Guess what?

Amp Mad Scientist said:
OK R6 is a fuse in case the tube draws too much current it's supposed to blow.
(it's a current limiting resistor)
You can replace that with 1 watt 1 ohm resistor and it doesn't matter which type.
Precision resistor is OK no problem.
It does not need to be a matching type resistor, any type resistor will work.

Note: do not change this resistor to a larger rating. It will prevent the resistor from blowing.
If the tube draws too much current the resistor is supposed to blow.

The bias failed, which caused the tube to red plate and draw too much current....
then the resistor is supposed to fail. This saves the output transformer etc.

The bias fails because:
The bias pot stops working (very bad design), then the tube red plates.

What makes the bias pot fail?
The B+ voltage is leaking into the B- voltage. This is what happened before you put the new board in.
This happens when the insulation of the old circuit board fails.

But now that the old circuit board is replaced,
the insulation should be good again. (that's what you test before you put the new tubes in).

So change the bias pots.
Change the 1 ohm cathode resistor R6.
Test the screen resistors. Test the grid resistors.

Then proceed with checking the bias voltages (I'll show you how to do that) on all the output sockets pin 5.
This is done with the high voltage turned OFF, and no tubes installed.
Click to expand...


I am getting a real potty mouth lately, but it is the only proper way to express a lot lately.

I learned a SHITload just from ampmad's post above.
 
Amp Mad Scientist said:
Many of the tests are done without any power turned on.
This does not need a current limiter.

The next tests are done with the high voltage turned OFF.

Yes
I am the one who wrote the first test procedure for DSL boards...because nobody else ever did it before.
Prior to that, there was no test procedures.
Only guessing, and random parts replacements.
Click to expand...

WTF,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, NO TEST PROCEDURES?
AND NOW I read from MCblink, NO Stock of replacement Bias Boards?
 
Ever since I began learning amp repair, I have been fascinated by schematics. ****** Disclaimer, I get frustrated at some hand written ones where I have trouble reading the letters, numbers words etc.

BUT I flat out love poring over the specs and components and then finding them in the physical actual component, then logically interpreting the logic on the amp's design and how all the parts interact. Determining any swapped out parts, correct values or not as per schematic vs actual board.

1619293329261.png

Something so logical about it all once one learns the principles.
 
Amp Mad Scientist said:
That's the ******* *** Method.
Click to expand...

How dare you soil the sanctity of this beloved hallowed ground with the name of that, that, that..... ANIMAL!

dG3WXoE.gif
 
mcblink said:
So @Amp Mad Scientist has mailed the bias board back towards my way and I await it's arrival.

Thanks for the test procedure AMS, I will get to it as soon as the bias board arrives and I can begin reassembling the nest!


It appears quite intimidating but it's really not too terribly bad. As I mentioned before, I have torn this thing apart enough times now to where I have stopped pooping my britches every time I open it up
Click to expand...
You can do all of that in 15 minutes.
 
Ghostman said:
How dare you soil the sanctity of this beloved hallowed ground with the name of that, that, that..... ANIMAL!

dG3WXoE.gif
Click to expand...
When he said all JJ tubes are defective, that's what pizzed me off.
He said that Bob at Eurotubes was a criminal, etc...
And I admit that I reacted.

I bought about 80 JJ tubes and I think 2 were not working right.
It's about average.
I buy almost any kind of tube, and there is an occasional bad tube. It's not that defects are limited to JJs.
I get just a many defect Groove Tubes as defect JJs probably....
And heck I use JJs all the time and I would notice if they were all defective.
 
Amp Mad Scientist said:
When he said all JJ tubes are defective, that's what pizzed me off.
He said that Bob at Eurotubes was a criminal, etc...
And I admit that I reacted.

I bought about 80 JJ tubes and I think 2 were not working right.
It's about average.
I buy almost any kind of tube, and there is an occasional bad tube. It's not that defects are limited to JJs.
I get just a many defect Groove Tubes as defect JJs probably....
And heck I use JJs all the time and I would notice if they were all defective.
Click to expand...
Ya see, if you're walking down the street and a crazy guy is screaming "ITS THE END OF THE WORLD!" you dont' get mad and try to argue with him. You just open your mouth and clearly reply, "AS YOU KNOW IT, AND I FEEEEEEEEEEELLLLLL FINE!!!!"
 
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