ACA Mini loud buzz/hum

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#42
6L6 said:
Are all the components (CD player, turntable, amplifier, etc…) all plugged into the same outlet and/or power strip in that same outlet? I’m wondering if this may be a ground loop through the AC earth…
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correct. You may be on to something here. I can plug the ACA into the one outlet and run a cord to the source from another outlet to see if that makes a difference.
 
#47
grataku said:
Like I said, start testing for differences between the side that works and the side that doesn't with a simple ohmeter without power. You will get some hints. Alternatively, under power, hookup an 8 ohm 10W resistor as load and test voltages on each channels so that the buzz doesn't bother you.
Don't worry about paste on the mosfet. That's not the issue.
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Tested both sides. Everything the same with minor variations
 
#49
sammythebull said:
The first night I plugged it in (late), I had sound and thought great! Next day hum/noise occurred.
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Can you answer the question I posed earlier? As I understand, it was working first, then some mishaps with cable occurred, then it went bad. Now that is bad, is there music along with buzz coming out of the speaker or just buzz and no music? It's unlikely that simply disconnecting the cable could cause these problems. Did the output get shorted out?
 
#50
grataku said:
Can you answer the question I posed earlier? As I understand, it was working first, then some mishaps with cable occurred, then it went bad. Now that is bad, is there music along with buzz coming out of the speaker or just buzz and no music? It's unlikely that simply disconnecting the cable could cause these problems. Did the output get shorted out?
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Sorry I thought I answered. A few nights ago I finished the build and biased both sides. It was late and I hooked up the speakers and a schiit SYS and played a cd and it sounded good (I thought), and didn’t notice anything unusual. But it was a short test. The next day, I went to move everything permanently on my shelf. The speaker wire came loose when I was reconfiguring it. When I re-connected everything that’s when I noticed the hum/buzz. If I plug the RCA into just the one side (green), I get music fine. On the Red RCA, I get the loud hum/buzz from that side. Does that answer better? I’m not sure if the output is shorted out or how to test that.

I’m sorry I might be in over my head. I thought I’d try this kit to build with my kids as a project that seemed fairly easy. Maybe I was wrong as a lot of the terminology here I’m not familiar with but I’d like to learn. I realize it’s hard troubleshooting on a forum also. My city (I think) has a repair clinic. Maybe I can find someone there who can troubleshoot it. I appreciate everyone’s time and suggestions to try. Not sure what else to look at.
 
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#52
sammythebull said:
Sorry I thought I answered. A few nights ago I finished the build and biased both sides. It was late and I hooked up the speakers and a schiit SYS and played a cd and it sounded good (I thought), and didn’t notice anything unusual. But it was a short test. The next day, I went to move everything permanently on my shelf. The speaker wire came loose when I was reconfiguring it. When I re-connected everything that’s when I noticed the hum/buzz. If I plug the RCA into just the one side (green), I get music fine. On the Red RCA, I get the loud hum/buzz from that side. Does that answer better? I’m not sure if the output is shorted out.

I’m sorry I might be in over my head. I thought I’d try this kit to build with my kids as a project that seemed fairly easy. Maybe I was wrong as a lot of the terminology here I’m not familiar with. I realize it’s hard troubleshooting on a forum also. My city (I think) has a repair clinic. Maybe I can find someone there who can troubleshoot it. I appreciate everyone’s time and suggestions to try.
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Almost. I understand your frustration as I have been there too many times. 😉
 
#55
sammythebull said:
Will you please measure the resistance between the two outer conductors on the input jacks with everything unplugged from the amp. Thanks
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