Welch Allyn Micro Tymp 1, Service Manual

Page: 15 / 82

Section 2.4 Service
MT 1 CALIBRATION PROCEDURE
Note: After the first six months of production, the circuit board was improved to the PCB+ circuit board. This
document, however, will explain how to calibrate both the Original PCB and the PCB+. Tell them apart by these
differences: Original PCB has Black and Red calibration wires, blue/white switch PCB+ has a test pin by R24, and
none of the above.
Step 1
USE ESD GROUNDING STRAP AND MAT TO PREVENT DAMAGE TO SENSITIVE COMPONENTS:
REMOVE BATTERY COVER RETAINING SCREW AND REMOVE TWO SCREWS LOCATED UNDER THE
LABEL. BREAK THE ADHESIVE JOINTS. DO NOT PULL THE HOUSINGS COMPLETELY APART SINCE
THE FLEX CIRCUIT AND THE HOSE ARE JOINED AT BOTH HOUSINGS.
PLACE THE MICRO TYMP 1 HANDLE INTO FIXTURE T-5609.
Step 2
PERFORM CURRENT DRAIN TESTS: (taken from A01785 Note #8)
64mA MAX CURRENT DRAIN AT +7.2 VOLT SUPPLY IN FAST BLINKING OPEN MODE, UP TO 200mA MAX
WITH PUMP MOTOR AND VENT VALVE ACTUATED.
Step 3
PERFORM FAST CLOCK TESTS:
FOR ORIGINAL PCB, DO THIS:
FOR PCB+ BOARD, DO THIS:
FAST CLOCK SHALL BE BETWEEN FAST CLOCK SHALL BE BETWEEN
412-456 (HEX), IF NOT ADJUST C3 412-456 (HEX), IF NOT ADJUST R22
(taken from A-00841,Lev.3,Item 4) (taken from A-01777,Lev.3,Item 5)
(use a trimmer adjustment tool (ignore acceptance criterion on spec.
such as Spectrol 8T000 for C3.) it was developed for manufacturing)
Step 4 (this step has four parts)
PERFORM PROBE TONE LEVEL TEST (sound level):
FOR ORIGINAL PCB, DO THIS: FOR PCB+ BOARD, DO THIS:
Open Sw 1 and apply +3.0 VDC Apply +2.5 VDC to TP2
to TP 2 (Red Wire). (taken from A-01785 Note #4)
(taken from A-00848 Note #4)
1. 1.
If Probe Tone level IS 85 +/-2 dB, If Probe Tone Level IS 84 +/-2 dB,
TURN PAGE, AND DO Orig.PCB Compliance GO TO PAGE 14. DO PCB+ Compliance Test. Test. Then
DO Step 5 on page 15. then DO Step 5 on pg 15.
2. 2.
If Probe Tone level IS NOT 85 +/-2dB, If PCB+ Probe Tone IS NOT 84 +/-2dB,
adjust R24 to this value. then adjust R24 to this value.
3. 3.
NOW GO TO TOP OF PAGE 15 and do NOW GO TO MIDDLE OF PAGE 15 and do
Orig. PCB Distortion Test. PCB+ Distortion Test.
4. 4.
NOW GO BACK UP TO PART 1 OF THIS STEP. NOW GO BACK UP TO PART 1 OF THIS STEP.
Reconfirm adjustments made. Reconfirm adjustments made.
pg 12