This is topic CP-50 card question in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=003604
Posted by Matt Close (Member # 996) on 06-18-2002, 11:42 PM:
I have just purchased an old CP-50 with the SRA5 SR adaptor.... Don't laugh! 
In a CP-50, can I just pull out the Cat22 Dolby A cards, and slot in the Cat280 Dolby SR cards from the SRA5 in their place, thus doing away with SRA5 and inter-connects? I did a search of the forums and found a thread from a couple of years back where somebody suggested doing the card swap..... However, the Cat280 cards have extra pins at one end connected to a 3-way 'mode' switch ??? Will the cards lose their 'magic smoke' and cease to function if I try this?
Posted by Steve Kraus (Member # 476) on 06-19-2002, 01:19 AM:
Yes, you can put them in place of the Cat.22's. You will need to turn up your main fader a bit as SR tracks are at a lower level than A. This assumes your cards are Cat.280T's. The standard 280 will go into encode mode when placed in a CP. Cutting a jumper makes them playback only and gives them the T designation. IIRC, the mode switch has no effect on CP usage.
Posted by Brad Miller (Member # 2) on 06-19-2002, 02:08 AM:
Yup, ditto to what Steve said.FYI, there are people who are seeking SRA5 units. You might want to consider posting that unit in the EQ&FS forum and make some of your money back. 
Posted by Steve Guttag (Member # 268) on 06-19-2002, 06:33 AM:
Presumming your CP-50 is modified for the SRA-5 you will also have to link your "preamp out" to your "To surround adapter" barrier strips to restore the signal path. Personally, I'd keep the SRA-5, but that's just me...it is the right way to do SR on that unit and a CP-200.Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by Jamie Sanson (Member # 1161) on 06-19-2002, 07:54 AM:
Hi matt
I have been after a SRA-5 SR adaptor for years. 
If you have rack space I would put the hole unit in, That way if someing goes wrong you can bypass the SR unit back to DOLBY-A.A great way to upgrade to DOLBY-SR.Good luck.
Posted by Matt Close (Member # 996) on 06-19-2002, 04:59 PM:
Do they even 'make' Dolby A prints anymore?
Posted by Mark Gulbrandsen (Member # 72) on 06-19-2002, 06:22 PM:
You should keep the SRA5 adapter especially if you are using it at home for a film collecting sort of thing. Its very possible you could end up with some type A tracks that you would want to play back correctly. Also, the CP-50 is not all that bad of unit for analog playback. It still holds its own quite well against other analog processors, especially if you have any of the later cards in it. Also the cat 280T's are a huge drain on the feeble CP-50 power supply!! I had to change mine out to a more modern switching supply as when I added a 108C optical preamp the rails sank too low for things to operate properly.
Mark @ GTS
Posted by Pete Lawrence (Member # 130) on 06-19-2002, 09:13 PM:
Does all this mean that a CP-50 with 280T cards can't decode Dolby A? Stated another way, cat. 280T cards can't emulate Cat. 22 cards? Both sets of cards, and a SRA5, are required? The CP-50 I have (with 280T cards) has a stick on label around the format push-buttons that shows format 04 and format 05 (as 'Future Format'). Does this mean format 04 isn't really Dolby A?
Posted by Gordon McLeod (Member # 33) on 06-19-2002, 09:27 PM:
The cat 280 is a SR only card so if it is inside the cp50 that is all it can do
Posted by Manny Knowles (Member # 1171) on 06-21-2002, 12:11 AM:
It's an ugly, clunky unit, but I have to agree that the CP-50 sounds better than the newer CP-45.
Posted by Matt Close (Member # 996) on 06-21-2002, 01:02 AM:
Well I hope it sounds good .... So I guess the best idea is to keep the SRA5 with it's cards as is due to power supply issues ... I have another question also ... before I power this thing up, someone has modified the back panel ??? 
Posted by Manny Knowles (Member # 1171) on 06-21-2002, 05:54 PM:
I'll check mine but I don't recall seeing that wire there on any of them. I have three CP-50's in service.
Posted by Matt Close (Member # 996) on 06-21-2002, 08:12 PM:
( just bumpin' it up ) ... any ideas.... anyone? I'd hate to see it go out in a blaze of glory....
Posted by Gordon McLeod (Member # 33) on 06-22-2002, 10:14 AM:
The jumpers are for bypassing the old surround adapter and using a 150 card
Posted by Steve Guttag (Member # 268) on 06-22-2002, 05:05 PM:
The Cat. 280Ts should have negligable affect on the power supply. It The NR cards run off of the +24 volt rail, not the +/- 12 volt rails. There are other cards that will indeed suck down the CP-50's power supply as Mark stated...and the newer cards have LEDs on them to add yet further drain. The wires on the backplane are where the signal path is broken (just prior to the Cat. 160 slot so the Lt and Rt signals can be sent to the SRA-5 (via the preamp out) and back in from the SRA-5 (output to surround adapter).
You might want to download the SRA-5 maunual, presumming it is in the library (which it should be by now...it has the modifications that were supposed to be done).
Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by Matt Close (Member # 996) on 06-23-2002, 05:58 AM:
Steve ... Thanks for your advice. I downloaded the SRA5 manual, and you were right, the mods are text-book from Dolby. All is well