Buzz when projector is idle

[Jesse Crooks]

I was able to do a little more troubleshooting on this today. The buzz goes away when the power supply is turned off, as well as when a piece of paper is inserted in the light path. The gear box is not grounded on either projector (I checked for continuity with a multimeter), but adding a jumper between the frame of the gear box and a ground point had no effect, so that does not seem to be the source of the problem. It’s not my booth and we have another 35mm marathon coming up this weekend, so I was not comfortable messing with the wiring on the reader. I have not had a chance to check whether the buzz is audible when film is being run, or if it’s only a problem when the projector is idle.

I was also getting a buzz intermittently on the non-sync input (which they no longer use, connected to a dead CD player) so I thought it may potentially be a grounding issue in the rack. Disconnecting the CD player eliminated the buzz on that input, but not on the film inputs. I did some poking around in the rack and everything I checked was properly grounded, and I confirmed that the outlets powering the rack are grounded. There is a ground lift switch on the rack, which I believe only affects an XLR/RCA aux input they have routed to Format 10 on the CP65. Toggling the ground lift switch and disconnecting the RCAs (which they use as their non-sync source) to that input did nothing.

And I confirmed it wasn’t the lights.

[Jesse Crooks]

What you also have on your Kinoton machines is our Cardinal interface that monitors your motor and changeover button presses to ensure that you are always on the opposite preamp when starting up. It is just working in the background. By virtue of pressing the "FWD" button, it switches the optical preamp to the other projector and then switches back when you press dowser open. That isn't factory.

Well that would explain some of the weird experiences I’ve had when running both projectors simultaneously. There have been a few instances where I’ve been testing something and alternating between both projectors rather than doing standard changeovers, and the audio switching did not behave the way I expected it to. It has only happened maybe three times, never under conditions that would be replicated during a public screening.

[Steve Guttag]

If interrupting the LED light reduces the buzz or eliminates it...then swap the supplies, they are interchangeable on a Component Engineering LS-30 (just a screw on each side of the supply holds it in...it is like a card. heck, the act of sliding it out/in could wipe a contact though, more likely a capacitor on the offending supply is ceasing to "capacitate" or a cold solder joint has revealed itself.

[Steve Guttag]

[duplicate]

[John Eickhof]

Jesse, what brand arethereaders? it sounds like a capacitor problem like Steve mentioned,I have had some problems in the past with Kelmar analog red power supplies of caps going bad. switch thgem out if you need parts or a replacement I have both CE and Kelmar units in stock

[Jesse Crooks]

Just to be clear, there’s a card in the LS-30 power supply that can be swapped out, rather than swapping the entire unit? I’ve got a handful of them in storage and could loan one to confirm the issue and hold them over until they can purchase a replacement. I’d rather not do a complete reinstall because I don’t think any of mine have the same frame size. The offending unit is a half RU. I think I have one full RU that contains supplies for analog and SRD and a handful of pedestal-mounted ones.

If interrupting the LED light reduces the buzz or eliminates it...then swap the supplies, they are interchangeable on a Component Engineering LS-30 (just a screw on each side of the supply holds it in...it is like a card. heck, the act of sliding it out/in could wipe a contact though, more likely a capacitor on the offending supply is ceasing to "capacitate" or a cold solder joint has revealed itself.

[Steve Guttag]

You can swap them between the two units. If the problem moves, you have your answer without having to supply anything. All LS-30 supplies are identical. The frames could be surface mount or rack mount...same power supply card. All the frame is doing is holding the card and transferring the contacts to the terminals/plug. The calibration stays with the frame so moving supplies shouldn't even affect that

[Jesse Crooks]

I just may need to get an LS-30 from you if that proves to be the problem. A year or two ago I had been in touch with you about purchasing a couple new sets of pad rollers for this theater. If you can supply them I’m still interested. Around that time I bought a pair of G-1985s from you… I’m hoarding those in case one of my theaters installs Simplexes in the future, but this theater could use them as well, if any more have turned up in your inventory since then. They have what I thought was an RCA style with multiple “tires” and they are pretty worn.

Jesse, what brand arethereaders? it sounds like a capacitor problem like Steve mentioned,I have had some problems in the past with Kelmar analog red power supplies of caps going bad. switch thgem out if you need parts or a replacement I have both CE and Kelmar units in stock

[Jesse Crooks]

Good news. Swapping out the power supply seems to have resolved the problem. I ran it for over an hour after making the swap and the buzz didn’t come back. Thanks for the help!

I see that Component Engineering’s website is still live and advertising film gear. Is this something they might offer a repair service for, or do we need to source a replacement?

[Steve Guttag]

Their website may be alive (on autopilot to update its date) but it is still boasting the DA-10 automation as new. I, personally, don't know of anyone that uses their stuff anymore as it all pertains to film equipment (more or less). I doubt that their traditional business would be sufficient to maintain anyone at the company. Odds are, what is wrong with the power supply is fixable (e.g. capacitor or the like). Either that or just permanently replace the module with another used one as there is bound to be MANY floating about in the post-film era.

[Tony Bandiera Jr]

Good news. Swapping out the power supply seems to have resolved the problem. I ran it for over an hour after making the swap and the buzz didn’t come back. Thanks for the help!

I see that Component Engineering’s website is still live and advertising film gear. Is this something they might offer a repair service for, or do we need to source a replacement?

Jesse, contact me. I can repair that module for a modest cost. They are pretty basic in design and easy to fix.

[Mark Gulbrandsen]

That's a pretty simple supply and can be repaired by any competent tech...