STRIPPIT Servo Drive Repairs

Strippit & General Electric Servo Drive Repairs

Machine Technologies Specializes in HECC80 Control Strippit Machines,

and Provides Servo Parts & Servo Board Repairs on Other CNC Machines Tools

that Used the General Electric Hi-Ack Model 2 & Model 3 Servo Drives Systems.

This Page will Show More of the

Parts & Common Failures & Fixes for this Servo Drive System.

SERVO CONTACTOR, comes in 2 Versions.

The original 90-Volt type Contactor was found in all Model 2 Servo Systems. Strippit #22591-000. Depending on the Vintage (year made) of the system, there was a external

Back-EMF Diode across the coil, and a 2nd Diode that fed the voltage input to the coil. Early Versions did not have the 2nd diode. There was also a external switch used to pull-in the next contactor in the system, in a daisy-chain way.

This 90-Volt Contactor was also used in early Model 3 (not 3A) 150 volt servo systems with a External Voltage-Dropping Resistor, so that it could withstand the higher system voltage.

Model 3A Servo Systems used a Special high-voltage contactor for that improved 150 volt system only. They had the 2 diodes Molded-Inside the coil, and did not have the external resistor, and did not (usually) have the external switch. Strippit #22803-000. These 2 Types of Contactors are Not Interchangeable!

There is 1 Contactor on Each Servo Drive Axis, so a typical Strippit Machine would have 3, 1 each for X, Y, and T Axis.

Contactors sometimes Burn-Out their Coils, and Contactor will No-Longer Close. We Stock Replacement Contactors!

The above Photo shows 3 more Parts of the Servo System that are of interest;

1 --- PWMR2 / PWMR3 Board on the Right ( this Board has been Updated by us with a

New MVR-Relay, and a Green-LED Light to show when the Relay is Pulled-In, Etc.)

2 --- Servo Power Supply Rectifiers, the 5 Blocks with the 4 Wires coming out of each Block

3 --- Servo Cooling Fan & Motor

The PWMR2 & PWMR3 BOARDS are just Different Versions of the Same Circuit Board, and are Usually Interchangeable. These boards often become Intermittent in Old Age, causing Problems such as "Servo Down" for No Apparent Reason. We Wet-Wash, Repair, and Update these Boards, Adding a Hi-Quality Relay with a Green LED-Light so that you know if the MVR-Relay is Pulled-In or Not. This all greatly Improves Reliability and Ease of Trouble-Shooting, as it helps telling you of Internal Servo Inhibit-Faults.

Servo Rectifiers & Servo Rectifier Retrofit Kit

Another Common Problem is Shorting-Out of the Rectifiers for the Main Servo-Drive Power Supply.

Rectifiers Short-Out, the 20 or 24 Wires to them Burn-To-Pieces unless the Servo Fuses Blow in Time. Makes a Lot of Smoke, and a Melted-Rats-Nest of the Many Wires. There are 5 Rectifier Blocks with 4 Wires each in a Single-Phase System like a Strippit FC750, FC1000, or FC1000/2.

Strippit FC1250's have a 3-Phase System with 6 Rectifier Blocks.

Rectifiers are Hard to Get At, and Replacing the many Burnt Wires is a Pain in the Ass.

To Solve this Problem, we have our SERVO RECTIFIER RETROFIT KIT.

We remove all the Old Rectifiers and the Rats-Nest of Burnt Wires going to them.

Bolt the Kit's Heatsink & Rectifier Assembly to where its Convenient for You.

Run the Transformer's 2 (or 3 wires in a 3-phase system) to our Hi-Current Rectifier Block.

Run the 2 Rectifier Output Wires to Servo Chassis Power & Ground Studs. And You are Done!

This is Much Easier than Changing All the Rectifiers & Wires the Old Way.

And if our Hi-Current Rectifier ever Fails (we have lost 2 in the last 10 years), You can Now Easily Change it in only 5 Minutes! The 2 Photos below show Our Rectifier Kit Retrofit Kit, and a Installation

in one of our Customer's FC750 Machine.

SERVO COOLING FAN

The Servo Cooling Fan Motor Typically

Locks-Up in old age, then the Servo Overheats and Shuts-Down with a "Servo Down" Message. We Stock a New Replacement Fan & Fan-Motor to Repair this Problem.

Our Motor is More Powerful than Original ,

to provide Better Cooling

And it has Ball Bearings to provide Longer Life than the Plain Bronze-Bushings

of the Original Type Motor.