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Old 3rd February 2005, 06:50 AM   #1
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Default Cyrus 3 amp problem

I hope someone can help me, I have a cyrus 3 amp, bought it as faulty. It destroys the bass unit of speakers on the right channel when turned on. I read on another thread that this could be because of the output transistors? Can anyone tell me how to test for the problem and where to get replacment components? Or any other ideas you guys/gals have.
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Old 3rd February 2005, 07:37 AM   #2
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You need to get replace output and driver transistors. You can buy these from Cyrus as well as a technical manual (they sell it as a service manual but it assumes repair knowledge), but they aren't great at responding to emails IME. I can't comment which devices would be suitable replacements as I've only fixed Cyrus 2.
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Old 3rd February 2005, 08:07 AM   #3
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Destruction of the bass driver means that it is due to dc at the speaker terminals. The output transistors might be blown. What part number due you see on it ? If not originals , you might get alternatives. You will however need to check if any other part is blown. Like for example the driver transistors.
Cheers.
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Old 3rd February 2005, 07:23 PM   #4
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The part number on the four main transistors is ST N527 SUV48A Morrocco. It would be great if I could source them from somewhere other than cyrus, I would imagine their prices are fairly high. Thanks for your help Richie, u anywhere near Plymouth!
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Old 3rd February 2005, 08:16 PM   #5
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I suspect you slightly misread the part number. I think it's BUV48A

Check out RS, Farnell, CPC and Rapid Electronics to buy some.

You should also replace the driver transistors. Even if they seem to function now, they will be damaged and may fail not too long down the line, taking your new output devices and possibly speakers with them.

And I'm not anywhere near Plymouth, although I did go clubbing at the Dance Academy there once and had a top night.
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Old 3rd February 2005, 09:23 PM   #6
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Hey, I respond to emails! Even posts I see.

I am warranty for Cyrus in Canada. Your outputs may or may not be damaged (probably not). There are some problems with a run of surface mount transistors. There are 24 of them. Not a fun job.

To the best of my knowledge, the guys at Cyrus (I met them in person) are a fine lot. When they repair a product, it undergoes a complete test as if it is a new manufacture. I have witnessed this, and it is a proceedure that is always followed.

My recommendation: at least contact the factory and go from there. It is worth fixing and they sound nice. If the factory repairs the unit, you can be assured that is will be as good as new inside. Every specification will be tested and met before the unit is released.

The repair is such that I wouldn't let just any tech work on it. Heck, I don't like doing all that small work and I've done it before.

-Chris
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Old 4th February 2005, 07:37 AM   #7
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Based on this new information, I would back Chris's recommendation to contact Cyrus. I wouldn't prefer not to mess about with SMT, and would actively discourage a newbie from doing so.
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Old 4th February 2005, 04:44 PM   #8
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thanks for the help on this everyone. ill test the output transistors first. and if no joy ill ring the factory if they want to mutch to look at it ill get another second hand amp or maybe even make a power amp and use the cyrus as a pre amp.
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Old 4th February 2005, 10:43 PM   #9
anatech is offline anatech  Canada
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Can't do that. Mr Cyrus will go into protection with DC on the output and turn off.
It really is worth repair. A new/serviced Cyrus III is worth more than a used ??? I wish you good luck. Let me know how this turns out for you please.

-Chris
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Old 5th February 2005, 07:28 AM   #10
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After looking back thru the posts, there is one fairly major thing I forgot to mention! That is, it works fine until it is put into STANDBY! Coming in and out of Standby causes the right hand channel to make a LOT OF NOISE! It is fine if left turned ON but the speaker must be connected when it comes out of standby!
That will probably help narrow this down a little more.
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