PowerTap stopped working

russelldb said:

Hi,
Just like to know if any of you have seen these syptoms and if so what the likely cause and remedial action might be:

Hub in wheel, wheel in bike all working fine yesterday. I chaged the battery and washed the wheel now I get ZERO for my power reading always.

The transmission Icon is on and transmission seems to work

The battery test (test 2) shows a good pulsing 888.

The torque test (test 6) shows a 415 on middle and bottom line even when I sping the cranks in a big gear.

The O-Rings are in place and intact. There is no moisture that I can see in the battery compartment. The battery compartment bolts had 6.5 turns each.

I tried the hub in two separate wiring harnesses. Both exhibit the same behaviour.

So...is it dead? Do I need to send it off for repair? Anyone know who in the UK can help if I do?

Any steps I can take to repair it myself?

Cheers

Russell

Is it an SL or a Pro hub?

If it's within the warranty period and it needs returning the dealer needs to sort it out.

Anyway, my SL stopped working on saturday (it's 18 months old). After having a fit and kicking it (like a 2 year old with a tantrum) i eventually worked out that the cone/axle had come undone. when i tightened the axle/cones up everything worked perfectly again, and i could relax. my blood pressure returned to normal.

I was joking about kicking it.

ric

ric_stern/RST said:

I was joking about kicking it.
ric

But did you have to retrieve it from the yard outside the window through which it was hurled?😄

These devices do sometimes fail. Some models were susceptible to moisture/condensation inside, especially with large temperature changes. It may just need to be left open to dry out. Later models seem much more resilient and mods were introduced to combat those issues. Other long time users have reported no problems with any of the models despite heavy usage in tough/wet conditions.

My Pro hub has been OK but never sees water (track bike). I did need to loctite the torx bolts which had worked loose (common on fixed gear application). I also put in the wrong batteries once recently - no wonder it didn't work!! There is a battery model that is very similar in size and actually fits the battery mount in the Pro hub better than the specified battery.

Both my (early model) SLs died and were replaced by Saris with later models at no charge (although it cost me to ship them back to US and to rebuild wheels on return). Both have been fine since and rain (heavy at times) has never caused a problem with my SLs.

I've gone through one wiring harness even though there was no visible damage and just replaced that on my race bike.

A client has just had an SL hub failure after about a year and needed to ship it back. We suspect he also had an early model similar to my original SLs.

Having access to another PT set up (your own or a mate's) is handy for diagnostics. Saris do stand by their product though.

Alex Simmons said:

But did you have to retrieve it from the yard outside the window through which it was hurled?😄

no, i just pretend kicked it in the lounge!

ric

ric_stern/RST said:

no, i just pretend kicked it in the lounge!

ric

PowerTap Pro. Thanks for the advice. I tightened the cone this morning (I had just checked the bearings as well as changing the batteries). But I also left the unit in the airing cupboard with the battery cover off overnight.

One of the two worked 'cos it is giving power readings again now.

I didn't actually kick or throw mine but I broke out some special reserve strong language and had a 30 year old man style hissy fit.

Thanks again,

Russell

russelldb said:

The torque test (test 6) shows a 415 on middle and bottom line even when I sping the cranks in a big gear.

I think this number is supposed to be in the 510-530 range or thereabouts. It's probably the reason that you're always seeing zero power--you have to apply 100 in-lb of torque just to get a positive torque value. I'd try this test again after re-zeroing properly just to make sure, and then call Saris. I think you'll probably have to ship it back to the states for them to fix it. I had basically the same problem with one of my wheels (an SL), and that's what I had to do.

rr9876 said:

I think this number is supposed to be in the 510-530 range or thereabouts. It's probably the reason that you're always seeing zero power--you have to apply 100 in-lb of torque just to get a positive torque value. I'd try this test again after re-zeroing properly just to make sure, and then call Saris. I think you'll probably have to ship it back to the states for them to fix it. I had basically the same problem with one of my wheels (an SL), and that's what I had to do.

Can you remember what caused it (or have you get a theory)?

My wheel was working after a night in the drying room but then, after a day in the cold garage it was not working last night. Today it is spending another day in a very warm, dry room.so it may work tonight.

rr9876 said:

I think this number is supposed to be in the 510-530 range or thereabouts. It's probably the reason that you're always seeing zero power--you have to apply 100 in-lb of torque just to get a positive torque value.

When you zero the torque, it's adjusting the offset so that it does send "0" when there's no torque on the hub. The torque value without the offset should be around 512, but even if it's off, as long as the torque displayed with the offset applied is zero, you're fine. I have two hubs and one reports 491 while the other reports 582. But after proper zero'ing, stomp test results for each hub are the same.

Here's an explanation from PowerTap Jesse...

Jesse said:

Test Mode 6 on the Pro or Test 3 for SL 2.4 users (note to the older black
cpu powertap users, the test modes don't exist) displays information about
the internal workings of the torque readings. The bottom display is the
offset torque value directly sent by the hub torque with no offset applied.
The hub sends a value of approximately 512 +/- 8 as the zero point. The
middle line display is the correction-offset value currently stored in the
CPU. This is the value that is changed when you do a manual zeroing of the
torque. The top display is the corrected actual torque (the bottom value
minus the middle value) or the number that is also displayed when you check
the torque from the normal ride screen.

So, as long as the top line is zero your PowerTap is reading properly, this
is one of the advantages of the system over our competitors.

The instructions on how to get into Setup Mode are on page 28 of the PowerTap SL manual:
http://www.saris.com/pdfManuals/232.pdf

...or page 37 of the PowerTap SL 2.4 manual:
http://www.cycleops.com/pdfManuals/257.pdf