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RadMini ST2 LCD display missing number segments

Started by John Rose, October 03, 2023, 04:58:35 PM

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John Rose

RadMini ST2 LCD display missing number segments.
The bottom segments of the large 7-segments numbers are blank, but the other parts, like the lettering, "PAS", mode, lines, and battery meter are okay. See attached image.
The numbers do change to reflect current values.

Now, I'm not absolutely sure, but I think there have been times when I've powered the bike off and on, and the numbers displayed perfectly fine. I did a 13 km ride today and the numbers were incomplete for the entire trip.

I bought the bike from a friend with something like 10-15 km on the odometer, so I don't know the complete history, other than than she stored it indoors.

Any ideas?
At least it doesn't cripple the bike, and I can still figure out what it's supposed to read.
RadMini ST 2 / RadExpand 5


I've seen that in calipers and thermometers. If you took the display apart, the "screen" part would have a row of too many copper contacts to count. Voltage on a contact will cause a certain segment on the display to be black. Moisture can let enough electricity leak away that a contact doesn't have enough voltage to turn its segment black.

If that's the cause, drying can fix it. I believe Radpower says not to leave displays in the sun, but heat from the sun can drive moisture out.

John Rose

Quote from: handlebar on October 03, 2023, 07:35:25 PM
If that's the cause, drying can fix it. I believe Radpower says not to leave displays in the sun, but heat from the sun can drive moisture out.
Huh. It's worth a try.
It could also explain the intermittent behaviour, if the ambient humidity is changing day-to-day.
I must have a bunch of silica gel packets around the house. I can microwave the packets to dry them out, and then seal them in a bag with the display unit.
(re: Microwaving silica gel - I used to do that to loose silica gel beads for lightly-pressurized satellite uplink waveguide air dryers.)
RadMini ST 2 / RadExpand 5


I haven't seen missing segments, but I've seen fogging in the aftermarket displays of both my bikes although they haven't been exposed to rain. It happens in the morning. Maybe the garage can be cooler than the dew point outdoors, so when I go for a ride, air flowing through the displays leaves condensation. Sunlight clears it up.

I hadn't thought of desiccants. I have dozens in a bottle. I've done the opposite with my string trimmer to keep the nylon line from being dry and brittle. I put a wet sponge in a ziplock bag and pull it tight around the trimmer head.

Radding Along

Just buy a new display from Rad. They are around $100. If they don?t have your display in stock, purchase one for the Rad Wagon and change the wheel size in the programming mode.

To check your current wheel size, press the top and bottom buttons at the same time on your handlebar switch. The wheel size will flash on the screen. When your new display arrives, go into programming mode and change the wheel size to what?s found on your old display.

If the wagon display is out of stock, buy a City 3 or 4, or a Rover 5 display. They are all the same, just different wheel sizes programmed in from the factory.

John Rose

Update ...
I powered it up yesterday to check the wheel size setting and noticed that all segments were displaying properly. Then I (did something?) and saw that they were back to looking like the photo.

I decided to see if I could open it up and see what's what, but I could only get as far as removing the black plastic bezel.
RadMini ST 2 / RadExpand 5