Controlling existing motors with resolvers

At work we have a robot with a dead servo drive. The manufacturer is still around, and says that the original drives aren't available by any means. As far as I can tell, the motors are ordinary 3 phase brushless servos, but with resolvers. I can't find any industrial servo drives or systems that use resolvers. A few manufacturers list drives that can take input from a resolver, but of course they all say "call for quote" before I can get any information on the device.

I'm aware of the Mesa 7I49 resolver interface board, and the 8I20 PWM amplifier (which is out of stock). Are there any other industrial servo amplifiers that work like the 8I20?

This is a professional application: I am not going to screw around designing boards, nor will I consider hobby-grade hardware. I'd like the next person who needs to work on this machine to be able to do so.

By providing detailed technical specifications for your servo amplifier and motor, you’ll significantly improve your chances of receiving an accurate answer.

The existing drives are:
Atlas Copco DMC2 31025P (X axis)
DMC2 31025 (Z axis)
DMC2 31025P (C axis) <- This is the dead one. It's also labeled as having been made by Inmotion Technologies AB

The C axis drive is labeled as 240VAC/7A input, 240VAC/7A output, 400Hz max. At the moment I can't see the labels on the other drives, but I will find out their ratings.

The resolvers are part of the motors, so I don't know anything about them (except Z).
The two motors I can get to are:
Wittenstein TPM004-031R-320P-BP1-0301F000 320V, 5.1A max (X axis)
Elmo PSA 90/6-79-P-PMB-4048 230VAC, 6.6A max continuous. Resolver: 56046-01 6-POL (Z axis)

I cannot get to the C axis motor. It's at the bottom center of the robot which is bolted down to the floor. All I know about that axis is that the motor is physically the largest on the robot, has the same color scheme as the X motor and was possibly made by the same company.

I have scoped the resolver signals: the existing drives run them at 4KHz and the resolvers all work as far as I can tell.

The X and Z drives list the same rating as C: 240VAC, 7 Amp output.

Pico Systems has a small board that converts a resolver to look like a standard quadrature encoder. Unfortunately, it can't provide commutation signals, but does provide an index pulse. This board will not work with variable reluctance resolvers, but is designed for "brushless" resolvers such as those made by Harowe Controls and Singer Kearfott. See:
picosystems.store/product/resolver-converter/
for more info.
There are AC servo drives that can operate without the commutation signals, these are often called "sensorless drives".
Jon

It seems that Glentek makes servo drives that can take input from resolvers for commutation, and emulate a quadrature encoder for other uses.
I've sent them an RFQ.

there are DMC2 31025P for sale on eBay but they are no cheap. As an alternative the Copley Controls Xenus servo drive. they take resolver input but you would need to have look at the manual (manual is online) and determine if it does accommodate your particular resolver type.  

tommylight wrote:

 i have resolvers that do not work with 7i49,

your particular resolver type.  

How can I tell what type of resolver I have?

I've done a little research, and have found three types of devices that are sometimes called resolvers:

1. brushless resolvers
2. variable reluctance resolvers
3. sin/cos encoders

It appears that brushless and variable reluctance resolvers are excited and measured the same way and should be indistinguishable by electronic means, whereas sin/cos encoders are driven with DC and produce sin and cosine signals only when the rotor is turning, but static voltages when it is stationary.