Fifty Plus (50+) - blackburn delphi 6.0 problem

I wonder if anyone has seen this problem. The speedometer on my 6.0 works fine until descending on a long slope. At 30 mph it stops working correctly, starts recording slower speeds, then goes to zero and stays there until the descent is over or I slow way down.

Everything else on the 6.0 works as it is supposed to work. This is a new unit that I just recieved as a replacement for another one that was completely bonkers.

My 4.0 did that, but at 28 MPH. Messing with the magnet seemed to fix it. Near as I could tell, it was off just enough that at higher speeds it didn't trip the sensor.

Wow! Just had the identical problem starting last weekend.

Speedometer stopped on downhills (over approx 28 mph.) Then sporadically it would indicate nonsensical speeds like 42, 5 and 19 in rapid succession. Fiddled with everything with no improvement. Altogether it was "off" for approx 4- 5 miles over the course of a 35 mile ride.

Never has any problems before - unit is only about 6 months old.
Sent an email to Delphi support but haven't heard anything.

Let me know if you figure out the cause or the fix.

You may want to try fresh batteries. Also look for sources of RF interference.

I think I've found the source of recent difficulties with both my 4.0s. It's taken me a month to track down because it seemed so random and it was happening with units on both bikes. I still have to confirm, but it looks like I'm getting interference from my headlights.

Everything was fine until I upgraded from the DiNotte Ultra 5 to the DiNotte 200L. Although I didn't realize it at the time, that's when both of mine started acting up. You want weird numbers? How about 176.8 MPH and 95.2 MPH average! That's without doping! I oughtta be on the TdF! Okay. How about 47.3 when stopped for a light?

I started carrying both head units on rides and on Sunday, in the last couple of miles it went nuts. It was nearly dark and I was almost home so I waited until I got home then took out the second head unit. It started doing the same thing, only with different numbers. Moving it around, it would stop whenever I moved it away from the bars. Even if I moved it closer to the sending unit (which at the time I thought was the source of the problem) it stopped being weird.

Then I turned off the headlight. And the problem stopped for both units simultaneously. Turned it back on, and voila, the problem returned.

Once I confirm this, I'll probably be looking for new cyclometers. I like the headlights a lot and it's cheaper to change cyclometers.

Anyone interested in a pair of six-month-old Delphi 4.0s?