281 Film Panning MK2 Card aka The Troublemaker Thread

[marcmozart]

Forget everything you had to fix on your console - here comes the single biggest troublemaker on my G-Series:

82E281 MK2 Film Panning Card

- responsible for crackling noises and little random spikes on different busses
- reduces the frequency response of the low end like NO other card on the 611 Channel (and this is an added card non film panning consoles don't even have)
- sits on the 611 Channel Card in a VERY improvised way, being prone to have solder joints break simply by a channel being removed.

I've had issues with nearly all of them in my console, and the problems keep coming back, so I am totally prepared to rework the connections and do whatever can be done to make these work more reliable across my console.

Funny thing is that I have two channels in my console that have the MK I Film Panning Card, and these are the only channels that show none of the problems I've seen across the other ones.
Of course, as the film panning was an option on the 4K, most of the consoles out there don't even have this card.

So, if you have worked on these cards, please share your experience - I will do the same as I examine them closer. Do the same if you have ideas for improvements.

As a start, here's a photo and the schematic.

Quick summary of what's on the card:
- a relay that is switching between Film (added Centre and Surround Channel) and Stereo Mode
- a standard 4001 Logic IC that controls the relay
- a total of 4 dual channel op-amps 5532
- a 5534 single op-amp
- three power rail capacitors 10uF 35V
- a 10uF Non Polar coupling capacitor (which I'm replacing with a 100uF Non-Polar as SSL did from Rev. 6 on
- cables directly soldered to the board that connect with the Pan Pot
- one connector that connects the card to the channel motherboard

[sintech]

This is removed from a 4k G, remembering this was in film mode as standard when put in the E series bucket, the 8k versions default as stereo in the same situation.

[marcmozart]

Yep, what you have there is the MK1 Version which I have in two of my channels. Never had any trouble with these. Pictures below!

This is removed from a 4k G, remembering this was in film mode as standard when put in the E series bucket, the 8k versions default as stereo in the same situation.

[marcmozart]

Today one of these 281 Film Panning MK2 Cards "shot" one of my channels. Must have been some kind of shortage between the different cables coming from the Pan Pot.
Can you guys point me to the Fuse on the 611G? The Channel seems dead, no LEDs, nothing, only Solo Bulb dimming at a low level.

On another note, the main problem with these Film Panning Cards seems to be the type of wire that connects them to the Pan Pot. It's quite a thick and inflexible wire and has a tendency to break (maybe because of age?). Perhaps Jim has an idea what to use as a replacement?
I will rewire all the Film Pan Boards with the Pan Pots. The cable should be flexible and of great quality. After all this is the final part the audio is passing before the mix buss.

BTW, I managed to get a better frequency response by replacing the 10uF Bipolar coupling cap with a 100uF Bipolar. That is something SSL also did going from to Revision 5 (mine are Rev. 3).
Maybe I should do all of the changes that were done to later revisions... a resistor replaced with a diode, few small changes.

[sintech]

The Pico Fuses are near the edge connector below the Input Amp, both Marked 2A (2 Amp)