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**Old School Alert** Has anyone here re-wired a Sony CA327/CA537 and CCU-M5 (or other) to run ClearCom on?
I’ve re-wired a Sony CA327 and CCU-M5 (using 14-pin) to run TW intercom on the Sony intercom line, basically making a straight-through connection from the Intercom terminal on the CCU to the Mic In jack on the CA327.
It works, but I get induction noise from the Serial Data channel (when making adjustments on the CCU front panel, it appears on the whole party line) and ground-loop noise from the R/G/B channels (variable loudness linked to video voltage level; appears only on the local beltpack), which their commons are tied to the intercom common on the 14-pin board in the CCU.
I can all but eliminate the induction noise and R/G/B ground-loop noise by grounding the TW common to the CCU. However, that then introduces another ground-loop (albeit much less offensive) that also has a faint “flanging” sound modulating in it. The first intercom line noise is produced when the camera is powered on. The second noise created by solving the first noise is produced even with the camera powered off.
How can I eliminate this noise? Has anyone here had experience with this? I have the schematics for the CCU-M5 but I don’t have the CA327 schematics.
Thanks,
Tim -
11 Replies
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WOW that is an old school question Tim! I dealt with this MANY moons ago in a public access studio. I’ll rack my brain and check my old manual stash/notes and see if I can figure it out.
Chuck
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Cool! Thanks Chuck.
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Looks like I purged all of those old manuals during my last spring cleaning. I’ve got another idea though.
I know that Telex/Clearcom has a very extensive equipment manual library online, as well as several detailed “papers” on two-wire system set up. Many of the older ones haven’t been updated in many years, and I seem to recall they had diagrams on wiring that old Sony equipment, and what modifications you have to make. There is one document in particular that is over 100 pages long, and discusses just about every possible wiring scenario you can ever run into. If you can find that one on their site, you will probably have your answer. If you cannot locate let me know, I may have it in my PDF database somewhere.
Chuck
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I’ll search it out and let you know. Thanks for the tip!
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It was many moons ago, but I had a similar problem interfacing an older Telex system through Sony CCU’s. Although I don’t remember the details, (it was almost 15 years ago) I remember I solved the problem by using a couple of 600 ohm isolation transformers from Radio Shack at the CCU to electrically disconnect the looping problems at the input. I remember that it minimized the crosstalk from the digital CCU data to/from the camera head as well. We eventually replaced the 14-pin systems with CamPlex units using a modem to relay the CCU data down the co-ax lines to the camera heads.
TomE=MC2+/-2db
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Chuck, I’ve scoured ClearCom’s and Telex’s websites, and Google, and the only thing I’ve come up with from ClearCom/RTS is RTS saying that “extensive modification” is required to run TW on multicore lines. If you’ve got something in your database that could help, I’d sure appreciate it.
Tom (and Chuck), that’s what I was thinking – to use an isolation transformer in the CCU. I’d assume it would go between the TW ground and CCU chassis ground?
Also, I did find this in someone’s expounding on RTS’s list of tips:
- “c) If the CCU is TW compatible and not earth grounded, connect to the TW line directly, or the two wire port of the VIE306.
- d) If the CCU is TW compatible and earth grounded, use an isolation transformer and safety capacitors and connect to the TW line or VIE306 directly.”
So maybe this is the way to go? Any idea on what specs/ratings the transformer and safety capacitors should be?
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Tom is certainly on the right track, I would second his suggestion, but not having the system schematics in front of me, I won’t be able to help much with specific connections. This intercom handbook is the document I was thinking of, see if there is anything that might help in here.
https://www.rtstw.com/binary/Handbook%20of%20Intercom%20Systems%20Engineering.pdf
Chuck
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Yeah, that’s the most information I could find from either company. It tells about the option of “extensive modification” but doesn’t tell how to do it.
I know I’m stirring up issues from 1992, but we are ramping up our mobile webcasting, and I got these 3 DXC327/CA327/CCUM5 camera chains for free from a sister government agency who was upgrading, and we don’t have the money to spend on 21st century gear!
I also have a couple of DSR370’s that I purchased a couple of M5A’s to work with over 26-pin, but that’s a more difficult intercom situation (that currently just uses TW lines taped to the 26-pin cables).
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I don’t know if this might be of any help…
https://www.rcrowley.com/ComClone/SonyCCU.htmI made my own ClearCom (1st generation) clones and then interfaced the system to my CCU-M3 units.
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[Richard Crowley] “I don’t know if this might be of any help…”
Kind of. I’m actually bypassing the CA327/M5 intercom system, and straight-wiring the connectors to just run a TW signal along the same 14-pin cable using the intercom channel’s wires within the mult. I’m basically putting the intercom cable inside the mult instead of taping it to it. A beltpack connects to the mic connector on the camera. I tried to be as specific as possible about what I was doing and how I was doing it in my first post.
I’ve actually read some of the stuff from your site a couple years ago. It seems this was a fairly common modification that people used to do, although I can’t find the specific wirings of how it’s been done. It also may have been primarily on 26-pin and not 14-pin (like mine). Would you have any idea of the components needed to remove the noise? Am I on the right track with my grounding solution?
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