Arfa Daily wrote:
Hi all

Anyone happen to know the value of the resistor in the CR network connected
in the synchronous motor feed ? Looks like brown - red - brown so 120 ohms,
but it's well overheated and discoloured, with a nice burn mark right around
the spiral element, right in the centre. Can't get a reading from either end
to the burn point. Looks at a guess to be rated about 3 -5 watts. Anybody
think of a reason *not* to use a wirewound rather than the original metal
film type ?

Arfa


Hi Arfa
Just took the cover off a Rega Planar 3 and the board has 5 components
on it.
1 x .22uf 275v ac cap (220nf)
1 x 10k 5% 1-2 watt parallel (physically) to the cap (bn bk or -gold)
1 x 1M 1% 1/4 watt (br bk bk yell -bn)
1 x 3k3 1% 1/4 watt (or or bk bn -bn)
1 x 120nf 400v dc cap
HTH
DaveD

"DaveD" wrote in message
...
Arfa Daily wrote:
Hi all

Anyone happen to know the value of the resistor in the CR network
connected in the synchronous motor feed ? Looks like brown - red - brown
so 120 ohms, but it's well overheated and discoloured, with a nice burn
mark right around the spiral element, right in the centre. Can't get a
reading from either end to the burn point. Looks at a guess to be rated
about 3 -5 watts. Anybody think of a reason *not* to use a wirewound
rather than the original metal film type ?

Arfa
Hi Arfa
Just took the cover off a Rega Planar 3 and the board has 5 components on
it.
1 x .22uf 275v ac cap (220nf)
1 x 10k 5% 1-2 watt parallel (physically) to the cap (bn bk or -gold)
1 x 1M 1% 1/4 watt (br bk bk yell -bn)
1 x 3k3 1% 1/4 watt (or or bk bn -bn)
1 x 120nf 400v dc cap
HTH
DaveD

Hmmm. Well Dave, I've got to say that that bears no relationship to what's
in this one, at all :-\

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 ?

Mind you, dunno about you, but I find this all the time with 'high-end'
gear. Guts that are nothing like what the the service manuals say they
should be, poorly done mods involving extra components stuck across boards,
bog-standard cheap as chips lasers fitted to CD players costing thousands,
metalwork that fits where it touches, holes drilled in wrong places,
inappropriate screw types and sizes - the list is endless.

I know that these things are often hand-built, which I guess is what
attracts the people with more money than sense to them, but when I look at
some items, I wonder how the companies that made them, and then stuck the
multi-thousand pound price tags on them, sleep at night. I guess I've just
got too much of a conscience ...

Anyways, I think tomorrow that I am going to fit a 5 watt 150 ohm wirewound
that I have to hand, and then bring it up gently on the variac, and see what
happens. I guess it's got two chances ... :-)

Arfa

In article ,
Arfa Daily wrote:
Hi all

Anyone happen to know the value of the resistor in the CR network
connected in the synchronous motor feed ? Looks like brown - red -
brown so 120 ohms, but it's well overheated and discoloured, with a
nice burn mark right around the spiral element, right in the centre.
Can't get a reading from either end to the burn point. Looks at a guess
to be rated about 3 -5 watts. Anybody think of a reason *not* to use a
wirewound rather than the original metal film type ?

Only thing I can think of is a metal film one will be more stable?

--
*Errors have been made. Others will be blamed.

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 17 May 2010 09:57:09 +0100, Arfa Daily wrote:

Hi all

Anyone happen to know the value of the resistor in the CR network
connected in the synchronous motor feed ? Looks like brown - red - brown
so 120 ohms, but it's well overheated and discoloured, with a nice burn
mark right around the spiral element, right in the centre. Can't get a
reading from either end to the burn point. Looks at a guess to be rated
about 3 -5 watts. Anybody think of a reason *not* to use a wirewound
rather than the original metal film type ?



IIRC the Rega motor is similar to the early Linn unit. There are 2
windings, 90 degrees out of phase with each other. Ignore the motor
voltage rating, they are usually set to run with something around 80v to
85v across each winding. The capacitor gives the phase shift (about 0.2uF
for 50Hz). The resistor is probably about 3.3k 5-7W.

I've been running a 230v Linn from 110v with no problem apart from a
slower run-up time. It reduces motor vibration. No component changes
needed.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

On Mon, 17 May 2010 09:57:09 +0100, Arfa Daily wrote:

Hi all

Anyone happen to know the value of the resistor in the CR network
connected in the synchronous motor feed ? Looks like brown - red - brown
so 120 ohms, but it's well overheated and discoloured, with a nice burn
mark right around the spiral element, right in the centre. Can't get a
reading from either end to the burn point. Looks at a guess to be rated
about 3 -5 watts. Anybody think of a reason *not* to use a wirewound
rather than the original metal film type ?



Ah! A bit more research... The voltage dropper resistor on early P3s was
12k, with a 2.2uF phase shift capacitor. Later P3s used a 2.2uF class X2
capacitor instead of the 12k resistor. As I said before, the winding
voltage works out at about 80v when run on a 230v supply.


--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.