***NEW ERROR***potential HUGE problem. Crate V18 PCB Trace... Wrong???

[jeff]

EDIT: NEW ERROR FOUND
There' another HUGE error!
The trace that connect pin 4 is passing through & connected to pin 1.
May not be a problem with EL84's that have N.C. on pin one, but..... SOME EL84's have i.c. internally connected pins 1 and 2. Tested all my EL84's with multi-meter and some do, some don't.
HUGE problem!


Also, pin 7 is connected to pin 6(another some have n.c. some have i.c.). Why I do not know. Even if Crate assumed ALL EL84's have n.c. on pin 6, why tie it to pin 7?


Most cases, won't be a problem, some cases HUGE problem

ORIGINAL
Not sure if it’s me, or these traces are wrong. There should be 470K to ground before the 10K grid stop resistors, but, am I crazy here, or are the traces wrong? This looks to me to form a voltage divider(10K/470K) with NO grid stop resistors.
First pic: original
Second pic: what I think it should be
Is it me?
Is the board wrong?

[jeff]

Fix?

[PRR]

That will grid-stop, good enuff for jazz.

The divider is 98%.... another 2% won't be heard.

[jeff]

So, wired as a voltage divider the 10K still acts as a grid stop resistor but the signal is slightly attenuated?
For some reason I thought the grid stop resistor needed to be placed after the resistor to ground to work as a grid stop.
I guess putting it after instead of before allows for full signal(no attenuation)?
Interesting, ya learn something new every day.
Thanks.

[shooter]

my mental mantra  "leaks ground, stops noise"

[jeff]

There's another HUGE error!
The trace that connects pins 4 of the output tubes is passing through & connected to pin 1!
May not be a problem with EL84's that have N.C. on pin one, but..... SOME EL84's have i.c. internally connected pins 1 and 2. Tested all my EL84's with multi-meter and some do, some don't.
HUGE problem!


Also, pin 7 is connected to pin 6(another some have n.c. some have i.c.). Why I do not know. Even if Crate assumed ALL EL84's have n.c. on pin 6, why tie it to pin 7?


Most cases, won't be a problem, some cases HUGE problem

[jeff]

https://el34world.com/Forum/index.php?topic=18789.0

[kagliostro]

To avoid the use of only some EL84 tubes is possibile to cut the unwanted connection on the PCB ?

Are this traks accessibile as to perform the cut ?

Franco

[jeff]

I'm thinking maybe snip the pin(of the socket)
Either that or cut the trace and try to jumper around pin one.
Cut trace jumper around pin 6


Any problems with just snipping the pin at the socket?

[JPK]

Is this related to Sluckey's recent thread?


https://el34world.com/Forum/index.php?topic=18789.0

[jeff]

That's the one

[sluckey]

Is this related to Sluckey's recent thread?


https://el34world.com/Forum/index.php?topic=18789.0

That thread is almost 8 years old.

[JPK]

Is this related to Sluckey's recent thread?


https://el34world.com/Forum/index.php?topic=18789.0

That thread is almost 8 years old.

Which makes it even more amazing.

[jeff]

Is it ok to just snip the socket leads of pins 1 and 6, or would it be better to cut trace and jumper around pin 1 and 6?
If you look at the original pic in first post, you can see just to the left of yellow and purple bands on resistor where heater passes through and connects pins 4 and 1.
https://el34world.com/Forum/index.php?action=dlattach;topic=30188.0;attach=105260

[kagliostro]

Is it ok to just snip the socket leads of pins 1 and 6, or would it be better to cut trace and jumper around pin 1 and 6?

If you are able to do it i'll snip the socket leads (NOT the tube pins)

Franco

[jeff]

Cool, thanks
I snipped pin 1, separated pins 6 from 7, then jumped pins 7 to O.T. quick disconnect.
Super-heated/lifted pad underneath pin 1(socket side of PCB) so there can be no contact at all.