Dim Tachometer.... bulb or ground?

[al_roethlisberger]

I've always noticed that at night the illumination of my tachometer has never been quite as bright as the speedo. But riding last night up to Oakland and back to meet Ed Milich and Co.... I noticed that it had gotten significantly more dim, and even wavered in brightness as I hummed along.

 

Having read Carl's write-up on Guzzitech: http://www.guzzitech.com/CuringTach-Elec-Carl_A.html

 

... I have a few observations and questions before digging into this.

 

First, I noticed that if I tapped on the tach, it would brighten back up for a moment. So, would this indicate a bad bulb/socket? ...or the ground ...and which one, bulb or instrument cluster?

 

And if it is the bulb, can one get into the tach to fix the bulb without the trouble of prying apart the tach as described in Carl's description above?

 

I can figure all this out by just taking it apart I suppose, but thought I'd ask.

 

I can certainly add the ground wires as suggested, as that's easy enough, but wanted to check into whether this might also be the bulb issue based upon others' experience.

 

Thanks!

al

[mik]

Al, I had a previous post up here but decicded to delete it...being that I have different instruments it probably wouldn't have helped. Still, it's probably just a loose or bad bulb....or at worst a loose connection somewhere.

[TX REDNECK (R.I.P.)]

Al , I have a freind that works at the " Johnson Space Center " I showed him your post & he agreed with mik.

[Murray]

Bulbs tend to ethier work or they don't very rare fo it to be a half measure. Would be going for some corrsion on the bulb holder or a sad earth. Not sure on the V11's but on the 1100sports the rubber isolation mount pionts are used as earths where they mount to the front fairing frame.

[callison]

The mounting post on your instrument is starting to detach from the instrument housing. Bet you a beer. I've seen this happen fairly consistently with the Veglia instruments.

[al_roethlisberger]

The mounting post on your instrument is starting to detach from the instrument housing. Bet you a beer. I've seen this happen fairly consistently with the Veglia instruments.

 

 

Thanks Carl.... that's the type of answer I was looking for

 

 

So, do I have to do the "pry apart" surgery to get in there and JB-Weld it? Or can I repair the stud without disassembly?

 

BTW, just as an aside, can one replace the instrument bulbs without prying apart the bezel to get to them? Just curious.

 

al

[belfastguzzi]

As far as I remember from opening the tacho to try to clear the Lake Como fog, the bulb just pulls out for replacement, once you have taken the unit out of the plastic housing. That's where I (vainly) directed warm air in.

 

That's probably enough access to fix the stud too. No need to pry the thing open. Surely NO-ONE would be so contrary as to make bulb replacement that difficult?

 

So it only takes a few minutes, though I don't know if your fairing slows things down.

[al_roethlisberger]

Awesome! Thanks

 

The instrument nacelle is one of the few things left on the bike that I haven't disassembled yet ....so was curious what I was "in for"

 

al

[belfastguzzi]

You must be disappointed that it will be so easy

 

I bet you really wanted to prise that bevel off.

[badmotogoozer]

He'll probably pry it off anyway, maybe in search of more fuel capacity...

 

 

Rj

[Mike Stewart]

The mounting post on your instrument is starting to detach from the instrument housing. Bet you a beer. I've seen this happen fairly consistently with the Veglia instruments.

 

 

Thanks Carl.... that's the type of answer I was looking for

 

 

So, do I have to do the "pry apart" surgery to get in there and JB-Weld it? Or can I repair the stud without disassembly?

 

BTW, just as an aside, can one replace the instrument bulbs without prying apart the bezel to get to them? Just curious.

 

al

Al,

 

I just happen to have a spare tach lying around if you need one. It does sound like a ground issue and I know of the stud that comes loose. You can always ground the tach housing anther way if the stud is loose (drilling a hole into the tach housing and pop riveting the ground to it is one way). It just might be a loose fit between the bulb socket and housing. Either way, the tach needs to come out. Just two 8mm. nuts hold it into place.

 

Mike

[al_roethlisberger]

Yep,

 

Uninstalled the tachometer by removing the two 8mm acorn nuts on the back of the plastic instrument nacelle. Then it comes right out.

 

It was then very obvious what Mike, Carl, and others have been talking about where the case of the tach is grounded, poorly at that, by a loosely attached eyelet under the press-fit mounting stud. The studs are both a tad loose, but loose enough that the ground eyelet moves all around. I tested the lighting of the tach by wiggling the ground wire, and sure enough... it wavered.

 

So, I tapped onto the ground wire with a vampire clip, and added a ground to the case with another eyeled under one of the various screws on the back of the tach. It seems solid now.

 

Of course, the tach is still a bit more dim than the speedo, but not as bad. But I don't think they were ever perfectly equivalent in luminosity

 

....at least it shouldn't blink now

 

al

[Guest Jeff Kelland]

In search of perfect luminosity one could install a variable resistor in the wire to the light and then adjust it to be equal, you know, if you just couldn't live with it! Sorry Al, I just couldn't resist, pun intended!

[Mike Stewart]

Darn,

 

Another lost sale.

 

Mike