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#26 pre amp
#26 pre amp
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Old 20th March 2013, 09:45 PM   #2661
stajo is offline stajo  Sweden
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#26 pre amp
Erik: I dont think he has any current thru the tubes at all atm. Surely the cathode needs to find ground somehow.

Merlin. Swich on once more and see if you have any current between filament pin and ground.
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Old 20th March 2013, 10:06 PM   #2662
merlin el mago is offline merlin el mago
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I have 1,485V in each heater
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Old 20th March 2013, 10:06 PM   #2663
andyjevans is offline andyjevans  United Kingdom
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If Rod's board is working correctly you should have about 1.5v between the two filament pins of the 26. You should then have around 11volts or whatever across the cathode resistor. You should check that these voltages are correct BEFORE you fire up the B+. Check all the wiring: Rod's board output has - to ground and + to one side of the 26 filament. The other side of the filament is connected to ground via the cathode resistor, and this should have about 11v on the top of it.

Last edited by andyjevans; 20th March 2013 at 10:10 PM.
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Old 20th March 2013, 10:11 PM   #2664
merlin el mago is offline merlin el mago
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Rod's filaments are working OK in both tubes.
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Old 20th March 2013, 10:14 PM   #2665
ErikdeBest is offline ErikdeBest  Switzerland
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Hi Merlin, just to confirm, how much voltage are you measuring between (one end) of the filament and ground - that is the voltage over the cathode resistor, as Andy is asking.
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Old 20th March 2013, 10:16 PM   #2666
merlin el mago is offline merlin el mago
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Rod's filament are floating.
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Old 20th March 2013, 10:18 PM   #2667
stajo is offline stajo  Sweden
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#26 pre amp
Quote:
Originally Posted by merlin el mago View Post
Rod's filaments are working OK in both tubes.
How many volts exactly do you have between each filament pin and trafo center tap/ground?
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Old 20th March 2013, 10:19 PM   #2668
ErikdeBest is offline ErikdeBest  Switzerland
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So you have the + and - of the filament regulator across the filament of the #26? In other words, you do not have it across the filament AND the cathode resistors?
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Old 20th March 2013, 10:20 PM   #2669
merlin el mago is offline merlin el mago
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Filament trafo haven't center tap. I use one separate for each tube filament.
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Old 20th March 2013, 10:21 PM   #2670
stajo is offline stajo  Sweden
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#26 pre amp
Quote:
Originally Posted by merlin el mago View Post
Rod's filament are floating.
filament trafo shall float, not the filaments themselves. if it all floats, you dont connect to ground and no current can pass the tube
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