And, aside from the common scenarios that Scott and Chris mentioned - there is also the possibility of damaged wiring making the chassis hot ... for example, crumbling power wiring going up the tube, generator wires routed incorrectly and eventually wearing through their insulation, etc.? It might also be possible to bring this about by mis-clocking a Leslie connector, etc....
When I build an organ, I verify transformer leakage, earth the chassis and install a master fuse.? This means that a hot chassis, due to either the Leslie or the organ, will blow the fuse before and kill power to the whole system.? Smaller fuses on the AO28, Leslie amp, and leslie kit should blow first, protecting the master fuse in case of faults in those systems.
There are few pieces of metal that are tricky to ground in a Hammond, though.? Like the reverb knob plate on an A100. Luckily, there is no AC wiring up there.? A 147 Leslie switch is a bit harder to safe.?? This is why I prefer 122 switching for pro rigs.? At least with a polarized inlet, you can ensure that the organist can only contact neutral in the event of a wiring failure inside the halfmoon....assuming the receptacle is wired properly and that there are no other wiring faults and that the coil in the Leslie's relay isn't shorted.
Wes
There are other ways to get a hot chassis on a Hammond Organ,
transformer or not, and a prime example that I've had to correct
numerous times is in conjunction with 122-type Leslies, which came
with so-called "death caps," which were meant to filter any noisy
AC coming into the amps. When these failed (shorted to ground), AC
would be present on the ground wire and thus returned to the
organ. These days we rplace the death caps with X2/Y2 caps, which
do not pass AC when they fail. Available at Tonewheel General and
other large electronics parts houses.? Delvon Lamarr was getting
shocked on his gig one night, and that's what was doing it!
On 2/29/2020 10:05 AM, Rich Reid wrote:
Old
often equals leaky.
?
Rich
Reid
208-861-9263
?
?
Why would anything with a power
transformer have a hot chassis?? Further, adding an IEC
with ground to a "hot" chassis would then tie neutral and
safety ground together, not something to do, yes?
?
I am just lurking around trying to
find time to dive into the C3, CV, M100 and 122 at my
house, and do not have a deep collection of Hammond
experience in my head.? However none of the schematics
i have looked at show a hot chassis.
I am not weighing in on the
ground-the-chassis-or-not debate.? There are pros and
cons to both, seems to be a matter of personal
preference.
?
Unless I was 100% sure that the
power cable couldn't be oriented incorrectly and the
power cable was wired correctly I wouldn't want to
touch a Hammond organ as there is a risk the chassis
could be live. This could happen if the original
outlet broke and was replaced with a non-polarized
one. Although the playing surfaces are plastic or
painted metal, there is exposed metal behind each
drawbar which poses an electrocution risk if you touch
it.? ?Better stay safe and put an IEC male connector
on the organ.? Do an earth leakage test first to see
if there are any problems that will need fixing as
leakage (e.g. from the transformer) will trip a modern
breaker.
--
Wesley W. Garland
Director, Product Development
PageMail, Inc.
+1 613 542 2787 x 102
