Fisher X-100 5AR4 screw-up

[ronton3]

Okay, now I see what you are saying, I misunderstood before. I will check that in the Morning and get back. Thanks for another very helpful lesson, and your patience. ron

 

[ronton3]

This is a Fisher X100 schematic for 30001 to 39999

https://elektrotanya.com/fisher_x-100_parts_sch.pdf/download.html

it definitely says 44v at pin 3 on the output tubes, which would give about 11v per tube. My point is that if the preamp tubes are not hot enough, they may not pass a signal. Get the heater voltage reasonably close to ballpark and see if it starts working before getting too far down a rabbithole.

With pin 3 correctly set to 44v,(it was 34) I now have 11volts across pins 4 and 5 on the first 3 12AX7s and 10 on the last. In the picture you will see 3 little black RT3's, I am showcasing those because all are bad, now both channels play nicely balanced, there was a verylight signal on B before but not much. I am guessing that the right voltage on the 12Ax7s and the new oils combine for a wonderful sound. All electrolytic's replaced, all the fixed caps replaced, the orange drops in 1998, the russian oils last night. I should receive the 120/7watt resistor Friday, them I will do another voltage check. The X-100 is a wonderful performer, currently driving a pair of Marantz Imperial 6 speakers, I am listening to Linda Ronstadt, from a Sota Saphire, with a Sumiko moving coil cartridge and both mag1 and 2 work with out hum(a small miracle), I am not certain yet which one is best.
Again thanks for the help, and patience. ron

 

[gadget73]

ah, the dog turd caps died. Yeah they aren't the most awesome devices unfortunately. One of the rare cases where film caps actually fail.

 

[ronton3]

I replaced the 150 ohm power supply resistor with the 120, made almost no difference anywhere. The voltage chart shows some problems, V1&6 are more than 20% low, the 20mfd cap to V1 pin 1 is only 136V instead of 150. the 6BQ5s are very close, C-15 B is a bit low. Any recommendations. It still sounds great. Thanks ron