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#1
September 25th 07, 10:18 AM
posted to alt.binaries.pictures.radio
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National tone control circuit
This thing's driving me to distraction...
For the longest time, I couldn't get the volume control to work (had been out of the chassis, and I had no idea how to reinstall it) but I finally have that working properly. Now, I can't get the tone control to work. There's no change anywhere on the control's excursion. It's an active control circuit. As of now, there is a low level motorboat oscillation with the volume below about half (~10 Hz). If anyone has seen the circuit before, and can fill in any of the unreadable parts, please do so. TIA -- Say no to institutionalized interference. Just say NO to HD/IBOC! |
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#2
September 25th 07, 12:31 PM
posted to alt.binaries.pictures.radio
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National tone control circuit
Well, how about starting with the motorboating, and checking the decoupling
caps? |
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#3
September 25th 07, 12:37 PM
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National tone control circuit
Brenda Ann wrote:
This thing's driving me to distraction... For the longest time, I couldn't get the volume control to work (had been out of the chassis, and I had no idea how to reinstall it) but I finally have that working properly. Now, I can't get the tone control to work. There's no change anywhere on the control's excursion. It's an active control circuit. As of now, there is a low level motorboat oscillation with the volume below about half (~10 Hz). If anyone has seen the circuit before, and can fill in any of the unreadable parts, please do so. TIA If that's the tone control between the 6AV6 and 6BQ5, looks like a (neg?) feedback circuit. If it got reversed somehow could cause motor boating. Ken |
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#4
September 25th 07, 01:37 PM
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National tone control circuit
"William Sommerwerck" wrote in message . .. Well, how about starting with the motorboating, and checking the decoupling caps? All caps have been replaced. I even doublechecked all my connections to make sure I didn't err installing any of them. |
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#5
September 25th 07, 01:37 PM
posted to alt.binaries.pictures.radio
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National tone control circuit
"Ken" wrote in message ... Brenda Ann wrote: This thing's driving me to distraction... For the longest time, I couldn't get the volume control to work (had been out of the chassis, and I had no idea how to reinstall it) but I finally have that working properly. Now, I can't get the tone control to work. There's no change anywhere on the control's excursion. It's an active control circuit. As of now, there is a low level motorboat oscillation with the volume below about half (~10 Hz). If anyone has seen the circuit before, and can fill in any of the unreadable parts, please do so. TIA If that's the tone control between the 6AV6 and 6BQ5, looks like a (neg?) feedback circuit. If it got reversed somehow could cause motor boating. Ken Negative feedback circuit is OK.. if I switch the polarity, it howls like a banshee..  |
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