Hi guys and gals.
I am new to this site and I was hoping someone here can help me with my Mission cyrus ii amplifier. I bought this amplifier with the psx power supply but the amplifier has 2 blowen fuses. I replaced some of the caps and put new fuses in and they blew again. I was told it's probably the output transistors? Where can I buy these? I live in Canada. Please any help would be greatly appreciated. Thank you
I am new to this site and I was hoping someone here can help me with my Mission cyrus ii amplifier. I bought this amplifier with the psx power supply but the amplifier has 2 blowen fuses. I replaced some of the caps and put new fuses in and they blew again. I was told it's probably the output transistors? Where can I buy these? I live in Canada. Please any help would be greatly appreciated. Thank you
🙂 Welcome to the Forum.
It may well be that the output transistors have failed but that may not be all - their associated driver transistors may have been burnt too. Make sure before taking guesses and listening to more guesses or pulling out parts, that you check out the relevant transistors for shorted Collector - Emitter pins (when unpowered).
Register free for manual downloads here and make certain you use the correct revision issue of the Cyrus 2 schematic/service manual for your model. https://www.hifiengine.com/manual_library/cyrus/2.shtml
You need a schematic for a road map plus some experience with electronic assembly before diving in and blundering about - these are quite compact products with an important requirement for re-fitting the power transistors. The heatsink may not be perfectly flat and smooth where the transistors are mounted and special insulating silicone rubber mounting washers were used rather than mica. This is not always understood. The power transistors will be marked with house code PT77 but they are actually BUV28 type which is still available BUV28 | STMicroelectronics BUV28 NPN Bipolar Transistor, 10 A, 200 V, 3-Pin TO-220 | STMicroelectronics
There are many other threads on this repair here which you can easily Google for yourself too. As a Canadian Cyrus service agent, Anatech's replies are usually the most reliable, professional advice on these.
It may well be that the output transistors have failed but that may not be all - their associated driver transistors may have been burnt too. Make sure before taking guesses and listening to more guesses or pulling out parts, that you check out the relevant transistors for shorted Collector - Emitter pins (when unpowered).
Register free for manual downloads here and make certain you use the correct revision issue of the Cyrus 2 schematic/service manual for your model. https://www.hifiengine.com/manual_library/cyrus/2.shtml
You need a schematic for a road map plus some experience with electronic assembly before diving in and blundering about - these are quite compact products with an important requirement for re-fitting the power transistors. The heatsink may not be perfectly flat and smooth where the transistors are mounted and special insulating silicone rubber mounting washers were used rather than mica. This is not always understood. The power transistors will be marked with house code PT77 but they are actually BUV28 type which is still available BUV28 | STMicroelectronics BUV28 NPN Bipolar Transistor, 10 A, 200 V, 3-Pin TO-220 | STMicroelectronics
There are many other threads on this repair here which you can easily Google for yourself too. As a Canadian Cyrus service agent, Anatech's replies are usually the most reliable, professional advice on these.
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Sorry, ran out of edit time but BUV28 is actually obsolete, though there are near equivalents and BUV48 (Mouser) has been suggested previously.
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to use the cyrus 2 amp with the psx.
you must remove the internal fuses.
you must power both amp and psx units with mains leads.
if your just using the amp without the PSX then replace the internal fuses.
you must remove the internal fuses.
you must power both amp and psx units with mains leads.
if your just using the amp without the PSX then replace the internal fuses.
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