Owners of Carver Crimson 275 -Caution/Warning--Potential Increased Risk of Electric Shock


What's going on?:   If you own a Carver Crimson 275 amplifier there is a real potential that your amplifier does not have a proper chassis grounding scheme inside.  There is a type of grounding system involved, but the third prong of the IEC socket (the actual electrical socket on the inside of the amplifier) is left wide open on my amplifier and and at least one other amp that I have virtually confirmed (not firsthand--only through another owner).  

What does this mean?:  If one of the hookup wires carrying power/B+ came loose from its soldered weld and touched either the chassis or something conductive to the chassis and the user then touched the chassis/unit with the power on they could get a significant electric shock. There are some seriously high voltages in this tube amp (like many amps of its topology) and the result could be lethal.

Carver Corporation's Response to Status on Grounding:  I have notified Frank Malitz of the Carver Corporation about this problem.  He responded to me in writing saying the following, exact quotation, nothing more or less:  

"the design is under review with engineering and I'll contact you tomorrow." (F. Malitz)

In the interim, users may be at an increased risk of shock and bodily harm.   I would encourage you to check with an electronics expert or the Carver Corporation for further guidance, as I'm not qualified to say more than there's no confirmed chassis ground in the unit that I have and at least one other unit.  

Finally, unless you are qualified in working with high voltages do not open your unit to check for the ground wire running to the ground prong on the IEC. Please note that doing so with or without a chassis ground should only be done by someone experienced with electronics--i.e. caps must be discharged and care taken to cause an issue.  Seek professional help. 

I'm just a music lover and hobbyist.  I'm merely relaying this information out of concern for the safety of fellow humans. I'm not an expert and perhaps an expert will rule out this identified potential increased risk as non-existent.  For now, I can say that it is my opinion that there is a real reason to believe that grounding scheme might be deficient and I will not be using my amp until this is sorted out.  

I'll report any response from the Carver Corporation as soon as I hear back.  For now, my amp will sit unplugged. 

 

128x128jbhiller

Hi James,

I want to thank you for emailing me about this grounding issue, it is very serious and I will disconnect my unit until I here back, I have read the whole thread and understand the issues brought up. Again thank you so much.

Take Care,

Bill

@jea48, You certainly have more knowledge and expertise than I do.  If I get motivated today, I could open the unit again and post phots of the grounding scheme.  

@wfarrell, Bill, you are welcome. I debated posting something at all on the issue. Then I thought--you know, even though it would probably be unlikely that a wire would come lose from its solder weld, it’s possible. Not to mention that the build quality on these amps varies. Amir at ASR has a copy of the amp that has like 26 gauge wire going to the speaker terminals, whereas mine has heavy duty wire. His had a lose screw rolling around the chassis and the power transformer loose.

So, I thought: How do I know the welds in these amps are solid? There could be owners who have units where things were rushed in assembly. No one deserves to get zapped in 2022 from just touching the machine in operation!

 

It’s super easy to test this with a multi-meter you know. :)

Unplug the system from the wall, and measure resistance in Ohms from the ground prong on the AC cable to the chassis. Should be near zero.

Post removed