Motorola TS-4J

[Electronic M]

Originally Posted by dieseljeep

I think he meant C97.
I just spent a half hour trying to find the B+ source. It seems it's sourced from the cathode of the 12SN7, 2nd clipper.
Slightly harder schematic to understand! Even the Sams isn't much better.

The TS-4 family created the B+ rail by using several stages between B++ and B- as a voltage divider. You know how some makes used the audio output as a voltage dropper instead of a resistor...Moto took it a step farther by using several tubes in series-parallel to make a voltage divider. Crazy but it worked.

[timmy]

Originally Posted by Electronic M

The TS-4 family created the B+ rail by using several stages between B++ and B- as a voltage divider. You know how some makes used the audio output as a voltage dropper instead of a resistor...Moto took it a step farther by using several tubes in series-parallel to make a voltage divider. Crazy but it worked.

And later with the ts18 they used half of the I think it was the audio amp for the verticle oscillator, well they had there ways back in the day.

[dieseljeep]

Originally Posted by Electronic M

The TS-4 family created the B+ rail by using several stages between B++ and B- as a voltage divider. You know how some makes used the audio output as a voltage dropper instead of a resistor...Moto took it a step farther by using several tubes in series-parallel to make a voltage divider. Crazy but it worked.

It only seemed to be the 12SN7 feed and I didn't explore the rest of the circuit to determine the rest of the voltage divider circuit.

[Zsuttle]

So, does anyone have any good tips to keep troubleshooting? I've gone through the schematics up through the power supply, but haven't really checked much else.

[timmy]

What exactly is wrong tubes won't light, caps won't charge to proper voltage ?

[Zsuttle]

Tubes light for about 30 sec and then they sorta flicker on and off and there's still something causing my caps to fry as well. The filament circuit problem is just caused by the faulty electrolytic caps, but I can't figure out what causes my electrolytics to fail in the first place. Some of the caps that were around 10-20uF are now testing in the hundreds range.