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The transformer 26V will be the center tap & is likely being used as the reference for 0V as there isn't a second AC wire going to the distribution board. The rectified 52V will be +26V & -26V in relation to it. I'd suspect a few decent capacitors in there would mean you'd have regulated voltages of around +/- 35V.
Any chance of some pic's of the circuit boards
 
Let me provide a little back story of the machine. I just bought it a couple weeks ago. I bought it knowing the cnc wasnt working. When I got it home, I plugged the controller in and it lit up the dro lights, but noting would work. I then noticed a cord unplugged in the back of control box. I plugged it in and the breaker immediately tripped. This led to a little testing with the meter to find what looked like a direct short. I opened the control box and saw that someone had been tinkering with the wiring. Lots of green wire spliced into the wiring harness. I started unplugging the cords out of the back of the control box one at a time until I found the one that was shorting out. Which of course was the one that wasnt connected in the first place. This cord went to the estop switch, so I removed the estop to find wires had been spliced inside. Naked wires so I thought that maybe one was touching the switch enclosure. I remade the connections to the switch and tested it before reinstalling in enclosure and no breaker tripping. Thinking this should of fixed it I reinstalled the switch and turned the machine back on, of course it tripped the breaker. The wire had been installed wrong to start with by who ever had been working on it before. The estop return (white wire) didnt go anywhere in the power cord and the green ground wire was being used to return the power from estop. Looking at the schematic this is correct, but previous person had ran the green to ground and hooked up the white wire to the estop, but the other end didnt go anywhere. The returning green wire went from case ground to transformer. I figured all this out and reconnected the way it was supposed to be. I am still using the green wire to carry the current from estop to transformer. I bought wire yesterday with plans to rewire to correct color codes. To many green wires used in all the splices, I can work around it, but it does make it confusing, especially to someone that hasnt already went thru what I have been going thru to trouble shoot. What i dont know yet is if all the cross wiring has actually burnt out the transformer, it was a direct short, so??? Anyways, that is where I am at now. I still dont have 3phase power to run the machine, but if I can get the cnc to work, the 3phase problem will just take a inverter to fix.
 
On your drawing up in the revisions there is a note "transformer 9581 was 56-12" Digikey lists a 56-12 transformer but they are out of stock and have a min quantity of 5. But there is a datasheet showing it is rated at 56v 12amps. Hope this helps.

https://www.digikey.com/en/products/detail/signal-transformer/56-12/1984769
This specs out as the voltage I got with my meter, 28/56v when the transformer decided to work. I also noticed out of stock with a 18week lead time, pretty much the same time line the manufacturer gave me for building the 9581. I think I need to find an alternative. I dont need, (Read as dont want to) to order $900 worth of transformers just to get one.
 
The transformer 26V will be the center tap & is likely being used as the reference for 0V as there isn't a second AC wire going to the distribution board. The rectified 52V will be +26V & -26V in relation to it. I'd suspect a few decent capacitors in there would mean you'd have regulated voltages of around +/- 35V.
Any chance of some pic's of the circuit boards
I would have to remove the boards from the cabinet to get any pic as the boards are enclosed in a aluminum cover.
 
The 26V is used as AC unless there is another rectifier.

So much for my battery idea.

BTW, that's a wiring diagram, not a schematic.
What do I know. But I am now going to confess my ignorance. With all this testing It just occurred to me I am looking for the wrong results. I was reading the input volts as AC which would be correct, but I was expecting output voltage to be DC, which is wrong. A simple switch of my meter from DC to AC shows the transformer is actually output'ting the required 56/26 AC, not DC, volts. The rectifier inside the control driver must be what is converting the AC to DC needed to make everything run.
I apologize to everyone that wasted their time trying to figure this mess out for me and the help everyone gave. I didnt find my mistake until I cleaned the terminals and installed new spade connectors. I also only figured out my mistake by not changing the setting on the meter by accident.

I will reinstall the transformer and see what happens, but I suspect my next project will be the driver board. If this doesnt fix it, I will again be in way over my head and need a lot of help.
 
i think most stepper motors are 3 phase, that need an electronic driver, and wont like 12v dc tested down the wires ?
I dont know if I have steppers or servo, dont know how to tell the difference. The motors look like a 312 ford starter motor, yep they are that big, and there is another motor right beside them. The second motor is supposed to be a encoder.
 
You know, I was going to ask if you were measuring AC or DC but from your description it sounded like you had it under control. I should go with my gut feeling!
 
16221377268764883810405160762607.jpg

So based on my previous post in this thread, you could use a 24-0-24 x-fmr, but the input would need to be 130v to reach the 26-0-26 of the x-fmr you are replacing.

T1 provides the extra 10v boost to the line voltage. If you read 130v at the primary of T2, you have hooked things up correctly. If you read 110v at the primary of T2, the phasing on T1 is incorrect, and you are now subtracting 10v from the line voltage. To fix this, simply flip the wires on the primary side of T1.

The secondary of T1 will need to be sized to handle the primary current of T2. A 56V, 12A secondary = 672VA (volt amps, which is literally V * A). The same VA on the primary = 672 / 120 = 5.6A. So the secondary of T1 should be rated for 5.6A or greater.

Putting 130V into T2 isn't ideal, but it is within the 10% tolerance that the power company is allowed to operate under.
 
I temporary reinstalled the transformer, connecting to machine power instead of extension cord. No output volts. Rechecked machine power, hit or miss 120v. Reconnected extension cord and the driver board lights up, transformer checks 28 and 56 vac. So this narrows it down to the wires coming out of the control box. One side (white wire and ground) checks 120v. Checking between white wire and black wire reads 80v sometimes. This is where the previous owners have been messing with the original wires. and also where he had the return side of the estop connected to a white wire that didnt go any where and green connected to frame ground. Anyway, now the black wire goes from control box to estop and returns as a green wire back to the transformer. Somewhere in that wire it isnt making a good connection. The connector cables are all very loose fitting and all the cords are cracked. I am going to leave the extension cord connected to provide power so I can check out the rest of the circuits. I will most likely order new male and female connectors and replace all the cords from control box to cabinet and from cabinet to the servo/stepper motors. That should eliminate all the bad wiring and loose connections. Did I mention I aint no expert and this is getting old real quick. I dont understand the white wire from control box being the hot leg, and the black wire to estop being the neutral, That sounds backwards to me. I cant open the control panel, it looks epoxy filled, to see what color the hot wire is coming out of the control panel. Also there seems to be a few ground wires missing, as per drawing, I havent traced that out yet to see whats going on but that might be part of the problem. Also while scratching my jead and staring at the control box, I noticed the driver board was missing a couple of mounting screws. The previous owner did say they replaced the driver board, if they reconnected it like everything else they have messed with, half the components might be still laying on their shop floor.
 
View attachment 909467

So based on my previous post in this thread, you could use a 24-0-24 x-fmr, but the input would need to be 130v to reach the 26-0-26 of the x-fmr you are replacing.

T1 provides the extra 10v boost to the line voltage. If you read 130v at the primary of T2, you have hooked things up correctly. If you read 110v at the primary of T2, the phasing on T1 is incorrect, and you are now subtracting 10v from the line voltage. To fix this, simply flip the wires on the primary side of T1.

The secondary of T1 will need to be sized to handle the primary current of T2. A 56V, 12A secondary = 672VA (volt amps, which is literally V * A). The same VA on the primary = 672 / 120 = 5.6A. So the secondary of T1 should be rated for 5.6A or greater.

Putting 130V into T2 isn't ideal, but it is within the 10% tolerance that the power company is allowed to operate under.
I think the transformer problem has been corrected, the meter operator is a dummy. Anyways, if you read my post right after yours, I explained the power supply problem. I have since went back to the shop and eliminated the estop, bypassed it completely. Now everything seems to be powering up, led lights on, fan motor running. Now I have to read the operators manual and figure out how to make everything move. Also there are 2 ground wires missing according to the drawings and I dont see no loose wires hanging in the cabinet, so that means a look inside the driver board to see if it was left unplugged or disconnected. I know one of the ground wires goes to the estop and the plug is missing the pin the wire connects to. I will probably replace the wire and plugs for the estop and get rid of the rotten and cracked mess of redneck engineered wiring.
 

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