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Hotwax
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Post subject: Realistic Clarinette II SS record player L channel noise Posted: Jun Sun 23, 2019 3:54 am |
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Joined: Jan Wed 16, 2013 12:04 am Posts: 2245 Location: 77001
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Hello all, I have a 1970's Radio Shack phono here that I've completed restoring the BSR changer.
With some old Panasonic speakers, it sounds very good, except the left channel is putting out a shushing or surf-like sound. Sound is not really loud, but I'm wondering if it is indicating a coming failure. I know very little about SS amps, would there be a logical troubleshooting starting point ? I have a good DMM to use. Thanks for bearing with me, Hotwax
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Artcurus
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Post subject: Re: Realistic Clarinette II SS record player L channel noise Posted: Jun Sun 23, 2019 4:26 am |
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Joined: Feb Wed 04, 2015 12:26 am Posts: 1479
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Hotwax
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Post subject: Re: Realistic Clarinette II SS record player L channel noise Posted: Jun Sun 23, 2019 3:53 pm |
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Joined: Jan Wed 16, 2013 12:04 am Posts: 2245 Location: 77001
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Okay, I figured it was a transistor.
I lucked out and found the schematic on the bottom of the cabinet. Posting it.
I did some reading on transistors (npn, pnp differences and how they appear on schematic)
Can someone now direct me on what to do next ?
Remember, this is my first foray into SS amps, so be kind and detailed, ha ! H
Attachments: |

Clarinette II Scheme.jpg [ 260.24 KiB | Viewed 1283 times ]
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Artcurus
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Post subject: Re: Realistic Clarinette II SS record player L channel noise Posted: Jun Mon 24, 2019 12:21 am |
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Joined: Feb Wed 04, 2015 12:26 am Posts: 1479
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Transistors consist of a emitter, base and collector. The legend is up at the top of the schematic. Start by taking voltage measurements with a vtvm. Unfortunately it needs to a sensitive meter such as this. The other option is that most modern meters have transistor checkers on them. The bad news is that you have to know the exact transistor number to find the replacement.
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Tim Tress
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Post subject: Re: Realistic Clarinette II SS record player L channel noise Posted: Jul Tue 16, 2019 1:46 am |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 10035 Location: Beaver Falls, PA. USA
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It was made by Arvin; they also made similar units for Sears.
The preamp stage is an FET (field effect transistor). If you have an oscilloscope or signal tracer, the noisy component should be easy to find. Remember, you have one working channel to compare the noisy one to. As old as that unit is, it is possible to have a leaky electrolytic capacitor or noisy resistor as well.
In the shop, we would hit all of the transistors and other components with cooling spray, one at a time. That would usually reveal the culprit.
_________________ Tim KA3JRT
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NumberMaj 1
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Post subject: Re: Realistic Clarinette II SS record player L channel noise Posted: Jul Tue 16, 2019 2:06 am |
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Joined: May Sat 06, 2006 4:03 am Posts: 3606 Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
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Id'n that sound to a transistor is highly probable. But I would replace all the electrolytics before probing the transistors and possibly blowing one.
Bill J.
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