Servo Drive Repairs & Servo Repair Parts Strippit_Servo_Drives

Strippit  &  G. E.  HI-ACK  Servo Drives

Machine Technologies Specializes in Strippit  HECC80 CNC Turret Punch Press Machines  built from about 1975 to 1987.    Strippits,  as well as many other  NC &  CNC  Machine Tools of this Era, 
like  DiAcro,  Burgmaster,  Wiedemann,   Monarch,   Motch,   Behrens,   Gidding & Lewis,   W. A. Whitney,   Kearney & Trecker,  Hardinge,  Warner & Swasey,  and  Many Others,  used the   General Electric 
Model 2,  Model 3,  &  Model 3A   Hi-Ack Servo Drives  to Power their Machine's Motion Axis.

Many Machine Tools also used  General Electric  Mark Century  550,  750,  1050,  &  2000  Series Numerical Controls which used these  Model 2  &  3  Servo Drive Systems.   These Servo Drives were widely used in
the World-Wide CNC Machine Tool Industry,  as they were  Well Engineered,  Reliable,  and  Easy to Service.
Around 1987,  General Electric  decided to  Stop  Designing  &  Manufacturing
CNC   Machine Controls  &  Servo Drive  Systems,
and  Partnered-Up with the  Japanese  Fanuc Company,
using  Fanuc's More  "American Sounding"  U.S. Division,  General Numeric.

This was Another  Incredibly  Stupid-Move  by     "Neutron JackJack Welch,
Giving-Up  &  Destroying   Another  High-Technology Industry 
That Was  Invented  here in the  United States.
The Very First  NC  Machine was  Developed at  M.I.T.  for  Aerospace Industry  back in 1952!

About the same Time  G.E. Quit Making CNC Controls,
Strippit also Quit Making Their Own CNC Controls  (the various  HECC80's Controls)
and thereby  Giving-Up  Strippit's  Big Unique Advantage  of Making
Both The Machine  And  The Control System  That Were Tailored  Just For Each Other.

Machine Technologies Does Not Work on the  Fanuc  /  General Numeric Controls,  as they are Far Too Secretive with Technical Information and Schematics.   They are Afraid you will Steal-It,   just like they did.

While these Hi-Ack Servo Drives are now out of production,   Machine Technologies has 
Hundreds of Servo Drive Boards  In-Stock!    We have  New Boards,  as well as  Used  and  Rebuilt Boards.

We also Offer a Fast  Repair Service,  and can usually Test & Repair your Servo Drive Boards in 3 days. 
Final Testing of Drive Boards are in our  Strippit   HECC80   FC1000/2,   FC1000/3,  or   FC750 Machines.
Other's Test  Circuit Boards using  "Bench Test"  Rigs,  but we feel Nothing Tests Boards Better than Running them  Full-Speed  in a Actual Strippit  Hi-Speed  CNC Turret Punch Machine!

We Stock other Servo Panel Repair Parts such as  Rectifiers,  Filter Capacitors,  Current-Sense Resistors, Cooling Fans,  Transformers,  and  90 & 150 Volt  Contactors.    Also Stocked are  Servo Motors,  Motor Brushes,  Resolver Feedback Package,  Resolver  &  Motor Couplings,  and many other
Servo Related Parts.     Call Us on the Parts you Need!

         Servo Control Boards
1 of these Boards is on the Right-Side of each Servo Chassis,  and  Controls 1 or 2 Power-Slice Boards. 
Each Boards has Special  "Compensation" Resistors  & Capacitors which Machine Manufacturer Engineered for that Particular Axis.    If you remove it for troubleshooting or repair,  TAG-IT  so you can put it back into Same-Axis
on a multi-axis machine.   Versions are;

P/N's   21239-000,   44A398795-G01  to  44A398795-G03
PWMC3,       PWMC3A,    PWMC3B,    PWMC3C,   

P/N's   22527-000,   44A398795-G02
PWMC4,       PWMC4A,    PWMC4B

There is a Red LED Fault-Light on this Board that is Normally-Off.    When it is  "On",  it means you have a
"Over-Current"  Fault in that Servo Drive.    Cause is usually 1 or more of the 2 or 3 Boards in that Servo Drive being bad,  bad Servo Motor,  or Short-Circuit in Wiring to Servo Motor.  Send us Board-Set for Testing & Repair.
             Power Modules
Sealed hi-power transistor Modules were used in the Model 3 and 3A Servo Drives,  instead of Power Slice Boards used in the Model 2 Drive.   2 Modules were used in  X & T axis,  and  4 were used in  Y axis of FC1000/3 Machines.   Modules are Not Repairable.

P/N's   22648-000   44B295239-G05

There are Different Versions of theses Modules.

In the Y-Axis Drive,  which uses  2-Pair
(4 Modules total),    Each-Pair on Each Heat-Sink has to be the Same Version Type,  so that they Share the Drive Current  Equally,  or else they Will Fail!
There Are Model 2 Servo Drive Failures That Can Be Prevented!
Over time, Servo Boards become Packed with Shop-Dirt blown in by the Servo Cooling Fan.
This Dirt and some Humidity can cause Short Circuits resulting in Impressive Amounts of Smoke & Flame. Capacitors and other Components also go Bad after Aging 10 years or so, causing Sudden Drive Failures.

Machine Technologies Can Do Preventative Maintenance Service On These Boards.
We Wet-Wash Circuit Boards,  Replace Capacitors and other Weak Components,  Add New Updates, and Finally Test Boards to Original Specs to help Prevent Expensive Servo Failures and Machine Down Time.

We can Schedule Preventative Maintenance Work over a 
Weekend,  Shut-Down, or  Vacation Period  for Minimum Production Down-Time.
Paying a Little for Preventative Maintenance Now,  Can Prevent Paying a Lot in Future Breakdowns!
A smaller version of the Model 2 Hi-Ack Drives were
PWM50,  PWM51,  PWM91,  and  PWM99  Servo Drives.

These combined small Power-Slice and Control Board into 1 large Circuit Board on a Metal Chassis. 
These were Lower-Power Servo Drives that were used
on Strippit FC75/30 Machines,  as well as many other Machine Tools.   G.E.  made some Special Versions of
these Drives for Different Companies,  often for
Spindle-Drives on Turning Center Machines.

P/N's   400295-100    PWM50G   44A399749-G01
                                      PWM51      44A399749-G03
                                      PWM99D   44A399749-G02
                                      PWM99H   44A399749-G06
Call us on your needs,
as we still have some of  these Servo Drives In-Stock.
  And for those of you that are Still Paying Attention,  Yes,  there was a  Model 1 Servo Drive System.
It apparently was  G.E.'s  First  Attempt at a  PWM-Type Servo Drive System. 
It was built in the early 1970's,  was quite Crude,  and was redesigned into the Vastly Improved Model 2
Servo System.   The Model 1 Servo was not widely used,  and was never used by the Strippit Company.
This page was last updated on: 1/25/2023
We Stock  Servo Drive Repair Parts
Repair All Servo Drive Parts  Listed Above! 
Call Us on What You Need!

Call  or  Email  Machine Technologies  for
Strippit Part Pricing and Availability

Remember,  We Need Your

Strippit  Machine  Model-Number
Machine  Serial-Number
Strippit  Part-Number

Of The Parts You Are Looking For!

Get this Information  BEFORE  you Call
as it's the
I Am Going To Ask You!

Phone  704-233-5229

In 1980, G.E. introduced the  Model 3  Hi-Ack Servo Drive. 

It was a Hi-Performance 150 volt DC PWM Drive.  The Higher Drive Voltage allowed Higher Servo Motor Speeds and therefore Faster Machine Axis Speeds.  It had a chassis for each Axis-Drive,
with a Control Board, and 2 or 4 sealed Power Modules which Powered each Axis Servo Motor. 

Strippit used Model 3's & 3A's on their HECC80 Control FC1000/3 Machines to achieve Very-Fast 3000 inch per minute X & Y axis speeds,  and  also used it on Some  FC1500/45  Machines. 
But,  Some FC1500/45's used Older Model 2 Drive.

Monarch Machining Centers,  Gidding & Lewis Horizontal Mills, 
Hardinge,  and  Warner & Swasey CNC Lathes  are the only other Manufacturers that I have seen,  that also used  Model 3  &  3A Type Servo Drive Systems.   This Drive was Not widely used by CNC Industry,  and  Part Availability and Repairs are more Limited and Expensive,  than Model 2 Servo Systems.

Early 3 Drives had Reliability Issues,  were hard to work on as components access was difficult,  and had a SCR Regeneration Circuit  (overvoltage)  that was to Backfeed Excess Current from  Decelerating Axis Back into 3-Phase AC Power Lines.
This Regen Circuit was Complicated,  did Not work well,
and  was Very Hard to Test, Troubleshoot,  and  Repair.
The  3 Servo Drive  was  Reworked into the
Much Improved  &  More Reliable  3A Servo  Drive

Strippit FC1000/3 Machines with Serial Number
#066  and Above had the Improved  3A Servo Drive.
Machines Below  #066  had the Original  3-Servo Drive,  though a couple of Problem Machines had the old 3 Drive Replaced,  in the Field,
with the Newer  3A-Servo Drive.

The  Early  PWMC5  Control Board  on the
"Small 2-Power Module"  Size 1, 2, and 3  Type  "3" Drives,  was  Redesigned into the  PWMC7  Board.

The Early  PWMC6  Control Board  on the
"Large 4-Power Module"  Size 4 & 5 Type  "3" Drives,  was  Redesigned into the  PWMC8  Board.

All Early "3" Drives with the  PWMC5  &  PWMC6 Boards were Suppose to have had them Replaced
with the  Newer  PWMC7  &  PWMC8  Boards.

Mechanical Access to Drive Parts was improved
and a much Simpler and More Reliable Overvoltage Circuit was used to replace old Regen Circuitry.

3A Drives  had 1  Big Wire-Resistor
that goes Across the Top of the Servo Panel. 

3 Drives  had  6  Big Ribbon-Wire Power Resistors,
Side by Side,  on Top Servo Panel.

Power Supply & Regeneration Board
Model 3 Drive used  PSRG3  Power Supply Regen Board.   This Board,  1 per Multi-axis System,  supplies Low Voltage D.C. Power to Control Boards,  handles Fault-Inhibits,  & Controls SCR Regeneration Circuits.

The Improved Model 3A Drive  used  PSRG5  Power Supply Regen Board to do the same
Servo System Power,  Inhibit,  and  Regeneration functions.

PSRG3  and  PSRG5  are  Completely Different Boards,  and are  Not  Interchangeable!
Servo Control Boards

PWMC7  Board Controls  2 Power Modules on the 
Smaller  X  or  T-Axis Servo Drive on Strippit Machines.

PWMC8  Board Controls  4 Power Modules on the Larger High-Current  Y-Axis Servo Drive on Strippits.

Very Early 3 Drives  (Built about 1980 to 1982)  had PWMC5 and  PWMC6 Control Boards.    These Early Boards were So Unreliable that General Electric Redesigned  PWMC5 Board  into  New PWMC7 Board,  and  PWMC6 Board  was Redesigned into New  PWMC8 Board.

At Strippit,  We Updated ALL Early Model 3 Drives to
PWMC7 & PWMC8 Boards in the Field back in 1983
40 years ago!   All Model 3A-Drives came from
Strippit Factory with New Type Boards.

Other Brands of Machine Tools that used these Old PWMC5  &  PWMC6 Boards  should have them  Replaced
with  New  PWMC7  and  PWMC8  Boards!!!

If you have any  Old   PWMC5  &  PWMC6  Type Boards
laying around,   Do  NOT  Use  Them!!!     They are
Unreliable  and  likely to  Blow-Out  Power Modules!!!
Replace them with  New  PWMC7  &  PWMC8  Boards!!!

There are 2 Fault LED lights on these Boards that are Normally-Off.    An  LED   "ON"  means a  "Over-Current"  Fault,  usually caused by,  a Bad Servo Control Board,  Bad Power Module,  Bad Servo Motor,  or  Bad 
(Short-Circuit)  in  Wiring to Motor. 

There are also  "False LED-Trips"  sometimes on some Machines caused by Electrical-Noise from  Poor Internal Machine Wiring-Layout,  Bad Suppressors,  or  Arcing in the Machine somewhere.  
These  "False Trips"  Can be  Very Difficult to find.

Note!!!             Note!!!           Note!!!
There are Components on these Boards that Wear-Out in Old Age,  and can cause Very Expensive Servo Failures!
Send-In your  PWMC7  &  PWMC8  Boards to be Updated
and  Save yourself a Lot of Expensive Grief!
We can Do these Board Updates in only  2 Days!

The Model 2  was a 90 volt DC PWM  (Pulse Width Modulated) Servo System that was Widely Used,  and was
in Production from about 1974 to the late 1980's.

Each Axis Servo Drive had its own Chassis,  which held 1 or 2 Power-Slice Boards,  a Control Board on Right-Side,  and Various capacitors,  resistors,  contactors,  and other miscellaneous parts.   So,  if you had a 3 Axis CNC Machine 
(X, Y, T)  you had 3 of these Chassis's Mounted on a
Back-Plate with a  Power Supply Board,  Cooling Fan,  and other Power Supply Components
usually mounted at  Chassis bottom.

Various Combinations of Power-Slice Boards were used, depending on Drive-Current Requirements of Machine Tool.

Model 2 Drives were used on following Strippit Machines;
FC750,  FC750/2,  FC1000,  FC1000/2,  FC1250/30,  FC1250/45, FC1250/45/72,  FC1250/30/1500,  FC1250/30/1500 LASERTOOL,  FC1250/30/1500 LASERCENTER,  FC1500/45,  BLANKING CENTER,  and  FC75/30.

Machine Technologies Can Supply Servo Repair Parts & Servo Board
Repairs On Any Machine Tool Using  G.E. Model 2 & 3 Servo Drives!
                                  Model-2  Power-Slice Boards
These are the Boards that actually Power the Servo Motors and are Easy to identify as they all had Large Aluminum Heatsinks.    1 or 2 Boards are used in each Drive-Chassis.   There are 5 Types,  Sizes 1's  to  5's.
As Boards were in Production for about 20+ years,  they Evolved somewhat,  and
Periodically the Updated Boards received  New Version Names. 

PWMP's  are the Earlier Versions,  PWMU's  are the Later  Underwriter Laboratory   Approved Versions.
For the most part,  they are all Backwards Compatible.    Example,  a Newer  PWMU-2B  could replace an
Old Original  PWMP-2 Board.     Following are the  5  Power-Slice Board Types;
Power Supply  &
MVR Relay  Board

Only 1 of these per multi-axis Servo System,  and it is usually located under the Bottom-Most Servo Drive.
Board Powers Control Boards  (up to 6 boards)  which Control Power-Slices,  which Powers Axis Motors.
There are also some Inhibit Functions on this Board,
which Disables Servo Drives if there is a Voltage or Current Fault. 

The  Early Versions  Are;
P/N's   21240-000   44A398788-G01  to  44A398788-G03
PWMR2,    PWMR2A,    PWMR2B,    PWMR2C

And  Late Versions  are;    P/N's   22526-000  
44A398788-G04  &  44A398788-G05  PWMR3,  PWMR3A
The  G.E.  Model 2  Servo Drives
G.E.  Model "3"  and  "3A"  Servo Drives
The Strippit  &  G.E. Part Numbers  &
  Model-2  Power-Slice Board  "Sizes"

  P/N's   21431-000,  22528-000,  44A398797-G04
  PWMP1,    PWMP1A,    PWMP1B,
  PWMU1,    PWMU1A,   PWMU1B

  P/N's   21241-000,  22529-000,  44A398786-G08
  PWMP2,    PWMP2A,    PWMP2B,
  PWMU2,    PWMU2A,    PWMU2B

  P/N's   21242-000,  22530-000,  44A398786-G07
  PWMP3,    PWMP3A,    PWMP3B,
  PWMU3,    PWMU3A,    PWMU3B

  P/N's  21887-000,  22531-000,  44A399729-G07
  PWMP4,    PWMP4A,    PWMP4B,
  PWMU4,    PWMU4A,    PWMU4B

  P/N's  21430-000,  44A399729-G08
  PWMP5,    PWMP5A,    PWMP5B,
  PWMU5,    PWMU5A,    PWMU5B
PWMC7  Servo Control Board
P/N's  22645-000   44A297086-G03
PWMC8 Servo Control Board
P/N's  22646-000   44A297087-G03
PWMC7  Servo Control Board
with  New  LSI-Chip Replacement Daughter-Board
As the Custom LSI-Chip that is the "Brains"  of the PWMC7 & PWMC8 Servo Control Boards are No Longer Available Anywhere,  A Custom "Daughter"  Circuit Board was Developed to take the Chip's place.

This Daughter Board has a Ribbon Cable that Plugs into the Old LSI-Chip Socket, and does all the Functions that the LSI-Chip used to do.

Daughter Board is Mounted in Front of the  PWMC7  or  PWMC8
Circuit Board.

At the Right is a Photo of a
Strippit  FC1000/3 Machine's
Model 3A Servo Drive
that has 2  PWMC7 Boards with Daughter Boards being used in the
T and X Axis Servo Drives at the
Topof the Servo Drive System.

A  PWMC8  Board,
Without a Daughter Board,
is in Y-Servo at the Bottom.
PSRG5  Board,  for  3A-Servo Drive
P/N's  22647-000   44A297093-G01
PSRG3  Board,  for  3-Servo Drive
P/N's  22609-000   44A294563-G03
The Model 2 Servo Drive  System,  while Old,  is Quite Reliable
and  Repair Parts & Servo Board Repairs are Readily Available.

We Have Hundreds of  Model 2  and  Model 3  Servo Drive Repair Parts In-Stock!

We also Stock  Model 3  &  3A  Servo Parts.   However,  the  Model 3  and  3A Servo System
is Not as Reliable,  and the Parts are more Expensive and Harder to Obtain. 
For these Reasons,  we are Working-On a Servo Retrofit to a Newer Servo Drive System for the Strippit Model FC1000/3 Machines that should be Both More Reliable and Lower in Price.
If you have Interest in this,  Call & We will Work on this Retrofit a Little Faster!
!!! Note !!!
Bad  Power-Modules  Can Burn-Out  PWMC7  &  PWMC8  Boards,
Bad  PWMC7  &  PWMC8  Boards  Can Burn-Out  Power-Modules!

"Swapping"   Parts Between  Different  Servo-Drives  While
"Troubleshooting"   Risks  Burning-Out  More  Boards  &  Modules!!!

Send-In Your  PWMC7  &  PWMC8  Boards  AND  Modules for Testing!

A Great Cover,   Drawn by  Fred Kasten  R.I.P.
for My  Servo Drive Manual  I put together for the Strippit Co.,
a  Long Long Time Ago.
But Fred,   Who in Hell  Is  The  Ugly,  Bald,  Bearded Guy???
We Also have In-Stock a Limited Supply of
G.E. Hi-Ack Servo Drive Manuals
if you have Lost Yours.

These come in  4 Types;
                                ---   Model 2    
                                ---   Model 2 UL
                                ---   Model 3    
                                ---   Model 3A 

You and Your Serviceman Cannot Work on Your Machine's Servo Drives Without Correct Manual!
We Do  Servo Board Repairs  on
PWMC7  44A297086-G03         PWMC8  44A297087-G03
PSRG5   44A297093-G01         PSRG3   44A294563-G03
and have,  In-Stock,  Repair Parts  like
Power-Modules  44B295239-G05    &    Contactors  44A399668-004
Strippit has been Telling Their Customers that
G.E. Servo Drive Parts are  "Not Available".
It's Not True!

We Have Plenty of
  #22648-000   Power-Module    G.E. #  44B295239-G05
  #22645-000   PWMC7 Board    G.E. #  44A297086-G03
  #22646-000   PWMC8 Board    G.E. #  44A297087-G03