Film-Tech Forum ARCHIVE: DTS + CP45 strange problem with format switching

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Posted by Luciano Brigite (Member # 1104) on 12-01-2009, 04:33 PM:

Hello ..

This is somehting new to me and started out of nowhere with a CP45 and a DTS6D.
The CP45 started to switch to NS2/digital input during the shows, this input is used to feed signals from the DTS6D but the strange thing is that the DTS unit isn't being used and is switched off ( thye film being presented at the time doesn't have DTS)wit show stopped ( interval) the NS2 led is blinking randomly, sometimes going fully on for a second or two then off again. Removing the automation/control cable linking the DTS to the CP puts an end to this random switching.
Question is.. what can be causing this problem? can it be a sign of an upcoming problem with the CP's logic control?
Again, the DTS unit is turned off, but if it's format control cable is left connected to the CP,the CP NS2 format led starts blinking and if left as is, it ends switching to that format at random. I'm lost on this because I never seen something like this..

Thanks!

Posted by John Hawkinson (Member # 1135) on 12-01-2009, 05:13 PM:

Well, bad cable, bad CP45, or bad DTS6D. Does it change if you:

Unplug the cable at the CP45 end versus the 6D end
Wiggle the cable
Swap the cable

Never heard of this... Maybe bad grounding?
--jhawk

Posted by Demetris Thoupis (Member # 833) on 12-01-2009, 05:40 PM:

5V are being send from the CP to the DTS to power up the internal switching relays for format change. It seems that when you have the DTS unit off, the formal relay for DTS pulse has remained latched and thus fooling the processor that DTS is actually active. When you power off the DTS unit make sure the discs are in stop mode and not in playback. Try switching the DTS unit on and have it on to check if the problem still is there even though you are not playing a DTS equiped feature. Try then switching it off and see if the problem occurs. If it does then it probably is the DTS6D unit. In any case in Europe there is a trade in promo for a 6D to exchange with an XD20 unit so perhaps its time to upgrade. Have in mind that the 6D is not currently supported as it outlived long enough its life span. Hope the above helps to narrow your problem down.
Demetris

Posted by Luciano Brigite (Member # 1104) on 12-01-2009, 06:27 PM:

Hello,

With the format control cable disconnected from the CP, it works ok, no led blinking and no random format change. re-connecting the format cable to the CP it starts instantly to do the problem mentioned. For now it's running with the control cable disconnected and the DTS unit wasn't being used at the time this problem started.
Switching on the DTS won't change the situation. removing the power cord from it also won't change anything. it only stops when the control cable is disconnected.

Posted by Demetris Thoupis (Member # 833) on 12-02-2009, 12:27 AM:

The relay inside the DTS must be latched. Check from the Processor end of the cable to see if Pin 25 and 13 or 25 and 10 are shorted together. If they are disconnect the cable from the DTS end and check again. If they are not when you disconnect from the DTS end the problem definately is a latched relay inside the DTS. Relays have the tendency when getting hot to stick together to the Normally Open connection.
Demetris

Posted by Pete Naples (Member # 761) on 12-02-2009, 02:30 AM:

The CP45 is a bit strange, well different to it's predecessors, in terms or automation switching and status ID lines.

Try sticking a wee signal diode in the NS2 and GND lines (observing polarity obviously). This should block the voltage coming from the CP.

I had a similar situation connecting a DMA8+ to a CP45, now the DA20 book desrcibes using some sort of automation interface card from Dolby which is not and never has been available in the UK. So I wired pin to pin and the damned thing sat there flip-flopping between NS1 and NS2. A couple of small signal diodes, I don't recall exactly what offhand, probably the same 1N4148 diodes used in Cat243/443 C55/65 logic cards, as I usually tend to have a pile of those in the car someplace.