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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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25th Jan 2020, 1:45 pm | #21 |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,587
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Re: Cyrus One
If David is right, and I'm sure he is, issues with the voltage ratings of the output transistors are most likely to arise if someone starts hot plugging the speakers. Cyrus made a point of warning against this in the owners manual.
Alan |
25th Jan 2020, 2:18 pm | #22 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,866
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Re: Cyrus One
Use ultrafast diodes made for SMPS rectifiers. They are quick to switch (1N400x aren't quick) and they usually have a controlled breakdown region designed to absorb a specified amount of energy.
David
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25th Jan 2020, 7:04 pm | #23 | |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,587
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Re: Cyrus One
Quote:
Alan |
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25th Jan 2020, 7:39 pm | #24 |
Octode
Join Date: Mar 2006
Location: Bracknell, Berkshire,UK.
Posts: 1,172
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Re: Cyrus One
Voltage rating is not really the issue as I have a box full of BUT11A (450V) and similar. The only doubt is that 5A is a bit marginal for 4 ohm speakers at full volume. If it is always used with 8 ohm speakers that is not an issue either.. I have the feeling that BUT11A's will do the job.
Back on the job on Monday. Dave |
3rd Feb 2020, 6:48 pm | #25 |
Octode
Join Date: Mar 2006
Location: Bracknell, Berkshire,UK.
Posts: 1,172
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Re: Cyrus One
Cyrus 1 has catching diodes on the outputs, clearly shown and described in the service manual (which is readily available on the web). Nothing 'sketchy' about it.
A couple of BUT11A's fitted along with one of the driver transistors and a new 0.22 ohm resistor. Now working fine again, did need to use some switch cleaner on the noisy mode selection switch but otherwise fine. All the caps also measured fine on my Bob Parker ESR meter. Thank for the help. Dave |
3rd Feb 2020, 7:13 pm | #26 |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,587
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Re: Cyrus One
The reason for using the word 'sketchy' was that the only manual I could find starts at Issue 6 and I couldn't track down any hard information about earlier versions some of which I believe may not have been fitted with catching diodes. Might be mistaken of course. Anyway it's good to know that the amplfier is working well again and that it has the necessary diodes.
Alan |
4th Feb 2020, 7:46 am | #27 |
Octode
Join Date: Mar 2006
Location: Bracknell, Berkshire,UK.
Posts: 1,172
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Re: Cyrus One
Then look again. Can't remember where I got my manual from, easily found with Mr Google, and covers all versions with detailed discussion of the differences between versions and how to identify them. 3MB so too big to upload here.
Dave |
4th Feb 2020, 8:20 am | #28 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,670
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Re: Cyrus One
I found it on elektrotanya, and that manual states that v6 was the first of three versions marketed.
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4th Feb 2020, 8:40 am | #29 |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,587
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Re: Cyrus One
My mistake then although I did find the manual on elektrotanya but clearly didn't study it closely enough. Apologies for the confusion caused.
Alan |