On Tue, 18 May 2010 13:03:20 +0100, Arfa Daily wrote:
"Meat Plow" wrote in message
news
On Tue, 18 May 2010 10:40:49 +0100, N_Cook wrote:
Arfa Daily wrote in message
...
"DaveD" wrote in message
...
Arfa Daily wrote:
"Geo" wrote in message
...
On Mon, 17 May 2010 17:28:20 +0100, "Arfa Daily"
wrote:
It definitely says "Rega Planar 3" at the top front right
corner, although
it's hard to see as the letters are just black 'shininess'
within the black
satin anodised finish of the cabinet. Underneath, directly under
the motor,
is a cover secured by two screws, When this is removed, the
motor and
a
small PCB are revealed. The PCB has just two components on it -
the burnt up
R, which is a large 'film' type, I guess something like about
5mm diameter
and 20mm or so long, and the 0.22u 400v cap, which is one of
those green MKT
monobloc types. These two components are mounted 'on the slant'
on
the
board. The mains comes in, and the neutral is joined immediately
to
two
grey
wires from the motor. The live leaves the board again on a white
wire which
goes to the on / off switch at the front top left of the deck.
Live returns
to the board on another white, and goes to the motor red lead
via the burnt
up resistor. The cap is between the red lead and the remaining
blue lead.
Doesn't sound much like the example that you're looking at, eh ?
How about this version from mine - looks like a 15k 5% (old 2-5w
carbon?)
http://www.8zero.co.uk/planar.jpg
--
Geo
Yes, that's closer - although still not quite the same
configuration. It's actually a different motor in yours, but the
supply still goes to the red via the resistor, and the cap still
appears to be between red
and
blue, and the same value, although a different type. Based on
that, I think I'm going to start with 15k now, and see if the
motor runs, and
if
it does, if it has enough torque to drive the platter.
Thanks very much for taking the trouble to post me the piccy.
Appreciated.
Arfa
Hi Arfa
Further info. The data I supplied earlier was from the Planar 3
upgrade motor assembly.
I have just pulled out the old motor and PCB. It has only 2
components on it.
1 x 220nf 250v ac X rated cap manufactured by Rifa. 1 x 12k 2-3
watt resistor, 8.5mm dia x 25mm long. The resistor is a mid brown
body colour and the bands are quite hard to read but measurement
confirms 12k 5% (as in brown red orange gold) The brown and orange
are hard to differentiate The motor is a Philips 110v 50hz 250 rpm
(12NC 990411131613) date of manufacture 1985 with the same colour
leads I would suggest going with what you have in the 12 - 15k ~ 5
watt resistor. Check that the voltage to the motor is in the region
of 110v under load and it should be good to go Cheers DaveD
Many thanks Dave. That's it exactly. I just had a look, and I haven't
got
a
high power 12 or 15k in stock, but I have got some 47k 2 watt film
resistors, so to save time and get the item back to the customer
(he's already put up with me being away on holiday for 2 weeks !),
I'm going to put three of those in parallel as there's plenty of
room. Thanks again,
all.
Arfa
Is there a fuseable resistor function to the original ? ie 2 watts of
dissipation from stalled motor and the R blows rather than the motor.
Would not some 1/2 watt resistors together giving 12K be better?
He has a point.
I wouldn't have said that there was an 'implicit' fusible function to
the resistor, but I suppose that you could argue it as a secondary
function. The plate on the bottom of the deck claims that the power
requirement is 4 watts, so given that the primary function of the
resistor is that of a dropper for the 110v motor, you would have to say
that this equates to around 2 watts dissipation in the motor, and the
other two in the resistor. As the original resistor is rated at around 4
watts, that would sort of indicate that it had been dimensioned to be
able to stand up to its job without burning out. I'm not actually sure
what happens to the current that a synchronous motor draws if you stall
it, but I wouldn't think that it ramps in anything like the same way as
that of a DC motor, or any kind of brushgear AC motor ??
I thought you should cover all bases as Cook did. Not really knowing
what the pwr supply capability was I thought it at least worth looking
into. Have you an idea why the original failed?