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Old 1st December 2009, 04:25 PM   #1
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Default Cyrus III power amp schematic here, but schematics of the later models wanted

From the integrated amplifiers Mission Cyrus1 and Cyrus2 there are PDF schematics here:
http://www.audio-circuit.dk/Schemati...-1-pwr-sch.pdf
http://www.audio-circuit.dk/Schemati...s-2-pwr-sm.pdf
and for Cyrus3 (Cyrus III) I did create a schematic diagram some years ago (see PDF upload)
But there are schematics of the later models like Cyrus 8, Cyrus 8vs, Cyrus 8vs2, Cyrus 7, Cyrus V, Cyrus 3i Cyrus 5 Cyrus IIIi ? By the home page of Cyrus I don't find a download aera. By companies such as Crest, Crown or QSC such download aeras for PDF schematics and manuals is normal practice.
I need it for realize interfaces for external separate power supply (apart for power amp, pre amp so as the digital part).

Here some other threads without help:
Mission Cyrus III
Cyrus 3
Cyrus 3 / Cyrus III amp help
Cyrus 3 reconfigure for use without PSXR
Cyrus 3 Amplifier Component Mistakes?
cyrus 3 rescue!!
Cyrus 3 amp problem
Cyrus 3 Service manual anyone?
Cyrus 3 gainclone project
Cyrus III intergrated amplifier

Thank you for your advices
Attached Files
File Type: pdf Cyrus III.ckt.pdf (23.7 KB, 1665 views)
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Old 1st December 2009, 06:32 PM   #2
anatech is offline anatech  Canada
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Hi tiefbassuebertr,
I know you are trying to help here, and I thank you for that. However, there are very good reasons why those diagrams are not published. The reasons are not really for secrecy as many might assume. The diagrams are not published simply to try and prevent the wholesale destruction of these amplifiers by iffy technicians and DIY attempts.

All,
I know there are a few of you out there that could probably handle repairing one of these amplifiers. However, those few of you are both very advanced in knowledge and skill working with surface mount components and amplifier design. That leaves about 98% who can not hope to be successful in this. My own experiences repairing other people's messes bears this out, and I have to agree that Cyrus made the correct decision when they decided not to publish or release these schematics. Most of you know I am normally on the other side of this argument. However, I also try to make sure people will be successful with these repairs. In this case, highly doubtful.

Personally, I am bound by my agreement with Cyrus that prevents me from releasing any information that they have sent me. But, I will say one thing. Has anyone out there tried matching surface mount transistors? I have, and I do. It's a pain in the keester! Something that needs to be done in servicing to maintain proper operation. Just a glimpse into the world of proper amplifier servicing as it relates to one built using surface mount components.

-Chris
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Old 1st December 2009, 06:51 PM   #3
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Post Something I forgot to mention ...

Hi all,
Servicing these means you must remove the main PCB from the chassis of the amplifier. This has it's perils and things to watch for.

Now for the really important part you should be prepared for. If you manage to remove the main PCB, you have created a problem (assuming the previous repair was done right). These use a special "plastic" transistor insulator and the heat sink is rough. You must do one of two things now. Either purchase the exact same insulators (they are not cheap) and completely clean the mounting area. If you are going to use any other type of transistor insulator, you must reduce the surface roughness of the mounting area to close to mirror smooth. This means starting with a course file and working down to a fine file to almost finish. This ensures a true surface and you must take your time. You will be tired after one side. Finally, a careful finish sand with 600 grit wet/dry paper using a true block. This is also how I actually do this, so I'm not recommending anything that I don't actually do myself. Once the mounting area is both really smooth and clean, you may mount the outputs as you normally would using thermal compound (not the stuff for computers!).

If you are not prepared to do this, do not open it up.

Hearing about someone working on one of these fills me with the same foreboding that hearing someone attempting to repair a Carver Cube (M-400 series) does. It's a sad moment as most attempts result in an amplifier that is not repairable any more.

-Chris
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Old 1st December 2009, 07:11 PM   #4
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If there are all cyrus service manuals published, then would be significantly less likely to try to repair undertaken than currently without the service manuals.
This is because I get the illusion after disass'y that it is a very simple design (through the lot of surface mounted design devices).
I have repair two devices after performing of bad work though other technican.
Would a service manual existed, this technican men didn't perform such repair try, because of the greater respect regarded to the actual much more effort of SMD devices than it seems after first look inside.

But even without the service manual are Cyrus amplifier 3i and above still significantly easier to understand than public address class G / H amplifiers, e. g. from QSC, for which there are all schematics for download go to
QSC - Schematics, Amplifiers
After read this service manual I carry out only simple repair - if there are faulty electronics, I will shipping for service even with exist service manual


All audio brands must actually have such download aera - I think, at least by the devices, that are out of production like about passlabs. Mr. Nelson Pass maintains such a download aera.

But I suspect a complete another reason why many small brands don't publish anything of documents and schematics:
The creating of a good to understand service manual is very complicated and therefore there are in most cases only first handcraft drawings, in which this brands ashamed to publish this.

Last edited by tiefbassuebertr; 1st December 2009 at 07:23 PM.
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Old 1st December 2009, 08:26 PM   #5
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Quote:
Originally Posted by anatech View Post
Hi all,
Servicing these means you must remove the main PCB from the chassis of the amplifier. This has it's perils and things to watch for.

Now for the really important part you should be prepared for. If you manage to remove the main PCB, you have created a problem (assuming the previous repair was done right). These use a special "plastic" transistor insulator and the heat sink is rough. You must do one of two things now. Either purchase the exact same insulators (they are not cheap) and completely clean the mounting area. If you are going to use any other type of transistor insulator, you must reduce the surface roughness of the mounting area to close to mirror smooth. This means starting with a course file and working down to a fine file to almost finish. This ensures a true surface and you must take your time. You will be tired after one side. Finally, a careful finish sand with 600 grit wet/dry paper using a true block. This is also how I actually do this, so I'm not recommending anything that I don't actually do myself. Once the mounting area is both really smooth and clean, you may mount the outputs as you normally would using thermal compound (not the stuff for computers!).

If you are not prepared to do this, do not open it up.

Hearing about someone working on one of these fills me with the same foreboding that hearing someone attempting to repair a Carver Cube (M-400 series) does. It's a sad moment as most attempts result in an amplifier that is not repairable any more.
-Chris
This trouble is through the use of diecast aluminium envelope include heatsink function. Also by the older models I and II the surface roughness of the mounting surface are to large. That is the nature of die casting heatsink surface

"This means starting with a course file and working down to a fine file to almost finish. This ensures a true surface and you must take your time. You will be tired after one side. Finally, a careful finish sand with 600 grit wet/dry paper using a true block"

I have perform this mechanical work in numerous cases (I already can smell again the aluminum dust) and I can only say "Made in UK", I don't like such work by expensive audio amplifier devices (for me it isn't permissible).
But for a reliable prevention of electrical connections between the heatsink surface and the metal surface of the output power transistor through the insulating material this work must be always performed in any case.
Here an example for a high quality insulators:
http://docs-europe.electrocomponents...6b8038a188.pdf
from
http://www.bergquistcompany.com/

Last edited by tiefbassuebertr; 1st December 2009 at 08:39 PM.
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Old 1st December 2009, 08:42 PM   #6
anatech is offline anatech  Canada
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Hi tiefbassuebertr,
Quote:
If there are all cyrus service manuals published, then would be significantly less likely to try to repair undertaken than currently without the service manuals.
This is because I get the illusion after disass'y that it is a very simple design (through the lot of surface mounted design devices).
We are in complete disagreement here, and for one rare time I agree with the decision to not publish the information. You will note that I am generally saying the same as you with respect to service information.

The main problem is that pride gets in the way of intelligent thought with most technicians. I've spend 30 years or so, cleaning up after stupid people who I'd swear couldn't fix a battery-switch-light type circuit. With these Cyrus products, the circuit may look simple, but the elegance is lost on people who do not understand how it works. It's the same with most things. I have similar problems when people decide to repair a Carver product, or even Marantz amps. The elegance is totally lost on most people, and they therefore make inappropriate choices when servicing these.

Now, when you add the fact that this is mostly surface mount, double sided with plated through holes, that should be enough to stop people from diving in without a clue. Most Cyrus products I get in after another shop or person has been in there has lifted and missing traces, and even torn out plating to the other side of the board. In short, a terrible mess. These issues are not caused by a lack of service information, it's caused by very poor workmanship. Sadly, this is also the norm for most service shops. Now, do you think for an instant these people are going to match their parts, or even buy them directly from proper distributors?? I can tell you the answer simply from observing what has happened in the past. It's a simple no.

Quote:
Would a service manual existed, this technican men didn't perform such repair try, because of the greater respect regarded to the actual much more effort of SMD devices than it seems after first look inside.
I wish this were true. It isn't.
Did you notice what type of transistor insulator that was used here? It's not in the manual, because you can see this with your eyes.

Quote:
But even without the service manual are Cyrus amplifier 3i and above still significantly easier to understand than public address class G / H amplifiers, e. g. from QSC, for which there are all schematics for download
Most people are incapable of properly servicing an amplifier, even a simple one. Perhaps I shouldn't say "incapable", because this isn't true in all cases. What is true is that most people do not think about what they are doing and choose to do a "make-it-go" job instead. The pro amps you pointed out are often in even worse condition. A very low level of service ability is expected these days, and "pro amps" are often found with different parts used in the same bank of output transistors. They even often are using the same insulators and thermal compound that was already there! This is of course a job that should never have left the shop, and yet here they are.

The availability of service information will always encourage people to begin a repair they have no ability to complete. The opposite from what you are saying. How does it go? "The more you know about something, the more you understand how much you don't know about it." People who don't know much always thing everything is easy.

How many pro BGW amps have I seen properly repaired? None.

Same goes for most other brands. Properly repairing an item means more than "it makes noise now". A repair includes properly adjusting bias and other things that may include protection limits, DC offset (sometimes there is no control) and even other currents or voltages (like a Carver) that are unique to one brand. Sometimes you have to change component values to make a required correction or adjustment, and this is the proper way to do this (example: BGW 750 series for DC offset), outlined in the manual. It's up to the servicing person to obtain the proper information, and some of it is expected as normal background info. In other words, things technicians are expected to know as part of their training. Some manufacturers did put out a manual of information common to everything, then never repeated it again.

As a servicing technician, you can not assume anything. As one of the Bavarian technicians who taught me a great deal (Peter Habenei for one) used to say, "if you don't understand exactly what you are working on, do not touch it!". I grew up with this mind set as taught by technicians further advanced than I was. So this rule, coupled with learning from another, will keep everyone out of trouble.

Quote:
All audio brands must actually have such download aera - I think, at least by the devices, that are out of production like about passlabs. Mr. Nelson Pass maintains such a download aera.
I'm of two minds on this now. Years ago I would agree without any reservations, but not now. I have seen how the quality of service people has declined over the years. It's actually very sad.

No, download areas should exist. However, only certified technicians should be able to access to areas. Another type of download area should exist for hobbyists that included "classic" circuits for study. The problem as I see it is that as soon as you charge for your work, the person paying should be assured of your competence. Even if you don't charge anything. For instance, it is possible to create a shock hazard, even if you didn't intend to do that. I've had to clean up many situations like this too!

Quote:
But I suspect a complete another reason why many small brands don't publish anything of documents and schematics:
The creating of a good to understand service manual is very complicated and therefore there are in most cases only first handcraft drawings, in which this brands ashamed to publish this.
There is some truth to this. The general quality of service manuals has also declined drastically over the years. For many "high end" equipment manuals, only rough, hand drawn schematics exist. Adjustment procedures have been verbal only!! A very poor business model if you ask me.

The other reason are those companies who believe their product is special and advanced, so it's a secret. Most of these are really common circuits with nothing special about them. John Curl's Blowtorch is a great example of this. The circuit is really basic, nothing to write home about. But, the magic is in how parts are matched and the actual construction is done. Materials used and component / wire routing may really affect how something sounds. This is commonly shown when servicing a classic guitar amplifier, an easy way to observe these effects.

There is far more to servicing than a schematic. Really good technicians are worth far more than what the industry actually pays or consumers can understand. People starting out have the least respect for how much a good technician actually knows. It shows in their work.

-Chris
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Old 1st December 2009, 08:56 PM   #7
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Hi tiefbassuebertr,
Quote:
This trouble is through the use of diecast aluminium envelope include heatsink function.
It would seem that both I and Cyrus engineers disagree with you on this.

Quote:
Also by the older models I and II the surface roughness of the mounting surface are to large. That is the nature of die casting heatsink surface
This is not the nature of die casting. By eliminating a machining step, the costs were controlled. If each mounting surface were to be machined, the overall cost would be much higher for the product. However, this means a technician must be aware that either the surfaces are brought to normal roughness, or the same thermal pads are used. No problem, but I'd prefer smooth heat sinks (as I've said).

Quote:
I have perform this mechanical work in numerous cases (I already can smell again the aluminum dust) and I can only say "Made in UK", I don't like such work by expensive audio amplifier devices (for me it isn't permissible).
Well, so have I. But really, what is permissible really depends on how much you wish to pay for the item. I mean, they certainly could finish these areas, but the cost would be increased a lot. Have you checked the cost of machining lately? Never forget, they still have to sell these. Perfect but not selling and out of business doesn't make a whole lot of sense. You can pick at almost any product that exists. At least they designed their stuff extremely well.

Quote:
But for a reliable prevention of electrical connections between the heatsink surface and the metal surface of the output power transistor through the insulating material this work must be always performed in any case.
Not true any more. Otherwise I would completely agree with you. The pads Cyrus uses actually flows the first time it gets warm and provides excellent heat transfer. Once formed, no problem. Now, if you wish to use a different material for thermal insulators, you'll have to smooth the surfaces. I believe I have been very clear and forthcoming on this.

I wish I had a machine that would resurface these castings. But, I don't. I therefore haul out the files and do the job by hand. I wish they were done, but I can see why they aren't. They had a problem in design. They solved it. What more can you ask? It;s not like they shipped defective products that fail! In fact, the failure rate is really extremely low on this product line, save the run of defective transistors. Even then, they did not fail for years after the warranty was up.

-Chris
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Old 6th January 2010, 05:55 PM   #8
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I still needed all schematic diagrams of Cyrus models later than series III.
This must be the follow 9 versions (similare outfit than series III):
IIIi (improved III) - 5 - 6 - 6vs - 6vs2 (6VSII) - 7 - 8 - 8vs and 8vs2
Who have make this of his own device?

Last edited by tiefbassuebertr; 6th January 2010 at 05:57 PM.
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Old 23rd February 2010, 06:16 AM   #9
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Hi tiefbassuebertr,
I wish I could release these, but I can not as I've mentioned. I don't know of any good information "out in the wild" either.

I have stated that this equipment is all surface mount, save drivers, bias and output transistors. The component placement is very tight on top of that.

I can not agree with the claim that available service information reduces repair attempts. All my own observations run counter to this, no matter what the brand name on the case. Any service technician who attempts a repair on an item that the service manual is not available for (or even the schematic), and is complicated, is fighting a losing battle. Even if the unit operates when the work is done, it will probably not be adjusted correctly. I also know that the factory doesn't overcharge for their work.

Yes, I do understand that there is some pride involved here. There is also the issue of being told you can't do something that rubs people the wrong way. I have been on both sides of this issue many times, so I know what you are feeling here. I would not trust the iii schematic either.

Every single time a manufacturer has released service information for unique products, there has been mass carnage in the field. Then the service depots are over-run with angry customers and hacked units. then, the service depot is expected to repair these and make them reliable again. The most common issue I've seen are destroyed PCBs. In other words, not worth repair. The owners do not like to hear things like that. It's also amazing how many attempt to hide the fact that someone else worked on it! Like we can't tell. They will deny this sometimes, even after being shown the evidence. A certain percentage of these people will accuse the service center of damaging the equipment, anything they can do so they aren't stuck with the bill.

I'm not saying you are a bad technician at all. What I am saying is that opening the floodgates to the sea of hackers out there is disastrous. This is an unfortunate fact that created the situation as it is today.

So, you are looking for the entire library. What are you trying to figure out? I can tell you right now that they will not release the diagrams or manuals. Sorry about that.

-Chris
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Old 23rd February 2010, 11:24 AM   #10
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Quote:
Originally Posted by anatech View Post
I can not agree with the claim that available service information reduces repair attempts....
Hi Chris,
I agree with your view, if the corresponding repair and replace advices in the concerning service manual are not clearly mentionned.
But if there is clearly described, how difficult work it is repair performing by SMT, then the threshold to do a self-repair it would be very large - at least by the greatest number of technican guys.

I need the complete schematic in the moment for the Cyrus 5 (Cyrus V). I want to create a external power supply - much more better than this one from Cyrus itself. It must have independend voltages (and independend transformers) for follow function blocks:
1) power amp left
2) power amp right
3) preamp (perhhaps also separate for L+R)
4) RIAA head amp
5) digital stuff such as MCU for operating and C-MOS swiches for input select

Because the power amp section shold be used only for the upper range (tweeter drive), I want to reduce the supply voltage to half its value. At the same time I double the quiescent current to get "class A" within a larger area.

The appropriate resistor replaces in the voltage amplifier output stage for the new conditions is't a problem, because I have the possibility of CAD simulation.

But a wide range of PCB wires I must cut to create the appropriate interface and without schematic it is much more difficult than with the concerning schematic. Also very helpful is the schematic printing of the PCB, both solder side and component side.

Such work I have perform several times by other amps and I know the amount of the increase by sonic quality in all respects.

An other possibility is make an upgrade with the appropriate stuff from Cyrrus itself (CyrusV>VI and "PowerX"), but with not so good results. Therefore I would prefer my own idea, because I have more choice in determining the quality standards especially concerning the transformers and capacitors.

Greetings to Georgetown/Ontario
Andreas

Last edited by tiefbassuebertr; 23rd February 2010 at 11:33 AM.
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