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Old 4th January 2007, 12:18 PM   #1
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Unhappy Rotel RA931 Amplifier

Hi There

My amplifier over heated this weekend , even though i have a fan blowing on both my amplifiers and it is now dead . Ive checked the fuse in the plug and all the fuses in the amplifier with a voltage meter and they are all ok . Is there anything else i can look for or is it terminal .

Many Thanks
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Old 4th January 2007, 09:25 PM   #2
moamps is offline moamps  Croatia
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Hi clapster and welcome to the forums!
I moved your post from the Everything Else forum to the Solid State, where it is more appropriate and should get you more feedback, IMO.
With some basic knowledge of electronics and a DVM, it shouldn't be too difficult to detect and repair the problem. First you should download a copy of the service manual from http://www.eserviceinfo.com/download...TEL_RA931.html . After that we may be able to give you some specific pointers on where to look.

Regards,
Milan
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Old 4th January 2007, 11:23 PM   #3
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Thats brilliant

Many thanks , ill download the manual and have a good read through and with any luck ill be one step closer to repairing my amplifier .

Thanks again
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Old 5th January 2007, 12:53 AM   #4
anatech is offline anatech  Canada
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Hi clapster,
Check the continuity of the power transformer primary windings. They have a thermal fuse that will open if the transformer gets too hot.

-Chris
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Old 15th January 2007, 08:41 PM   #5
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Hi There Chris

Thanks for the tip and you were spot on . The power transformer is the problem as there is no continuity so the thermal fuse must be blown . Only problem is , were do i buy a power transformer from or will it be cheaper just to buy a new amplifer which would have to be the very very last resort .

Many Thanks
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Old 15th January 2007, 09:18 PM   #6
anatech is offline anatech  Canada
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Hi clapster,
Sometimes you can get to the thermal fuse and replace it. It will make an opening in the windings and can normally be found on the outer layers. Access it between the layers without damaging any insulation.

Make sure that it is okay by your local code to replace this fuse. DO NOT SHORT IT!!!!!!!! Otherwise you must buy a broken unit and use it's transformer or buy a new exact replacement transformer. I suspect that this is the only legal option you have. It is also the only truly safe way to get your unit working.

-Chris
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Old 15th January 2007, 10:23 PM   #7
jaycee is offline jaycee  United Kingdom
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In the UK if you bypass a safety feature and your house burns down etc, you are liable.

Contact Rotel themselves - they might well be willing to sell you a spare part.

You could also use a standard 2x25V 225VA transformer. The rail voltages would be slightly lower (35v instead of 37v) but i doubt it would make any big difference.
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Old 16th January 2007, 01:36 PM   #8
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Thanks for the replies .

Will the standard 2x25V 225VA transformer fit inside the amplifier ( in the place of the old one ) or will it have to be external .

Thanks
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Old 16th January 2007, 06:49 PM   #9
anatech is offline anatech  Canada
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Hi clapster,
Do yourself a favour and make sure you can install it inside the original location.

-Chris
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Old 16th January 2007, 08:35 PM   #10
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Hi There Chris

Thanks for that , i will do . I managed to find someone who sells the transformer mentioned in one of the replies , so ill have a look and see if it will fit in the place of the broken one .

Thanks Again , Clapster
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