Homebrew01

It's the yellow head unit, "SL" hub. Bought it used 2 years ago and it's been fine up to now.

If I clear it -CLR-, then mount it and start riding slowly on the trainer, the speed jumps all over the place, but no power shows at all. Even when I stop, the speed numbers jump arounf for a bit more then just stop at a number, and never go to 0.

It seemed to be working fine on the road the other day, but just cut out towards the end. The wire seems to be ok, nothin obvious and I don't remember anything that would have damaged any of the parts.

Something's wacked.

svtmike

Battery in the hub?

Homebrew01

The batteries are fairly new in hub & head.

svtmike

I'd still eliminate them as a cause. After that, about all you can do is swap in a known good hub/head and see what's what.

Homebrew01

Thanks. A couple friends have PT, so maybe I can swap to test each part.

jrobe

Always test the batteries with a voltmeter (or just replace them). I had to replace my wired PT wiring harness at least once. As I recall I had to update the firmware once to correct some error readings.

Psimet2001 

Wired or wireless? Check the transmission icon to make sure it's transmitting and then check your offset value. DOn't be surprised if you have to send it in. If it's too old of a unit they will extend an upgrade option to you

Homebrew01

Wired sharkfin. I'm at work now, so I'm not sure about any icon. It must have been transmitting to some degree because the display was all "--" until I started pedaling, then the speed numbers went crazy while soft pedaling (45, 23, 17, 32 ..). The power display remained "--"

cmdr

I've been having the same problem. Saris alludes that you can do a calibration test if you are using one of their head units (not a Garmin like I have). If you have to send it back to them to be calibrated it will set you back $350.00. When I expressed how expensive that seemed the guy replied "Well yeah, it's expensive equipment." Kind of a ******y thing to say if you ask me. I'd like to know what you can find out and I will post any results I have.

Psimet2001 

I hate playing remote troubleshooter with old PT units as it was never really my forte to begin with. I have had this issue arrise before. I remember Saris telling me that the unit was too old for them to service and offered me a deal on a new unit which equated to what I could get at the time through other deals....so I just sold it off - as is...after disclosing it's condition - to someone who said he could fix it.

Check the offset number. It is most likely out of range. Make sure the hub is dry and that the contacts for the battery are good. use someone else's wiring harness to make sure....those cables in those harnesses used to break - often.

Psimet2001 

Well...it is. The process for servicing and troubleshooting takes a great deal of time on their end. They have made a concerted effort to reduce this by redesigning their units. At one point they talked to me briefly about possibly being a service center for them as they were thinking about outsourcing their service.

In reality it's a fairly high precision piece of equipment that gets treated very poorly. The older wired units were more susceptible to issues. Honestly I think all of the units have flaws that seem to have been resolved with the new G3 design.

MJH2

I've had this happen twice, on two different powertaps. The first one was cured by zeroint the torque (which you should do often, anyway). That happened after I replaced the bearings.

On the second one, I replaced the battery and it went nuts shortly thereafter. After some phone calls back-and-forth with Saris, I updated the firmware for the headunit and everything worked fine.