Turn off digital

[Frank Raia]

Is there a safe way to add a switch to the led on digital penthouse reader?

I know they are NOT hot swappable. I am hoping this is not the answer.

I have a BACP penthouse SRD reader and a CP500.

I already have a switch that turns off my BACP Analog led and to turn off the DTS 6d when not in use. IMG_20250901_112141.jpg

[Ryan Gallagher]

I've read here of many having added this feature. So I assume yes, but curious as to best methods as well cause I would also like to save those LEDs when we are running stereo, mono, or 70mm.

702 readers in our case.

[Josh Jones]

Break the LED line and add a switch. The case is steel, so just drill a hole to mount the switch.

[Frank Raia]

Josh, adding a switch to the led line will not violate the hot swap rule? Just want to make sure. Have you done it?

[Steve Guttag]

The hot-swap issue is the CCD, not the LED. On the BACP, the LED wires that route around to the reader PCB is where you break the line and put in a switch. And yes, I've done it. We used one of the available holes on the top of the reader and just mounted a small toggle switch:

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[Frank Raia]

Thank you Steve.

[Josh Jones]

That's one of the reasons I like the older penthouses, separate power supply for the LED. On my setup, both the optical reader supply and the penthouse supply are on a separate switched outlet controlled by the automation. When the automation run status is present, a relay switches an outlet on the back of the pedestal on, and the readers light up. If I'm running an analog movie, I just switch off the penthouse reader. For print QC, I'll often switch off the analog reader so digital dropouts are more noticeable.

[Steve Guttag]

I always preferred basement readers. I only have the LEDs come on when the movie is running (either). Normally, each LED is powered separately so it is possible to turn it off for analog only movies.

I liked basement readers because:

1. I could make them track reliably.
2. If they aren't tracking digital well, then they are not tracking analog well either. Fix the problem.

[Ryan Gallagher]

We can kill our basement optical diodes, but it requires giving up our cooling loop pumps too.... all on the same pedestal circuit. Something else to consider!

[Frank Raia]

IMG_20250906_093217.jpg Added the switch! And reminder label, even though I'm the only operator, lol

[Mark Gulbrandsen]

I'd place the switch on the DC line from the processor that powers the entire penthouse, not right on the LED.

[Steve Guttag]

I feel a copyright infringement lawsuit coming on...

[Tj Hopland]

I presume you would want to switch the power going into the little led driver board rather than between the board and the led itself? If nothing else maybe a little more current and voltage to keep the switch working on the power side than the led side?

[Frank Raia]

Tj I didn't mess with any of the supply lines. I put the switch in line going to the led.

[Tj Hopland]

I'm curious to hear where Steve put his. Either side is easy to access because its after the camera board. Mark's method to kill the whole head is slightly more involved because you have to get into that shielded cable which is certainly possible just not as easy as where its paired off going in and out of that little driver board. Also could be a little more hassle because the mod would then be part of the cable rather and soundhead rather than just the soundhead so do you then put another connector in for if you had to separate the soundhead and cable for some reason? Again not like any of that is that difficult just thinking about pros and cons out loud.

I think one reason my brain is going to the feed side of things is from when we were first doing analog conversions and there was quite a few systems out there that didn't have any way to kill the optical input other than killing the light. Not a problem with the lamps they have a built in slow start but with the leds if you switched on the led with no film it it you were at the very least clearing some dust out of your stage speaker, maybe even clearing the cone right out of the basket. Also didn't work well if you were using the same contacts/switch that had been switching 4 amps for the previous 20 some years, not enough current to get through the crud on the contacts. Switching the AC to the LED power supply was the way to go you got a bit of a ramp up or if you had the CE LS40 you could use the terminals they provided to trigger the power supply to ramp the led on or off.

As long as you had a real processor and didn't care when the LED came on I would wire the power supply power up with the projector motor so it came on with the motor. That way you were not running it when not needed and there was a time buffer between the LED coming on and the processor going live so if there was any sort of thump or noise from it coming on it should not be making it out to the speakers. I did the same thing with the Cat 700 701's to save on light source life too and same thing that seemed to be enough time that even if you were doing change overs it had time to sync and buffer up or what ever magic was going on.