Weird behavior from CP650

[Peter Foyster]

A strange thing happened on Sunday night when the centre channel level suddenly increased noticeably and then after a few minutes went down again. It was prior to the show starting while the non-sync was playing. This happened a couple of times and then started doing it again during the trailers. The main feature seemed to start out OK but then it happened again, regularly, right through to the end of the movie. The fader level remained unchanged throughout.

I had a couple of queries from patrons but most did not seem to notice or just preferred to say nothing.

I am hoping to get a tech out to check it out and I do have a spare CP650. My concern is that if I have to copy the settings across, the units may not recognise a USB to serial connector. I assume, however, that the tech will have that covered.

I thought at first it was an issue with an amp or speakers but I could see it happening on the monitor VU, which gets its feed from the centre channel audio output from the processor. Has anyone got any thoughts on what may be causing this?

If I can't remedy the problem I will have no choice but to close the cinema .

[Leo Enticknap]

This model of USB to RS232 connector works reliably with the CP650. It's what I have in my toolkit and has never let me down. I've also installed several permanently hooked to remote access PCs. I can't find it on the Australian Amazon site, though, sorry. Presumably you would be able to order it from the US site, but forex and shipping would add significantly to the cost. I have tried others that don't, which is why I always go for this model when equipping a PC to connect to a CP650. Others may be able to provide links to other models, more easily available in Australia, that are also known to work. The bottom line is that some do, some don't.

This likely is a CP650 issue if it appears on the meter on the LCD panel, and is happening with multiple input sources. I've never experienced it myself, though.

[Peter Foyster]

Thanks Leo.

The problem is I have to get it working by tomorrow or I close up shop.

I think the settings in the old unit were pretty much the same so if worst comes to worst i will just have to do a straight swap and tweek it a bit

[Leo Enticknap]

Ah.

If you have to run it flat (untuned), that won't be the end of the world. You can always copy the EQ settings across later. If your backup unit doesn't have a cat790 (AES input) card, you'll have to swap the one from the suspect CP650, if you're running AES in directly (plus Odyssey boards, if there are any). I don't think the cat790 is the source of the center channel glitch, given that you report it happening with other input sources as well.

[Peter Foyster]

Well, apparently the tech who is attending on Thursday, has the necessary cable. The replacement is the original unit that we swapped out a few years back, thinking it had a fault, which it didn't.

I guess it just leaves the question of what could possibly cause the issue? And, if it is repairable.

[Marco Giustini]

As Leo said, some rs232 adaptors work, some don’t. Keep trying and make sure you have a backup handy anyways as 650’s are old ladies and can and will fail.
never had that issue either. What software are you running?
what usually goes bad on those units is the power supply. Sometimes you can see the LCD backlight flickering, indicating a supply issue. You can also measure the voltages across the test points at the front.

[Steve Guttag]

I have had a CP650 that slammed its outputs up full (I don't recall the up/down nature that is being described here). It seemed to be part of the umbrella of "Robosound" in that a mere power cycle "cured" the issue. It comes back occassionally and the client has been advised to replace the CP650 as they have now removed their film capability (its reason for originally staying on the DCinema conversion, and before we knew about "Robosound").

[Peter Foyster]

I have been reliably assured that the cinema tech has the necessary cable to connect to the CP650 so I will assume that is not an issue.

The original unit has been at the cinema since 2014 and has not received a software update as far as I am aware. I do not know what version of the software it is running.

I think I had the "robosound" occur once in the past 7 years which was easily fixed with a reboot.

Is a software/firmware update available for the 650? I imagine that the tech will be able to do an install and perhaps that will remedy the problem.

Could it be some external source that is interfering or a fault somewhere down the B chain that is causing the issue? It is very strange to see the level in the monitor amp suddenly increase for no apparent reason. As I say, the CP650 volume level does not indicate an increase when this happens. The monitor amp gets its signal from a split in the centre channel output from the 650.

The tech will not be there until Thursday so I will be checking it out again on Wednesday. Are there any basic tests I could conduct as a user that might point to the root of the problem?

The only unusual thing I noticed with the 650 in the past week was that the display panel showed some weird hieroglyphics, that cleared when I switched the input source. There is no reason, that I can think of, to suspect that there is any connection. The unit usually stays on 24/7 even though it is only used on weekends or when I am testing.

[Marco Giustini]

The 650 has been discontinued for a while. The SW version should be displayed when you power it on.
Hieroglyphics - I suspect the PSU When voltages get unstable, the system starts behaving weirdly.

A split in the centre channel? Does that mean the centre channel out is going to BOTH the monitor AND the amplifier?

[Leo Enticknap]

Per my notes, the current software versions are 2.3.6.3 for the regular (5.1) version of the CP650, or 2.3.6.6 for the 7.1 upgraded variant. If you have anything earlier than 2.3.6.3, your unit could possibly do with upgrading, though if the bug fixes and additional features that the upgrade would bring are not relevant to your use case, it's worth asking yourself if it's worth the risk of upgrading a machine in which the firmware is stored on flash memory, given the risk of bricking it if the procedure goes wrong; especially if there is no more OEM support for the machine in question.

I've only ever seen hieroglyphics during the boot sequence, which then clear to the regular message: I've never seen them suddenly appear out of the blue.

[Marco Giustini]

Upgrading is always risky but the firmware is stored on an EEPROM which can be re-programmed with a cheap programmer. Granted, I wouldn't expect the technician to carry a programmer with them

[Jim Cassedy]

Just chiming in to say that I have that same DB-9 > USB adapter that Leo recommends and can confirm
that it is one of the most reliable I've had. I also have a slightly cheaper one in my toolkit, and it doesn't
always communicate with certain devices on occasion. But I've never had trouble with that one like Leo
mentioned. I also like the fact that it has little LED's that give me some sense of signal communication.
activity. Back in the pre-USB days of working with modems & numerous RS-232 ports on various devices,
I was always a big fan of "blinking lights" on modems & T-1 terminal adapters - which were of great help in
confirming connectivity, & troubleshooting stubborn connections.

[Phil Ranucci]

Curious about the "robosound".
I have one 650 that occasionally has a high pitched buzzing that goes away with a reboot, in non-sync, I've never switched it to format 11 when it's happened.
I don't believe it's happened during a show.
I don't believe it has a 790 card installed, wasn't that the cause?
Thanks.

[Steve Guttag]

Robosound (in all of its variants) is a "feature" of the CAT790 card, in particular. It affects primarily, if not exclusively, audio coming in via AES (Digital Cinema). I would think their Non-Sync buzzing is something else.

[John Thomas]

Can confirm the NS will get robotic occasionally as well.

My understanding is that the later revisions of the 790 card only go robo, but earlier versions will also affect channel volume.