Film-Tech Forum ARCHIVE: Cat 150D problem

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Posted by Matthew Taylor (Member # 2310) on 12-17-2005, 08:19 AM:

I've just got a CP-50 and bought the 150d surround card. I don't seem to be getting any surround channel from it though. I've set the dolby levels and if I put the older 150B card in, I get surround. Out of the 4 LEDs on the 150D, only the top three light up while stuff is playing. Could this be a faulty card or have I missed something obvious?

Posted by Louis Bornwasser (Member # 3063) on 12-17-2005, 09:26 AM:

The D model is a good bit more discrete especially on the surround channel. There are 3 possibilities:

1. Both work, but the D is working better; providing no surround leakage.

2. the D is partially defective.

3. something external in the CP-50 is "turning off" the surround channel.

To test, feed anything mono into both of the processor inputs ;BUT reverse the phase of either channel. This will give you surround only. (The center channel will now feed the surround decoder.) If the mono shows up on the surrounds, the surround decoder is working OK. Louis

Posted by Amanda Mundin (Member # 3386) on 12-17-2005, 11:36 AM:

Just on the Topic of CAT 150 cards, I don't know which model CAT 150 is installed in my CP55 is there any way to tell by just looking?
Should it say which model CAT 150 it is somewhere?

Posted by Sam D. Chavez (Member # 1841) on 12-17-2005, 11:41 AM:

The model number of the card is on the bottom edge of the circuit board art work, close to the stamped serial numbers.

Up through version D it was a dual sanwich board. From E onward, it is one circuit board.

Posted by Matthew Taylor (Member # 2310) on 12-17-2005, 12:29 PM:

Well, I've reversed the phase of the left input and run the dolby tone (mono, I presume) and I can only hear a very faint sound if I turn the surround amp right up. There are no leds lit up on the 150 when I do this. I guess it's kaput then :-(

Posted by Matthew Taylor (Member # 2310) on 12-20-2005, 12:59 AM:

Someone has suggested that the CP-50 may need some sort of modification to get the 150d to work with it. Is this the case? Is there some reason the D version of the card would not work with a standard CP-50?

Posted by Gordon McLeod (Member # 33) on 12-20-2005, 09:45 AM:

Matthew your profile says you are service engineer in what field, if it is cinema most has a large collection of dolby buletens regarding backplane mods many are on this site
I would suggest that you check on the terminals for the surround adapter what signals are actually present and if the command for surround is there from the format
There are many revisions of the CP50 backplane and adapter boards that without all the info it is hard to tell what the issue is
On some vintages of board the terminals for the external surround cage allows you to directly address the card
also what is installed in the 110 slot?

Posted by Matthew Taylor (Member # 2310) on 12-20-2005, 09:57 AM:

Hi Gordon, I am, or rather ,was (profile is out of date now) a service engineer for photobooths, so no, my background isn't in the cinema field. I do cite electronics and electrical work as a hobby as well, and therefore feel I would be capable of making any modifications necessary if provided with the right information.

In the 110 slot is the bypass card. This is mounted with the smaller sized edge connector in the backplane - marked 'Insert thsi end for CAT 110/160 bypass).

Not sure about how to check commands from the format - I assume you mean the switch card? (which in my case is an automation card).

Just to clear things up, the standard cat 150 works fine on this CP50. I do get surround out from that. It's just the 150d that isn't outputting surround.

Regarding the backplane version, all that's marked is A1PM1590 and in hte lower right corner as you look at therear, there's an '02'. This particular backplane has a switch for the output levels (hi/low) rather than the jumpers on other cp-50's.

Posted by Gordon McLeod (Member # 33) on 12-20-2005, 10:30 AM:

I reffer you to drawing A2B2218 fig 9.7.1 of the Dolby CP50 diagrams on this site
Unplug the link card and inject a tone at 300mv to terminals SK7/5 and sk7/1 market R and L To external surround adapter
with Dolby stereo with surround selected one should see the center channel LED lit and a signal of around 300mv on terminal sk6/7 marked c on the from external surround adapter (may not be possible on all units c out is pin 5 surround is pin I on the edgestrip)
reverse the phase of ne of the inputs and you should see that signal on the surround channel
If not I would verify that pin 15.S of the cat 150 is being held at ground which is the surround command on
If it is I would think the problem can be determined to be on the 150D and it would probably require an repair exchange

Posted by Matthew Taylor (Member # 2310) on 12-20-2005, 11:51 AM:

Gordon, thanks for your help.

I haven't got a signal generator but I ran dolby tone with the bypass card in place and checked I had a signal on pins 7 (R)& 10(L) of the rear connector of the 150 and I did (~420mv). Pin 15 is definitely held to ground as per the diagram in the manual. I had a nice output from pin 5 (C) but when I reversed the phase of one side of the solar cell, the voltage on pin 5 disappeared but no voltage appeared on pin 1.

So, does this mean the 150 card is faulty?

Is there somewhere I can get a circuit diagram of the 150D to try to trace where the problem is?

Posted by Sam D. Chavez (Member # 1841) on 12-20-2005, 05:40 PM:

Sounds like the surround output is definitely dead on the 150D.

There are no published schematics of the Cat. 150D and the parts are largely obsolete so it is no longer possible to repair a Cat. 150D. I'll check my list but I believe Dolby no longer supports this board for repair or upgrade to a newer revision. Best to try to find a used replacement.

Posted by Gordon McLeod (Member # 33) on 12-20-2005, 08:02 PM:

there is no repair exhange offered on that board to the best of my knowledge

Posted by Steve Guttag (Member # 268) on 12-20-2005, 08:28 PM:

The current Dolby RXO sheet lists the Cat 150D as a "Note 6" which reads:

"This is not a repairable item. Contact our Sales Department to purchase the replacement item that is listed in the Repair Price column."

The item listed in the Repiar Price column is the Cat 150F. The Cat 150F carries a list price of $900.00.

Posted by Gordon McLeod (Member # 33) on 12-20-2005, 08:34 PM:

Smart does make a DSP based replacement that I believe is still available for the 150 serries

Posted by Louis Bornwasser (Member # 3063) on 12-21-2005, 09:16 AM:

In the US, Dolby has a special (slightly) reduced price on replacements for certain obsoleted boards. The 150 series is one of them. Louis

Posted by Pete Naples (Member # 761) on 12-21-2005, 11:34 AM:

They do, or did, something similar here.

Matthew, I know where's there a CP65 SR that could be yours.

Posted by Matthew Taylor (Member # 2310) on 12-21-2005, 12:02 PM:

Just an update on this;

The seller has very kindly offered to replace the defective card. ALthough he's not sure, he wondered whether the card I have could be for a CP55 ands not a CP-50 and that's why it won't work. Is this a possiblity?

Pete, I have emailed you for info. Thanks.

Posted by Brad Miller (Member # 2) on 12-21-2005, 12:41 PM:

A cat 150 is a cat 150. There was no special cat 150-55 or anything like that made.

I have a spare used 150 I'll swing you a deal on if you email me privately about it.

Posted by Matthew Taylor (Member # 2310) on 01-07-2006, 09:32 AM:

Just an update - I bought a cat 150e from the seller instead and it works great in my CP-50.