Panel Instrument Lights - Switch or Knob?

[Zippy_Bird]

Hi All,

Embarrassed to ask this question, but I have not been able to discover the answer on my own... "How do I control the post lights/instrument lighting" in my bird?

This is a 1966 M20E Serial Number 1285.  It has the original shot-gun panel but did receive some upgraded Bendix Avionics along the way.

I have read through the POH multiple times, but only found mention of the pilot knee adjustable spotlight that illuminates the tank selector valve.  I have a breaker labeled instrument lights and and there are post lights all over the panel.

Did the original production provide control of these post lights OR were the post lights supposed to be ALWAYS ON?  Is the barrel adjustment on the pilot knee spotlight maybe an on/off rheostat?

Just looking for a starting point to troubleshoot my lights-out situation.  BTW - the over head spotlights work fine!

Thanks All, Zach

 

 

 

 

[47U]

20 minutes ago, Zippy_Bird said:

"How do I control the post lights/instrument lighting" in my bird?

Are the post lights OEM or were they added later?  Are they on all the time?  Is the problem that they cannot be dimmed?  Are your overhead spotlights controlled by a rheostat on the overhead panel?  Does the rheostat work?  

I would think that the post lights would (should) be controlled with the same circuit as the overhead spotlights.  If the post lights are not factory, you might be tracing wires to see where the power comes from.

[AH-1 Cobra Pilot]

On my J, I have two control knobs on the panel; one labeled PANEL LITES, the other RADIO LITES.  I think the RADIO lights up my two CDIs via rheostat and turns ON the backlight for the flaps and trim.  The PANEL uses a rheostat to adjust the brightness of the under-glare shield lights.  Your E may or may not use a similar system.  If you have a similar knob/switch, your lights may be connected either to the ON or rheostat.

Many people have had the issue of transistors blowing.  Since the rheostats have several terminals, the ON position may still work, while the rheostat does nothing.  My blown transistor is in an impossible-to-get-to place, so I have had to jury rig an alternative.

[Joshua Blackh4t]

On my 65 E, they are controlled by an overhead knob, and yes its slightly confusing.

It looks like one knob for each overhead, but actually its one for the overheads and one for panel lights. 

[Zippy_Bird]

Thanks @Joshua Blackh4t, Thanks @47U!

Going to the Airport now to test!  Z

[Zippy_Bird]

Thank you All!

I incorrectly attributed both rheostat knobs on the ceiling to one per map light.  I was very WRONG.  I did a retest in the dark hanger just know, one knob at a time.  Every single one of the panel post lights work (all red bulbs) via control of the over head passenger (right) side rheostat control.  The labels on the knobs tell all, but in my defense one has to contort forward and spin around to read them.  I feel ridiculous, but happy!  The forum saves the day again!

Much Thanks, Zach