I have encounted a slight problem that I was hoping someone else had experienced. I have two projectors hooked up to a CP200. One has an exciter lamp based soundhead and the other I have just fitted with a reverse scan LED reader. After installing the new reader and getting the alignment spot on, I ran some film and got this crackling sound through the front loudspeakers like eggs frying. Most people whould say this is an old/dirty cell or dirt on the optics but after cleaning these elements the problem remained. I then ran some film on the other projector and found it has exactly the same problem. This has led me to beleive that the problem is not with the soundheads but the processor. The sound is only obtrusive when there is little signal however could prove to be annoying. The CP200 is equip with the old cat 108 optical pre-amp card. Could this be part of the problem or is it something else?
Apparently this sound has been present for some time now.

Russ

So what if you completely disconnect the wires into the CP200 on the newly upgraded reverse scan? Does the egg frying problem go away?

I consider it could be one of a variety of cards. The processor is now 16 years old, but from memory we a few spare cards for the CP200 in the store.

Is it only audible on optical film sound? If so I would not discount a static charge building and arcing across to the cell.

As stated, test in bypass to start narrowing down the possibilities.

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You didn't mention if it happens on Non-Sync or not. If it does, then there are only a couple of cards left or the DA-20 has a noisy connector from JM-11 or relay contact. If the problem is just on optical then we have narrowed the problem quite a bit.

One thing to check is the solder connections on the card connectors mounted to the back plane. Rewet them and many strange intermittent problems will evaporate.

What channel is it in? All or just one? The most likely suspect is the Cat 150 for most noise and only optical related in a CP-200

If you are running an older Cat. 108 (prior to the Cat. 108C) then you should upgrade as a matter of course (I doubt it is the source of you noise, but certainly possible, it is just that both projectors share rather little circuity on it). The Cat. 108C will match your new reader's (or narrow slit lens') response MUCH better. With the Cat. 108C you can expect a cleaner, quieter response and MUCH flatter in the high frequencies.

Steve

Gordon, Yes it does have Mag capabilities so that's another thing I will try as well as swapping over the C150. Interesting what Russ said about 3 conductor cable for each channel. If I get that desperate i'll do a rough cable run using that method and see how I go.

Steve, it is not present in Non-sync. I don't think it's the DA20.

I'll try to see if we have a 108C floating around. It's worth one anyway now with the improved HF response we get from the reverse scan.

David, if none of these tests fixes the problem, static could be a viable answer. Anyone else had a static soundhead?

One thing that recentlly occured to me is that the SRA5 could be faulty or not installed correctly. It does sound like i'm listening to A-type with little or no noise reduction.
I didn't have time to investiagte this last time I was on but it's worth a look.
The unit was put installed in 98 if I recall correctly.

Anyway, thanks for all the feedback. I have plenty to try now next time i'm in. I'll keep you posted!

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This will place the noise problem between the 1st and 2nd switch cards.

So what is left? Cat. 22s, Cat. 109Cs, the SRA-5 and related wiring, Special 1 (and possible poor soldering for SRA-5 modification, Cat. 160 (could be putting noise on the Lt, Rt lines), Cat. 150 (often is the source of noise problems, if yours is a Cat. 150C or earlier, then upgrade to Cat. 150F as a matter of course for improved decoding and quieter) and finally Special 2 (again, possible poor solder joints).

Knowing which channels the noise is in will help isolate the problem further.

Steve

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