Hello. New member here.
This phono is giving me FITS with it's low treble response!
I bought this a few years ago. It arrived with a brtoken power tube, and a burned / snapped resistor between some E caps.
I replaced the broken tube, and all electrolytics, as well as the 3 paper caps as a start.
Played, but odd low treble.
Shotgunned the resistors, same result.
Removed the loudness compensator couplate, and replaced with individual components, same result.
Went so far as to replace every single ceramic capacitor, and even a high reading balance pot... Still, low treble.
I began some slight circuit tracing in the way of powering the turntable itself from a separate power supply (my finger), and hooking the cartridge up directly to the home stereo (1970s Technics) aux input. Sounded great. Rivaled a magnectic cart.
Hooked the Silvertones speakers up to the same home stereo amp, and they sounded great too.
So, this eliminates the cart, and the speakers as any sources of trouble.
A little further (same finger powered setup) I tapped the cart at the volume control wiper. Sounded great to the home stereo amp at full blast, but as soon as the volume control is backed off even just a litte, boom, there goes the treble. Same response with the loudness compensator couplate removed from the volume pots 1 meg taps. The volume was louder, but still the same treble bleed.
Here's the schematic and parts list that's inside the cabinet.
Here's the Sams schematic.
The differences in the 2268 and 2268A chassis are as follows.
The loudness compensator couplate in the 2268 has 100K resistors, mine (2268A) has 68K resistors.
The capacitors going to the positive speaker leads in the 2268 are .01, mine (2268A) are .02.
The resistors just in front of those two capacitors are 33K (left), and 68K (right) for the 2268, and mine (2268A) both have 15K.
The tone control has .004 caps for the 2268, and mine (2268A) has .01 caps.
ALL is wired according to the schematic posted inside the cabinet, for the 2268A
Something I noticed that doesn't jive between the Sams schematic, and the original cabinet schematic is how the negative of each transformer is connected back to circuit. My wiring (in line with the cabinet schematic) show the negative of the left channel going directly to chassis.
The negative of the right channel is connected thru a .02 cap to B-.
The Sams schematic shows for the 2268A the left channel negative going to directly to B-, and the right channel negative going thru a .02 cap to chassis.
Which one makes more sense?
And how is the voulme pot wiper bleeding treble to the home stereo amp?
Am I barking up the wrong tree?
