Arfa Daily wrote in message
...

"N_Cook" wrote in message
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Arfa Daily wrote in message
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"N_Cook" wrote in message
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Assuming no obvious internal o/c connections to electrodes, then a
stripped
cathode is about the only thing. However, I don't quite understand your
statement "no gain at all at any anode current". It seems to me that if
you
are able to see *any* anode current, then the valve is, to whatever
degree,
'working', and hence has at least some gain ?? How does the tester control
the anode current ? By varying the g1 voltage ? If it does, then that
would
confirm that the grid is not o/c. Thinking a bit more, you might well see
some anode current, but little 'gain' if the g2 connection was open ?

The schematic for the '60 that I pointed you at, has a detailed diagram
set
of the primary connection arrangement for different voltages. Probably a
similar scheme to the '150 ?

Arfa



Other than heater continuity it tests as though no valve placed in the
socket.

Same colour code of primary, not secondaries , as that blue voodo and
seemingly the same significances. But I'll have to take apart to check what
is jumpered to what, and also the HT1 smoothing is different as it uses 3 ,
not 4 caps there. I forgot to check each voltage on the 7 primary wires,
will do so next.

With the duff 6L6 and one other removed
Putting 199V on the existing setting of primaries gives 5.65V ac so
suggesting 6.53V ac if 230V fed in on existing internal set primaries. Is
6V ac on that Crate BV60 schematic a strict ie +/- 0.1V, or nominal 6V (with
all 14 heaters supplied presumably)
Also 199v "mains" gives 407V HT1

The hum is present but with my variac I can lift the ground and doing that,
the hum goes and amp works fine , normally testing an amp there is no hum
and lifting the ground can introduce hum , so I wonder what other problem
lurks. 1000V megga test on the mains Tx shows nothing amiss to ground.


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Diverse Devices, Southampton, England
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