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Author Topic: CP65 PSU fault caused full volume? Bill Langfield Master Film Handler Posts: 280 From: Prospect, NSW, Australia Registered: Apr 2001 posted 03-07-2003 08:02 AM                        HI. This story is proberly longer than it needs to be... And is proberly not the exact chain of events, as it freaked me out and it was first thing in the morning!! Yesterday a trailer suddenly started playing at full (amp-setting) volume, then suddenly went back to normal, and everything was fine for the rest of the night. A dolby 50% test tone loop was run at the end of night and checked out ok. So I got a call last night, to before I startup today to go around and run the dolby tone in all cinemas. (mainly that one) When I got to the problem cinema things did not go well. The cinema is analogue only (our smallest) running off a CP65 and Pennywize Ezymation IV with a Century C and Speco platter (the old double roller take elevator model). After powering up the air-conds/blowers/CB's, I started threading up the test tone loop when I heard a rapid clicking (similar to a small relay cycling VERY fast) coming from the amp rack. On a closer look the sound was coming from the CP65. This sound would go for intermittant amounts of time, like for 10 secs then stop for 20secs, or just for a few seconds then stop, while this noise was happening the by-pass light would be flashing on the front panel. The sound was coming from the general direction of the right side where the power supply transformer and regulator card are located. So I selected bypass to shut most of the proccessor down, and the click went away altogether. After getting the loop threaded in such a way that it would not be trashed after 30 of turning the projector on! (I hate that) I turned by-pass off and all the proccessor's cards LEDS lit up nicely and LIFE WAS GOOD, no clicking. Set the master volume lower to 4.0 (on the Ezy) and the monitor level at zero because I don't like killing cleaners/anyone in the cinema or myself with the noise. Ran the loop and the levels were in the green SPOT on. - GET READY... Then I thought I better just have a bit of a listen to the tone, turning the monitor up, nothing, monitor to full nothing,checked cinema nothing. So selected mono/stereo/sr/nonsync1/2/slides on the ezy nothing. So selected mono/..ect anything on the CP65, then out of no where the clicking on the proccessor came back, IMMEDIATELY followed by the deafing BEEEEEEEEEEEEEE of the the test tone. Turned the monitor to zero, only to realise anyone in the cinema would be in great pain right now, because, I could still hear it very LOUDLY from in the projection room. (At this point a call came over the two-way from duty manager to turn that alarm off!) I pressed mute on the CP nothing, then remote/local and zero'd the front panel fader, nothing. Suddenly it dropped back to seem to be normal, for about 10 seconds, then it was all gone, no sound at all. I opened the front panel of the CP to see what was going on, and the thing went nuts again. Looking at the amps (and these are the only ones that are not QSC amps, instead of signal/clip leds they have VU meters) both left and right channel meters were at FULL SCALE!! So I just shut them off, I was not going to turn the projector off, as I know the wind down of the test tone would make things very bad. (Imagine BEEEEE-RRRRRRR-WWWWWW at full volume!) I think I proberly have that titius ear problem in both ears now! With amps now off, I looked at level leds in the CP, no longer in the two green ones, but in the top red one. Pretty sure the power supply is shot, techs have spare on on the way, if thats not the problem, will start pulling cards. Ran the rest of the day in bypass, which is a pain, as automation cant control sound on/off, have to be there at the start and end of every show to set the amps levels. At least in the old days automation could turn the exciter off, but RED LEDS are always on. How loud was the BEEEEEEE loop during PSU failure/fault? VERY. The amps were set to level 7 in normal operation, while I was running in bypass I could not set them (Left/right) over level 2.0 or it was too much - 3.0 was painful, so 7.0 woah! ------------------------------------------------------------------------ The bottom line of all this, is that I've never had this problem before, techs have not either and I've not read of it here on film-tech (though it is a giant site/forum and could be in there somewhere) Be the problem be the PSU unit or not, it's pretty scary that a CP(65 or others?) can suddenly go FULL VOLUME. Just a note about almost blowing my left ear drum apart. In some cinema's (getting from bio to audiotorium can be quite a walk) when running a buzz track you (well I normally) turn the montior up full and get close to it, to overcome the projector noise or use head phones. Never did I expect this thing to go SO loud, and take so long to stut it off. This is a lesson for everyone, if the fault is described as sound suddenly going VERY loud BEWARE!! (In th past that type of volume problem has been a spike or something taking the sound from remote to local) My ear still hurts and that was 18 hours ago. Bill!  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 03-07-2003 08:25 AM                        You (or your tech) need to adjust the bypass gain control on the Cat 249 Power Supply Card so that it isn't so loud in bypass mode. It sounds like the hi/low jumper (J1) on the Cat 249 might be in the high position also... so you might need to disconnect the power from the processor, pull the card and move the jumper to the low position. Of course if you replace this card don't forget to set the bypass gain on it too.  |  IP: Logged Jon Bartow Master Film Handler Posts: 287 From: Massachusetts Registered: Nov 1999 posted 03-07-2003 08:50 AM                     I'll Second what Daryl Said, you or your tech need to set the bypass level and or the hi/low jumper. Also check the bypass relays on the back of the backplane (they are what you heard clicking) three little white blocks behind the power supply. They are not soldered in, just pushed into IC sockets. Perhaps switch them with another house.  |  IP: Logged David Graham Rose Expert Film Handler Posts: 187 From: Cambridge, UK Registered: Sep 2002 posted 03-07-2003 02:29 PM                     Again I agree. However, one must look to why ther relay contacts were pulling in. Are they defective relays? or is there a problem with the CP voltage rails. If the voltages fall outside a set range, then a comparator will automaticaly send the CP65 into bypass mode. If the bypass gain is not set, then one will experience the rather annoying phenomenon you describe. All the best Dave Prof. D.G.Rose Department of Cinema Technology St. Johns, Cambridge Tel: 07787 520645  |  IP: Logged Chris Byrne Expert Film Handler Posts: 102 From: Kirwan, Australia Registered: Jan 2003 posted 03-07-2003 08:02 PM                     Yeah Bill, I can vouch for what Daryl said. I had a similar fault happen a couple of months back, when the Cat 249 Voltage Regulator Card failed and crystallised the fuses (both Normal and Bypass, which I had also tried while fault finding.) When I subbed in the new Cat 249 card (with fuses), it had the jumper that Daryl mentioned set to high and the gain was also wound up to near its peak. You should adjust all your bypass gains to match the level on your feature faders in one hit. An opportune time is on end credits when the last of the patrons have disappeared.  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 03-07-2003 09:14 PM                        Like Dave said, get the main problem fixed. But in the meantime fix your bypass level so your not winding down your amps. Before adjusting: Turn the gain all the way down (clockwise) so that you don't blow your speakers -- if you haven't already. The quickest way to adjust the level (if you don't have the gear to do it properly) is to get someone in the auditorium that isn't a complete idiot and A/B, Normal/Bypass, until you have similar levels on both. Don't foget that bypass will be a little quieter (~3dB) since it is mono -- that's fine. Of course if 'normal' isn't working at all you'll just have to set bypass to a comfortable level, and adjust it to match 'normal' when the unit is fixed.  |  IP: Logged Bill Langfield Master Film Handler Posts: 280 From: Prospect, NSW, Australia Registered: Apr 2001 posted 03-08-2003 08:42 AM                        You were all correct. Thanks Guys!! When I got into work the tech had it fixed, great work BARRY (I'm sure your lurking here after our discussion) It was the power supply, it had a dry joint on the secondary winding that supplies the 249 regulator card, so it was jumping back and forth from main supply to back-up supply (by-pass) The high volume, yup, It was the by-pass level, it was set to FULL! Everything has now been fixed. I learnt lots of stuff of him, that we have never really discussed before, Seemed to me it was in regards to things I've said here. Like how the Speco take-up plate only have 3 speeds. OFF / Equal-to-take-up-speed / Full, I always thought it was fully variable like the CNR's. I tested it and, damn it, he was right. Anyway guys, thanks for your input, because at another place I work it WOULD have required me to fix the problem if I could. The place the fault was at says CALL the TECH have him here in at 6am, which is what happened. (erm we settled for 9am:) Bill.  |  IP: Logged

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