This video covers general resistance troubleshooting for the Stairmaster 4400CL, 4600CL, and SC916 Steppers.
Tools Needed: Multi Meter, Jumper Wire
Resistance problems could be either mechanical or electrical in nature.
Mechanical problems are easily identified by noise. If a grinding noise is heard while pedaling, this is an indicator the drive hub assembly is having a problem. If a ratcheting sound is heard while pedaling, this is an indicator of a loose belt or a belt that could be coming off.
Once you've eliminated the possible mechanical causes for resistance problems, then it is time to investigate the electrical system.
The easiest test of the electrical system when investigating a resistance problem is to step onto the pedals and access Diagnostics. This is done by pressing Level ^, 6, ENTER. (DIAGNOSTICS will appear in the upper display window.) Press Level Down twice to get to the alternator test. (ALT TEST will appear in the upper display window.) Press ENTER to begin the test. As the video shows, resistance drops out when the test begins. So, if this occurs, press the Level ^ one time. This will turn the field ON. This verifies that voltage is passing from the display through the display cable to the lower control board. This confirms there is good communication between the console and the lower control board and that the voltage is being supplied to the alternator. If resistance is lost during this portion of the test, inspecting the cable should be the first step of action. Look for bent pins, loose connection or crimped wire.
Other components of the electrical system to inspect for resistance problems are the battery, load resistor, speed sensor and alternator.
We'll discuss the battery first. In order to get a proper reading, testing the battery should be done with the pedals in motion. There are 3 different battery readings a person may encounter. A reading of 6 VDC or greater indicates a good battery. A reading below 6 VDC but higher than 4.8 VDC indicates the battery needs charged for 24 hours. A reading below 4.8 VDC indicates your battery is bad and needs replaced. For more information, watch our battery testing video.
If your battery is good, the next item to check is the speed sensor. The speed sensor should be spaced a business card thickness away from the speed disc. If the speed sensor is spaced properly, the function of the speed sensor can be verified by confirming that proper voltage is present. For more speed sensor troubleshooting, watch our video on speed sensor testing and adjustment.
Next to inspect is the load resistor. Load resistor testing is pretty simple. Load resistors are ohm rated, and you want to verify the proper ohms for the load resistor being tested. Load resistors can cause the resistance to come and go. This means you may pedal a few steps and then the pedals will drop or loose resistance. Then, as the load resistor cools down a bit, you may get resistance again for a few steps. If the resistance goes back and forth like this, the load resistor likely needs replaced. For more information, see our load resistor testing video.
The last electrical component to inspect when investigating a resistance problem is the alternator. The alternator can be easily tested by performing the B+ to Field jumper test. For details on how to perform this test, watch our alternator testing video.
How to Test the Relay Board on Stairmaster 7000PT Stepmill
How to Test Relay Board of a Stairmaster Stepmill 7000PT Disconnect power from the machine.
Disconnect the main cable from the relay board J1 terminal. Main cable should remain disconnected for the duration of the relay board tests.
With the Power ON, place a jumper wire across the GND/BLK and RLY/RED test points. (Ensure jumper wire only makes contact with the designated test points.)
Verify that the Relay LED is lit. Remove jumper wire.
With the Power ON, place jumper wire across the +/WHT and FLD/BRN test points. (Ensure jumper wire only makes contact with the designated test points.)
Verify that the Field LED is lit. Remove jumper wire.
With the Power ON, place jumper wire across the +/WHT and with the other end touch the ALT/C, FLD/NC, and RES/NO.