Bright spot in gauge lighting

[Dogma]

Is there anything other than a bright bulb that can cause an annoying bright spot at the top of a speedo? When I replaced the gauge cluster after the crash, I kept the speedo, because the odometer is correct (in my mind). Everything else, including the bulbs, came from the replacement.

[Steve]

Any chance the bulb got knocked out of position and is now closer to the back of the gauge face?

Does it look like a small enough bright spot to be that, or is it a larger area, which might be part of a mask that has broken off?

.

[roeme]

IIRC I noticed the same issue on my dash – top of speedo brighter than the whole rest –, but it isn't pronounced enough to bother me.

[Dogma]

The bright spot is roughly 20 mm wide, with the lower parts of the gauge poorly illuminated (or seem so, compared to the tach). I suppose that kind of data might have been useful when I asked the original question.

I dug out my spare speedo to refresh my memory of how many bulbs there are and where. Just the one, and it's directly behind where I see the bright spot. I looked inside, and there is a shade directly in front of the bulb. It's pretty stout: A little piece of bent sheet metal, probably 0.8 mm. I don't think I could have damaged that in the crash without enough acceleration to smash the whole thing to bits. I'll have to make a little project of getting back in there to check on it, and see if maybe the bulb looks wrong or damaged somehow. I might swap the old tach back in while I'm at it. The replacement has the remains of a spider showing in the fuel gauge now, and is slow to follow the engine down to idle from about 2k.

[cowboyup3371]

Dale, even the speedometers on both of our bikes are brighter on the top than the bottom thanks to just that one light. I had thought, at one time, to maybe install a second light but after looking at it, I'm not sure it's possible. I'd love to find a way to illuminate the entire gauge better

[roeme]

A little piece of bent sheet metal, probably 0.8 mm. I don't think I could have damaged that in the crash(...)

I have found that the superglue holding these shades doesn't hold up very well after 30yrs. Mine came loose in a crash.

Also, the speedo on my 550s have two bulbs? (See the second picture in this post: Clicky.)

[Dogma]

I have found that the superglue holding these shades doesn't hold up very well after 30yrs. Mine came loose in a crash.

Also, the speedo on my 550s have two bulbs? (See the second picture in this post: Clicky.)

Oh, they're glued in? OK, I can see it becoming dislodged in a crash, then. Hmm. In the image it looks more like a spot-weld sort of thing. Hmmm. Tomorrow evening I should have time to get into mine to see if that shade is missing.

Dale, even the speedometers on both of our bikes are brighter on the top than the bottom thanks to just that one light. I had thought, at one time, to maybe install a second light but after looking at it, I'm not sure it's possible. I'd love to find a way to illuminate the entire gauge better

Scott, that bright spot was definitely not there before my crash. I can remember on several night rides marveling at how even the illumination was with just one or two incandescent bulbs, and wondering how it was done. It sounds as if we'd both like to solve the same problem.

[Dogma]

OK, I finally took time to get back into those gauges, and found a bunch of humility gumming up the works. I thought the speedo was lit with only one bulb, but there's a second at the bottom I failed to notice on the spare. Which is why the bottom of my speedo looked so dim. That bulb was toast. A quick replacement from the old gauges fixed that pretty quickly. The top third of the gauge might still be a little brighter, but I might be imagining that.

[80GS850GBob]

I just happen to have the original speedo cup opened up...the PO had gotten in there and removed whatever the speed sensor was..and he removed the whole timer box too, so I opened it up just to see what was in there. Those bulb shrouds are glued in but as said...old glue and a good whack, and they could get knocked out. Problem is that on this gauge one has to uncrimp the meter face to get into it...a real pita.
speedo cup and light bulb shroud 001.jpg

[80GS850GBob]

Here's one of the bulb shrouds...speedo cup and light bulb shroud 002.jpg

[Dogma]

Oh, now I get where there would be glue. OK. Thanks for the pics. It didn't click for me when I looked at roeme's pics.

So, if one of these got dislodged, you could theoretically pull it back into place with a dental hook and carefully re-glue it without having to open the gauge.

[80GS850GBob]

If your that lucky to pull that off...quickly go buy a lottery ticket!

[Dogma]

If your that lucky to pull that off...quickly go buy a lottery ticket!

Well, just an idea for something to try before opening the thing.

[80GS850GBob]

Hey, you can try...right? However, that cover is a wrap of sorts...to keep tension. If you look at the second pic you might see where it overlaps - other side of the tall section. You'd have to fish it in place first, then pull it back knowing it'll need an assist to get over the plastic step inside of the gauge....like I said..if you pull all that off - go buy a lottery ticket!

[Dogma]

Hey, you can try...right? However, that cover is a wrap of sorts...to keep tension. If you look at the second pic you might see where it overlaps - other side of the tall section. You'd have to fish it in place first, then pull it back knowing it'll need an assist to get over the plastic step inside of the gauge....like I said..if you pull all that off - go buy a lottery ticket!

Surgeons do stranger things, and according to a study by Dunning and Kreuger, I should be better at it than them.