0434148 JOHNSON MANIFOLD, Intake

General Troubleshooting And Repair Of The Engine Horsepower Meter And Accessories
General Troubleshooting Procedure
The following section gives a general procedure for isolating a faulty portion of the entire Engine Horsepower Meter Arrangement. It is written to enable a person with reasonable knowledge of electricity and a multimeter to find simple faults which are field repairable, without taking the unit to an electronics repair facility or returning it to the manufacturer.If the following procedure does not isolate the problem, U.S. dealers should return the unit (Horsepower Meter or flowmeter only) to the appropriate address shown on page 49. Dealers outside the U.S. may wish to have the unit further inspected and repaired locally by a qualified electronics shop which is familiar with digital circuitry.The material on pages 20-23 and pages 26-48 is intended only for those situations where it is not practical to return the unit to the U.S. for repair. U.S. dealers are urged to send their units to Fluidyne Instrumentation where repairs and calibration can be performed more precisely and efficiently. Be sure to check out the components by using the following procedure in the order indicated. Do not omit any tests unless the unit is known to operate correctly in that specific mode.
Do not use a continuity light to trace circuits on either printed circuit board. Some semiconductor components can be damaged if 3 volts is connected across them.
1. Turn the POWER switch to ON (Be sure the knob has not slipped on the shaft).2. Do any of the display lights light? a) YES - Go to Step 3.b) NO - Open the Horsepower Meter and perform the steps shown on page 6. If the problem cannot be identified as a blown fuse, bad switch contact, broken wire, loose battery connection, dead batteries, etc., return the unit to Fluidyne Instrumentation (see page 49). If the problem is known to be in the power board, return only the power board to Fluidyne.3. Are the display lights dim? a) NO - Go to Step 4.b) YES - Check for a voltage at the batteries of greater than 5.2 volts. If the voltage is less, recharge the batteries to over 6 volts and recheck. (If the batteries won't charge, go to Step 15.) Check for voltage losses between the batteries and wiring point 16 and the displays. The voltage should be greater than 5 volts at wiring point 16.4. Do any of the lights have the correct brilliance? a) YES - Go to Step 5.b) NO - Review Step 2. If the problem cannot be found, return the unit to Fluidyne.5. If all digits light correctly, go to Step 6. Individual lamps or related 7447's (integrated circuits) may fail while most digits work properly. Interchange known good components with suspected components. See page 24. Be sure to remove the plug-in lights carefully so they separate correctly from their sockets. Replacement lamps and 7447's are available from Fluidyne. If any soldered component is suspected, return the entire unit to Fluidyne.6. With the POWER switch ON, turn the MODE switch to the BATT. TEST position (be sure the knob has not slipped on the shaft). Is the displayed value greater than 5.0 volts? a) YES - The power supply circuit and displays are basically operational. Go to Step 7.b) NO - Review Step 2. If the problem cannot be found, return the unit to Fluidyne.7. If the BATT. TEST value is less than 5.80 volts, recharge the batteries so there is sufficient power to complete the remaining tests. If the batteries cannot be charged, Step 15.8. Turn the MODE switch to the ENGINE SPEED VERIFY position. Is 6000 rpm displayed? a) YES - The tachometer circuit in the Horsepower Meter is operational. Go to Step 9.b) NO - Is only one digit wrong? (1) YES - See step 5.(2) NO - Check for broken wires, a broken switch, etc. If no physical defects can be seen, an oscilliscope is needed for more testing. Return the unit to Fluidyne. A tachometer circuit defect will not affect the flow rate readings or horsepower tests.9. Connect the Tachometer Generator and RPM cable to the Horsepower Meter. Turn the MODE switch to any position except ENGINE SPEED VERIFY. Spin the generator shaft by hand. Is a fluctuating reading displayed (approximately 300 - 500 rpm)? a) YES - All tachometer components are basically operational. If difficulty is encountered while running on an engine, check the tachometer generator and adjustment (see the NOTE below and page 8). Be sure to install the generator only finger-tight and check that the tachometer drive ratio is correct (shaft running at 1/2 engine speed). Electrical noise (from older electric sets) can be eliminated by using a shielded 9S3048 Cable Assembly between the tachometer generator and the 5P2159 Cable. If the tachometer circuit is correct while running an engine, go to Step 10.b) NO - Check the rpm cable for continuity and for shorts, and the tachometer generator (see page 13). If the generator and cable check is satisfactory, look for obvious physical defects in the readout box. If none can be seen, return the unit to Fluidyne. Pin A of the threaded connector of the rpm cable should be connected to the center terminal of the phone jack on the opposite end. Some cables may be assembled wrong.10. Turn the MODE switch to the GAL/HR CALIB. position. If the unit has been turned on for at least 5 minutes, is the GAL/HR CALIB. value (top display) stable and within the tolerance given on the lid of the unit? a) YES - The gallons per hour circuitry is basically operational. Go to Step 11.b) NO - If the value is within 1.0 gph, the unit may simply need to be calibrated. See pages 9 - 12. Special electronic equipment is needed for calibration (see page 11), so it is suggested that the unit be returned to Fluidyne for correct calibration. It is also possible that the Digital-to-Analog Converter (DAC) is malfunctioning.