hum from carver CT27V

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brusso
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Joined: Sun Feb 15, 2004 2:03 pm

hum from carver CT27V

Post by brusso » Sun Feb 15, 2004 2:24 pm

Hello, I hope someone can help with this strange question. I was replacing the factory power cable with a one from Harmonic Tech. I added a male plug to the rear of the unit. While doing this I removed the Power supply/Pre out PC board. I noticed there was a wire broken from the end of the ribbon cable connection to J903 on the Pre/out side of the PCB. It was the third wire in marked ground. When I connect this wire I get a low hum coming from the speakers. How can I find out if this wire is supposed to be disconnected?
Thanks in advance.

lkapphahn
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Joined: Fri Mar 05, 2004 9:22 pm

Post by lkapphahn » Fri Mar 05, 2004 11:35 pm

Hello. A question, did you replace the standard power cord (no ground pin) with a grounded cord? Was this replacement cord installed to reduce noise? And if so did this alone improve line noise (speaker Buz). My TFM-55x suddenly developed a buzz to the speakers, and now I am wondering if I should look inside the amp for broken connections too. I measure 60VAC from the case to receptacle ground, the 60V goes to zero when the amp is plugged into any other equipment, ie preamp. I think my noise is from this 60VAC, and probably trouble with the transformer. Any insight to amplifier buzz/humm is welcome, Thanks.

brusso
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Posts: 4
Joined: Sun Feb 15, 2004 2:03 pm

re:

Post by brusso » Sun Mar 07, 2004 1:37 pm

Hello, I replaced the stock power cord to see if it would improve the over all sound quality. I did it to my CD player at it made a huge differance. I used a ground cord however I didn't connect the ground wire. I was not sure if doing that would cause any problems. My problem is I found a broken connection and I'm not sure if I caused it or if it's supposed to be broken. When I connect the broken wire I get more noise from the speakers then if it's dissconnected. For some reason I can't get all the noise to go away completely. Any Idea on how I can figure out ir this wire should be connected or not? Thanks -

lkapphahn
Newbie
Posts: 4
Joined: Fri Mar 05, 2004 9:22 pm

Amplifier BUZZ

Post by lkapphahn » Sun Mar 07, 2004 2:46 pm

Thanks for your reply. I don't have the same Amp you have, mine is a TFM-55x, so I can't help you with the broken wire on your ribbon cable, my amp has no ribbons inside. Maybe you can find a service manual or schematic and track it down that way. I was interested in your posting because my amp has developed a Buzz too. My amp does not use a grounded power cord, and I would not install one because the 60VAC I measure on the chasis to the ground screw on the wall receptacle would then be a short to ground, would probably let the smoke out of something! The 60VAC goes to zero if I connect the Audio input RCA jacks from my preamp, the shield on this audio connection is common to the chasis. The BUZZ is even heard when this amp and speaker is the only thing hooked up, I even connected it up in a different room and still have the BUZZ(I believe it is line noise, 120VAC 60hz). It just might be typical ground loop problem, wish I knew. If I had to guess I probably need to replace the transformer or power supply filter capacitors. Anybody out there who can help with this BUZZ please reply.
Attachments
TFM-55x inside.JPG
This forum only allows attachments up to 256k, so if anyone wants a much larger image, let me know and I'll send it to your email instead, I have many more photos of the inside of a TFM-55x available.
TFM-55x inside.JPG (75.46 KiB) Viewed 1476 times

brusso
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Post by brusso » Sun Mar 07, 2004 3:02 pm

thanks again for the response. the problem is with my pre-amp not my amp.

brusso
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re

Post by brusso » Mon Mar 29, 2004 12:38 pm

Hi,
](*,)

Does anyone know how I can get my question answered? Is there some place I can call?

Thanks Bill

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DaveS
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Post by DaveS » Tue Mar 30, 2004 7:10 am

Try calling Carver Service at 380 862 1742

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