CP750 level drop disease

[Mark Gulbrandsen]

10 years is pretty decent life

I couldn't disagree more. Dolby used to build broadcast quality products that lasted a very long time. I had CP-50's CP-65's and CP-500's go 20+ years without failure, although the Cp-500 screens were pretty dark by then... it seems with the advent of the CP-650 that the quality slipped down hill a bit, and then and even more so with the CP-750. Very glad I went with USL during conversions, because they are all still running just fine and some are well over 10 years old now.

[Marcel Birgelen]

I'm not convinced that capacitor failure is at fault for the level drop.
Dolby has never published the signal path for the 750, let alone a schematic. It's pretty much impossible to troubleshoot a multilayer SMT board without a schematic and a boardview. I don't know if there's a spec for output voltage with alignment signal and specified channel fader level.

I also couldn't find any schematics and Dolby doesn't want to give them to you either. When I repaired our failed CP750 a few months ago, I just did it by pure luck. In my case, it seemed to be capacitor failure, despite not one capacitor measurably having failed, but there is obviously a big chance this has been caused by something else.

Still, someone with decent soldering skills and about $15 to $30 worth of components could easily recap one of those failed boards (replace all the capacitors besides those tiny SMT ones, which seldomly fail b.t.w.), we would know soon enough if it is a simple capacitor failure after all.

So, nobody here with a "faded motherboard" willing to give it to someone who wants to try a re-cap if he/she doesn't want to try it him/her selves?

[Randy Stankey]

There are so many times, lately, when I feel like an old man standing on a soap box, ranting, “Kids, these days, have no sense of responsibility!”

When I think about it, I realize that their was more truth in what those those ranting, old men in my past we’re saying than I gave them credit for.

Do I get tired? Do make mistakes? Do I, sometimes say, “Just get ‘er done?” Yes, yes and yes.

Life is work. Life is hard and often painful. People need to get used to it.

I remember days when people complained about having to carry heavy film cans up a flight of stairs.
Then I remember people whining when they had to plug a hard drive in and wait for it to ingest.
I have heard people bitch about having to go up to the roof and clean snow off a satellite dish, maybe one per year.

I have done all of those things and, as hard as they may have been to do, the fact remains that we are paid to do a job and there’s no getting around it. Work is work.

When I work hard to make things for industry and for people who use those things, I feel pissed off when I am made to feel like others aren’t returning the favor.

”Damned kids, these days, don’t know the value of work!”

[Carsten Kurz]

As to CP750 spare parts pricing - this is a public document:

https://www.dolby.com/in/en/professi...parts-list.pdf

[Steve Guttag]

You may "think" it is a public document and Dolby may not necessarily blocked its download (I don't know) but in the lower-right of every page is "Confidential" which is not on their public documents. It could be lazy formatting left that on but it is still on the document and thus isn't anything I'd post or email.

[Marcel Birgelen]

It's a corner-case situation. The thing has been indexed by Google, so if you know what to search for, it will turn up in Google's search results. I think that the general consensus is that anything you put on the World Wide Web without really protecting it, can generally be assumed "free to access", as in, you can't blame anybody from accessing this information, even if it was supposed to be private.

What's not so certain though, is what the legal situation is, when you share something you've found that's clearly private information.

[Carsten Kurz]

It's the first hit when you google the conspirational words 'dolby price list'. And it's not the dealer price list (Dolby does have a separate dealer price list). Like it or not - it is certainly public, because Dolby made it so.

[Leo Enticknap]

You may "think" it is a public document and Dolby may not necessarily blocked its download (I don't know)

It's on the public Internet, fully search engine indexed, and available for all to see at the click of a link. The footer has to be a mistake. In any case, no court would entertain the claim that this document actually is in any way confidential for a nanosecond, and no Dolby representative could sanely take offense or have any sort of an issue with us discussing it on a public forum, as long as that discussion does not include information that has actually been given to us in confidence (e.g. dealer pricing).

[Steve Guttag]

You'd be amazed at what people may or may not do, especially when it comes to law. When it comes to the wacky rules of copyright (seriously, life of the author +70 years?). I recently saw a documentary based on patents whereby shell companies buy up patents for the sole purpose of making money on common practices. At the end, the "star" and doc maker discussed that patents should be more like copyright and some how that a patent shouldn't last more than 5-years (someone who has never invented something from start to patent award to see just how long it can take to profit off of an invention...if ever).

Do I think Dolby cares, in this case or would they go after anyone when one can download it via link like that (no password or other restriction)...of course not...however, when I see "Confidential" I don't post/email it. It is safer. Posting the link, as Carsten did, is fine as it was to the author's site.

[Marcel Birgelen]

All things considered, I think this link is mostly harmless (just like humans, according to the Hitchhiker's Guide to the Galaxy). If e.g. one of your customers would want to do a price check on the stuff you're offering to them and they're only halfway competent at Googling, they'll probably already find exactly this file. If Dolby put the information out there by mistake, they can easily fix it and we know some of their folks are at least monitoring this forum.

The law is a difficult thing and stuff might play out differently in different jurisdictions or even with a bunch of different judges in some cases. But, it's not as easy that anything that can be found on-line is free to share with everyone.

Let's say while googling around you find an exposed Excel sheet that contains all kinds of private information of some customers of the site you found it on. Let's say it contains stuff like addresses and maybe even credit card information. In this case, you could reasonably assume that this information is not supposed to be public. And while legally nobody can really do anything about you stumbling upon it, if you would share this information, then you'd probably committing a criminal offense. If you'd profit of sharing this information, the consequences will most likely even more dire.

Now, as if things aren't complicated enough... let's suppose this information you found is highly classified, contains private information, but also contains information that would be important for the public to know? But yeah, I guess I'm going a bit too off-topic for a topic about premature CP-750 failures.

[Mark Gulbrandsen]

JSD...why?

I can tell you the JSD was at least 4 years newer in design than the CP-750 was when it hit the market, There were prototype CP-750's installed at The Megaplex District multiplex in Salt lake City around 2007ish. The JSD-100 had newer D to A and A to D converter chips that ran at higher speed, 2 to 4 channel matrix done by D to A instead of a 2:4 analog decoder, better product support at the time, and no stupid front panel display to fade over time. It also sounded better in direct comparison tests to a CP-750 in the same sound system, in fact it did not sound digital at all. And not one that I installed has ever died, and while that outcome certainly can't be predicted before hand... it reflects my past experience with USL over the years.

[Steve Guttag]

And yet...no complaints on the CP750 and particularly no complaints on its sound. Quite the opposite. The JSD60's service record for us has been mixed and the JSD100 has not enough sample size for me to comment by personal experience. What JSD100's I've worked with and heard have never had me feeling that they were in any way superior, acoustically to the CP750 and feature wise, they just weren't what I was looking for. But hey, anyone that likes them are welcome to them. I agree that USL support was second to none, however. There was never a single person there that I didn't like.

[Dave Macaulay]

I've been replacing CP750 main boards. Out of the box they come with (unreleased) software version 1.2.6.8, and the display reads "MFG - 7.0" on powerup.
This version allows the saved serial number to be changed to match the chassis it goes into using the setup program. After installing v1.2.8.3 the board SN can not be changed... if it was not revised before updating, it stays at 603647 - all the new boards I've opened have this SN.

[Steve Guttag]

Good point Dave! I forgot about that one.

[Dave Macaulay]

And a Dolby tech has told me that the issue is due to capacitors... the MANY rectangular caps all over the board - these are dropping off somewhere around their design MTBF so it can't really be called premature. I haven't spec'ed or priced out replacements but maybe we will have a "slow time" project to recap the ones I'm swapping out for new this week. I think these caps should have been a higher lifetime type, if they exist.