Instrument lights

[The Veg]

Am I correct to guess that they're not supposed to be this dim? This is with 12.3-12.4V at the battery and 11.6V at the lamp. I can not discern any light from the lamp making it to visibility in the face of the instrument.

[MarkDa]

Check the earth/ground path?

[The Veg]

Earth seems good, and I even scrubbed the contact areas for the lamp holder and the corresponding surface of the instrument. Since I haven't dealt with this type of lamp before I'm not sure how bright they should be.

[billwill]

It may be worn out with age, but if you have checked all connections it is far more likely that it was intended for a higher voltage such as 18 or 24 volts.

[MarkDa]

To answer your specific question, Yes the light should be brother than that.

[alan.barker]

The earths are rings fitted to the studs that hold the instruments in place. On the studs there are little knurled nuts that can need tightening with your fingers. The earths are a daisy chain.
Alan

[gjz30075]

Ben, what's the bulb type you're using?

[The Veg]

Fairly certain that it's an E10 base but I can't make out any of the microscopic markings on it. Looks like what flashlights used in the old days.

[Chrispy]

Mine are a lot brighter than that, and give enough light to read the instruments at night (just!)

[JonB]

Remove the bulb and connect it straight to the battery. If it is still dim, you know it's faded with age. If it's bright, you know your wiring is suspect.

[EPA]

It?s worth noting that these bulbs are rated to cope with the voltage with the engine running which is likely to be a couple of volts higher and the bulbs would be brighter. Having said that I would invest in some led bulbs which would potentially provide a stronger light. I have these in my speedo and tachometer and have been a great improvement
I would agree with Jon B that connecting the bulbs directly to the battery would prove if you have a bad connection.
Ed

[The Veg]

Yeah LED is ony radar. Will probably do that since they're such a pig to access once the dashboard is all in.

[billwill]

A multimeter, Ohms, Volts, Amps is as important a tool as a socket set for classic cars.

So if you haven't got one.. Buy a multimeter as soon as practical. they are really inexpensive nowadays.

You would have a definitive answer to your dim bulb problem in just a few minutes with a volt meter.

[The Veg]

See my post up top. The question isn't whether or not the voltage and earth are good- they've already been checked; less than 1 volt drop from battery to lamp socket and the dashboard earths are connected straight to the battery via jumper cable. The question is whether the lamp should be so dim, because I have no prior experience with these. I think the answer is 'no' at this point, so I'm looking at some LEDs so I won't have to go in after them again for a while.

[mbell]

It does look dim to me but very hard to tell in photos. Does the bulb have a wattage rating? Or can you measure it's resistance?

That should confirm if it is the right bulb or not. Maybe a mute point thou if going to go to LEDs...