Curtis Mathes tube console...No sound on phono
- Thread starter Cbesing
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many factors
Just a little background info. I am not expert but have managed to fix a few things and learned a few things.
Is the CM phono input a ceramic cartridge or magnetic? The old tube stuff was in the days of ceramic and they didn't need a phone pre-amp in the circuit, so plugging a "new" magnetic TT into the input won't work without a phono pre-amp. Ceramic was about the same line level as a AUX input, so plugging a CD into it would be one test.
The old tube stuff is, well, old. So a bad capacitor is very possible, the old caps were a bit crude. A bad resistor is also possible as well as a bad tube. The phono circuit is suspect but its probably best on the old tube stuff to replace all the old electrolytic and wax paper caps (coupling caps?) right off the bat. Its a bit of work and figuring out all the values without a schematic can be a challange. Even with a schematic, things can be confusing due to "changes".
One nice things about the tube stuff is that they are "exposed" so you can sort of follow the connections from the input through the circuit and wonder about everything in the circuit having failed.
It would be nice to test all the tubes first, but having or finding a working tube tester is tricky these days.
Just a little background info. I am not expert but have managed to fix a few things and learned a few things.
Is the CM phono input a ceramic cartridge or magnetic? The old tube stuff was in the days of ceramic and they didn't need a phone pre-amp in the circuit, so plugging a "new" magnetic TT into the input won't work without a phono pre-amp. Ceramic was about the same line level as a AUX input, so plugging a CD into it would be one test.
The old tube stuff is, well, old. So a bad capacitor is very possible, the old caps were a bit crude. A bad resistor is also possible as well as a bad tube. The phono circuit is suspect but its probably best on the old tube stuff to replace all the old electrolytic and wax paper caps (coupling caps?) right off the bat. Its a bit of work and figuring out all the values without a schematic can be a challange. Even with a schematic, things can be confusing due to "changes".
One nice things about the tube stuff is that they are "exposed" so you can sort of follow the connections from the input through the circuit and wonder about everything in the circuit having failed.
It would be nice to test all the tubes first, but having or finding a working tube tester is tricky these days.
things
Like I said, the tubes are suspect, the caps and resistors too. She's an old dog.
It seems to me that there may have been different tape signal types back in the day. I've seen odd things on the really old units.
Unless someone here pops up with a lot of knowledge, it could be a long fun project getting it all up to snuff. I've been reading and searching here for over 2 years and just getting a little "learned up". Managing to fix a lot of stuff has helped with the educatrion.
Like I said, the tubes are suspect, the caps and resistors too. She's an old dog.
It seems to me that there may have been different tape signal types back in the day. I've seen odd things on the really old units.
Unless someone here pops up with a lot of knowledge, it could be a long fun project getting it all up to snuff. I've been reading and searching here for over 2 years and just getting a little "learned up". Managing to fix a lot of stuff has helped with the educatrion.
