ISSPRO R8588 User Manual
ISSPRO Measuring instruments
ISSPRO, INC. 2515 N.E. Riverside Way, Portland OR 97211
Telephone: (503) 288-4488 Toll Free: (800) 888-8065
FAX: (503) 249-2999
Form No. IS074 (9/10/02 Rev. C) Page 1 of 5
ISSPRO 3 3/8” Dia. Programmable Tachometer
Aircore Version
GENERAL INFORMATION:
OPERATING VOLTAGE: 11-30 VDC: NOTE – Instrument comes equipped with a 12V lamp. Replace lamp with
one of proper voltage when installing instrument on 24V systems.
24 Volt Lamp is P/N 656
INPUT SIGNAL: Geartooth sensor, AC generator, alternator tap
PROGRAMMABLE RANGE: 1 – 255 pulses per revolution (gear teeth, magnets, etc.)
TRANSIENT PROTECTION: +100 V, -400 V
REVERSE VOLTAGE PROTECTED
HOURMETER operates only when engine runs
CALIBRATION: Remove the hole plug by pressing above the
center enough to allow a small coin, screwdriver, etc. to be
inserted in the slot behind the upper edge. Twist to remove. Each
of the eight switches has a different value as shown in the table on
the right. Add the switch values to equal the number of pulses per
engine revolution. These switches will be set “on” (up). All
others will be off.
EXAMPLE: Find switch numbers by subtracting the switch value
from the remaining number. Always use the largest value that can
be subtracted from the remainder for each successive step. For
gear with 103 teeth:
Sw Value New
Remainder Sw.
Start
103
-
64
= 39 #7
ON
Remainder 39
–
32 =
7
#6
ON
Remainder
7 – 4
=
3
#3 ON
Remainder
3 – 2
=
1
#2 ON
Remainder
1
–1
= 0 #1
ON
Or use the calibration chart provided (pages 3 and 4.)
SIGNAL GENERATOR (Sender unit): Generator is installed on tachometer cable drive
of engine:
# PULSES / REV = (# sender pulses/turn) X (ratio of take off RPM to engine RPM)
If the number of pulses per revolution from the above equation is not a whole number, the tachometer will not be accurate.
In this case, either select a generator so that this number is non-fractional or, using a photo tach as reference, trim the
calibration adjustment.
EXAMPLE: # sender pulses per turn = 15. take off ratio = 0.5:1 (i.e. cam drive);
#PULSES / REV = 15X 0.5 = 7.5. This will result in an error in the tachometer reading. Select a sender with an even
number of pulses per turn (e.g. ISSPRO R8970). The # pulses per revolution will then be a whole number, in this case 15.
Switch #
Value
1 -
-
-
1
2 -
-
-
2
3 -
-
-
4
4 -
-
-
8
5 -
-
-
16
6 -
-
-
32
7 -
-
-
64
8 -
-
-
128
REAR VIEW OF TACHOMETER
LAMP & SOCKET
(REMOVE CCW)
CALIBRATION
SWITCHES
ON
ADJUST
CALIB.
1
8