Another cp200 question.

[Mikael Christensen]

Sorry for all the question about cp200:
Can I replace the fader card (cat. 117) in the Accessory unit, with cat. 517 ?

[Steve Guttag]

Yes but...

The CAT117 only contains 2 line amplifiers despite having four channels. Dolby was big on reusing things. The CAT117 was designed for the CP50...which had two CAT22s (noise reduction cards) that, each had a line amplifier. So, they sent two channels over to the CAT22s to pick up the line amplifiers that were already available.

For the CP200, they made the CAT137 as a 4-channel line amplifier card so the neighboring CAT117s could use it instead of routing all of the way back up to the Processing unit and back down to the Control unit.

The CAT517s are not constrained to 1970s discrete technology so when using a CAT517, they have their line amplifiers (all of them) on-board. Thus, the CAT137 should be bypassed. Back in the day, when one updated a CP200, they had a CAT137L (link card) to bypass it.

CP200CAT517.jpg

Note, the card between the two CAT517s is a big finger hole in it and no parts. If the card was removed, you'd see traces on the board that merely connect the inputs to the outputs.

You can remove the card and put wire jumpers on the backplane.

Left: A8 -> A4
Le: A9 -> A3
Right: A10 -> A2
Re: A11 -> A1

Just make sure you don't ever plug the CAT137 back in! Alternately, you could modify your card by removing key components (and/or cut traces) to break the signal path and jumper right on the card. If you do go with the card modification method, I would also cut/remove components that would have it connect to the power supply too.

[Mikael Christensen]

Thanks for the reply.
Maybe I wasn't clear enough, I want to replace the fader card ( cat. 117-2) in the Accessory unit, with cat. 517.
I use it for Aux1, Aux2, P and Q.

[Steve Guttag]

Oh. Theoretically yes, but it is complicated...

You still have the line amplifier problem. The Aux 1 and Aux 2 channels run back to the Le/Re CAT22 cards...so you'd need to modify the backplane to let the CAT517's output connect directly to the outputs on the terminal block while also cutting the lines that feed the CAT22 and cut the lines from the CAT22.

But wait, there's more. The Fader control line from the Control amplifier has to be buffered. Dolby chose to do that on the completely unrelated CAT213 (L/Le, R/Re interchange card). Without that card or a suitable substitute, that CAT517 won't have the fader signal.

it all begs the question...why? Are you really wanting to implement a mid-P and mid-Q? If so, why not do so externally with a suitable DSP system that will give you more flexibility.

The cool-kids converted much of those slots over to internal Surround-EX by adding another CAT150 with a suitable set of switching. Dolby actually made the cards, Cat815 that went into "P" delay line and the CAT150 going into the "Q" delay line. One then added a relay board on the output fanning strips so it would switch surround outputs between 5.1 and EX.

SurroundEX1.jpg
SurroundEX2.jpg
SurroundEX3.jpg

If you're tricking out a CP200, that is where I would go rather than a mid-p/mid-q.

[Mikael Christensen]

I want to use the two delay functions (P Q), to adjust the delay separately on the rear channels, Yamaha decoders use that function.
From Le and Re out, I use a Dolby SDU 4 to extract EX.
Removing the "link" to Cat. 22, will be no problemo :-)
I know about the Cat. 213 issue, so I made a little buffer for the fader card.

[Steve Guttag]

It sounds like you have a plan well in hand.

[Mark Gulbrandsen]

I would never use a CAT 117 in anything, nor install in a cinema anything containing a 117. They're pretty awful actually, especially at high frequencies. It's an antique, and has high distortion at high frequencies. Just a product of it's time. I installed later version Dolby fader cards in many CP-50's and a few 100's a long time ago when they were still popular. It's not all that hard to do, and the much higher quality sound is a benefit of a little time well spent.

[Mikael Christensen]

Ihigher quality sound is a benefit of a little time well spent.

Exactly why I switch to 517 in the accessory unit :-)

[Mark Gulbrandsen]

Exactly why I switch to 517 in the accessory unit :-)

Yes, am just reinforcing what you're doing. If you ever have a chance to look at high frequency low to mid level 20 khz signal from a 117 on an oscilloscope, it has bad crossover distortion, and horrible harmonics.