EMT245 digital section (doc needed)

[psych60s]

Hello guys

I have a EMT245 on the bench which was in poor condition. Bad power supply, bad RAMs, cleaned them and their sockets. Was ok but problems popped after some hours of use. Memory errors sometimes appears. Sometimes they can be cleared thanks to the RESET switch, sometimes not.

I have to check the digital part of that beast  but it appears that nobody on earth has the technical doc for it. Could someone tell me if there is hope to see them one day?

Thanks a lot!

 

[synthiaks]

Have you tried emailing EMT? They might have a service manual for sale, if so, it will be costly though.

 

[jensenmann]

Try EMT, but IIRC they sold their docs to David Kulka of studioelectronics.biz when their lifelong service tech retired. David is a member here, btw.

 

[psych60s]

I have tried EMT, in fact the studio which owns the EMT bought the service doc. We received it and when I checked it, what a surprise: digital section schematics were absent. I emailed EMT and they told me that have nothing more. I was quite disappointed as they never told us these schemos are not included.

I'll try asking David. It is always difficult to ask for such things, which are essential info for each tech, to another tech I'm not close friend with. I presume there is some NDA in there too.

 

[Michael Tibes]

Afaik all the chips in the EMT 250 were filed, so that the numbers were unreadable. Only very few people in the pre internet era were able / alowed to fix them. Lexicon schematics (224 / 480) were unobtainium as well back then. It was their copy protection, so I am not surprised that there are still no official schematics available for EMTs 'cpu'. Nevertheless I hope you'll get hold of what you need, this is the internet age... 

Michael

 

[psych60s]

You're right Michael. Internet is great for that, allowing us to get useful schematics.  back in the days, as far as I know by talking with fellow techs (because I wasn't born in the 80s), they could have access to some info directly from the manufacturer, often because the studio they were working for was a big, well-known place. Manufacturers were notrelunctant to give some tips or useful infos.

Try asking SSL, Lexicon, or other companies. Some have vanished, and if they still exist they just tell you that they can't do anything, their archives are empty blablabla. In other words they tell you it's over, stop living in the past.

 

[gyraf]

Try maybe asking  someone that software-implemented the unit? They probably sourced all available hardware information in the process.

Or even a competing company's R&D department?

Jakob E.

 

[Bo Deadly]

Try replacing all the electrolytics around digital stuff maybe? I would say it would be weird that it works and then sometimes it doesn't if the digital stuff were truly dead. Intuition would suggest that it's not and it's just peripheral components that are failing. But with such an old piece of digital gear it's hard to say how the digital will behave when it starts to die. But be careful. No doubt really old digital chips probably have crappy input protection. Probably a good idea to wear one of those wrist straps whenever touching the boards.

Here's a link to someone claiming to have the service manual:

https://groupdiy.com/index.php?topic=27733.msg357434#msg357434

Honestly I'm not sure it's worth it since it will no doubt stop working quite regularly. And performance-wise it's really just a novelty. You could upgrade by hiding the PCB of a $40 Behringer digital reverb pedal inside. People will be blown away by how awesome it sounds.

 

[psych60s]

The service manual is probably missing the digital part too, and the guy said he doesn't have the scans anymore. David Kulka also told me he's never seen the schematics for that unit.

Digital gear could be tricky, and sometimes it is not 0 or 1. I've seen bad RAMs in Lexicon that were easy to fix because it wasn't working from the beginning and crashed like mad. But on some occasions you have to dig around because you have a nice reverb but the tail is distorted, or you have a RAM failing because of heat...

I do have a static wrist strap when working on such beasts.

About reliability, vintage digital gear are quite reliable. They have been in use for more than expected but suffer being not serviced. Some experiences I have:
Lexicon (200, 224, 480, PCM) are quite okay, they suffer from bad ram or bad line buffer most of the time
AMS are definitely plagued by bad daughtercards contact, but I've seen terrible job from people destroying tracks
EMT are ok, but sometimes converters failed, or the output amps/filters.

 

[psych60s]

It appears that EMT keeps saying that they don't have anything more than the service manual in their archives but I'm aware of a tech who get them when last EMT tech retired. He tells me that they are still copyrighted, unpublished and so fall under non-disclosure agreement.

What a strange situation. EMT doesn't want to take care of the service of these old units but they don't release all the infos.

Neve at least still service the AMS range of products, so it is quite logic that they don't release them.

 

[jensenmann]

Today´s EMT company has nothing to do with the original EMT. They changed owner several times. There business model today is very different from back then, mainly targeted to HiFi clients. They live from the legacy of their brand name.

 

[gyraf]

Neve at least still service the AMS range of products, so it is quite logic that they don't release them.

They SO much don't. Even back in the 90'es it was impossible to get ANY support information on e.g. their "Studio computer" (automating our Calrec) or the AudioFile harddisk-recorder system, after the Neve takeover. An insider that I believe told me that they got rid of all back documentation because supporting their old units would be too time-consuming and thus costly. And you're better allowed to "have lost" your archives than to reject detailed one-to-one help...

In other words - burning everything allows your brand to benefit from your legacy without paying the price of support.

It may be that they have later decided to support their iconic delay and reverb, but I'm 99% sure that even this support is based on information they re-imported into the company, not something they saved from the bookburning

Jakob E.

 

[SPbStan]

New Member...first post.
The early digital equipment from EMT have no digital section schematics in the wild because EMT never had them. I tracked down the origin of the digital boards because I had a large studio and a number of the 244, 245 and 250, plus an isolated room filled with plates.
EMT did not design the digital portion and contracted it out to a military contractor design agency in Mass. I tracked down the guy to had the data and he said their company was still active in the contract design business but he was retired and had a set since he had worked on much of it. He said they got the contract and applied the same security policies to digital audio makers as their did for the defense manufacturers: everything was kept from EMT and they supplied boards and EMT would ship back defective board to be repaired by the contractor.  The contracting company merged with a larger one in  the late 70s but the work relationship with EMT was not a priority and faded away.  This was about 1990 when I counted him. His first questions was "how did you find me?"  I kept the 244 and 245 going and repaired some for other studios in the  90s. But none were easy.  In the 90s until 2001 when I moved from the US I had a large repair shop for pro audio and warranty for all the digital decks, analog, and 54 MI brands. That was the heyday of the home studios before computers replaced decks and mixers and everyone has a stack of ADATs and Da-88, plus our Studer work, keyboards etc. 
Most of the digital board EMT ended up being memory chips that were critical on timing back in that day, that was a weak point of those 1k ram chip in the late 60s and early 70s. Luckily they used military common ICs and the Burr-Brown converters that were in abundance in the surplus warehouses.  Any later ones using Tantalum bypass caps need full recapping since they are far past their service life.  If one is really familiar with 70s era discrete digital logic they can track down  stuck buss signals or malformed pulse chains but a rough guess is 80% of the problems I found (people sent a lot of them to us in the 90s as they were being sold off by commercial studios and a lot of junkers ended up  in home studios which had no in-house service) were memory related. Having scoured the surplus bins I was able to amass a large stock of obsolete memory and could do shotgunning if it looked like it was memory related.
So, I am pretty sure there are no schematics available from any source for the digital boards for old EMTs. We had those sent to us and also a surprising number of Quantec QRS which I loved the sound of but was a weird mixed signal design...using a single line for clocks, signal data and control data. I had rare prints of that however and collected a large collection of surplus parts so was pretty successful in resurrecting that device which I think was the best sounding of the lot.

 

[gyraf]

Hi Stan - and welcome to GroupDIY!

Thanks for your explanation of this strange behavior - everything is much clear'er now...  ;D

Jakob E.

 

[psych60s]

That's a really interesting story, I didn't know EMT didn't design the digital sections of these reverbs.

You may be right about the fact they never get the schematics. I think the guys at VintageCity.de does have them, or I have misunderstood their email. They said "schemos are still unpublished and protected, and we can't give them out".

So it remains a little bit obscure, but I am sure of one thing: I won't see these schemos soon!  ;D

 

[pvision]

There was an EMT - Lexicon link in the early days. IIRC Lexicon did the digital design for the 250, and that was all 7400-series logic

Lots of ex-MIT brains floating around Massachusetts

The 244 and 245 had a very distinctive, dense sound. You can hear a 245 on the snare on Runaway Boys by the Stray Cats

IMHO the EMTs are definitely worth saving

Nick Froome