Zebra ZebraStat ZS-2 User manual
ZebraStat
Operation Manual
®
Model ZS-2
2Contents
Safety Information........................................3
Using the ZebraStat.............................4-5
Troubleshooting Electronic Boards..........6-7
Voltage Problems......................................8-9
Feature Identification (Photo)................10-11
Continuity Mode....................................12-13
AnalysisMode.......................................14-15
Activation Mode....................................16-17
CircuitProtection........................................18
Avoiding Problems......................................19
Warranty......................................Back Cover
Your ZebraStat will give you longer life if you
treat it carefully, like any other sensitive tool.
Maximum Input Voltage.........................28 Volts
Maximum Current Through Unit............5 Amps
Overall Circuit Protection.............5 A. @ 24 V.
White Wire Circuit Protection.......3 A. @ 24 V.
Unit Size............................8”L. x 5”W. x 2.25”H.
UnitWeight...............................................18 oz.
Warranty................One Year Limited Warranty
Specifications
Safety Information
Please read these instructions before using
your ZebraStat.They contain information to
protect you, your customers, and their prop-
ertyfrom harmordamage. Understanding the
proper use of this tool may also assist you to
make quicker and more accurate diagnostics
on the equipment that you service.
Maximum Input Voltage.....................28 Volts
Maximum Current Through Unit.........5Amps
• NEVER connect any lead to (nor allow
any unconnected lead to touch) Line Volt-
age, or any voltage higher than 28 Volts.
• Do not perform an activation that a normal
thermostat could not perform, such as calling
for heating and cooling simultaneously.(Un-
less you are servicing a heat pump.)
• If the equipment requires it, respect staging
precedence. (i.e.: Do not turn on stage two if
stage one is not already activated.)
• Do not allow your ZebraStat to get wet. If it
does get wet; dry it thoroughly before using.
3
Using the ZebraStat
4
To use your ZebraStat, follow these steps:
1) Decide the mode that you want to use
2) Hook up appropriate leads to equipment
3) Manipulate Mode & Component switches
4) Observe the LED’s and equipment tested
Explanation of steps:
1) Mode. ZebraStat operates in 3 different
modes.You caneasilyleaveithookedupand
use all 3 modes on the same equipment as
needed. The 3 modes are:
• Continuity - This mode tests that the wires
that you connect to electrically ‘go some-
where’. For instance, the wire that you con-
nect to the FAN lead normally goes through a
fan relay, and the continuity mode will tell you
if there is a continuous circuit through that re-
lay on the other end of the equipment’s wire.
• Analyze - This mode simply displays the
power flowing through the circuits that your
leads are connected to. First, the red LED’s
tell you power is available in the equipment.
YellowLED’slightwhenthe thermostatis call-
ingforheating,cooling,fan,orreversingvalve.
Using your ZebraStat (continued)
• Activate -This mode is like having a remote-
control thermostat. Technicians often use it
when the thermostat is not easily accessible:
when making a diagnosis or repair to a unit in
an attic, basement, roof,or new construction
where the thermostat hasn't been installed yet.
2) Hook-Up. Start with the Mode Switch in the
ANALYZE position and have all component
switches OFF. The hookup of Zebra-Stat’s
leads is the same for all modes. First, connect
the component lead’s alligator clips to their re-
spectivewiresattheequipment.(Commonuses
of wire colors are listed below the component
switches.However,youcanuseanyofthewires
to test any other 24V function, like ‘Emergency
Heat’.) Then connect the Red and Blue leads
totheequipment’s24V power, observingpolar-
ity. All modes exceptANALYZE require that all
thermostat functions be OFF.
3)& 4)Manipulate Controls& ObserveLED’s
&Equipment. Seethefollowingsections(Con-
tinuity, Analysis, or Activation) for the proper
steps to follow next.
5
6Troubleshooting
Electronic Boards
A blown fuse on an electronic control board
presents special challenges. Rather than just
replacingthefuse(andpossiblywatchit‘blow’
again) the ZebraStat offers a diagnostic al-
ternative. The White wire (the HEAT1 circuit)
has a special function built into it. Between
the Red and White wires is a low-amp, auto-
reset, solid-state 'circuit breaker'. This circuit
breaker is set to ‘trip’ at 3 Amps,providing a
safe alternative to repeatedly replacing fuses
while looking for the cause.
Here’s how it works: Remove the blown fuse.
Attach the Red and the White leads of the
ZebraStat to the board or fuseholder where
the fuse was. No other leads should be at-
tached for this mode. Turn the mode switch
to ACTIVATE and turn ON the HEAT1 com-
ponent switch. All other component switches
should remain off. Now, the ZebraStat’s cir-
cuits are acting as a 'circuit breaker'with a rat-
ing of 3 Amps.
Troubleshooting (continued) 7
If the current flowing into the Zebrastat
through these two wires should exceed 3
Amps, the breaker will ‘trip’, and the lower Trip
LED will light. The breaker will stay in this
‘tripped’ condition until the power is removed
from one of the leads for about 15 seconds.
(Some electronic thermostats may start a set/
reset cycle as they lose power and drop out.)
A typical problem causing a fuse to blow on
one of these boards is a shorted thermostat
wire. Diagnosing which wire is accomplished
much easier with a ZebraStat: Hook up the
ZebraStat as described above. When the
Zebrastat’s breaker trips, remove power to
the system for 15 seconds. While the power
is off remove one thermostat wire at a time
from the control board, turning on the power
again after each disconnection. When theTrip
LED does NOT light up after removing a wire,
the suspect circuit has been found. If all ex-
ternal low voltage control wires are removed,
and the Trip LED still lights, it’s time to suspect
that the board itself may have a problem.
Voltage Problems
Voltage problems in a system are frequently
overlooked, but are very easy to find. For in-
stance, many technicians don’t compare the
current draw on contactors when replacing
one. In most cases there won’t be a problem,
but if the transformer is already close to its
output capacity, and the new contactor re-
quires a higher current level to close, inter-
mittentproblems arelikelytoarise,especially
ifthelinevoltagedropsafewpercentbecause
of high demand, say, on a hot afternoon.
The ZebraStat has a built-in voltage monitor
section that makes it easy to tell if the voltage
being supplied at the Red and Blue leads is
adaquate.(Thesevoltagescouldeasilybede-
terminedwithavoltmeter,ofcourse;butmany
technicians do not check for low-voltage lev-
elswhileunderload,eventhough theycould.)
Getting used to glancing at the VOLTAGE
section of the ZebraStat may help you de-
tect some of these problems before they ac-
tually causea fault.
8
Voltage Problems (continued)
There are 3 red LED’s in the voltage section:
ON, ??, and OK. The ON LED will light when
thevoltageapplied tothe powerinputleads is
at least 8 volts. The ?? (Questionable) LED
glows about half-brightness at 19.5 volts, and
full-brightness at 20.5 volts. The OK LED
glows about half-brightness at 21.5 volts, and
is fully bright at 23 volts.
Any time that you are using the ZebraStat
and notice that the OK LED isn’t fully lit, you
may want to check the voltage level at the
component that is farthest away from the sys-
tem transformer while under load. (The volt-
agedropfromthewireswillbegreatestthere.)
IftheOK LEDisn’tglowingatleasthalf-bright-
ness, there is the potential that higher tem-
peratures (higher wire resistance) and lower
line voltage (due to high demand) may cause
that component to not be able to close fully,
or, in the case of a reversing valve, not be
abletochangepositions. Ahigher-ratedtrans-
former may be called for, or larger wiring.
9
10 Feature Identification
Mode Switch
Voltage Monitor
Lower Trip LED
Lead Compartment
Magnet (on back)
Quick Reference
ZebraStat Model ZS-2
Upper Trip LED (Red)
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