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Old 8th September 2006, 10:46 AM   #1
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Default cyrus 3 rescue!!

Hi, hope your all well and clever!!

I have a Cyrus 3 amp, but its ill!!, it blows the main fuse at the back of the case, the torroidal trandformer is unserviceable, so i wanted to use it for DC battery use only, bit like haveing a Cyrus PSX PSU forever??- i dunno... but thats the plan.

I have removed the transformer and rectfier diodes but one channel "sinks" the whole 12v from my regulated lab type supply, its beyond the fuse part in to the surface mount area (but not necessarly confined to the surface mount components as there are some descrieet ones to ) also the amp dosent blink on to say "HI" this comes from another regulated supply (so i have 3 supplys in total) .....does any one have a circuit diagram for a cyrus 3 amp??

OR... the input daughter PCB is linked to the main mother board by a 24 way ribbion cable, can this be salvaged as it has a very nice phono stage on it.

Its to nice to throw away so any info greatfully received.

thanks you lot

Johnny555

ps wot no spell checker!
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Old 8th September 2006, 12:26 PM   #2
anatech is offline anatech  Canada
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Hi johnny555,
Contact Cyrus. You are closer to them than I am. They are very friendly but I don't know about the schematic thing.

Your current draw is either a shorted rectifier, or output stage. They normally will shut down and blow a fuse on the board.

How the devil did you kill the main power transformer??? I've never seen that done! I have my doubts that it is blown (they normally open, not short).

You are correct. The Cyrus III is a nice amp. I'd fully repair it if I were you. Because of it's smt construction, consider sending it to Cyrus for service. If you want to check the easy stuff, test the diodes.

My own experience on these is that non-Cyrus techs often ruin the board while changing something as simple as outputs or rectifiers. It's double sided with plated through holes.

-Chris
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Old 8th September 2006, 12:42 PM   #3
AndrewT is online now AndrewT  Scotland
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Hi,
I second Cyrus service.
__________________
regards Andrew T.
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Old 8th September 2006, 01:47 PM   #4
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Default that cyrus amp!

Dear Gents, thank you both for your replys, if only it were the rectfier, that yould be easy!!, the fuses were blowing in the back, i observed the tranny was sparking when the fuse blew, i removed the tranny, tested it on a megger, it flashed over, got a second opinion, it was breaking down, i wanted to make it a DC amp (ie batts, ) so i removed the rectfiers (a couple of which were not conducting) and put DC directly to the big input caps (those nice black ones, 4.700 uf),after carefull connection of both channels and the other i/p for the micro processor?? any how thats the state is in, a bit beyond cyrus to economicly fix (ie its more that the psu and its in the SMT part of the PCB, so thats the state of play gents

johnny555
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Old 8th September 2006, 02:01 PM   #5
anatech is offline anatech  Canada
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Hi johnny555,
If it were smt parts, you would have traces going POOF! right before your eyes. There are a pair of fuses in line to the the rest of the world, so maybe a cap is shorted?

It must be outputs and / or drivers. Battereis can dump silly amounts of current, so ...... Use a current limited supply to test. 1/2 A is enough.

You need a 7 VAC winding and about +- 33 VDC for the amplifier section. The 7 V winding will generate about 8.2 VDC for the uP power supply.

I have repaired some that were "struck by technician" with a damaged PCB. That is considerably harder than what you have there. How much is a transformer? Never priced one.

-Chris
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Old 8th September 2006, 02:53 PM   #6
ash_dac is offline ash_dac  United Kingdom
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Hi,

http://cgi.ebay.co.uk/Mission-Power-...QQcmdZViewItem

Not sure which Cyrus amp' this transformer is for!
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Old 8th September 2006, 03:20 PM   #7
anatech is offline anatech  Canada
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Hi Ashley,
Cool, looks like Cyrus I or II. The newer III or IIIi have only two windings plus the primary.

-Chris
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Old 8th September 2006, 03:34 PM   #8
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Default thanks ash dac and and ant tech

Thanks lads, dont seem feasable for 30 odd volts from a battery, so that may be out then, perhaps that tranny then, thanks again

johnny555
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Old 8th September 2006, 06:20 PM   #9
ash_dac is offline ash_dac  United Kingdom
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Quote:
Originally posted by anatech
Hi Ashley,
Cool, looks like Cyrus I or II. The newer III or IIIi have only two windings plus the primary.

-Chris
Any ideas why that transformer has 34-0-34 and 20.5-0-20.5 windings ?



Edit: 4.5Kg transformer. I wonder what the 20.5-0-20.5 current handling is ?
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Old 8th September 2006, 06:23 PM   #10
anatech is offline anatech  Canada
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Hi ash_dac,
That means I'd have to look it up.

Heck, it may not even be for a Cyrus product. The terminals appear to be from the Cyrus I or II. Not a Cyrus III for sure.

-Chris
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