Centracom Series II Consoles

Discussion about Centracom (Button & LED / CRT / Gold / Elite), MC Series (MC5500/7100/7500), and legacy console equipment.

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Centracom Series II Consoles

Post by ayaresr »

Hi All,

It's been a while since I've been here. Looking back, it has been roughly 10 years since my last dabble into the world of Centracom consoles. I've had the bug again here recently and would like to again pursue getting one setup. I've been working on a Linux project to create a Raspberry Pi/USB SDR based receiver console to run within Linux. I'll release more details on that as it comes together if anyone here is interested. Simultaneously I have been trying to figure out how I could implement one of the B&L consoles in my home shack, and as I started digging I think I came up with the answer. If I combine the two projects, the Raspberry Pi handles all of the channelization, P25 demodulation, etc. From there, each channel outputs to its own channel on an audio device, which then goes to the input of the dual rx cards in the Centracom system. Before anyone points it out, I know I should just finish coding my interface and let it be PC based. Doing so would save space, money, and potential frustration. With that out of the way, putting one of these together is something I've wanted to do for a long time, in some sense for nostalgia, in another sense for the challenge. I think the use of the Pi and SDR is about the cheapest way to implement the RF side of this.

With all of that said, I have a few questions. I no longer have the manuals on the Centracom that I used to, so bear with me. I'll be ordering them shortly.

First, what are the primary differences between variations of the Centracom system? For example, the II, II+, Gold, Gold Elite. I know the Plus had a CRT option, and I know the Gold Elite was the newer PC based version with the gray Motorola hardware at the OP. Aside from that, are there any differences to be aware of? Gold versus non-Gold is something I don't really know the differences on.

I'd like to leave open the option to play with some of the newer stuff later, but want to primarily build this out as a B&L setup. Were there any differences in the card cage/backplane between the various versions? Obviously the cards themselves differ, but what about the backplane and cage itself?

Next up is a question on the OMI/TOMI cards. As I started back down this path, I had in my head that 1 OMI/TOMI card was required for each OP. Something I read now has me wondering if this is correct or if each channel module at the OP requires an OMI/TOMI.

If memory serves, the channel modules plugged into a board at the OP. My question here is how this interfaces back to the CEB. In consoles with multiple boards worth of clustered channel modules, does each board have a home run back to the CEB, or do these interconnect at the OP and then have a single run back to the CEB?

I do have other questions, but I'll leave it at that for now. I know some of these are probably pretty basic. I have a better understanding of these consoles than I did 10 years ago, but I still have a ways to go.

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Re: Centracom Series II Consoles

Post by desperado »

Where do I begin.
The biggest difference with a CC2 up to the Gold Elite was the OP card in the CEB and how it was programmed.
The CC2 originally Had A special set of OP cards with custom firmware that you programmed with terminal and a printer. I don't remember the names given to these cards, but I believe I still have a set of them and the documents to support them.

Then there was the TOMI. Of which there were two versions. The first version you had to create an image and write that image to a PROM that you had to erase with a UV eraser. The second version had an EEPROM that you could via a serial cable program with the required software.

Then there was the COIM. The COIM was the first to support the full PC based CIE OP position. The CIE was the gray audio interface box at the op position. COIM's would also support B&L positons of old which is how my system is configured currently although I do have a couple CIE's floating around if I was to decide to attach them.

All OP positions on all CC2 and above systems interfaced to the CEB (central Electronics bank) via a 7 pair cable or 2 7 pair cables if you got crazy with the monitor speakers. Not sure when ROCI CORI was implemented but that would extend your 7 pair cable a very long distance over leased lines and data circuits. BTW I am looking for a couple sets of ROCI CORI interface boards if anyone knows where some are.

The other major change in the CC2 to the last iterations of CentraComm consoles was the power supplies. The original supplies were large and heavy linear power supplies that were very power hungry. They used a magnetic resonant transformer to create a very clean power rail. The newer designs were switch mode and the new power supply weighed less that just the heat sink and circuit board of the old design and had much less current draw.

As far as BIM's and other cards. The original cards were red boards. All original system cards were red. This was iteration 1.0 of CC2. But BIMS never changed enough to make them incompatible. And you can use them in a Gold Elite iteration CEB with no issues.

I will also say that the CC series of consoles were built in an age before the FRU or Field Replaceable Unit. Meaning that there was FULL documentation available with schematics and troubleshooting guides for board level repair. Unlike the Motorola equipment of today where you can't get any info and you simply ship it to the depot for repair. If you are planning to ride this train, you need to find an MSS shop that still has their documentation and buy it from them, or somehow get access. Most of this stuff is being torn out and scrapped so there is little use of it in a commercial shop any more. The equipment is out of support and calling Motorola for support on it is pointless as the last guy that knew anything of it retired several years ago.
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Re: Centracom Series II Consoles

Post by ayaresr »

Hey Keith,

Thanks for the information. Interesting timing for a reply to pop up here, as I've just started back to this project after a long period away from it. I'm presently waiting for a Compact console position with power supply to arrive.

I've started building out a CEB in my mind. So far I figure I'll need:
-The cage and backplane (obviously)
-Power supply
-At least 1 timer (can I assume the newer BLN7011 will be compatible with any older hardware I may end up with, or are there instances where the BLN6650 variant is the only one that will work?)
-1 COIM with audio expansion card per console position
-Y cable to tie together the COIM, audio expansion card, and console position
-BIMs and/or receive modules
-An RS232 card for programming

Round that out with the console to CEB cabling and programming cable. Have I missed anything? There are features I'd like to experiment with and build on as this comes together, but I'd like to get the basics going first.

I'm still looking for a good set of manuals on these at this point. I also realize I'm going to need access to the programming software, which shows NLA from Motorola (not that that's a surprise). That's looking like that might be a challenge. I'd definitely appreciate any suggestions from anyone who has undertaken a project involving these old consoles. I'm not sure if I should just start calling shops asking if they still have anything setup to program these or how to go about this. I can only imagine I'd get laughed out of most shops at this point for how old these are.

Appreciate the help as always!
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