Film-Tech Forum ARCHIVE: Dolby DA20 faulty or not?

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Posted by Andy Frodsham (Member # 4061) on 05-10-2011, 01:13 PM:

We've just purchased a secondhand DA20 and new CAT 702 reader ready for installation over Summer.

I thought I'd quickly test both units before putting them away for the next two months. I temporary fixed the reader onto our projector and ran the reader cable through to the DA20. I connected the audio output from the adapter to our CP65 but not having the appropriate gendered cable couldn't connect the automation link, thinking, perhaps wrongly, that this would only affect the way that the DA20 addressed the processor!

When I ran some film through the reader, all the digital signal level indicators activated and error rate count displayed correctly (a rather good 2 to 3). Unfortunately, the output signal and digital signal indicators did not illuminate and no audio was sent from the unit.

Does the 'sense' cable need to be connected before an audio signal is sent to the output connector of the DA20 and in order for the output signal indicators to illuminate?

Do I need to use special non-standard 25pin cables to link the DA20 and CP65?

I'm hoping to do another test of the units later in the week - this time with the 'sense' cable connected. I'm hoping this will show that all is okay?

Should I be prepared for a dissapoitment?

Yet another stupid question, I'm afraid. Sorry guys!

Posted by Gordon McLeod (Member # 33) on 05-10-2011, 01:24 PM:

Did you set the CP selector correctly

Posted by Andy Frodsham (Member # 4061) on 05-10-2011, 01:34 PM:

Thanks Gordon! I'm pretty sure I did, but will need to check tomorrow!

Would this make any difference if the 'sense' cable wasn't connected to the processor anyway?

Posted by Brian Woods (Member # 3521) on 05-10-2011, 01:47 PM:

You may want to check the 611A CP Interface Board if all of your settings are correct. I have had a few of them get zapped. The rest of the processor will act normal, but the channels will not have or show any output.

Posted by Andy Frodsham (Member # 4061) on 05-10-2011, 02:02 PM:

The card is still showing the selected projector and power-supply rail status!

Should the output present LEDs illuminate without the DA20 being connected to the processor?

Posted by Markus Ito (Member # 6207) on 05-10-2011, 03:10 PM:

I could be wrong but I don't believe the connection to the processor would change the behavior of the DA20 since the processor merely selects between the inputs. When we switch between analog and digital, the DA20 still processes the digital signal, but it doesn't get fed through the processor. It sounds to me like the problem lies with the processor since you say the the error correction display is working.

When you say the digital signal levels activated what do you mean exactly? On each of the outputs, if no data is being sent from the reader, one led should be lit. I think its the second from the bottom. When you run film, those 4 leds in each of the channels should alternate depending on the signal strength for that particular channel. If that isn't happening, and the error display is still showing a number, it could be a problem with the DA20.

Posted by Brian Woods (Member # 3521) on 05-10-2011, 03:47 PM:

The card will still register fine, but on the LEDs where the signal output, you will get nothing. If you turn the selector switch around the dial, you may get the channels back (like on A, B, C, but these are test modes) see if that works. If that does, and doesn't work on 1 through 3, you have a bad card. I had this happen recent and it was a card issue. The card got zapped, and when I put the new card in, all the channels came back and things were normal. I found it happened when I hooked up the automation up and it had voltage on it for changing.

Posted by Andy Frodsham (Member # 4061) on 05-10-2011, 03:55 PM:

No, the digital signal level indicators are behaving normally. The bottom LEDs are illuminated until film is run through the reader. When I run some film, the individual channels show activity. Similarly, the the error rate window is displaying normally.

The output signal indicators on the 611A are not illuminated. Also, the 'digital' or 'analog' LEDs are not illuminated on this card. The 'projector', 'motor running' (for selected projector one) and 'power rail' LEDs are illuminated.

More significantly, no audio is being outputted from the DA20!

Posted by Sam D. Chavez (Member # 1841) on 05-10-2011, 07:34 PM:

What type of cat. No. 611 do you have? There is an A version which is considered more desirable.

You need to study on the description of the different modes possible on the CP selector switch. There are some "forced" digital positions which are good for testing this sort of thing.

Is the nine pin d-sub plugged in? Usually this has a white default jumper between pins 1 & 9 if I remember. This jumper eliminates the need for a motor start relay and sets it to default to projector 1.

Posted by Andy Frodsham (Member # 4061) on 05-10-2011, 09:04 PM:

The unit is fitted with the 611A card, this being one of the main reasons that I bought this particular unit.

The D sub shorting plug is indeed fitted and the relevant 'projector' selected LED is illuminated on the bottom of the 611A.

The unit follows the normal boot-up sequence.

Posted by Andy Frodsham (Member # 4061) on 05-11-2011, 05:40 AM:

Following my second test today (this time with the relevant 'sense' cable connected)I can confirm that the DA20 is functioning perfectly okay.

The unit obviously requires the automation link with the processor to be present, before it can either output audio or display level on the otputs LEDs! Switching-off the associated processor (in our case the CP65) also caused the DA20 to cease audio output and LED output indication.

So, the absence of a linked processor actually prevents the DA20 from producing an output. Makes sense I suppose, since all the control of the adapter is allocated to the linked processor anyway!

Thanks for the help and suggestions. I'm glad I haven't got to go hunting for a repacement CAT 611A!

Posted by Christos Mitsakis (Member # 143) on 05-11-2011, 08:54 AM:

The control cable is needed because in normal operation initially the cinema processor triggers the output of the DA20. Afterwards the DA20 takes over until another format is selected (presuming you have the auto digital disabled).
Sam gave you a hint: by setting the CP selector to 9, A (in your case) or B you force DA20 to remain in digital and have active output.