[parametric.ms]

Hi guys,

I just bought old machine DAEWOO PRO G with Fanuc System 6T control. The operator panel still using 7 segment and LED Display to select any command.

First time I power up this machine, everything seems to be fine. I check every button, make a reference point and works great. But when I try to rotate my spindle (manual or MDI) the problem show up.

I rotate spindle manually then rotate potentiometer to increase speed of spindle, still Ok ( it shows almost 1000rpm on RPM gauge). But when I try to stop the spindle (rotate potentiometer ccw or push stop button) the machine looks like goes to emergency stop condition. I look into spindle drive and look the LED alarm lit (OVER FIELD).

Anyone here can help to solve my problem? (Especially Dan Fritz... )
Thanks for all your kind attention

Regards,
Andre

[Dan Fritz]

You have one of the original 6T model A controls (they just called it a "6T" back then). It's a good control, with many parts interchangeable with the 6T-A model that has a CRT.

The spindle problem is not in the CNC control itself. It's in the spindle drive or possibly in the motor itself. The CNC control just sends a speed command signal to the spindle drive board, and that board is responsible for making the motor run at the correct RPM.

Your spindle motor is a DC motor with a "field" coil. Smaller DC motors have a permanent magnet for a "field", and the drive unit just supplies a DC current to the armature to vary the speed. This motor has a field coil (an electromagnet) which is supplied with current by the drive unit. As the motor speed increases past about 1000 rpm or so, the field current is supposed to begin to decrease (weakening the field) which results in a higher spindle RPM. The Spindle drive board controls BOTH the field current and the armature current. Behind the board is a set of heat sinks that have a set of 6 big SCRs for forward and 6 big SCRs for reverse (two for each phase). There are also a pair (2) of smaller SCRs and a pair of diodes that control the field current. A bad field control SCR can cause this, or it could be a bad adjustment or component on the spindle drive board.

Before you replace SCRs or the drive board, be sure that the spindle drive unit is getting the correct 3-phase AC voltage. If it's getting the wrong line voltage, you may need to put a transformer on it if it doesn't already have one. Follow the big AC 3-phase wires from the bottom of the spindle drive and see if they go to a multi-tap transformer or not. If they do, look to see how the transformer is jumpered to see if it matches your line voltage. If the input voltage is OK, you may need to look for someone who can repair and adjust that spindle drive board. You said that you just bought this machine, so it's possible that the shop it came from had a different AC line voltage.

[parametric.ms]

Thanks Dan for your attention,

Just FYI :
My Spindle Drive & Motor specification:
Spindle Servo Unit : A06B-6041-H108
PCB Type : A20B-0008-0373

DC Spindle Motor Model 8
A06B-0818-B002
Voltage : 220V
Rating : 7.5 / 11 RPM : 1160/3500
Ampere : 38 / 58 Tach : 6V/krpm

Dan, how to measure the SCR? What is standard checking for Good or Defective SCR?

I got the schematic of DC Spindle Motor from Fanuc 6M, is it same with mine?
I read many information about setting & adjustment for that Control. But I have no guts to do that, maybe you can give some advise, what is the first thing should I set or adjust, related with my problem?

About AC Line, I think it all same with the shop that I bought this. I use step down transformer from 380V t0 200V.

Regards,
Andre

[lmostafa]

pleas i need help
i need a manual fanuc dc pindle A06B-6041-H103
pleas send it me in my email:[email protected]
thanks