Faulty on/off switch with Anthem MCA2 Amp. Please Help!!

[stevanrk]

Hello all. I have a basic understanding of circuitry and can solder. That said, I am havinga mild problem with my Anthem MCA2 amp. It will not shut off when I press the button on the front. It stays on and I have to unplug it to turn it off. Is the front on/off swithc faulty or something else. Where would I buy the parts for this amp anyways? Any help would be appreciated. Thanks in advance.
Steve

 

[mike c]

are you sure the switches at the back of the amp like : auto sense or 12v trigger is off?

edit:
make sure switch letter C of figure 2 page 3 of this manual:
http://www.anthemav.com/OldSitev1/pages/anthem/mca/oldmca/mca2man.pdf

is set to 'manual-on'

 

[stevanrk]

Yes, there is a switch on the back which has not been touched and is set to manual which means the front switch should do all the controlling. I flipped the back switch to trigger and some other setting but it did nothing to help the problem. Sorry for not mentioning that originally.
Steve

 

[mike c]

no problem. but in that case, you know more than I do

 

[3db]

Hello all. I have a basic understanding of circuitry and can solder. That said, I am havinga mild problem with my Anthem MCA2 amp. It will not shut off when I press the button on the front. It stays on and I have to unplug it to turn it off. Is the front on/off swithc faulty or something else. Where would I buy the parts for this amp anyways? Any help would be appreciated. Thanks in advance.
Steve

Have you contacted the dealer yet?

 

[mike c]

im guessing its out of the warranty period because its the MCA2 instead of the current model that is the MCA20.

 

[stratman]

The same thing happened to my Krell amp, (I sent it to Krell) the dealer that I bought it from originally looked at it, he said that Krell integrates some sort of relay or something into their power switches and if it trips it needs to be reset at the factory (I know it sounds dumb, that's what I was told.)

 

[TLS Guy]

You will need to get a circuit diagram, at least, and preferably a service manual out of Anthem.

That is another thing wrong with modern gear, this information is not forthcoming. It used to be that the user manual nearly always had a circuit diagram.

I doubt the switch switches the amp directly. You can pretty much bet on a relay at least.

Talk to the dealer or Anthem and see what they have to say.

 

[3db]

You will need to get a circuit diagram, at least, and preferably a service manual out of Anthem.

That is another thing wrong with modern gear, this information is not forthcoming. It used to be that the user manual nearly always had a circuit diagram.

I doubt the switch switches the amp directly. You can pretty much bet on a relay at least.

Talk to the dealer or Anthem and see what they have to say.

Thats because alot of the sub assemblies are considered throw away. Its cheaper for a company to replace an assembly then to repair it.

 

[stevanrk]

Thanks to all the posts so far. I have already e-mailed sonicfrontiers (makers of the amp) to see if they have anything to say. Will call them today if I haven't heard back from them by noon just to get an answer. I hate waiting.
Steve

 

[3db]

Thanks to all the posts so far. I have already e-mailed sonicfrontiers (makers of the amp) to see if they have anything to say. Will call them today if I haven't heard back from them by noon just to get an answer. I hate waiting.
Steve

Anthem makes Anthem. I believe Sonic Frontiers may be a dealer.

 

[AcuDefTechGuy]

That's it!
I'm getting Bryston's 20-year warranty products from now.

 

[stevanrk]

Well I fixed it. I got an email back from sonicfrontiers who told me to take it to a dealer and they would let me sonicf know what is needed. This sounded like a 80$ diagnostic fee to me or something similar. Anyways, just for fun, I opened it up and based on the Krell experience above, I decided to see if there was something I could reset. Well, all I did was pull the main 10A 250V fuse which actually did not have the typical glass between the ends, but rather a white possibly ceramic material. I pulled it because there were two other fuses that looked "typical" with the glass in between and a thin filament in both that looked good. I initially thought the white main fuse was blown and hence the white look. Well, I plugged it back in without the fuse and nothing happened. That was expected. I put the fuse back in and simply gave up after that "thorough" search. I turned it on and off a few times and it worked every time. I tried it with the receiver and it works perfect. What I don't understand is why would it "reset" or whatever, by pulling this fuse and turning it on? I have been unplugging this thing for around two to three years so I am finally happy that this little inconvenience has been solved. Thanks to everyone again. Hope my trial and error can help a similar problem in the future for ZERO dollars.
Regards,
Steve

 

[TLS Guy]

Well I fixed it. I got an email back from sonicfrontiers who told me to take it to a dealer and they would let me sonicf know what is needed. This sounded like a 80$ diagnostic fee to me or something similar. Anyways, just for fun, I opened it up and based on the Krell experience above, I decided to see if there was something I could reset. Well, all I did was pull the main 10A 250V fuse which actually did not have the typical glass between the ends, but rather a white possibly ceramic material. I pulled it because there were two other fuses that looked "typical" with the glass in between and a thin filament in both that looked good. I initially thought the white main fuse was blown and hence the white look. Well, I plugged it back in without the fuse and nothing happened. That was expected. I put the fuse back in and simply gave up after that "thorough" search. I turned it on and off a few times and it worked every time. I tried it with the receiver and it works perfect. What I don't understand is why would it "reset" or whatever, by pulling this fuse and turning it on? I have been unplugging this thing for around two to three years so I am finally happy that this little inconvenience has been solved. Thanks to everyone again. Hope my trial and error can help a similar problem in the future for ZERO dollars.
Regards,
Steve

I'm sorry to tell you, you were just lucky. Pulling the fuse is no different to unplugging it. You must have a shock sensitive fault, and it was the force of pulling and reinserting the fuse, that cured it. You have a fault with mechanical sensitivity. I would expect the fault to return at some point. Was there a relay in there? If there was that is likely the culprit. Tapping on errant relays frequently will effect a temporary fix.

 

[stevanrk]

The only relay switches that I actually felt clicking on and off were right before the audio outputs; one on either side of the amp. One for the left and one for the right. Why would they both be sensitive/broken at the same time though? I would expect one of them to not shut off if it was broken, but not both of them at the same time. And I only jiggled the fuse on the right out of its socket, so that would have "fixed" the right relay switch only. I don't understand enough to enter this conversation any deeper than that, but I hope what I said helps and doesn't confuse.
Regards,
Steve

 

[TLS Guy]

The only relay switches that I actually felt clicking on and off were right before the audio outputs; one on either side of the amp. One for the left and one for the right. Why would they both be sensitive/broken at the same time though? I would expect one of them to not shut off if it was broken, but not both of them at the same time. And I only jiggled the fuse on the right out of its socket, so that would have "fixed" the right relay switch only. I don't understand enough to enter this conversation any deeper than that, but I hope what I said helps and doesn't confuse.
Regards,
Steve

They sound like the speaker protection relays. I don't know what you jiggered, but you jiggered something. May be a dry solder joint near by. Impossible to say at this range. I just know that removing the fuse was a very indirect cause of your success.