tempus fugit wrote:
We're talking about a capacitor between the chassis and one side
of the line, right?
I havent reopened the chassis, but it seems to be connected between the
ground of the speaker and the chassis.
OK, that's something totally different.
something is shorted somehwere else. Oh, and I checked the voltage
between
the record player chassis and the scope chassis - 120VAC
Reversing the plug in the wall socket should change that (but don't
count on it).
Reversing the plug did correct that. Is this a design shortcoming (if so,
there's gotta be a safer way to set that up) or should I be looking for a
fault somewhere?
That's normal for a "hot chassis" device. But such a device won't have
a power transformer, and I thought you said this one did. Could you be
confusing an output transformer with a power transformer?
If you are (and I suspect you are) then you are such a newbie that you
had better stop now and enlist the help of somebody who knows what
they're doing before you kill yourself. No kidding. I don't want to
have anything more to do with this pursuit.
tempus may fugit, but not for the dead
You really need to be careful with this device. I can't stress that
enough. Death is not to be trifled with.
I am being very careful, not to worry, but I appreciate your concern and
helpful advice (including those on personal safety).
Thanks again
Thanks
"CJT" wrote in message
...
CJT wrote:
tempus fugit wrote:
Tried the turining around the plug trick, but it made no difference. I
also
disconnected the phono plug that connects the tone arm to the amp
unit,
which also made no difference.
Here is something curious though. I accidentally touched my scope
while my
hand was on the record player chassis and got a fairly good shock. The
scope
has a 3 prong AC plug (the record player doesn't). I should've
measured the
voltage difference between the sope chassis and the record player
chassis,
but I didn't think to. I'll have to do that. Perhaps he chassis is
live. I
didn't think this would be the case though, since there is a cap with
the
negative connected to the case, as well as a few other green wires.
That capacitor might be leaking or (worse) shorted. It can be a lethal
failure (I read just this week about a minister in Waco who was
electrocuted during a baptism when he grabbed a microphone that was
"hot."). Be careful.
Here's a cite to that story:
http://www.cbsnews.com/stories/2005/...in995829.shtml
Thanks
"Asimov" wrote in
message
news:MSGID_1=3a167=2f133.0_43612958@fidonet. org...
"tempus fugit" bravely wrote to "All" (27 Oct 05 11:17:42)
--- on the heady topic of "unit hums loudly regardless of volume"
tf From: "tempus fugit"
tf Xref: core-easynews sci.electronics.repair:346437
tf Hey all;
tf I'm trying to repair an old tube portable record player. When it
is
tf on, it hums really loud, regardless of the volume.
Have you tried turning the ac plug around?
Which way the plug is inserted matters with these. Let the record
player warm up, then insert the plug one way or the other, and then
paint a mark for which was the quietest way. One way: lots of hum, the
other: quiet hiss.
Those old tube units used to get B+ directly from the powerline (or
sometimes a voltage doubler) and used a large value resistor bypassed
by a 0.01uF to RF ground the tone arm shielding to neutral. The power
for the filaments often came from a secondary winding in the motor
coil. Don't use this type of record player near the bathtub. Lethal!
Another possibility is a broken wire at the cartridge.
A*s*i*m*o*v
... Just a little force field zap.
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