I have a completely dead Dual 505, no power getting to it at all. My
best guess is that some internal fuse has blown but I can't see how to
open it up.

Does anyone know?

"Ken Rennoldson" wrote in message
om...
I have a completely dead Dual 505, no power getting to it at all. My
best guess is that some internal fuse has blown but I can't see how to
open it up.

Does anyone know?

Hi Ken,
Not being a 505 owner, I can only go by my experience with the CS5000
(it's big brother)

remove the rubber turntable mat
there should be a couple of holes in the aluminium top of the platter -
rotate the platter until you can see the drive pulley on the motor, and
unhook the belt
carefully lift off the platter

the innards should then be exposed - if there's a fuse, it'll be visible on
the baseboard, if it's intact (check with a meter if you have one, they can
look ok when they're actually open circuit)
if the fuse is ok, there are a pair of large(ish) electrolytic capacitors,
power it up and check if there's voltage present on their terminals - should
be 70 - 80% of the marked rated voltage on the cap. If there's voltage
present but no action, take a *careful* look at all the connections (the
5000 has ribbon cables linking the motor and the speed control board, and
speed control to the speed switch board, 505 may differ).if all is ok there,
i've had problems with the motor coils - the points where they attach to
small pins standing up from the motor can fracture, leaving the coil
open-circuit - if the motor is the same as the 5000, you should be able to
wriggle it free from its rubber shockmount and lift off the rotor, unwind a
turn from the coil (extremely carefully), scrape the enamel off the copper
(extremely carefully) and resolder to the pin.

HTH,
Dave H.
(The engineer formerly known as Homeless)

"Dave H." wrote in message
. ..

"Ken Rennoldson" wrote in message
om...
I have a completely dead Dual 505, no power getting to it at all. My
best guess is that some internal fuse has blown but I can't see how to
open it up.

Does anyone know?

**There are three bolts placed around the top of the turntable. Easy to
find. They look a little like large Philips head types, but can more easily
be undone with a flatblade driver. Loosen them. Once loose, they can be
tilted. Tilt one or two and lift the entire top section. Then tilt the other
screw/s and lift the turntable section away from the base. At this point
you may need to removed the signal and mains cables from the base. Depending
upon the version of the 505 you have, this may involve removing a couple of
hex head screws, or some plastic spring clips.

Now, as to what is wrong. Two likely probabilities:

* The main drive belt is broken. In this case, you've just wasted your time,
because you don't need to perform the above procedure.

* The motor bearings are seized. Solution? Strip the motor down, clean the
bearings with alcohol and relube with light machine oil. Much cheaper than a
new motor.

* Motor switch is faulty. Repair or replace. Check the suppression cap too.


--
Trevor Wilson
www.rageaudio.com.au

"Dave H." wrote in message
. ..

"Ken Rennoldson" wrote in message
om...
I have a completely dead Dual 505, no power getting to it at all. My
best guess is that some internal fuse has blown but I can't see how to
open it up.

Does anyone know?

**There are three bolts placed around the top of the turntable. Easy to
find. They look a little like large Philips head types, but can more easily
be undone with a flatblade driver. Loosen them. Once loose, they can be
tilted. Tilt one or two and lift the entire top section. Then tilt the other
screw/s and lift the turntable section away from the base. At this point
you may need to removed the signal and mains cables from the base. Depending
upon the version of the 505 you have, this may involve removing a couple of
hex head screws, or some plastic spring clips.

Now, as to what is wrong. Two likely probabilities:

* The main drive belt is broken. In this case, you've just wasted your time,
because you don't need to perform the above procedure.

* The motor bearings are seized. Solution? Strip the motor down, clean the
bearings with alcohol and relube with light machine oil. Much cheaper than a
new motor.

* Motor switch is faulty. Repair or replace. Check the suppression cap too.


--
Trevor Wilson
www.rageaudio.com.au

"Ken Rennoldson" wrote in message
om...
I have a completely dead Dual 505, no power getting to it at all. My
best guess is that some internal fuse has blown but I can't see how to
open it up.

Does anyone know?

Hi Ken,
Not being a 505 owner, I can only go by my experience with the CS5000
(it's big brother)

remove the rubber turntable mat
there should be a couple of holes in the aluminium top of the platter -
rotate the platter until you can see the drive pulley on the motor, and
unhook the belt
carefully lift off the platter

the innards should then be exposed - if there's a fuse, it'll be visible on
the baseboard, if it's intact (check with a meter if you have one, they can
look ok when they're actually open circuit)
if the fuse is ok, there are a pair of large(ish) electrolytic capacitors,
power it up and check if there's voltage present on their terminals - should
be 70 - 80% of the marked rated voltage on the cap. If there's voltage
present but no action, take a *careful* look at all the connections (the
5000 has ribbon cables linking the motor and the speed control board, and
speed control to the speed switch board, 505 may differ).if all is ok there,
i've had problems with the motor coils - the points where they attach to
small pins standing up from the motor can fracture, leaving the coil
open-circuit - if the motor is the same as the 5000, you should be able to
wriggle it free from its rubber shockmount and lift off the rotor, unwind a
turn from the coil (extremely carefully), scrape the enamel off the copper
(extremely carefully) and resolder to the pin.

HTH,
Dave H.
(The engineer formerly known as Homeless)