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Old 18th May 2006, 08:52 AM   #11
Did it Himself
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That should be an easy fix.

The sound of the Cyrus 2 is good, the nice punchy bass is the best aspect. The sound can be a little on the bright side but if you like a detailed sound it's good.

The Cyrus 1 and Cyrus 2 are very similar indeed. I repaired a friends Cyrus 2 a while ago and bought the service manual from Cyrus, not that cheap and not a brilliant document either
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Old 18th May 2006, 09:50 AM   #12
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Default polarity

thanks so much for the help
So I unsolder the capacitor, Go to maplins and ask for one with these specs 470F / 63V
Resolder ( will the polarity be marked on the circuit board ).
You mentioned checking the voltage after soldering Is there any particular voltage i should be reading .
sorry Its been years since i looked at a circuit and kinda lost
I'll see if i can get the capacitors today one spare incase the other goes and i need a voltage meter also.
Am just concerned about getting the polarity right , is there a sure fire way of knowing if i dont see any markings.
thanks
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Old 18th May 2006, 09:58 AM   #13
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Make sure Maplin's sell you a cap with the same pin pitch.

I think there is a + sign on the silk screen, but it's possible there isn't. If you remove the cap then post up on here which number it is on the board (e.g. C102) then I can look at my manual and see where it is in the circuit and tell you which way round it needs to go. But please don't bother me if there is a + on the silk screen as I will have to move a load of stuff to get to the manual
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Old 18th May 2006, 10:27 AM   #14
Luke is offline Luke  New Zealand
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thanks for your comments, I have bid for used Cyrus ones, but they fetch around 300 dollars used here (around 100 pound). Will wait for a bargain:-)
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Old 18th May 2006, 10:31 AM   #15
Geoff is offline Geoff  United Kingdom
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Default Re: polarity

Quote:
Originally posted by atomised
Am just concerned about getting the polarity right , is there a sure fire way of knowing if i dont see any markings.
thanks
From your photo, you have one of the earlier Cyrus 2s with the non-metalic case. The capacitor which has failed is C64 and the +ve leg is the one which is nearest to the edge of the pcb, i.e. it is the opposite way round to the adjacent similar capacitor C63. The board is marked with a (+) to show the correct orientation.

I would sugest that you replace both C64 and C63. Ideally you should use some new insulation pads for the output transistors when you reassemble the amp unless you leave them connected to the heatsink and remove the heatsink along with the pcb. If you choose the latter option take care not to put any strain on the output transistor legs or solder pads.
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Old 18th May 2006, 10:41 AM   #16
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Does anyone know the replacement Power transistors for a 1988 cyrus 2? Are there any other replacement Nos. available for this? My C2 is rated 150watts say a label on the casing. Any help would be appreciated.
The Nos> on the power transistor on my set is C8834 and the Driver ones are 243 and 253. The tech at Cyrus UK has not heard of power transistor C8834..

thanks & kind regards to all.

Henry:
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Old 18th May 2006, 10:49 AM   #17
Geoff is offline Geoff  United Kingdom
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Quote:
Originally posted by qrius4ever
Does anyone know the replacement Power transistors for a 1988 cyrus 2?
If this is the later metal-cased version then I believe that the original Cyrus output transistors were labelled PT77 and the Cyrus recommended replacement is the BUV48A.

The C8834 marking is probably the year (88) and week/batch (38) when the power transistors were manufactured.
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Old 18th May 2006, 10:57 AM   #18
jaycee is offline jaycee  United Kingdom
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I find it odd that both Cyrus 1 and 2 have switching transistors for outputs. Arent these supposed to be non-linear?
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Old 18th May 2006, 11:23 AM   #19
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Thanks Geoff,

Much appreciated... yes its the metal casing version and heavy too.

Henry
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Old 18th May 2006, 11:25 AM   #20
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The early Cyrus 2 has two TO220 devices per rail, inhouse marked as PT7. The later Cyrus 2 has one TO247 device per rail, inhouse marked as PT77.

The drivers in both cases are MJE devices. I replaced them with MFE340/MJE350 without issue.

Cyrus want a silly price for new output devices. I would use TIP41C (or B if you're brave) for the TO220 devices, and TIP35C (or B if you're brave) for the TO247 as an easy substitute.
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