News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

Twilight sentinel

Started by Cadillac1967inthenorth, March 08, 2023, 09:19:04 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Cadillac1967inthenorth

My 1967 deville has twiligh sentinel (and guidematic). However, the sentinel wont turn the lights of when I torn the key off. To turn the lights of I must place the sentinel i OFF position.

Is there a schemantic för the sentinel amplifier/relay? The shop manual dont show it and states that the whole unit should be replaced.

billyoung

The Sentinel option should give you the ability to delay the Lights turning off up to 90 seconds after the ignition is turned off. Ae you saying the Sentinel when engaged will not turn the lights off at all ?. I am aware of the replace the unit statement you stated, I am not sure if anyone specializes in repairing this option.
Age 68, Living in Gods waiting room ( Florida ) Owned over 40 Old Cadillac's from 1955's to 1990 Brougham's. Currently own a 1968 Cadillac DeVille Convertible and a 1992 Cadillac 5.7 Brougham.

Cadillac1967inthenorth

Quote from: billyoung on March 09, 2023, 06:36:41 AMThe Sentinel option should give you the ability to delay the Lights turning off up to 90 seconds after the ignition is turned off. Ae you saying the Sentinel when engaged will not turn the lights off at all ?. I am aware of the replace the unit statement you stated, I am not sure if anyone specializes in repairing this option.

Yes! Turas on but not off

cadillactim

The reason the shop manual says to replace the photocell and control box together is that they have to be calibrated together. One just can't replace one or the other, even a nos photocell would not be automatically calibrated to a nos control box.

A couple of components go bad in the control box simply because of age, and a photocell also goes bad just because of  age.

I used to rebuild these units but it was a matter of too much time involved to get it working just right. Basically could make more profit rebuilding other parts. Same is true repairing the 67-68 T-T signal switches.

Tim
Tim Groves

Cadillac1967inthenorth

Quote from: cadillactim on March 09, 2023, 09:19:30 PMThe reason the shop manual says to replace the photocell and control box together is that they have to be calibrated together. One just can't replace one or the other, even a nos photocell would not be automatically calibrated to a nos control box.

A couple of components go bad in the control box simply because of age, and a photocell also goes bad just because of  age.

I used to rebuild these units but it was a matter of too much time involved to get it working just right. Basically could make more profit rebuilding other parts. Same is true repairing the 67-68 T-T signal switches.

Tim

I suppose it has something to do with the 2 capacitors. The relay gets its current from one of them, I think, when the engine is turned of. The photocell etc works. I think its just the circuit that supply the relay thats bad. I suppose Its possible to draw the schematic by looking careful on the printed circuit.

badpoints

Capacitors on a relay are usually to prevent the relay from wearing out. It lowers the inductance of the circuit when the relay is opened. Capacitors go bad when old and will short your power to ground. All old electrolytic capacitors should be replaced.

cadillactim

The capacitors in the box are what store battery voltage for the delay circuit, and that is usually the problem in the box. You can replace them, I did when I rebuilt these units.

You can try replacing the capacitors, but a 55 year old photocell will have higher resistance values than it did when it was new simply because of age. So your auto delay still may not work properly because of calibration issues with the increased resistance of the old photocell.

Capacitors are cheap, so you can give it a try.

Tim
Tim Groves

Cadillac1967inthenorth

Quote from: cadillactim on March 10, 2023, 02:02:19 PMThe capacitors in the box are what store battery voltage for the delay circuit, and that is usually the problem in the box. You can replace them, I did when I rebuilt these units.

You can try replacing the capacitors, but a 55 year old photocell will have higher resistance values than it did when it was new simply because of age. So your auto delay still may not work properly because of calibration issues with the increased resistance of the old photocell.

Capacitors are cheap, so you can give it a try.

Tim

Do you know how the photocell work in the delay circuit?
The sentinel works in al other ways. It turns light on when dark and of in daytime. Its only the delay circuit that seems to have a shortcut.

cadillactim

The photocell takes the brightness of the light and converts it to a resistance value. There is a preset resistor in the box that is lower than that of the photocell when bright light is present. So the circuit will flow through the lower value resistor to ground and the lights won't come on.

When it is dark enough the photocell resistance is lower and the circuit completes through it and the lights cone on.

Basically there is a threshold resistance that has to be calibrated for the control to work properly.

Tim
Tim Groves

Gabe Davis

Does this theory of operation apply to the 1959 Autronic Eye as well? From what I read that was a one year only design but I don't know how different from its predecessor/successors.
1959 Coupe DeVille
Rosewood with Dover White Top

cadillactim

I would imagine so, but I'm not familiar with how the tube types handled resistance thresholds.

Tim
Tim Groves