My Rotel RB-1050 stopped working. Normally, a second after I push the button I hear a click when the amp's power stage switches on. Today, the red light comes on but no click and no output. 4x15Amp fuses inside are OK.
I bought it used and it worked then, then it sat unused for 6 months and now it doesn't work.
I thought this amp was bullet-proof...What do you think the problem is?
Thanks for your comments, - d
the relay connects the speakers, not the power to the output stage. Look at the circuit operating the relay, it'll be faulty.
nb if you dont have troubleshooting skills, most amps operate ok if you bypass the relay, it just means you get a slight clunk from the speakers on powerup. Thats why the relays there.
NT
On Mon, 04 Dec 2006 19:10:24 -0800, broken amp Has Frothed:
Check speaker wiring/speakers.
-- Pierre Salinger Memorial Hook, Line & Sinker, June 2004 COOSN-266-06-25794
Actually in most (all?) amps the relay is part of the protection circuit. If the protection circuit detects DC voltage to the speaker outputs of the amplifier stage the relay will not connect the speakers. This protects the speakers from damage. Although the fuses are still good there may be one or more failed components in the amplifier and if you bypass the relay without checking first, you could blow your speakers. Sometimes the protection circuit itself fails, but if you're going to bypass the relay to test this theory, you had better have some really inexpensive speakers connected that you won't mind possibly destroying.
You can often check for DC offset (the common speaker killer) with no speakers attached. Anything more than half a volt is suspect. Otherwise, a pair of 8 ohm large (as large as you can afford) wattage resistors is the ticket.
I picked up a couple of 100 watters surplus some 20 years ago, for $5 apiece. They've been part of my bench ever since. Mounted on a large chassis, I've stressed them up to 200 watts for brief periods--just long enough to make measurements--with no damage. They 'do' get hot, though.
jak
I guess I was wrong to assume V_out would be checked before connecting up.
NT
Thanks for your comments.
The speakers are DIY and work on another amp. I think I would hear the output click even with no speakers attached and I don't.
I wonder if it could be the 12V/signal trigger (set to bypass since I don't have the preamp)
How do I find a circuit diagram for a rotel RB-1050?
Thanks, Dave
p.s. The last setup with the amp was computer soundcard speaker out to a 25Kohm stepped attenuator (another DIY) that I just finished, and a set of crappy speakers that I could blow and not care about. Resistance values on the attenuator checked out. RB-1050 input overload is 1V/33kOhm, I think soundcard output is up to ~1V
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