GArmin GSC 10 speed sensor not working
richarde_2005
Posts: 4
A few months ago I noticed that my Garmin Edge 810 had started to flag that I'd apparently stopped whilst climbing steep hills. Didn't think too much about it until doing some maintenance on a bike stand, and realised that only the cadence sensor was working and not the speed component on the GSC 10 speed/cadence sensor. (With the speed sensor not working the Edge 810 had been relying on GPS only to determine movement, and so, on steep hills with low climb rates, it thought I was stopped!). After doing some Googling I found a number of posts - including one on this site - that suggested battery replacement, leaving the battery out overnight and so on. However there were also a number of posts detailing a failure in the wiring or of the reed switch itself so this was also a possibility.
Wiping a magnet past the sensor you could hear a slight tick which indicated that the reed switch was opening and closing. Taking the sensor arm off the unit however, and it was clear that one of the wires to the reed switch was disconnected. (This may be an assembly or general design issue with the wire being under too much tension?).
So I thought I would share my repair process which has restored the speed sensor to working condition.
The unit is made in two halves which are then bonded together (with glue or ultrasonic welding?) so you can't simply take it apart to get at the reed switch.
1. Cut the remaining wire about 1cm outside the main sensor unit so that the arm containg the speed sensor could be completely removed.
2. Use a fine hacksaw to carefully cut half way through the back of the sensor arm just up from the elbow where the reed switch is located.
3. Use a sharp knife to break the joint in the plastic of the elbow and pry the back section away. If you're lucky (like I was) the piece remains slightly attached to the rest of the housing but otherwise just keep it to hand. The small pcb with the reed switch on it is then exposed and can then be pulled out of the housing.
4. Solder a new pair of fine wires onto the reed switch pcb and feed them back into the arm (from the bottom end), re-inserting the pcb.
5. Join the new wires to the wires from the main sensor unit making sure they don't short together and put it back together and test.
6. Replace the elbow section and reglue the joint - I used Bostik Hard Plastics clear glue. Job done.
I have photos of the process available but haven't been able to work out how to add them to this posting. They can be downloaded from the link below:
https://app.box.com/s/5heg43zskjzuyv3ejysei9csm0lvsrji
Wiping a magnet past the sensor you could hear a slight tick which indicated that the reed switch was opening and closing. Taking the sensor arm off the unit however, and it was clear that one of the wires to the reed switch was disconnected. (This may be an assembly or general design issue with the wire being under too much tension?).
So I thought I would share my repair process which has restored the speed sensor to working condition.
The unit is made in two halves which are then bonded together (with glue or ultrasonic welding?) so you can't simply take it apart to get at the reed switch.
1. Cut the remaining wire about 1cm outside the main sensor unit so that the arm containg the speed sensor could be completely removed.
2. Use a fine hacksaw to carefully cut half way through the back of the sensor arm just up from the elbow where the reed switch is located.
3. Use a sharp knife to break the joint in the plastic of the elbow and pry the back section away. If you're lucky (like I was) the piece remains slightly attached to the rest of the housing but otherwise just keep it to hand. The small pcb with the reed switch on it is then exposed and can then be pulled out of the housing.
4. Solder a new pair of fine wires onto the reed switch pcb and feed them back into the arm (from the bottom end), re-inserting the pcb.
5. Join the new wires to the wires from the main sensor unit making sure they don't short together and put it back together and test.
6. Replace the elbow section and reglue the joint - I used Bostik Hard Plastics clear glue. Job done.
I have photos of the process available but haven't been able to work out how to add them to this posting. They can be downloaded from the link below:
https://app.box.com/s/5heg43zskjzuyv3ejysei9csm0lvsrji
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