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About Rick Montgomery
Expertise
Most questions about 1970's-1980's audio equipment. Most 1980's -1990's VCR's and VCR combo's. Most 1980's-1990's car audio, except original equipment. I know name brand after-market such as Kenwood, Pioneer, JVC, and some Sony. I am not so good with TV's, DVD's or camcorders. I do not work on Projection TV sets at all. I also have no access to documebntation for sets outside of the United States.

Experience
Professional Electronics Technician since 1975, specializing in most audio, home, portable and car. Also all VCR's. Limited TV knowledge. No projection TV experience

Organizations
Through work, NESDA.

Publications
n/a

Education/Credentials
High School. Graduated with 2 yrs Vocational Electronics in High School.

Awards and Honors
Certificates of completion of factory training seminars for various brands

Past/Present Clients
Thousands of customers to the Service Centers I have worked for.

You are here: Experts > Home/Garden > Home Appliances > TV/VCR/Stereo Troubleshooting > Toshiba 51H84 followup

TV/VCR/Stereo Troubleshooting - Toshiba 51H84 followup

Expert: Rick Montgomery - 11/8/2009

Question
But, does the thumping sound stop when the volume is reduced to zero?

IF NO: The problem may be what is called "motorboating" and is mostly caused by an instability from the power supply that is feeding the audio amplifier.

IF YES: The problem may be related to a bad speaker that has a damaged mounting of the cone and the thumping is caused when the audio program or music gives too much power and causes the cone to rub or bounce off the internal parts of the mechanism.

I need to know your take on the sound after you have considered the comments above. If it continues to wobulate in both channels regardless of the position of the volume control please explain it in detail. If it goes up and down with the volume control setting tell me if it changes in frequency or pitch, etc.

Thank you.

--Answer: The noise goes away when you turn the volume all the way down to zero. Even with this volume down to zero on the TV, the noise comes through the surround sound system. The noise does sound the same regardless of the volume level, it just gets louder the higher the volume level.

The noise is sounds a little like a constant low level thumping. Like a "whop, whop, whop, whop".

Hope this helps.

Thank you advance for your help!

Have a great day.

Answer
Lee,
I wish you had followed up with me from the original question. I was unable to locate it in my history, and do not recall if you mentioned, or if I asked you the following questions to.
Please follow up to this email as I answer a lot of questions, and cannot remember all the information nearly as well as these postings do.
1) Is the thumping sound present on all inputs?
2) is the thumping sound still there if you COMPLETELY disconnect your Surround System?
3)One at a time, COMPLETELY disconnect ALL other devices such as DVD, video game, VCR, etc. from the TV. Does disconnecting any of them make a difference?
I am asking these questions to attempt to determine if the sound is being internally generated on it's own due to a defect in the TV, or if it is caused by a polarity incompatibility from interfacing with one of your other components.
regards,
Rick

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