mattywhi Posted October 31, 2004 Share Posted October 31, 2004 Hi, I have an Inkel MA-620 which is used to power some monitor speakers in the booth of my local theatre. When it powers on the protection LED flickers red and then goes and stays green and we can get no sound from it. Initally we thought it was a speaker problem but we have changed the speakers to no avail. I have looked for inkel on the web but not found anything so any help would be useful. We have taken the top off and all the fuses are intact so we are at a dead end. Any help would be much appreciated. Matt & James DST Sound & LX Link to comment Share on other sites More sharing options...
Andrew C Posted October 31, 2004 Share Posted October 31, 2004 Inkel had/did a name/badge-change a while back. Was it Millbank, or Rotel? Might be worth a look, and I'll keep thinking about who changed to what. Link to comment Share on other sites More sharing options...
Pete Alcock Posted October 31, 2004 Share Posted October 31, 2004 Matt, Inkel are now known as Inter M. A very good Korean manufacturer. The name changed in May 1996. Can't find anything about an MA620 on the web site at www.inter-m.com though. Sounds like the protection circuit is detecting something it doesn't like and is not connecting the speakers (can you see an LS relay in there?). Protection circuits usually sense a combination of correct rail voltages, no DC on o/p, temperature OK etc. Without a schematic, you're poking about in the dark really. As a very last ditch effort, if you can't find a circuit diagram and you've checked all the internal fuses, you could try bypassing the relay, (disconnect any speakers first), and see what comes out. If it's DC, chuck the amp away. The Inter-M products I've used in the past have helpfully had a circuit diagram actually in the user manual. Good luck, Pete. Link to comment Share on other sites More sharing options...
slim_mcslim Posted October 31, 2004 Share Posted October 31, 2004 if it is the relay, which is a common amplifier problem especially with touring kit, just picking the amp up and dropping it squarely on the floor from a height of about a 8" to 1ft usually free's them, works on most crest and crown amps I have ever had problems with... Link to comment Share on other sites More sharing options...
mattywhi Posted November 1, 2004 Author Share Posted November 1, 2004 if it is the relay, which is a common amplifier problem especially with touring kit, just picking the amp up and dropping it squarely on the floor from a height of about a 8" to 1ft usually free's them, works on most crest and crown amps I have ever had problems with...<{POST_SNAPBACK}> So a small shark drop may fix it. I will see - not too sure whether thats gonna be my first choice - I will hunt for the amp manual first and see if that turns anything up if not will try the drop treatment! Link to comment Share on other sites More sharing options...
James Posted November 1, 2004 Share Posted November 1, 2004 You should be able to hear the relays operating or not as the case may be. Link to comment Share on other sites More sharing options...
mattywhi Posted November 1, 2004 Author Share Posted November 1, 2004 I just pulled the user manual pdf off inter-m's site and the block diagram is awful!!! I tried to get into the service bit but u need and id/password to get there. Im gonna see if I can get a colleague to decipher the diags we have and see what happens from there. Link to comment Share on other sites More sharing options...
mattywhi Posted November 4, 2004 Author Share Posted November 4, 2004 Update: Took the amp out of the rack, plugged in some other speakers and another desk turned amp on and the protection light flashed red then turned green and stayed green. turned levels on the amp up and got sound through the speakers. Is the amp safe to use or should the protection light go out? This LED indicates the state of the amplifier’s protection circuitry. When the Protection LED is on (illuminated), the protection circuitry is active, indicating that the unit is not operating normally. This is typically due to overheating or power limiting. Please check the Input and Output condition of the amplifier. (Note that the Protection Indicator lights for approximately six seconds when the amplifier is first powered on.) that is what the manual says about it.... Anyone got any ideas? Link to comment Share on other sites More sharing options...
Peter Russell Posted November 5, 2004 Share Posted November 5, 2004 Sounds like the speakers that the amp are normally connect are shorting out somewhere and that is why the amp is going into protect. Try tracing the cables to the speakers and check that they have not been damaged or come loose on the back of the speakers, it could even have been that the cables were touching on the the back of the amp.HTH Peter Link to comment Share on other sites More sharing options...
mattywhi Posted November 5, 2004 Author Share Posted November 5, 2004 The cables are fine. I am now running the amp on completely different cables, speakers and the input is coming from a different desk. Im running jack inputs as there is no balanced out on the desk and then using bananna plugs to link the speaker cable to the amp and then speakon into the speakers. The manual does state that the protection light should go off after a set amount of time yet it is staying on but green and the speakers work. One other thing I noticed was as the amp is turned down and then off the capacitors inside discharge slowly and as the last bit of charge drains from them it is sent to the speakers in a mid-high pitched tone. Any ideas on the last point? Link to comment Share on other sites More sharing options...
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