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cyrus 1 output transistor question. push-pull?
cyrus 1 output transistor question. push-pull?
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Old 31st December 2017, 10:36 AM   #221
randombeliefs is offline randombeliefs  United Kingdom
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Originally Posted by Mooly View Post
Sounds like a plan
keep waiting for the catch ... but so far so good. I've just left the presets in with blobs of nail varnish to stop em moving
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Old 31st December 2017, 11:05 AM   #222
AndrewT is offline AndrewT  Scotland
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Originally Posted by randombeliefs View Post
keep waiting for the catch ... but so far so good. I've just left the presets in with blobs of nail varnish to stop em moving
the sealed presets are usually for the bias setting.
But the Cyrus has fixed resistor bias.
Are they for output offset?
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Old 31st December 2017, 11:08 AM   #223
Mooly is offline Mooly  United Kingdom
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cyrus 1 output transistor question. push-pull?
Well hopefully there isn't one

(When you fit the new fuses, make sure the fuse holders are reasonably tight)
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Old 31st December 2017, 11:10 AM   #224
Mooly is offline Mooly  United Kingdom
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cyrus 1 output transistor question. push-pull?
We modified the amp to adjustable bias to cover the possibility that the replacement transistors might be different in terms of turn on voltage. It does happen with older stuff as semiconductor doping processes might have changed.
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Old 31st December 2017, 11:38 AM   #225
randombeliefs is offline randombeliefs  United Kingdom
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Originally Posted by AndrewT View Post
the sealed presets are usually for the bias setting.
But the Cyrus has fixed resistor bias.
Are they for output offset?
I added the presets across the solder posts next to R81 after removing R81

I expect mission provided the posts fir service convenience ?
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Old 31st December 2017, 11:42 AM   #226
randombeliefs is offline randombeliefs  United Kingdom
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Originally Posted by randombeliefs View Post
I added the presets across the solder posts next to R81 after removing R81

I expect mission provided the posts fir service convenience ?
Ice just swapped out the old 470uF caps on the preamp psu side for nichicon finr gold 100v jobs. Panasonics I wanted to git are a bit too big. And putting fine golds in where the 22uF polarised caps are on the preamp side. Have nichicon muse forcthe bipolars
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Old 31st December 2017, 01:28 PM   #227
Mooly is offline Mooly  United Kingdom
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cyrus 1 output transistor question. push-pull?
Looks like you are having fun Just be careful
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Old 31st December 2017, 01:39 PM   #228
randombeliefs is offline randombeliefs  United Kingdom
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Originally Posted by Mooly View Post
Looks like you are having fun Just be careful
yeah it's like the victory lap now. hope i don't fall on my face
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Old 3rd January 2018, 01:26 PM   #229
randombeliefs is offline randombeliefs  United Kingdom
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Default How it going ?

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Originally Posted by cardiffborn View Post
Hi.

Recently I let someone borrow my Cyrus 1 for a charity event and unfortunately it returned as a dead Cyrus. I did a visual check and replaced a 3.15A fuse, only to discover that one of the output transistors was shorted. Trying to find a replacement has lead me to some interesting sites, without much luck. Then I found this thread and have been amazed by the help being given to someone who wants to learn by doing. I'm an advocate of learning by failing, though I don't actually see it as failure.

I've registered and read all the posts and am about to put together my own shopping list. I just wanted to say 'thanks' to all who have been helping because it's going to help me no end. Also, it's a change to read comments that actually inform and share, rather than recommend that one finds an expert to do it for you.
My Cyrus 1 got fixed by this thread and the brilliant help within it.
How are you getting on with yours ?
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Old 4th January 2018, 10:56 AM   #230
cardiffborn is offline cardiffborn  Wales
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Default Cyrus 1 might get back on the road again

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Originally Posted by randombeliefs View Post
My Cyrus 1 got fixed by this thread and the brilliant help within it.
How are you getting on with yours ?
Hi and thanks for asking about my Cyrus 1. I have to admit that I have been following this thread until the final chapter before I jump in myself. OK, I could blame the Christmas festivities but that's not true. The thread reads like a crime novel and fortunately has a happy ending. I've made notes from all the posts and will be ordering some goodies from Farnell soon. I have also unearthed my old Sinclair meter to complement my other cheapie meter. All I need to do now is tidy the shed, cut the grass, paint the house and then jump in with both feet.

The support you have been given is amazing, and my faith in humanity somewhat restored by those prepared to offer assistance patiently and without recourse to bitchy comments. I may not be as speedy as you but I reckon that with all this info I should be able to do something.

Actually, I am going to build a bulb tester first seeing as many posts indicate its importance.....

Watch this space, but don't hold your breath. Have a great 2018
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