McElroy Acrobat EP800AD User manual

Safety and General
Information
1EP800AD (Acrobat™ HPU)
SERVICE MANUAL
EP800AD (Acrobat™
Hydraulic Power Unit)
Manual: 718601
Rev D 11/19

This manual contains information and procedures that are
intended for experienced service technicians. Study and
understand these procedures thoroughly before servicing or
repairing the machine. Do not attempt any service which you
do not fully understand, or cannot be done safely with the tools
and equipment available to you. Failure to do so could result in
personal injury or equipment damage.
There may be components which are not user-serviceable. If you
have questions or encounter a issue that you do not understand
or cannot solve, contact McElroy Technical Services at 918-831-
9224 or [e-mail].
Service training is available from McElroy University at www.
mcelroy.com/university.
The instructions, illustrations and specifications in this manual
are based on the latest information available at the time of
publication. Your machine may have product improvements and
options not yet contained in this manual.
McElroy Manufacturing, Inc. reserves the right to make changes
at any time without notice or obligation.
Additional copies of this manual are available. When ordering,
use the part number on the front cover.
McElroy, McElroy Logo, are trademarks of McElroy
Manufacturing, Inc. in the U.S. and/or other countries.
This document may contain portions of technical materials
of various suppliers. Such component suppliers shall not be
responsible for the direct results of their technical materials being
presented out of context.
Designations used by component suppliers to distinguish their
products which appear in this manual are the property of the
respective trademark owner(s). McElroy is aware of the following
component suppliers trademarks.
No part of this manual may be reproduced in any form or by any means, electronic or mechanical,
including photocopying, recording, or by any information storage and retrieval systems, without the
express written consent of McElroy Manufacturing, Inc.
Copyright 2019, 2018, 2017 McElroy Manufacturing, Inc.
All rights reserved.
P.O. Box 580550
Tulsa, Oklahoma 74158-0550, USA

TABLE OF CONTENTS
SAFETY AND GENERAL INFORMATION 1
Using the Service Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
Safety Alerts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
Read and Understand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
Do Not Modify Machine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
General Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Safety Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Electrical Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Hydraulic Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
Disconnect Machine Before Servicing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Reference Designators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Fastener Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
SAE Bolt Torque Value Chart (Grade 5). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Fastener Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
MACHINE SPECIFICATIONS 2
Machine Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Nameplate Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
EP800AD (Acrobat™ HPU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
Machine Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Hydraulic Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2
COMPONENT LOCATIONS 3
Component Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
Complete HPU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
Cover Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2
Control Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Power Pack Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4
Hydraulic Manifold Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5
TROUBLESHOOTING 4
HPU Motor Does Not Shut Off. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
HPU Motor Does Not Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
No Output Pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Pressure Control Is Not Stable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Pressure Selector Switch Not Functioning (selecting between pressure control knobs) . . . . . . . . . . . . . 4-3
Open/Close Switch Not Functioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Main Circuit Breaker Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4
Fuse F5 Blown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5
Fuse F1/F3 Blown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Fuse F2/F4 Blown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

Heater Receptacle Not Functioning Properly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Oil Foams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Quick Disconnects Leaking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
ASSEMBLY/DISASSEMBLY 5
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
End Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Cover Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2
Power Pack Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-3
Mounting Plates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
Torque Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
ELECTRICAL 6
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Components and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1
Theory of Operation (Electrical) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Service and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Electrical Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12
Electrical Schematic (719904) Sheet A, Rev A 100-120V, 50/60Hz, 1Ph w/ Outlets . . . . . . . . . . . 6-13
Electrical Schematic (719904) Sheet B, Rev A 100-120V, 50/60Hz, 1Ph w/ Outlets. . . . . . . . . . . . 6-14
Electrical Schematic (721002) Rev A 208-240V, 50/60Hz, 1Ph w/ Outlets . . . . . . . . . . . . . . . . 6-15
Electrical Schematic (721002) Rev A 208-240V, 50/60Hz, 1Ph w/ Outlets . . . . . . . . . . . . . . . . 6-16
HYDRAULIC 7
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Components and Functions (Hydraulic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Theory of Operation (Hydraulic). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
Service and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
Hydraulic Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9
Hydraulic Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10
Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11
Hydraulic Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-12
PREVIOUS REVISIONS 8
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Revision 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Revision 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
Electrical Schematic Revision 1 and 2 (719902) Sheet A, Rev D 100-120V, 50/60Hz, 1Ph, No Outlets . .8-5
Electrical Schematic Revision 1 and 2 (719902) Sheet B, Rev D 100-120V, 50/60Hz, 1Ph, No Outlets . .8-6
Hydraulic Schematic (Revision 1 and 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-7
Service and Repair (Revision 1 and 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-8
Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-10
POST SERVICE FUNCTION CHECKS 9
Post Service Function Checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
NOTES 10
Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

Safety and General
Information
1-1Safety and General Information EP800AD (Acrobat™ HPU)
Using the Service Manual
This manual provides information and service procedures based upon current machine knowledge and configuration at the
time the manual was written. The instructions, illustrations and specifications are based on the latest information available at the
time of publication. Due to ongoing efforts to continuously improve the equipment, there may be changes on the machine not
yet reflected in this manual.
McElroy Manufacturing, Inc. reserves the right to make changes at any time without notice or obligation.
Procedures given in this manual provide one method for completing a given task. Additional information may be available
through McElroy Technical Services.
Additional copies of this manual are available. When ordering, use the part number on the front cover.
Operating instructions are found in the Acrobat™ 160, 180 and 250 Fusion Machines Operator’s Manual.
Section titles are located on the edge of the page to aid in locating information.
IMPORTANT: The digital version of this manual has hyperlinks to other portions of the manual. After clicking on a hyperlink,
press Alt – left arrow key to return to the page with the hyperlink.
SAFETY AND GENERAL INFORMATION
Safety Alerts
General safety messages appear in this section of the manual. Specific safety messages are located in the applicable
sections of the manual where a potential hazard may occur if the instructions or procedures are not followed.
You will see the hazard alert sign with these words: DANGER, WARNING, and CAUTION.
Indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.
Indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.
Indicates a hazardous situation which, if not avoided, may result in minor or moderate injury.
In this manual you should look for two other words: NOTICE and IMPORTANT.
NOTICE: can keep you from doing something that might damage the machine or someone’s property. It may also be used to
alert against unsafe practices.
IMPORTANT: can help you do a better job or make your job easier in some way.
Warranty
McElroy Warranty
McElroy 5 year limited warranty is printed inside the Operator’s Manual.
¡PELIGRO!
¡ATENCIÓN!
¡CUIDADO!
ОСТОРОЖНО
ATTENTION

Safety and General
Information
1-2 Safety and General InformationEP800AD (Acrobat™ HPU)
Read and Understand
Do not operate this equipment until you have carefully read, and
understand all the sections of this manual, and all other equipment
manuals that will be used with it.
Your safety and the safety of others depends upon care and
judgment in the operation of this equipment.
Follow all applicable federal, state, local, and industry specific
regulations.
McElroy Manufacturing, Inc. cannot anticipate every possible
circumstance that might involve a potential hazard. The warnings
in this manual and on the machine are therefore not all inclusive.
You must satisfy yourself that a procedure, tool, work method, or
operating technique is safe for you and others. You should also
ensure that the machine will not be damaged or made unsafe by
the method of operation or maintenance you choose.
General Safety
Safety is important. Report anything unusual that you notice during
set up or operation.
LISTEN for thumps, bumps, rattles, squeals, air leaks, or unusual
sounds.
SMELL odors like burning insulation, hot metal, burning rubber, hot
oil, or natural gas.
FEEL any changes in the way the equipment operates.
SEE problems with wiring and cables, hydraulic connections, or
other equipment.
REPORT anything you see, feel, smell, or hear that is different from
what you expect, or that you think may be unsafe.
Safety Equipment
Wear a hard hat, safety shoes, safety glasses, and other applicable
personal protective equipment.
Remove jewelry and rings, and do not wear loose-fitting clothing or
long hair that could catch on controls or moving machinery.
Ensure shop has proper fire prevention and fire-fighting and that all
personnel know how and when to use it.
Do Not Modify Machine
Make no modifications to your equipment unless specifically recommended or requested by McElroy.
WR00052-12-1-92
ДУМАЙТЕ
О
БЕЗОПАСНОСТИ
В ПЕРВУЮ
ОЧЕРЕДЬ
PENSEZ
Sécurité
en
1er
SAFE1ST-12-22-92
WR00053-12-2-92

Safety and General
Information
1-3Safety and General Information EP800AD (Acrobat™ HPU)
Disconnect Machine Before Servicing
Disconnect the machine from power before servicing, cleaning,
repairing, or transporting machine.
Electrical Safety
Always ensure equipment is properly grounded. It is important
to remember that if you are working in a wet environment with
electrical devices. Proper ground connections help to minimize the
chances of an electric shock.
Frequently inspect electrical cords and unit for damage. Have damaged components
replaced and service performed by a qualified electrician.
Do not carry electrical devices by the cord
NOTICE: Always connect units to the proper power source as listed on the unit, or in
the owner’s manual. Use GFCI electrical connections when available.
Hydraulic Safety
It is important to remember that a sudden hydraulic oil leak can cause serious injury, or
even be fatal if the pressure or oil temperature is high enough.
Escaping fluid under pressure can penetrate the skin causing serious
injury. Keep hands and body away from pinholes which eject fluid
under pressure. Use a piece of cardboard or paper to search for leaks.
If any fluid is injected into the skin, it must be immediately removed by
a doctor familiar with this type of injury.
Unwanted movement of the machine could result in serious injury or
damage to machine. Unwanted movement of the machine may take
place if switches do not match machine state when the machine power
is turned on.
NOTICE: Wear safety glasses, and keep face clear of area when bleeding air from
hydraulic system to avoid spraying oil into eyes.
¡ATENCIÓN!
¡ATENCIÓN!
WR00055-4-7-93
WR00025-11-30-92
WR00078-4-8-93
¡ATENCIÓN!
¡ATENCIÓN!

Safety and General
Information
1-4 Safety and General InformationEP800AD (Acrobat™ HPU)
Replacement Parts
Refer to the McElroy parts finder at www.mcelroy.com to locate parts for purchase.
Reference the model number on the nameplate of the machine when using the parts
finder.
Contact your customer service representative to order replacement parts.
Reference Designators
Reference Designators are assigned to components shown on the schematics and other reference diagrams.
Each code-like designator identifies a specific component. The designator is comprised of an uppercase letter(s) followed by
a number. The letters identify the type of component and the number specifies the exact component.
Legend for Reference Designators
Abbreviations
A list of commonly used abbreviations used in this manual are listed below.
Commonly Used Abbreviations
CB1 On/Off Switch
K1 Motor Relay
K2 Relay
K3 Relay
LF1 Line Filter
PS1 Power Supply
R1 Facing Pressure Regulator
R2 Heating Pressure Regulator
R3 Fusing Pressure Regulator
S1 Pressure Selector Switch
S2 Carriage Switch
F1 Motor Fuse for 120VAC/220VAC
F2 Power Supply Fuse for 120VAC/220VAC
F3 Motor Fuse for 220VAC
F4 Power Supply Fuse for 220VAC
F5 DC Power Fuse
HPU Hydraulic Power Unit
PSI Pounds per Square Inch
PRV Proportional Pressure Reducing Valve
VDC Voltage Direct Current
VAC Voltage Alternating Current
LED Light Emitting Diode
COMM Communications
IEC International Electromechanical Commission
SSR Solid State Relay
QD Quick Disconnect
EVC Electronic Valve Controller

Safety and General
Information
1-5Safety and General Information EP800AD (Acrobat™ HPU)
Fastener Identification
SAE bolt strength grades range from grade 2 to grade 8.
The larger the value of the grade number, the greater the
strength of the bolt. Identification of a bolt is determined by the
arrangement of line marks on the top of each bolt head. The
strength grade of each bolt corresponds to the number of line
marks on top of the bolt head plus 2. The higher the value of
the class number, the greater the bolt strength. All bolts used in
the assembly of the EP800AD (Acrobat HPU) are SAE Grade
5 bolts. For help identifying torque requirements for all bolts
used, refer to the SAE Bolt Torque Value Chart.
Fastener Usage
During any maintenance or repair procedures outlined in this document, it is important to salvage all fasteners (nuts, bolts,
etc.) for reassembly. If the fastener is not salvageable, a fastener of equivalent specification must be used. During reassembly
it is important to use retaining compound where referenced on the assembly drawing or assembly procedure. Drawings and
assembly procedures can be found in this document and at:
www.mcelroy.com
SAE Bolt Torque Value Chart (Grade 5)
Bolt Size Torque, ft-lb Torque, N•m
1/4-20 9 7
1/4-28 12 9
5/16-18 20 15
5/16-24 23 17
3/8-16 40 30
3/8-24 40 30
7/16-14 60 45
7/16-20 65 50
1/2-13 95 70
1/2-20 100 75
9/16-12 135 100
9/16-18 15 0 11 0
5/8-11 18 0 135
5/8-18 210 15 5
3/4-10 325 240
3/4-16 365 270
Grade 2
Grade 5
Grade 8

Machine
Specifications
2-1 Machine SpecificationsEP800AD (Acrobat™ HPU)
MACHINE SPECIFICATIONS
CD01402-10-5-15
Nameplate Location
Every unit has a name plate that includes the machine’s model
number, serial number, and power requirements. The model
and serial numbers can be used to register the machine online
and activate the warranty. Reference Operator’s Manual for
information on registering your product.
Machine Orientation
Left, right, front, and rear of the machine are noted from the perspective of an operator
standing in front of the electrical box.
Nameplate
EP800AD (Acrobat™ HPU)
FRONT
REAR
LEFT
RIGHT

Machine
Specifications
2-2Machine Specifications EP800AD (Acrobat™ HPU)
Machine Specification
Machine Length: 22.1"(562 mm)
Machine Width: 12.25"(311 mm)
Machine Height: 19"(482.5 mm)
Machine Weights: 56 lbs (25.4 Kg)
Hydraulic Specifications
Reservoir Filling Capacity: 0.375 gal (1.41 liters)
Hydraulic Pressure: 800 psi max. fusion pressure
Hydraulic Fluid: Refer to the Hydraulic Fluids section of this manual.
19"
(482.5mm)
12.25"
(311mm)
22.1"
(562mm)
Electrical Specifications
System Voltage: 24VDC
Power Requirements: 120V, 50/60Hz, 1Ph, 6.5A, 0.3HP (120V package), 208-240V, 50/60Hz, 1Ph, 4.5A,
0.3HP (240V package)
Fuses: F1 3.15 Amp Motor Protection 120VAC and 220VAC
F2 2.5 Amp Power Supply Protection 120VAC and 220VAC
F3 3.15 Amp Motor Protection 220VAC
F4 2.5 Amp Power Supply Protection 220VAC
F5 3 Amp Protect VDC circuitry fed from Power Supply
22.1"
(562mm)
12.25"
(311mm)
19"
(482.5mm)

Machine
Specifications
2-3 Machine SpecificationsEP800AD (Acrobat™ HPU)
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Component
Locations
3-1Component Locations EP800AD (Acrobat™ HPU)
COMPONENT LOCATIONS
Bypass Filter
Indicator
End Plate
Hydraulic
Pressure Gauge
Handle Tube
McElroy
Branding Label
McElroy
Branding Label
Electrical
Receptacle Label
Hydraulic Quick
Disconnects
Electrical Power
Receptacles
High Voltage
Label
Hour Meter
Machine and
Heater Amperage
Label
Control Box
End Plate
Voltage Label
Cover Assembly
Complete HPU
Component Locations
The components of the HPU outlined in this section reflect the latest revision of the machine. For information on component
functions and locations on HPUs of previous revisions, refer to section Previous Revisions in this manual.

Component
Locations
3-2 Component LocationsEP800AD (Acrobat™ HPU)
Hydraulic Fluid
Filter
Cover Assembly Feedback Pressure
Transducer
Control Box
Control Box
Electronic Valve
Controller
Capacitor
Cover Assembly
Cover Assembly (Control Box Cover Removed)

Component
Locations
3-3Component Locations EP800AD (Acrobat™ HPU)
Motor Fuse
Fusing Pressure Knob
Line Filter
Power Supply
Terminal Boards
Motor Relay (SSR)
DC Power Fuse
Pressure
Selection
Relay
Pressure
Selection
Relay
Heating Pressure Knob
Facing Pressure Knob On/Off Switch
Carriage Switch
Pressure Selector Switch Motor Fuse
Power Supply Fuse
Power Supply Fuse
F1
CB1
LF1
PS1
S2
R1
R2
R3
K1
F5
K3
K2
S1
F2
F3
F4
Control Box

Component
Locations
3-4 Component LocationsEP800AD (Acrobat™ HPU)
Proportional
Pressure Reducing
Valve (PRV)
Hydraulic Breather Cap
Open Valve
Solenoid
Close Valve
Solenoid
Accumulator
Dump Valve
Hydraulic
Manifold Block
Pressure
Switch
DataLogger®
Port
Hydraulic Quick
Disconnects
Hydraulic
Check/Fill
Plug
Pressure
Relief
Hydraulic
Drain Plug
Power Pack Assembly

Component
Locations
3-5Component Locations EP800AD (Acrobat™ HPU)
Manifold to
Filter Port
DataLogger®
Port
Pressure Control Port
Pressure Switch Port
Dump Valve
Port
Carriage Open Port
Carriage Close Port
Filter to
Manifold Port
Accumulator
Port
Gauge and
Transducer Port
Directional
Valve Port
F1
TR
A
F0
DMP VLV
PRESS CNTRL
PS SW
ACC
G
DIR VLV
B
Hydraulic Manifold Block

Troubleshooting
4-1 TroubleshootingEP800AD (Acrobat™ HPU)
TROUBLESHOOTING
HPU Motor Does Not Shut Off
Is the black dump valve knob fully closed?
No: • Close it tightly clockwise.
Does the unit have adequate hydraulic fluid level?
No: • Add hydraulic fluid. Refer to the Hydraulic Fluid section of this manual
for fluid recommendations.
Does the unit run much longer than it should and/or have a very
short cycle time?
Yes: • Normal cycle time is on for 5 - 7 seconds and off for 30+ seconds
(depending on temperature). If the cycle time is much shorter and there
is not a hydraulic leak, then the pump may be working, but leaking
internally. Replace pump. Refer to Hydraulic Pump in the Service/Repair
section of this manual.
• The accumulator may have lost its charge. Contact McElroy Technical
Support or McElroy Certified Mechanic.
If the motor is running continuously this means either there is no pressure building up on the system pressure
side of the hydraulic system or the pressure switch circuit is not functioning correctly. Either way the HPU motor
cannot run very long before overheating. Please take precaution to avoid overheating when troubleshooting if
the motor will not shut off.
Does the unit have adequate system pressure?
No: • Check hydraulic system for bypass/leak. Check HPU main pressure
relief, it should be set to 1/2 turn counter-clockwise.
Does the motor shut off when the pressure switch is unplugged?
No: • SSR is defective.
Yes: • Check Pressure Switch.
• Check pressure at pressure switch port with a test gauge.
• Check hydraulic system leakage by inspecting/cleaning PRV and
carriage spool valves.

Troubleshooting
4-2Troubleshooting EP800AD (Acrobat™ HPU)
No Output Pressure
Check electronic valve controller for error codes
• Refer to Electronic Valve Controller section for error codes.
Is HPU motor running at normal cycle times?
No: • Check fuses.
• Make sure high side hydraulics circuit is OK and building pressure.
Check pressure at pressure switch port with a 2000 psi test gauge.
Check carriage for free movement
• Turn up all pressure knobs to half or greater range.
• Cycle open/close and pressure selection switch and look for any
movement.
No: Check low voltage fuse F5.
Check PRV valve wiring.
Remove & clean PRV & Open/Close spool valves.
Clean with a standard parts cleaner.
HPU Motor Does Not Run
Is main power switch light on when On/Off switch is on?
No: • Check input voltage entering unit.
• Check power switch input voltage CB1.
• Is hour meter hourglass blinking when power is on?
No: Check fuse F2 (110V), fuse F4 (220V).
• Check DC voltage on DC bus: Electrical Schematic (719904) Sheet A
No: Check fuse F5.
Is fuse F1 OK?
No: • Check and replace Fuse F1 (110V).
Is there power present at the motor plug: J1-A : J1-B?
No: • Check SSR for signal & power, check low voltage circuit, check F5.
• Check motor wire, motor, and capacitor deutsch connectors.
Yes: • Replace motor. Refer to HPU Motor in the Service and Repair section
of this manual.