I've got a marantz 7t with very low level audio even with the pot cranked. In addition, the audio is heavily distorted, kind of like listening to a big piece of gunk on the phono needle. I'm trying to find a schematic, or if anybody out there knows what type of transistors were used, any drop-in replacements, etc., that would be very helpful.
I've got the schematic (came with the owner's manual for my swap-meet 7T). I'll scan it later today if someone doesn't beat me to it. (version is Aug 1966 - Units Starting With Serial No. 12501)
There's a penciled note on it saying that the transistor with Marantz part no. DTM4 is equivalent to F2N3638A, or 2N3626 or SK3025
The 7T is beautifully made, and ready for a 1960's home theater with a TV input and center channel output. I was disappointed that it wasn't a 7C, but bought it anyway since it came with a Dynaco ST-70 and FM-3. The last time I used it I though it sounded "grittier" than the Hafler DH101; when I get around to it, I want to test it with RightMark Audio Analyzer and see if it meets specs.
According to the owner's manual:
IM distortion was rated at 0.15% at 10 volts rms equivalent peak output; the Performance Documentation card for this unit says it did 0.05% to 0.08% on the bench.
THD was "non-measurable" at 1 volt @ 2kHz, 0.03% at 10 volts @ 2kHz.
There's a penciled note on it saying that the transistor with Marantz part no. DTM4 is equivalent to F2N3638A, or 2N3626 or SK3025
The 7T is beautifully made, and ready for a 1960's home theater with a TV input and center channel output. I was disappointed that it wasn't a 7C, but bought it anyway since it came with a Dynaco ST-70 and FM-3. The last time I used it I though it sounded "grittier" than the Hafler DH101; when I get around to it, I want to test it with RightMark Audio Analyzer and see if it meets specs.
According to the owner's manual:
IM distortion was rated at 0.15% at 10 volts rms equivalent peak output; the Performance Documentation card for this unit says it did 0.05% to 0.08% on the bench.
THD was "non-measurable" at 1 volt @ 2kHz, 0.03% at 10 volts @ 2kHz.
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