Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 19
*Piezo Output
The piezo out-put test can be used to help diagnose
problems or failures with piezos on the 950/1050, 1025
(Limited Edition), 850, and 700 balancers. When the
test is activated the weight display will show four dif-
ferent readings as the Dynamic, RV, Alloy 1, and Alloy 2
LED's alternately light up. The values needed are the
Dynamic (1st LED) and Alloy 1 (3rd LED). Dynamic
value is the amplitude, or signal strength, of the left
piezo. Alloy 1 is the amplitude of the right front and rear
piezo added together (except for 850 that only has two
piezos). It is the consistency of the readings through
five or six spins that is important, not the value of the
readings.
To use the codes perform the following steps:
1.
Mount a balanced wheel on the balancer with a 4
oz. weight on the outside, enter the wheel parameters.
2.
Enter the piezo test code for the model balancer
being tested. Ignore the initial set of values displayed.
3.
Spin the wheel by closing the wheel guard and/or
pressing the spin button. When the balancer stops,
write down the values when the Dynamic and Alloy 1
LED's are on. These values will be slightly different on
each balancer. Typical readings for 950/1050 balancer
Left Display 1150
Right Display 1050
4.
Repeat step 3 above for five more spins.
Remember you are looking for consistency of the read-
ings.
5.
If the Dynamic value fluctuates more than +/- 10,
check and/or replace the left piezo.
Note: The following steps will allow both
right piezos to be tested individually by
unpluging one at a time.
(The 850 only has two piezos and may be tested by
reviewing the left and right readings.)
6.
If the Alloy 1 reading fluctuates more than +/- 10
test the right front piezo by unplugging the right rear
piezo and repeating step 4.
7.
If the reading is stable the right front piezo is good.
Check and/or replace the right rear piezo after testing.
8.
If the reading in step #7 fluctuates, check and/or
replace the right front piezo.
9.
Reverse steps #6 and #7 to test the right rear
piezo. Both piezos should be checked individually
before replacing either piezo.
Note: Rust, corrosion, and trash under the
piezo ball or between the piezo and the
chassie can cause a bad ground and make
the readings fluctuate. Cleaning, reinstalla-
tion, adjusting to proper torque and cali-
brating may be all that is necessary for
repair.
Note: For 850 use the Dynamic LED for the
left reading and Static LED right reading.
For the 700 balancer use the Dynamic LED for the left
and Alloy LED for the two right piezo's.
When checking these two balancers only use the left
display readings (rounded off to 3 places).
Code 52 (Shift 0 - 52)
Code 27
950/1050, 1025, 700
850
Direct Drive
