Posted by Damir [ 213.202.69.230 ] on January 13, 2005 at 07:06:44:
In Reply to: Today's Puzzler posted by TubeCraft on January 12, 2005 at 13:52:31:
Frequency selective fault, hmm ?! I`d try to disconect input and output connections from this triode and cathode bypass cap, too. Install grid leak (say, 100k from grid to ground) and then you have only Ra, Rk and Rg. Be sure that B+ is OK (no bypass caps to the "wrong" places, etc.).
Then try the 100Hz input direct at the grid pin, and measure the output, direct on the anode pin. You must get the good result, check everything. Check 220uF cathode bypass capacitor, polarity, and solder it, then check again (more amplification). Then check input jack and input pot and install them. Check again. If everything is allright, then check and install output cap, etc.
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