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Old 12th September 2011, 11:00 AM   #1
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Default CROWN POWERTECH 1

CROWN POWERTECH 1 amplifier to repair but seems that the broken ventilator is space technology ...

The actuall ventilator has only 5 ( !!! ) cables and two windings while one of them is double

then again nothing is wrong with the amplifier except some electrolytics but protection circuits will "see" absense of ventilator ( if removed ) and will not allow amplifier to start

seems that schematic is not there ( crown web page ) so any information will be very welcome ...

Kind regards sakis
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Old 12th September 2011, 11:19 AM   #2
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removed the vent and realized that is not really space technology more like a clever circuit

the ventilator has actually a primary winding to run the vent but on the same core there is a 18+18 volt transformer winded which probably goes to supply the protection circuits

theory will be if vent fails there is not going to be power to the auxiliary circuits so amp will not power up ...

Long run show that all worked fine and idea was good but the bearing of the vent failed before the coils .... ventilator become noisy cooling was not enough vent coil and boards boiled but seem to survive..

idea is to put any available ventilator ... add a small 18+18 trafo and a thermostat...

kind regards sakis
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Old 12th September 2011, 11:23 AM   #3
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ohhh and by the way

local service center of Crown asked for 250 euros to replace the blody vent .....
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Old 12th September 2011, 11:43 AM   #4
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I think that maybe when you say "vent" you mean FAN??
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Old 12th September 2011, 11:49 AM   #5
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yeap
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Old 12th September 2011, 12:00 PM   #6
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you could try to disassemble the "transmotor" clean it and lubricate it with thick grease (I use WD40 to remove dirt from the brass bearings) a bit of light sanding on the shaft of the transmotor after cleaning it (to remove rust spot that would otherwise make the fan run noisy) If the clearance of the shaft and the bearing is too wide, you could try inserting shim brass of the appropriate thickness. Careful with the fan blades they are a bit brittle.
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Old 12th September 2011, 12:08 PM   #7
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no i wont bother
will replace the fan with a new one to be on the safe side ...as said since the fan's power was low both coils and amp have obvious stress marks from heat ...

i will be more happy with a brand new one ...as about the trafo thingy i think i will do the same only wire the protection circuits in series with a thermostat ...

kind regards sakis
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Old 12th September 2011, 12:24 PM   #8
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signs of heat stress,wrong racking perhaps? air intake from the front and exits on the sides, unlike the usual front to back air flow.
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Old 12th September 2011, 01:29 PM   #9
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can also be possible ...dont know amplifier is quite old
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Old 12th September 2011, 01:36 PM   #10
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I have a bunch of fan-formers removed from the MA series. Adding a few drops of synthetic oil to the bearings has restored them to good working condition. However they are not the model you seem to have.

The discoloration is normal as the coils get hot and all the dirt flows right by them in use.

The newer versions used a separate power transformer and fan.

250 euros is a very high price for this part!
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