Sportsmith Blog

StairMaster Stepper Resistance Troubleshooting

About This Video

This video covers general resistance troubleshooting for the Stairmaster 4400CL, 4600CL, and SC916 Steppers

Tools Needed: Volt 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.

For more information about this video click here.


SPORTSMITH™ Announces StairMaster® and Schwinn Fitness® Product Support Tech Center

Tulsa, OK – June 7, 2010 – SPORTSMITH™, the nation’s largest supplier of fitness equipment parts, today announced its alliance with StairMaster® and Schwinn Fitness®. Beginning June 1, 2010, the company will launch the Official Authorized Product Support Center, sourcing all non-warranty replacement parts and providing technical support worldwide for legacy StairMaster® and Schwinn Fitness® Models.

An additional 20,000 square feet of warehouse space accommodates its expanded parts selection. StairMaster® and Schwinn Fitness® non-warranty equipment owners will now receive around-the-clock service through the new StairMaster Product Support Center accessible at

Using this web portal, consumers may purchase replacement parts, view parts diagrams and watch repair tutorial videos. Live web-based technical support will also be available via online chat. Improved shipping rates have already been secured.

"This alliance allows us to better utilize our staff and focus on growing our business,” explains Dustin Grosz, StairMaster CEO. “We chose SPORTSMITH™ because of their vast knowledge of the StairMaster® and Schwinn Fitness® brands, including their innovative warehouse capabilities and same day shipping of fitness equipment parts and fitness products."

Moving forward, StairMaster™ will concentrate efforts on manufacturing and warranty services for existing business segments. “As the business grows, we are relying on SPORTSMITH™ to be the experts and manage the non-warranty aspects,” continues Grosz.

StairMaster® and Schwinn Fitness® models include:

StairMaster® Stepper Models

  • 4000PT
  • 4100PT
  • 4200PT
  • 4400CL
  • 4400PT
  • 4600CL
  • 4600PT
  • 7000PT StepMill
  • SC916 StairClimber
  • SM916 StepMill

Schwinn Fitness® Bike Models

  • AC Classic
  • AC Performance
  • AC Sport
  • IC Elite
  • IC Evolution
  • IC Evolution SR
  • IC Pro

With a 15-year legacy, SPORTSMITH™ is proud to be the nation’s leading product support company with a solid reputation within the fitness industry. The company has built its stellar reputation by consistently delivering world-class quality product support, efficient customer service and expert technical support. The company offers the most technologically advanced user-friendly website in the fitness industry.

"We are honored to be chosen by StairMaster® as the company’s preferred product support provider,” states Brad Schupp, President of SPORTSMITH™. “We’re ideally poised to add real value to the company’s existing operations. We’re driven to ultimately enhance the industry as a whole by helping organizations focus on their core strengths, whether that is manufacturing world-class exercise equipment, developing the finest fitness facility within their community  by making exercise equipment maintenance as fast, easy and cost efficient as possible. SPORTSMITH™ is a proven asset to the OEM manufacturers we work with and health clubs alike, that incorporate SPORTSMITH™ product support services within their business practices."

For more information, call 888-713-2880 or visit


Founded in 1995, SPORTSMITH™ is the nation’s largest supplier of fitness equipment and parts for health clubs and health-conscious individuals. The company is recognized for its superior quality, express same-day shipment on all orders, comprehensive selection of more than 40,000 individual items and overall value, with products 10 to 30 percent below competitive retail prices. The company serves customers through its 40,000 sq. foot state-of-the-art office warehouse, with orders placed by mail, fax, phone or online via its direct mail catalog and secure ecommerce website.