To "mono" the L, C and R signals together (so those speakers would be in use with a mono film) would take more than just setting switches. Wire jumpers on the link card would also have to be changed. Not too easy, and it would have to be changed back before regular films could be run.

Regarding the DIP switch "programming" of a CP200:

The CP200 manual really isn't that well written. It gives you enough info to figure it out, but it looks like Dolby started out doing a good job on the manual, but then just wanted to be done with it. So, you have to look at it carefully and try to fill in missing bits. Which is too bad, because the processor is really well designed.

To be able to figure out how the DIP switches work, you need to know how formats are created.

If you look at the front panel of a CP200, you will see an area labeled "system status" and a bunch of LEDs. Each one of those LEDs light up when a single, specific function is activated (there are some exceptions, but I'm keeping it simple.) When several functions are combined, it defines a certain format. Not every function gets a front panel LED; there are 32 functions, but only 18 LED's.

Take 04 - (Dolby A optical stereo), for example. When you dial 04 and activate it, you are really activating the separate specific functions that make up 04, and you can see most of them light up on the front panel LEDs:

optical
Dolby A noise reduction (the "nr in" LED will light - it's just labeled nr since SR wasn't invented yet)
bass extension
mono surround
filter (switches out the mono Academy filters - there's no front panel LED for this function)

If you pull out the optical Cat.153 format card, you will see a bunch of diodes soldered to the PC board in (what looks like) a random manner. Those diodes "translate" the number you dial in (04) to the functions that you want activated (in this case: optical; Dolby A; bass ext., mono surr, filter.)

Each format card defines up to 18 formats (ie: the optical format card defines format numbers 00 to 18.) Although there are four format cards (optical, 35mag, 70mag, non-sync) the cards are really identical, except for a jumper that sets the number range (00 to 18 for optical; 20 to 38 for 35mag; 40 to 58 for 70mag; 60 to 78 for non-sync.) Dolby did not "wire-up" the last format on the card, so; 19, 39, 59, 79 can not be used by the card(s).

Dolby knew people would want to create their own formats, either for "one-time" shows or for testing. Rather than make a person solder in diodes to create a format they may only use once, they placed DIP switches on the format card. By setting the switches, you can turn on each function you want. These DIP switches become active by dialing in the next to last format number on each card (ie: 18 on the optical format card.) So, if you just wanted to hear what format 04 sounded like, only without any bass extension, (which would mean it's not really 04 anymore) you would set a few switches, dial up 18 and go.

You need to know which functions can be activated at the same time and what they do. They don't work unconditionally together. With the DIP switches, you could do stupid things like turn on Dolby tone and the mic at the same time. Also, you need know exactly what each function does. For example, the mono function does not mono the signals together, it shuts off all channels except the center, and runs the center channel through a separate preset level control.

So, for learning purposes, you could try to set up an already existing format by using the DIP switches. The usual "don't try this at home; for professional use only" disclaimers apply. But, you need to try it to learn, and with a little common sense I don't think anything could get damaged.

Lets start with the CP-200 manual. I must disagree on the quality of it. I find that it is very well written. The fact that it doesn't hand-hold people into modifying it is not a mark of being poorly written. As far as the installation and tuning...it pretty well covers everything. The User manual which seemed to always be in "DRAFT" form until the very end when the "DRAFT" was removed from the title page was reasonably good. It told you what you needed to know.

In my opinion, anyone that should be tinkering with new format creation, particularly if it involves changing the normal signal flow, should easily be able to read the signal flow page and figure out what they need to do. If you can't, you probably shouldn't. And lets say you are a marginal technician....there is/was always someone at Dolby to call...There was Clyde, Sam or Lonny (and now Ken) to help you "crack" the CP-200 for a special format (and that is just the SanFran office, there are other fine people in NYC if you are in the states). There was/is also "Dolby School" where such subjects as making custom formats can and was covered and could certainly be asked.

The CP-200 manuals always worked well for me...issue 14 was my favorite but I keep both issue 13 and 14.

Oh and John, don't be so definative on your assessment on how to handle such things as 3-channel mono. With the CP-200 there are often more than one way to handle a given situation and 3-channel mono is no exception. In fact, without much thought or even looking at the flow chart I came up with a couple of different ways. I believe there is a way to do it with just the proper diode stuffing (switch settings) and a couple of wires but no soldering needed...neither of my ways needed to be undone either. Why don't I post them? I don't condone the 3-channel mono thing; it has never sounded better to me!

Steve

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"Old projectionists never die, they just changeover!"

For this kind of situation (where a person would simply like to learn how to do something for fun) I don't think calling people at Dolby is proper. And, not everyone can go to Dolby school.

Nothing in the above statement implies opinion. Stating "Wire jumper on the link card would also HAVE to be changed." are not the words of an opinion but a declared fact. A fact that would only be true if one wanted to accomplish the goal in the way you seemed to intend (a valid way, I might add).

My point was that with the CP-200 there is more often than not, more than one way to accomplish a special format. And furthermore a 3-channel mono is just such a format.

I have no desire to post how I would accomplish this (and I confirmed, it would take merely cat. 153 programing and two wires (soldering is optional). Heck, the CP-200 even gives one the option of "draping" the sound so Center is boosted. This is something that just shouldn't be done.

Steve

>>"On the front panel of a CP200, there is a 3-position switch; "Normal, "Proj 1 and remote" and "Proj 2"
When the switch is thrown to "Proj 1 and remote" several relays are switched which feed the Dolby optical preamp directly to the CP200 output and connects the power amp inputs together. Everything gets sort of connected to everything, including the non-sync 1 signal, and the mag preamp outputs. The relays also removes power from some PC boards, but not all- the optical preamp, the non-sync and (if running mag) the mag input PC boards still need to be working. A simple 2-relay circurt with a resistor and cap will allow c/o's.
I don't think proj 3 or 4 (if the theater had them) would work. If I remember, a LED would blink, reminding you the unit was in emergency mode (as if you would forget!) Again, a resistor and cap setup would provide the blink. Problem was, you could hear a "tick" in the sound as it charged and discharged during quiet scenes."<<

I reprinted the above since it was started in a different thread and this thread seems the best to continue the discussion...

John, I don't want to sound like I am picking on you but "what the hell are you talking about?"

First the bypass circuit on the CP-200 does not connect the optical preamp directly to the amplifier inputs. The Cat. 143 Non-Sync card contains the bypass circuitry. It takes the mag preamp, optical preamp and Non-Sync 1 and mixes them with center pre-emphasis in level. In fact, the only level control (other than the amplifiers) is located on the Non-Sync card at that point.

As to changeovers...it is already built in without the external relays if you are in projector 1 remote changeover. Presuming you have the CP-200 remotes (cat 204 or cat 202 and most all of the c/o booths I've had/have them) then the changeover fucntion is already taken care of. Flip down the Processing panel and you can seen the LED on the optical preamp switch as you press the appropiate "GO" button.

Steve

If there are no further questions (posts), I assume that person is satisfied with my answer, or maybe is so dissatisfied they don't wish to pursue it any longer.

If the questioner asks for more detail, I try to gauge the way they asked to see how technical they may be, or where I mis-spoke. Then, I try to tailor an answer accordingly. I would feel pretty bad giving a misleading answer because I misjudged the questioner's knowledge, and welcome anyone else's comment to clarify.