Road Bike, Cycling Forums banner

21 - 38 of 38 Posts

·
naranjito
Joined
·
785 Posts
Bill70J said:
I have a Polar 720i with the T61-CODED transmitter (N2965). I saved this post knowing I would need it some day.

My transmitter went dead yesterday, so I attempted to do the "clamshell repair' described here. Having just gone through it, I must say the appraoch is slightly different, plus the replacement battery is No. 2354 vs. 2032.

If anyone is interested and wants to try this with a T61, let me know and I will post pics.
Have you still got those pics? My T61 doesn't have much life left, and I want to try and change the battery myself. Any tips before cutting it open would be appreciated!

thanks
 

·
Registered
Joined
·
80 Posts
Discussion Starter #22
Followup:

The strap only lasted a few weeks before the silicone started to give. So I would recommend putting some heat shrink tubing to hold it together, that way the silicone is just there for sealing. I ended up getting a new Polar HRM so that I could download the data.

Here is the cost breakdown from Polar:

Transmitter replacement:
T31 (with trade-in) $24.95
T31C (with trade-in) $30.95
 

·
Registered
Joined
·
74 Posts
Washing the contact points on the strap with warm water and soap does wonders for these straps as body oil builds up and interferes with transmission. Also, on the wearlink model, cleaning the snaps with some alcohol on a Q-tip will often bring it back to life.
 

·
Registered
Joined
·
17 Posts
hi. my 720i coded t61 transmitter just died. can you post pics? i'd like to attempt to replace the battery myself ...


Bill70J said:
I have a Polar 720i with the T61-CODED transmitter (N2965). I saved this post knowing I would need it some day.

My transmitter went dead yesterday, so I attempted to do the "clamshell repair' described here. Having just gone through it, I must say the appraoch is slightly different, plus the replacement battery is No. 2354 vs. 2032.

If anyone is interested and wants to try this with a T61, let me know and I will post pics.
 

·
Registered
Joined
·
1 Posts
Thank you so much Kickit for your detailed instructions!

I have a Polar T61-CODED transmitter. I used the same method (steps 1-3) as described above to access the circuit board. For the T61, there are two small screws on the circuit board to remove. However, the T61 transmitter has two gold parts of the circuit board which extends partially into the straps. With a flat head screwdriver, you can work it in between the plastic strap and the gold portion of the circuit board to pop out one side of the circuit board. Once that is accomplished, the CR2354 battery should be accessible. Since batteryspecialists.com has them for 5.99 with free shipping, I am ordering the battery from them.
 

·
Registered
Joined
·
1 Posts
T61-coded transmitter

Bill70J said:
I have a Polar 720i with the T61-CODED transmitter (N2965). I saved this post knowing I would need it some day.

My transmitter went dead yesterday, so I attempted to do the "clamshell repair' described here. Having just gone through it, I must say the appraoch is slightly different, plus the replacement battery is No. 2354 vs. 2032.

If anyone is interested and wants to try this with a T61, let me know and I will post pics.

I'm interested and want to try this :thumbsup: Also which transmitter should i buy for the polar 720i?
 

·
Increase your member
Joined
·
56 Posts
jordachebike said:
I'm interested and want to try this :thumbsup: Also which transmitter should i buy for the polar 720i?
I would go with a coded Wearlink transmitter (just don't get the WIND version which is for the newer CS series). The Wearlink is much more comfortable and has a user replaceable battery. :thumbsup:
 

·
Registered
Joined
·
197 Posts
My T-61 Died for a Second Time

Bill70J said:
I have a Polar 720i with the T61-CODED transmitter (N2965). I saved this post knowing I would need it some day.

My transmitter went dead yesterday, so I attempted to do the "clamshell repair' described here. Having just gone through it, I must say the appraoch is slightly different, plus the replacement battery is No. 2354 vs. 2032.

If anyone is interested and wants to try this with a T61, let me know and I will post pics.
So rather than trying a second battery replacement for the T61, I elected to go with the Wearlink+ 31 Coded Transmitter. Unfortunately, I have since discarded the T61 and the battery replacement pics.

My personal experience using the Wearlink+ with the 720i is mixed. It generally works fine for me if I rigidly follow the Care and maintenance instructions, which call for washing after every use and laundering periodically. However I find that it has trouble transmitting if I am wearing more than two layers, especially if one of the layers is a windbreaker. There seems to be no other alternative, short of replacing the 720i, which continues to work fine after five years of use (but with multiple self-done battery replacements).
 

·
Registered
Joined
·
1 Posts
Great project! I followed your lead and thought the following may be helpful:
After removing the screws from the back, I was able to pry the battery out from the black case without cutting up the front and then replaced it with a fresh battery. I also used a window and door silicone sealant and wrapped it up tight with blue painters tape until it dried. Also the watch battery is the thinner CR2025 while the belt battery is the thicker 2032 both available at a drug or food store. The batteries are cheap, 2 packss for about $2.50
 

·
Registered
Joined
·
2 Posts
Polar T31 Transmitter battery replacement

DIY Repair of the Polar T31 HRM transmitter

Knowing that I’m always up for a fix it challenge, last week my wife brought me her dead Polar T31 for repair. Unfortunately I didn’t run across kickit’s article above until after the fact and took a slightly different approach to replace the battery. The entire project including pictures only took a couple of hours. Using heat shrink has the advantage of future battery swaps taking ten minutes or less.

Step 1, Use an exacto knife and very carefully remove the skin in the rectangle around the polar emblem exposing the transmitter coil and molded plastic above the battery compartment.

Step 2, Using the exacto knife carve a “nickel sized, 13/16” or 32cm” circle in the molded plastic over the battery.. Be careful not to cut through on the left side of the battery where the negative contacts are exposed, see photo. Once a groove is cut into the hard plastic use long nose pliers to remove the plastic in small pieces exposing the battery below.

Step 3, Carefully pry the exposed “V” shaped battery contact upward and remove the battery by prying it up and out.

Step 4, Slip the new battery in making sure the polarity is correct ( positive against the circuit board, negative up ), then install plastic shims over the battery to take the place of the molded plastic just removed. Pretty much anything from your plastic recycling tub, cut to size will work here. Secure shims with a small piece of tape so they don’t move around when you slide the heat shrink in place.

Step 5, Slide a piece of 1” x 3.5” heat shrink in place and heat to complete repair. Let cool and enjoy your refurbished Polar T31.

Notes:
One inch heat shrink is available on e-bay, some electronic parts stores like Norvac and Digi-Key.

Good Luck!
 

·
Registered
Joined
·
2 Posts
Yes, the T31 transmitter is completely sealed and not designed for battery replacement. Although the battery is supposed to last 2500 hours, Polar would have you send it back for an exchange transmitter. The battery life on this particular model was several years.
 

·
Registered
Joined
·
1 Posts
Thanks dude. Please note people, my unit is theT31-coded, and it has the logo upside down to the T31. Take note of the orientation of the band to determine where the battery is located. Here's a pic.
 

·
Registered
Joined
·
1 Posts
problem is the gasket glue seal is thick and likely can't be cut through with a razor

problem is the gasket glue seal is thick and likely can't be cut through with a razor in the future.

anyway, $17 replacement chest strap free delivery:Search "heart chest strap" in ebay.com

and,

full heart rate monitor set $30 free delivery:
search 'heart rate monitor watch diving watch' in ebay.com

Please reply.
 

·
Registered
Joined
·
2 Posts
T61 battery replacement

Hi, I hope you still read this forum.

I have an almost dead T61, and I'll try and replace the battery in it.
Could you please send me those pics you mentioned?

Thanks

I have a Polar 720i with the T61-CODED transmitter (N2965). I saved this post knowing I would need it some day.

My transmitter went dead yesterday, so I attempted to do the "clamshell repair' described here. Having just gone through it, I must say the appraoch is slightly different, plus the replacement battery is No. 2354 vs. 2032.

If anyone is interested and wants to try this with a T61, let me know and I will post pics.
 

·
Registered
Joined
·
197 Posts
Thanks for the question. I am out of town until Sunday. When I get home I will look at my archived files and see if I still have them. Pretty sure I do. Let you know Sunday sometime, one way or the other. I sent you a pm also.
 

·
Registered
Joined
·
197 Posts
Back In Town

Thanks for the question. I am out of town until Sunday. When I get home I will look at my archived files and see if I still have them. Pretty sure I do. Let you know Sunday sometime, one way or the other. I sent you a pm also.
I checked my archived images and did not find the Polar Battery Replacement pics. Sorry about that.

About a year ago, I sold my S720i and moved to a Garmin. I had upgraded the transmitter to a T-61 coded before I sold it, and it worked every bit as good as the original transmitter. Turns out I have a used T-61 transmitter and strap left over. If you're interested, pm me and I will mail it to you for the cost of postage. I just checked it out on our LifeCycle and it doesn't transmit, so I suspect the battery is bad.

Let me know.

Regards, Bill
 

·
Registered
Joined
·
2 Posts
Thanks for checking. No problem, I'll try and replace the battery with the pics of the t31 then.

I'll have the T61 coded, too.

So thanks for the offer, but I'm okay with mine now (unless I kill it when changing the battery, then I'll contact you again! :D)

Thanks again
Tamás
 
21 - 38 of 38 Posts
Top