A lot of folks interchange the names filament and heater. Both light up but their purpose is
different. A filament acts as the cathode in what is known as a directly heated tube. This type of tube
has no separate cathode. A heater is used in an indirectly tube. It is fitted inside a small metal
tube and is isolated from the filament. That "tube" is the cathode. The heater is used to heat
the cathode so it can produce the electrons need to make the vacuum tube conduct.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
resistance checks done from chassis to each 6sq7 pin
*removed all tubes to help isolate the readings
**if tube needs to be in, then tell me
results
1=0/chassis
2=9.9M
3=0/chassis
4=4.5M
5=790k
6=8.3M
7=open
8=25.8ohms
now to part 2,,,, WHICH JUST NOW really sucked!,,, "disconnect pins 4 & 5 connections"
-powered up and within 10 seconds the rect tube glowed that purdy blue "ish" color
then.................
-the 25ohm resistor on the N leg of my power cord to chassis blew a hole out the side of it letting out all the air and smoke. I tried fix a flat and the hole in the resistor still remains!
this is one of those perfect examples where i need to learn exactly what i can actually disconnect and what i cant with power applied.
the bright side is yes the radio did remain silent but its a foul ball because nothing really had time to warm up yet before the smoke.
with pins 4 & 5 empty on the 6sq7, i think that allowed the rect tube and the 25ohm resistor to become the path of least resistance.
what next?
(This post was last modified: 06-27-2018, 10:10 AM by jcassity.)
certainly seems that way but i am careful,, and did not so............
i will land things back on 5 & 4 pins of the 6sq7 and determine if i am able to get things back to the way they were.
if not.. summit delivery just happend,, Hpipe & header back exhaust setup then chip the eec and maybe a test hit this week for the coug
A resistor in the heater line should not blow, reguardless what you've disconnected on other pins. Requires a major short.
Operating, the total current draw for tube elements is roughly 70-80 ma, by far most of that is the pair of 50L6 audio outputs. The 25Z6 operating with elements in parallel can safely supply maybe 150ma, above that it's in failure mode. The purple was either a severely overloaded tube or it catastrophically failed by it's own accord.
By chance were you using the 25Z6 that was previously overloaded?
My Birdie is still in pieces, maybe one of these days.
>My Birdie is still in pieces, maybe one of these days.
So is mine. Just got a gas tank for it.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
update...
yes i was at fault,, but it was over at the area called the door of the garage.
i had it open,, and i do have cats.
so........
update......
with all leads off pin 4 & 5 of the 6sq7,, the noise remains.
it took a good bit of warm up time to confirm but the noise remains. does this mean the issue is closer towards the antenna input?
or does this tell us the problem is down the ckt towards the 6sc7?
(This post was last modified: 06-27-2018, 04:57 PM by jcassity.)
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
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