I've got 2 Shutter Precision PD8 hubs. One on the road bike and a PD-8X on one of the mtbs. I use an Exposure Revo front light which I switch between bikes.

Issue 1:
On the road bike, I recently installed a Busch and Muller Toplight View rear light on my pannier rack. Previously used an Exposure Redeye, but on the seatpost it occasionally gets blocked if I have stuff on the rack. I can't see the light properly as I ride, but spinning the front wheel up by hand when the bike is on the workstand, or having a look when stopped and the light is powered by its standlight, its frankly crap. Compared to the Redeye which is like the sun, I can only get one of the two LEDs powered up, and that only dimly. I've checked the polarity of the connector (the other way it didn't work at all) and the checked the current of the output of the Revo when stationary at the plug and at the rear light and its pretty much the same, so no major losses in the wire. As I say, the same output power to the Redeye is painfully bright. Any suggestions?

Issue 2:
Riding the MTB the other night, I got a branch caught in my front wheel. It pulled the plug out of the socket and also pulled the hub-connector around the axle a bit. Reconnecting, the front light, it didn't turn on when I got going again. Sure enough I've checked and one of the wires got pulled out of the connector, put it back in and still nothing. Using a multimeter, my hub isn't producing any current at all (for reference, the road-bike hub produces "some" noticeable current when spinning up by hand).
Again, any suggestions?

Using a multimeter, my hub isn't producing any current at all (for reference, the road-bike hub produces "some" noticeable current when spinning up by hand).

Are you testing straight from the hub or the end of the wires? If the wires, then maybe the inner wire go damaged in the incident?

For issue 2. Use the multimeter on resistance and without turning the wheel check for a reading across the two hub terminals. This should be very low, mine measures 2.5 ohms. This is the coil of the generator. If there is no reading then the rotation has severed a connection internally, the coil wires will be very thin.

For issue 1, the red eye is powered by approx 3.6 to 4 volts DC, which the revo outputs. Without knowing your rear light is it designed to be powered by 6 volts from a dynamo system, hence it will not work correctly fed from the revo output.

Thanks numplunz.
I'll check resistance tonight.

And AARRGGHH about the light output. I assumed all dynamo rear lights were 6, apart from a few 12v ones. Need to to do some digging into 4v-6v conversion

Just connect your new light directly to the dynamo by doubling up the wire connection if you intend to keep it, its what its desingned for.
Doing a quick google it looks like the light has some capacitive stop reserve.

Your problem is your trying to mix a dynamo powered device with an exposure device which was primarily designed to plug into the range of battery powered lights, so they created a DC output on the Revo.

Best bet is to buy a cheap dynamo light and put this on your road bike with the new backlight, then if needed cut and extend the cable on the red eye exposure one if a longer lead is needed.

Thanks.

Road rear light now a veritable beacon!

And MTB dynamo hub definately borked I see Ison are distributing SP Hubs so I'm going to see if they can help, rather than sending it back to Taiwan.

ir_, try getting n touch with the guys at SP distributors in Germany if Ison can't help. The guys there are very helpful. http://www.sp-dynamo.com/Support.html

Cheers James.
I've actually been in touch with Vic at SP in Taiwan, through Lloyd at Ison. He agrees its an electrical connection failure, so the hub is going back to him to be fixed (and have new bearings in it)
Means I need to strip and then rebuild the wheel, but Vic has suggested a design improvement to prevent it happening again. Watch this space...

That's good. Vic's a good guy, really into the product.