MC2100 Running Hot

[tuffstuff1]

I finally had a chance to test my newly acquired 2100 and it is gorgeous and looks new. The gentleman told me after the fact (funds wired) he had it upgraded. When I received it I notice the blue caps. Anyway, I had a chance to test it last night. My plan all along was to quad amp. I have Kappa 8's with the 2100's paired on the highs and the MC250's paired on the low's (biamped). I was so excited to hear these speakers rock with all this power. Well it is everything I expected and then some. Now these speakers jump right out of their cabinets, Lol! One problem. I placed my hand on each of the amps and the new 2100 is hot to the touch.:scratch2: The other amps are just slightly warmed. I am going to switch 2100's from side to side tonight, but I don't think it will make a difference. If it does not what should I ask the seller? Will upgrades cause an amp to run hotter? Thanks a lot.

 

[dshoaf]

First, check to see which channel is getting hot. Likely only 2 of the heat sinks have that problem - not all 4. Certainly do not run the amp until it is looked at.

Also, look inside the cage and see if the driver boards are fully seated. If it was shipped to you _and_ they were not locked down properly, this may be a clue.

Hot heat sinks indicate a large amount of power being dissipated by the output devices. If the problem proves not to be mechanical in nature, driver board and/or output board problems are likely.

I know that's not much to go on right now but others will be along shortly with more suggestions. Are you willing to open it up and take pics? That will help from the remote diagnosis standpoint.

Otherwise, prepare to ship it to Terry or Audio Classics for the proper treatment.

Cheers,

David

 

[dewickt]

The 2100 should idle (no output) with the heat sinks getting barley warm, if one or both get hot you have a bias problem. This problem can be a bad output device or drifted bias resistors.

 

[tuffstuff1]

I am not really sure what you mean by "bias problem". The unit is still on (plugged in) as I never switch my 2100 and 250's off. I believe that's what you mean by idling. If I go home tonight and the unit is hot then there is possibly a bad output device or drifted bias resistors? What does it mean if it starts cooking only under a load? Not sure I should really be messing with this because I paid a descent buck and the seller said he would take it back. Shame of it is we will be out about 120.00 in shipping. Bummer.

 

[kevzep]

I am not really sure what you mean by "bias problem". The unit is still on (plugged in) as I never switch my 2100 and 250's off. I believe that's what you mean by idling. If I go home tonight and the unit is hot then there is possibly a bad output device or drifted bias resistors? What does it mean if it starts cooking only under a load? Not sure I should really be messing with this because I paid a descent buck and the seller said he would take it back. Shame of it is we will be out about 120.00 in shipping. Bummer.

Don't leave it on unattended, or on at all while it is running like that, you could be on the verge of something failing big time, and then if it does and you are not there, it will destroy itself.....

Bias is the amount of current flowing in the output section, not enough, and you have crossover distortion, the output section is not balanced, too much and the output and driver transistors turn on fully and then you will have component failure, IE; burned resistors, blown output and driver transistors, and I have even seen the current limiting transistors fry as well....

So you need to sort it before you use it....

If you are not comfortable doing the work or have little experience, you might be better getting it into a tech....

 

[tuffstuff1]

Thanks everyone. The seller asked me to set it up in stereo and try it, but I think I am going to return it to him. I did switch amps and mine still runs cool and the one I just bought starts cooking pretty fast. Oh well, back to tri amp for a while. :tears: Have a good one.