goes to ground....it opens the circuit so power to the coil is interrupted...Its a "latch" setup...The "ON" switch applies power to the relay coil...it closes and power flows across the main contacts...power is taken off the output of the main contacts and routed through the "OFF" switch and back to the coil....as long as the contacts are closed the "OFF" switch (NC) has power . Pushing the off switch opens the coil circuit and the relay drops, thereby opening the main contacts and opening the power to the "OFF" switch and the coil.....Both the switches (OFF/ON) as i recall can be disassembled , very simple construction prone to corrosion and dirt, but you have to get to the back to get inside.

Believe some here have replaced original switches with modern more reliable switches... some time with the search function might prove valuable.
Cheers Ross

Might have a look here:
 
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If those magnetic contactors are bad Just replace them with another one Any contactor with the same voltage for the coil and same contactsetup will do You do not want to mess around with replacing contacts
Btw That diagram is from a machine with a DC powerfeed motor. 2 Generations after yours And this is not the kind of electrical cabinet you see over here Other components are used But the scematics still might match
Peter
 
Don't think that schematic is correct.....think that is for a later two motor FP2 ...The motor shown on the print is the feed motor which you don't have.
Some transfer on the main contactor contacts is normal i think.
Don't think the "Off" switch goes to ground....it opens the circuit so power to the coil is interrupted...Its a "latch" setup...The "ON" switch applies power to the relay coil...it closes and power flows across the main contacts...power is taken off the output of the main contacts and routed through the "OFF" switch and back to the coil....as long as the contacts are closed the "OFF" switch (NC) has power . Pushing the off switch opens the coil circuit and the relay drops, thereby opening the main contacts and opening the power to the "OFF" switch and the coil.....Both the switches (OFF/ON) as i recall can be disassembled , very simple construction prone to corrosion and dirt, but you have to get to the back to get inside.

Believe some here have replaced original switches with modern more reliable switches... some time with the search function might prove valuable.
Cheers Ross

Might have a look here:


Thanks for the link to the thread. I will read through it tonight. I saw someone on the welding forum who has been rebuilding a newer generation of my FP2 and he installed new switches-- but did not explain-just show them working. They lit up with LED lamps.

I knew that the schematic was not correct but it was the only one I could find when searching FP2. Your explanation makes sense. You are saying that the Seimens is a "latching" relay with the off switch as a means to break the circuit.

Still not sure why the relay would drop out. Somehow the circuit is cut during the operation- so somewhere a contact in the loop must be going. Could be the off switch is the culprit. If the contacts on the relay were going bad and losing contact of one or more of the legs-I think I would see more welding and arcing on the contacts. I dressed them with a white Scotch pad-but I do see signs of pitting.

As Peter mentioned- perhaps after all these years the relay should be replaced rather than the contacts themselves. Without an accurate schematic, I would have to trace all of the red lines coming into the relay. All the six black ones are obveous.
 
If those magnetic contactors are bad Just replace them with another one Any contactor with the same voltage for the coil and same contactsetup will do You do not want to mess around with replacing contacts
Btw That diagram is from a machine with a DC powerfeed motor. 2 Generations after yours And this is not the kind of electrical cabinet you see over here Other components are used But the scematics still might match
Peter

Peter- Thanks for reaching out.

That is a thought. It is an ancient Seimens K915 iii-2. I am not sure of its specification. I am sure the machine was made for the US market so 60 hz and each leg would be normal US voltage. Do you have any suggested relays that you have used?

As far as finding a wiring diagram--I have not seen another cabinet like mine and the serial number of my FP2 does not seem to fit in the year lists I have seen. I cannot find 2870 in any list so I do not know what generation to search for. It looks like the 60's but all the photos I have seen of 60's cabinet show different internals with push buttons on the relays.
 
This link may be of help, and includes a schematic for an FP2 of similar age:
 
This link may be of help, and includes a schematic for an FP2 of similar age:
Ballen-- Thank you for pushing this link my way. I found this same thread yesterday and have been reading through all the pages--very good and I am learning a lot.
 








 
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