I’m Back! Pilot TV37

[jr_tech]

What do you mean by “fried” and “baked”?

jr

[Chris K]

Originally Posted by jr_tech

What do you mean by “fried” and “baked”?

jr

No emission...zero

[jr_tech]

Do the heaters lite up on the zero emission tubes?

jr

[Chris K]

I don't know but...in the absence of any good 12AT7 tubes, I substituted 3 12AU7 tubes, not a good direct replacement but good enough to check function, and things are back to semi normal function. I suppose something transient caused the issues, not a persistent connection problem or a wiring issue. The tubes now all light up and there's light on the screen. Sorry I pulled everyone down a rabbit hole.

[Chris K]

Originally Posted by jr_tech

Do the heaters lite up on the zero emission tubes?

jr

Obviously lots of work left to do and I'll wait for the correct tubes but we're back online again.

[Electronic M]

That's good to see.

You need 12AT7 or IIRC 12AV7 for RF/Osc/IF applications(the capacitances and such of the AU/AX are too different), but the 12AU/AX7 will basically work close to audio frequency.

[timmy]

Make sure the b+ is where it should be. mine no matter what I did couldn’t get the b+ right so I put a 1n4007 across the positive rectifier tube that fixed it.

[jr_tech]

Originally Posted by Chris K

Obviously lots of work left to do and I'll wait for the correct tubes but we're back online again.

Looking promising! Any clues/theories as to what caused the big transient?

jr

[Chris K]

Originally Posted by jr_tech

Looking promising! Any clues/theories as to what caused the big transient?

jr

Yeah I'm always very careful to have power switch on the unit off and the Variac/Dim Bulb setup all powered down and shut off when I plug in the unit but I didn't have everything in that configuration so when I plugged it in there was a flash...that was the 3 ohm resistor in the string blowing and the tubes getting whacked. Or it was when I unplugged it in the same condition. Can't completely remember but it was not while the TV was in operation.