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.
The 7T uses Germanium transistors. They may be difficult to get.
If the 7T has a relay, I would clean its contacts first. If that doesn't help, you'll need an oscioolscope to signal trace the signal.
Ron
If the 7T has a relay, I would clean its contacts first. If that doesn't help, you'll need an oscioolscope to signal trace the signal.
Ron
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.
Check your serial number. The previous schematic is the 1966 for serials starting 12501. I have the 1967 starting 15001 if needed.
If both channels are misbehaving in the same way, that suggests a single cause. Check the power supply first. A wild guess would be that Q601 or the DC fuse is open.
Marantz t7
caracteristique du transfo alimentation please
primaire 220v secondaire ? puissance ?
merci de me repondre
caracteristique du transfo alimentation please
primaire 220v secondaire ? puissance ?
merci de me repondre
Marantz 7t
Which are lack characteristics motivation for realization
its tensions in not watch not potency
thanks to all
Which are lack characteristics motivation for realization
its tensions in not watch not potency
thanks to all
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