Bench test instrument panel - lights, etc

[AR67GTX]

Trying to get ready to install my refurbished instrument panel. I tested each dash light individually and cleaned all the socket contact areas up but I wanted to test the assembled panel before putting it in the car.

I have my brand new battery and the instrument gage panel on my bench. I ran a ground wire to neg battery pole and to the housing and a hot + wire to a probe/alligator clip to attach to the plug pin on the rear of the gage panel. I wasn’t getting any lit bulbs so I put a test light in line with the positive lead and it lights up when I touch to the bulb base contact area but the bulbs are not lighting up (or at most very dimly). Our Razorbacks game started so I had to quit before going any further. Not sure what I’m doing wrong or what is wrong.

I have an auxiliary ground lead attached to the screw on the speedometer housing but grounding to it or the ground plate on top the panel doesn’t seem to make any difference. It’s probably an issue in how the light bases are grounded that I’m not clear on. Is one the clip on one side of the bulb socket the ground and the clip on the other side power? How are the individual bulb sockets grounded.

thanks

 

[Canadian1968]

Each bulb has a power wire ( usually pink ). Then they are grounded threw the instrument cluster , which is grounded to the dash frame when installed in the car . There are 2 style bulbs in the dash. THe style that light up your speedo , blinkers, and tach/clock. These are the ones that are feed power threw individual wires. If you look at the socket , you will see the claw like metal tabs around it. These ground when pushed into the instrument cluster. The other style are the push in, which light up the small gauges ( fuel , oil, heat, ammeter ) These are feed power threw the circuit board that they are installed in , and grounded the same way.

I think I explained that right !

 

[AR67GTX]

Maybe - this is a 66 and these are all bayonet type sockets and all are feed by the printed circuit from the two - 5 contact stud plugs. Just thinking I put some no-ox electrical contact grease on the copper area of the bulb contact after cleaning them - which is a conductive grease. I wonder if that could be bypassing power past the bulbs to the ground.

 

[AR67GTX]

After the bummer game ( lost by 1 point after failed 2 pointer) I studied it more and realize everything grounds through the printed circuit to the attachment screws that secure it to the gage panel housing. So cleaned the bulbs, holders, contact points on circuit board at bulbs and ground/attachment screws and everything lights up now.

 

[Triplegreen500]

Yep, I remember clipping my ground to the screws that hold the circuit boards to the chassis on my '70 Charger cluster. Using LED lamps, I had to bench-test everything to make sure I didn't have any installed 'backwards'. Incandescent bulbs don't care about polarity, but LEDs do. I knew I had good power connections by using one of the old bulbs that still worked; from there I started installing my LEDs.

I had about half of them backwards. THAT would have pissed me off, if I'd found out after I reinstalled the cluster!!

Glad you got yours figured out!