Friday August 29, 2014

Repairing a FitnessQuest Edge 491 Exercise Bike Computer

Author: Wayne Eggert
Date: 08/14/2011


FitnessQuest Edge 491Introduction
I've had a FitnessQuest Edge 491 Recumbent Bike sitting in pieces in my home gym for over 2 years.  That's the bad part about being motivated to fix things, you tend to keep some broken stuff that maybe one day you'll figure out =)  This particular bike worked fine for a few years and out of the blue the computer started messing up.. basically you would get 5 or 7 minutes into a workout and it would seem to end the workout and reset the machine.  Usually it's almost as expensive to have the manufacturer send you a new computer circuit board as buying a new bike.  I figured I'd keep the bike around cause A) I could still set resistance on it and then pull the batteries after resistance was set and B) I might be able to hook it up to a bike fitness program using the CSAFE protocol.


Problem Description
Computer would end a fitness program part-way through & shut off.  It was not consistent in when this would occur, sometimes around the 5 minute mark, sometimes longer.  Tried new batteries, looked for anything obvious on the circuit board and cables to the bike's computer, but did not see anything.

Further Investigation
I spent probably 20 or more hours a few years ago looking at the bike computer's circuit board, taking pictures of the front and back and tracing out some of the components.  There was no schematic for the board, so I was trying to identify the inputs and outputs -- cpu chip, speed circuitry, power supply, lcd pinouts.  I thought maybe the "speed" sensor wasn't working right and the bike was turning off because it wasn't sensing any movement.  My first thoughts were the cable from the speed sensor switch on the wheel.

The bike has a magnetic switch on its wheel.  It's pretty cool.. every revolution the magnet on the wheel passes by a stationary magnet on the bike's frame and it makes a connection.  I checked that this switch was working properly by using the continuity test on the multimeter.  All seemed fine.  I also checked the wire harness & connection to the bike's computer circuit board.  Again, all seemed good.

I was just starting to learn some about diagnosing electronics a few years ago so had used the diode test on the multimeter to test some of the transistors and also unsoldered/resoldered a few things to verify the components.

Oops.. No More Speed?
While trying to figure out if the issue was related to the speed input to the CPU chip, somehow I hosed things further.  Now when you rode the bike, it wouldn't register any speed.  This of course affected the distance, calories, etc too -- since that is all based off of your speed & resistance.  So I looked at the board for a few more days and finally gave up and tabled the project.

Enter 2011.. Free Exercise Bike
Last week someone gave me a free recumbent bike.  The bike's computer wasn't working and they said the display never came on at all.  When we loaded it to take it home, the computer made a few beeps.  I played with the batteries some but couldn't get it to beep any more.  After taking it home and exposing the circuit board / battery holder I determined the batteries weren't making a good connection.  There was no voltage at the battery tab, but the batteries themselves had about 5.5v.

I suspected something with the connection at the battery terminal or wiring to the circuit board.  As I pushed against the battery tab, the computer beeped and display lit up.  So it appeared the tab wasn't making a good connection with the battery, even though it looked like the battery was touching it.

I bent the tab with a flat head screw driver, put the batteries back in and all was good..

Exercise Bike Battery Compartment
Picture: Battery compartment on exercise bike.  Bent tab out slightly with a flathead screwdriver


Revisiting The Broken FitnessQuest Bike
Now I started thinking more about the broken FitnessQuest bike.  I knew that the computer had 2 voltages going to it -- +5v and +3v.  It does this via 3 wires to the battery compartment, red wire (power for 5v) at the 1st battery, ground at the 4th battery, and a yellow wire (power for 3v) at the 3rd battery (essentially a wire between half of the batteries so instead of 6v you get 3v).  I hooked some alligator clips to the battery compartment tabs and determined that the CPU chip and other functionality was running off of the 3v.  The motor that changed the resistance needs the 5v however.

During these little experiments I also noticed the CPU wasn't acting flaky and shutting off after a few minutes.  A-ha!!! So that was the problem after-all!  The battery tabs over time had been bent enough from putting batteries in and out that they were no longer making a good connection.  I bent the battery tabs out with good hope it would fix the issue.

Need For Speed!!
Unfortunately I still had the problem I created, no speed registering on the bike.  I traced the wires from the speed sensor switch again and everything checked out properly with continuity test.  I looked at the few components I had cut/unsoldered and resoldered on the board from a few years ago.. but connections seemed okay.  Darn...

Then I saw it!  A lifted solder pad near the CPU blob on the circuit board, possibly from a component I had unsoldered at one time.  The trace from the solder pad ran toward another solder pad around the transistors involved in measuring speed.  I checked continuity between both solder pads and.... BINGO!  No connection.  I then tried testing continuity just before the lifted solder pad and continuity was there.  So, I soldered a jumper wire between both solder pads.

Crossing Fingers, Was It Fixed?
I still wasn't 100% sure the lifted solder pad related to the speed sensor but I was really hoping that was the issue.  After hooking the computer back up to the bike and going for a test ride, it started displaying speed!!  Yeah baby!

Now for the real test, a 15 minute workout.  That was the initial problem with the bike that we had a few years back.  You'd be riding along and 5 or 6 minutes in the computer would just reset.  After 15 minutes the computer was still working and did not flake out once!

Conclusion
Often the problem is simpler than it may seem.  In the case of the FitnessQuest bike, the battery tabs for the +3v were not making a proper connection sometimes.  When riding the bike, as the bike shook slightly or you bumped the handle bar, it would cause the voltage to be lost for a split second, resetting the computer which also down-cycled the magnetic resistance on the bike.  To the user (me) it appeared that the program had ended prematurely and the computer was "on the fritz".  But it was all due to the power supply (batteries & battery tabs in this case).  It's easy for most people to look over these things and just suspect the entire computer died cause everything "looks okay" and it used to work & it now doesn't.  So I have a fully functional exercise bike back!

2012 Update - No Speed Again
The bike stopped reading speed again.  I checked my wire jumper I had added for the lifted solder pad and connections seemed fine.  At the bench I kept probing different points with the meter (black lead on ground, red lead probing for DC voltage).  Somewhere along the line I realized probing the crystal resulted in a beep from the computer.  On a hunch I finally decided to replace the 32.768KHz "watch crystal" which looked like it was involved in the timing of the speed calculations.  I bought a huge number of these on eBay for a cheap price.. after replacing the crystal the bike started reading speed again & has been working great all of 2012!  I guess after all the mis-handling of the circuit board as I was diagnosing it, I shortened the lift of the crystal.  It took a long time to get everything worked out with this bike but I saved it from the landfill and really is a good feeling to finally have it fixed!

32.768kHZ Crystal




Comments:
491 stationary bike
Posted 01/21/14 6:16PM by gizmo
While working out on the 491, pedals went into a free spin. Felt like something snapped or broke. Thought Id post first, to see if its worthwhile to open it up. Thanks
Edge 491
Posted 10/21/13 1:04PM by judyb28
A few months after I purchased my new Edge 491, I became ill, so I stored the bike away. Unfortunately, I stupidly forgot to take out the batteries. I guess I don't need to tell you that now its corrodid and doesn't work. Its practically new and I can't afford a new bike. Is there something I can do? Can I buy a new control box? Please ad use. I relay need to start using it now. Thank you so much.
Thanks sooo much for this original post and follow up comments
Posted 07/10/13 3:35PM by Anonymous Techdoser
I have the 491 and have for quite a while. Just recently the display quite working completely so thought I was going to have to scrap it. Found this post and found that bending in the connections to the batteries with a screwdriver did the trick!! Awesome! Have also nearly always had to deal with problem of screen going to -0-, 4 to 4.5 minutes in. I've always gotten around this by just hitting up or down to the speed control before it resets. So in other words right around 4 min of continued use I'll hit the speed level up or down a notch and immediately adjust it right back. This buys me another 4 mins.
Thanks again for putting this post up and saving me from having to buy another mediocre piece of exercise equipment!!
edge 491
Posted 05/04/13 12:15PM by hardenberg
are there manuals available for the Edge 491
No Speed
Posted 01/22/13 3:04PM by rsvends
First of all, thanks for all the info from earlier posts. I had no speed readout after the bike had been in storage for a few years. I replaced the "watch crystal" on a lark, but it did not fix the problem. The board looks like new ... no spills or anything. I have not checked the speed sensor. How does one get to it and what do I look for?
Repairing a FitnessQuest Edge 491 Exercise Bike Computer
Posted 11/26/12 12:25PM by Tazfix
Was having some of the same problems. E1 error code Still not sure if that one is taken care of don't won't to take the batteries out to test it yet. Made the mods to the battery case. Took the circuit broad off and found that someone had spelled something on it. Cleaned it the best I could. But was still getting a low battery Symbol. But everything worked but the mag tentsioner. So I took the motor off the bike and plugged it into the monitor. After working with it the motor started to turn. It came to the end of a cycle and popped a few times. It looks like it has a slip gear in it and was forced out of seqenace think the cable was adjusted to tight. Reinstalled everything and everything seems to be working good for now. I'll kep mt fingers crossed and update at a later time. Thank you
Edge 491
Posted 11/22/12 4:44PM by Tazfix
Came across this recumbent bike looking for a deal, have bad knees, this one has E1 and a continues beeping. Saw your post and started checking all wiring and was checking the batteries. Modified the battery pads and in the process a dime and nickel feel out of the monitor. Went to install the batteries and had to do it a couple of times before it started working. Everything seem to be working fine but couldn't get the resistists to work. After a minute the low battery symbol came on. I've had the monitor apart and it looked like the board may have gotten wet with something. Tried cleaning it the best as I could put it back together and it seem to work but the resistants didn't work still. And the low battery symbol was still on. You could push and hold the stop button and it would reset but the low batt would come back on. Took the batteries out for awhile and when I try to put them back in it errored out every time to E1. Can anyone help me? Tazfix@aol.com
Re: Edge 491 E1 error message
Posted 08/30/12 5:35PM by AceBHound
You might want to try reseating all the connectors on the wire harnesses that connect the monitor/computer to the bike. Looks like that fixed it for someone here -- http://www.fixya.com/support/t2582863-edge_491_exercise_bike_monitor_panel
Edge 491 E1 error message
Posted 08/30/12 11:54AM by bnolan55@gmail.com
Attemped to use my 491 bike the other day, after entering mode and time into the keypad the large display had lines of the LCD squares traveling from top to bottom. Once that stopped I could hear what ever makes the resistance change (it went to a higher resistance) at which time "E1" was displayed on the display. Changed batteries but all that happens now is a beeping alarm type noise and the display of "E1". Also when batteries are absent the resistance is at minimum. Am hoping there is a way to reset program. Bill Nolan
Re: replacing small crystal / oscillator
Posted 08/21/12 11:52PM by AceBHound
I was probing around on the board & got a beep from the computer when I touched one of the leads of the crystal. It would happen practically every time I touched the probe to the lead (black probe on ground on location on board, red probe touching crystal lead). I think I was essentially causing a current or voltage drop at the crystal, triggering a single oscillation for the computer to read -- so it would start the computer & beep, thinking someone was on the bike. Usually the computer turns on & bike beeps as soon as you first start peddling. So on that hunch, I replaced the crystal & all was good. I added this updated info to this repair & also a picture of the circuit board showing the location of the crystal. I probably killed the crystal after all the handling of the circuit board. If you want I can probably ship you a few crystals for just the cost of shipping -- contact me via email on the contact form on this website if interested, or you can get a large number of them from eBay like I did if you think you might use them for other projects. Apparently 32.768KHz crystals are commonly used in a lot of circuits. If you try replacing the crystal, please do comment here again on whether it fixed your issue -- might be someone else it could help out in the future =)
Re: replacing small crystal / oscillator
Posted 08/21/12 10:16PM by Anonymous Techdoser
Actually I noticed that my speed is also reading 0 as well. How were you able to determine that component was bad? How can I check if I am having the same issue?
Re: I found something in the manual. I think is interesting
Posted 08/20/12 6:02PM by AceBHound
Yes, this bike is designed for batteries, there's no power adapter for it. The batteries last a pretty long time, longer than you would expect. I use the bike 3-4 times a week and go probably 6mo+. The monitor should not turn off while you are riding the bike unless the computer isn't detecting that there is bike activity (ie. speed always says 0mph even when you're peddling). Mine stopped reading speed (always said 0mph) until I replaced a small crystal / oscillator on the circuit board -- I think I broke it while I was attempting to diagnose the board. Without that crystal it doesn't have the timing information needed to compute the speed.
I found something in the manual. I think is interesting
Posted 08/01/12 8:44AM by Anonymous Techdoser
I picked up a 491 second hand and I thought that the monitor was broken as well. I downloaded the manual and found something interesting. "The monitor will turn off automatically
after approx. 4.5 minutes of non use. All values will then be reset to "0". So I am guessing that this is by design as it runs on batteries and not on AC power. I now periodically will press the Mode button when I am on the bike to keep the monitor from turning off.
many thanks!
Posted 01/26/12 12:11PM by kendoinus
WOW! I'm experiencing exaclly the same problem, and suspect your fix will work! many, many thanks for taking the time to post.



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