Using your VZ-7 - Surplus City Liquidators

Using your VZ-7 - Surplus City Liquidators
Speed Zebra
Model VZ-7
Operation Manual
Safety Information .......................................3
Using the VZ-7 ..........................................4
Hooking-Up ...........................................4-5
Choosing the Mode ....................................6
Voltage Checking .......................................7
Observe Mode ......................................8-10
Control Mode ......................................11-12
Winding Test Mode ............................13-14
Help and Avoiding Problems.....................15
Warranty......................................Back Cover
The DVD enclosed with your VZ-7 has training
sessions and suggestions not included in this
manual; please watch it to learn more.
Maximum Input Voltage.........................29 Volts
Overall Circuit Protection...........1 A. @ 24 VAC
Unit Size.....................10.75”L. x 7.25”W. x 3”H.
Unit Weight...............................................2.0 lb.
Warranty................One Year Limited Warranty
Safety Information
Please read all of these instructions before
using your Variable Speed Zebra.They have
information to protect you, your customers,
and their property from harm or damage. Understanding the proper use of this tool will also
help you to make more accurate diagnostics
on the equipment that you are servicing.
Maximum Input Voltage.....................29 Volts
Maximum Current Through Unit.........1 Amp
• NEVER connect any lead to (nor allow
any unconnected lead to touch) Line Voltage, or any voltage higher than 29 Volts.
• Do not alter the connection plugs. Use only
cables supplied by Zebra Instruments. If a
Zebra 24V Power Cable is used, use only the
recommended fuses and never connect to a
voltage source higher than 24 Volts AC.
• Never allow your Variable Speed Zebra to
get wet. If it does; dry thoroughly before using.
Using your VZ-7
To use your VZ-7, follow these steps:
1) Carefully hook up the wire harnesses to
2) Choose the mode you want to operate in.
3) Optionally, manipulate the Step switches.
4) Observe the displays and equipment.
Explanation of steps:
Hook-Up. The VZ-7 receives its power from
the furnace or air handler being tested. Start
by disconnecting the power in the equipment.
Next, squeeze the ends of the 5 wire power
connector on the motor. This gives access to
the unlocking tab on the 16-pin motor connector. Press the tab and disconnect that connector from the motor also. (The opposite end
of this harness plugs into the circuit board on
your equipment.) Now, carefully plug that
same 16-pin connector into the mating connector on the end of the VZ-7’s yellow wire
harness. Do it carefully, rocking the connector side-to-side instead of applying more pressure. You can permanately damage the
connectors by forcing them!
Hook-Up (continued)
The connector on the end of the VZ-7’s blue
harness should be carefully plugged into the
motor’s 16-pin receptacle. Finally, re-insert the
5 pin power connector into the motor’s socket.
(Because of the power surge to charge the
motor’s capacitors, NEVER plug in the power
connector when voltage is on!) The VZ-7’s white
harness isn’t connected at this time. Power up.
Note: A small number of furnace or air handler
manufacturers chose not to run a 24V hot wire
in their harnesses to the motor. This makes using the VZ-7 more difficult, because an outside
source of power must then be used. An optional
wire harness connector (#VZH04) is available
for these few units. It has special fuses to protect your VZ-7 and the motor from damage that
can occur if 24V is applied out of phase with
the other wires. Never modify the connectors to
try to get 24V any other way. Your warranty will
be void and you may damage the VZ-7 and/or
the motor. We chose to keep the cost down on
your tool by not including this harness in all units
because the lack of a 24V hot line is rare.
Choosing the Mode
Your Variable Speed Zebra operates in 4
different modes: Voltage Check - Observe Control - and Winding Test.
• Voltage Check- Always use this mode first
to rule out low voltage as a problem. The AC
voltage is shown on the display when this
switch is pressed. Additionally, the LOW
VOLTS LED will flash red if it is below 20 VAC.
• Observe Mode- is just that: all you are doing is observing the signals that the equipment is sending to the motor’s electronics. Use
this mode to see if the furnace or air handler
is sending the proper signals to the motor.
• Control Mode- This mode allows you to
simulate any command that the equipment
would send to the motor, observing the resulting RPM and CFM to see (a) if the motor
operates correctly when that setting is used,
and (b) if a tap setting change is desirable to
change system performance characteristics.
• Winding Test- If you have concluded motor
failure, this mode determines which section
of the motor is not working properly.
Voltage Checking
If the control voltage to the motor is below
about 20 volts, the motor may operate erratically. Since this is such an easy test, perform
it first. The VZ-7 displays the AC voltage between the Hot and Com harness wires when
the VOLTAGE switch is held down. Most units
display between 21 and 29 VAC. Voltages
outside this range indicate problems that must
be investigated. The LOW VOLTS LED
flashes if the voltage is below 20 volts.
The SHORT LED flashes if a short is detected
in the motor’s electronics unit. DISCONNECT
POWER IMMEDIATELY to keep damage from
occuring. The VZ-7 has an automatic-reset
circuit breaker to minimize damage. If the
SHORT LED is flashing, it means this breaker
has tripped. You must disconnect power to the
VZ-7 to reset this breaker. The motor’s electronics package should be replaced.
The DVD demonstrates how to test the line
voltage to the choke and motor.
Observe Mode
OBSERVE mode (Green MODE LED) is meant
for you to use when you’re diagnosing if the
equipment is sending the proper signals to the
motor. It is sometimes confusing because a few
manufacturers do not follow the suggested uses
of the signal lines. For instance, one manufacturer sends a signal to the motor down the FAN
line when they want the motor to operate at heat
speed. Also, many manufacturers choose to require the FAN line to be activated any time the
motor should be on; other manufacturers don’t.
Getting used to the signal pattern that occurs
on the equipment you service most often will
give you experience in this area. Additionally,
we will be building a database of furnace/air
handlers’ manufacturers usage of these lines
on our website. (
Note: This tool will not display these signals if
they are not sent in 2.3 ECM format. One manufacturer uses special signals from the thermostat to the motor; a future Zebra tool will help
diagnose these systems.
Observe Mode (continued)
The OBSERVE mode uses the three upper
areas of the VZ-7’s control plate to display
operation information:
The SETTINGS and OPTIONS area indicates
which lines are currently active to the motor.
The DIGITAL DISPLAY area alternates back
and forth every 5 seconds or so with the calculated RPM and programmed CFM that the
motor is pumping. This display may take up
to 30 seconds to stabilize after the motor has
reached a constant speed. Wait for accuracy.
The 4-LED TAP section has tri-color LED’s that
indicate the 4 tap settings that can send setup information to the motor. The status is reported as: 1) No color means no option selected on this tap. 2) Green color means the
first option is selected. 3) Red color means
the second option is selected, and 4) Yellow
color means that both options are selected.
Observe Mode (continued)
Usually these tap settings are set with DIP
switches or removable shunts. They control
the ramp-up and ramp-down speeds, functions like humidity control, and sometimes,
allowing you to set up a unit to run slightly
faster or slower; to the customer’s preference.
We display the settings here so you can spot
something that is set incorrectly. Remember
that you must remove, then reapply power to
the motor before the new settings are active.
Some manufacturers choose to use other
schemes than the standard HEAT, COOL,
ADJUST, and DELAY taps, making it confusing for those of us who service these units.
Similar to the SETTINGS and OPTIONS displays, getting used to the schemes of the
manufacturers you service most frequently will
give you experience. Additionally, we will be
building a database of manufacturers’ usage
of these tap settings on our website.
Control Mode
CONTROL Mode is similar to OBSERVE
mode, except that you decide what signals you
would like sent down to the motor electronics.
The MODE LED will glow RED in this mode.
The CONTROL mode is used for further diagnosis, and also to test various settings for
problems without having to reset the system
thermostat. Detecting RPM and CFM of the
various modes that a system could be set to
is best accomplished here. Please remember
that the Digital Display may take as much as
30 seconds after the motor has reached a constant speed to stabilize. Be patient.
The OPTION STEP switch selects one or
more options. It selects the options in a circle;
that is, they repeat after the end of the list.
Initially OFF, repeatedly pressing the up switch
turns the R. VALVE option line on; then the
HUMID. line; then BOTH; then back to OFF;
and then starts over again. You can use either UP or DOWN to get to your choice quickly.
Control Mode (continued)
The SETTING STEP switch operates in the
same way, but it’s choices are: OFF - H1 - H2
- C1 - C2 - FA - h1 - h2 - c1 - c2 - OFF. Selecting the capital letter for H or C will simultaneously send the FAN line active. Alternately,
stopping on a choice that has a small h or c
will send signals only down those lines; the
FAN line will NOT be activated. The 1 or 2
after the Heat or Cool means which stage,
when using a multi-stage unit. There is a delay of a few seconds after you stop on your
choice, before the lines switch to that choice.
In the CONTROL mode, you will notice that
only the right-hand set of 7 LED’s change. The
left-hand set remain displaying what the system is calling for. This allows you to effectively
isolate the rest of the system from the motor
(assuming the connected line voltage is correct) and positively prove which component
is having problems. If you conclude that the
motor is defective, go on to the WINDING
TEST to identify which section to replace.
Winding Test Mode
The WINDING TEST Mode is performed on a
motor that is shown to be defective. It’s used to
identify if the windings section of the motor
(which is really just a three-phase, three-wire
motor) is defective also, or if you can get by
with just replacing the electronics module on
the end of the motor. Since the complete motor
costs hundreds of dollars, and the electronics
package is often less that $100, it makes good
sense to replace just the pack if possible.
• Hook-Up - Shut off power. Disconnect the Line
Power plug at the motor. Disconnect the 16pin plug at the motor. Remove blower assembly and electrically isolate it from furnace/air
bolts that hold the pack onto the end of the
motor. Carefully squeeze the locking tab on
connector inside pack, gently rocking the 3-wire
plug to separate it from the motor. Now, connect the white VZ-7 harness to that connector
and the alligator clip to a bare area of motor
case; leave the blue harness off.
Winding Test Mode (continued)
Now, press and release the WINDING TEST
switch; the display makes circular patterns to
remind you that the motor shaft needs to be
turned one or two revolutions to test it.
The digital display gives the results of the test:
“00” means connector is not connected.
“02” means motor not spun 1-2 turns in time
“11” means a winding is shorted to the case
“21” means winding phase “A” is open
“22” means winding phase “B” is open
“23” means winding phase “C” is open
“31” means winding phase “A” is shorted
“32” means winding phase “B” is shorted
“33” means winding phase “C” is shorted
“77” means the winding section shows OK.
Display returns to last mode after 10 seconds.
Of course, there could be problems with the
bearings. If motor slows after getting warm, disconnect as in above steps to eliminate EMF
backfeeding from electronics pack as a possible symptom that acts like bearing seizure,
before condemning bearings themselves.
Avoiding Problems & Help
Don’t disassemble the VZ-7. IC’s inside are
sensitive to static charges that might occur if
they are touched. Warranty will be void.
Be very gentle when connecting cables; the
pins can easily be damaged. Never force connectors together, gently wiggle them. If cable
harnesses are damaged, replacement harnesses are available; follow their instructions
carefully to avoid static discharge.
Our website (
will be expanding to include training video for
the VZ-7 as well as Frequently Asked Questions, and databases of information specific
to equipment manufactures configuration settings and motor programming.
Please watch the training DVD a few times;
this is the fastest way to acquaint yourself with
the VZ-7, and to learn how to use it to positively identify which component in a Variable
Speed System has failed.
One Year Limited Warranty
For a period of one year from the original
end-user’s date of purchase, Zebra Instruments warrants that this tool is without
manufacturing defects. Should you encounter any problems, please contact us
and we will attempt to resolve your problem as quickly as possible. This resolution may include replacement, exchange,
or repair of a defective tool; at our option.
This warranty does not apply to tools that
have been exposed to: voltages and/or currents that are higher than those specified
in this manual; abuse or rough handling;
any damage to connectors, or damage
from moisture or exposure to chemicals.
Out-of-warranty repairs are available for a
nominal charge plus shipping. Please contact us for an RMA (return authorization
number) before returning a tool for repair.
Zebra Instruments 512•869•7000
©2006 Zebra Instruments
Manufactured under license
U.S. Patent No. 6,826,454
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