My Linn Axis is Sick. Please help fix

[bubbamc119]

Lately my axis has needed a twist of the platter when starting to get up to speed (it used to start by itself) and will not hold speed well. 45rpm mode does not work, the green light comes on but it's well below speed.

Does anyone know what I could do to troubleshoot?

[d to the g]

Usually a slow start up is a sign of a worn belt. How long has it been since you replaced the belt?

[YNWOAN]

I'm pretty sure I have read about this issue on the 'Pink Fish Media' forum and what you describe is a well known electrical fault with the PCB that controls the motor. Sorry, not to be of more help but my knowledge base is mechanical rather than electrical.

[tkwou]

The problem is likely with the power supply. I have rebulit three of these units in the past two months. If the unit has never been serviced the most likely culprit are the output coupling capacitors and the HV filter caps. You will need to check to see if you are getting full HV supply which is anywhere from 310-320VDC. The output voltage from the negative side of the output capacitors(33uF/250V) should be about 70VAC from both of these capacitors for the first 7-8 seconds. After that it should fall to between 22-30VAC depending if you are on 33 1/3 or 45. Both voltages from the output caps should be equal. If you are unfamilar with with the handling and testing electronic equipment I would send it out to be serviced. These are lethal voltages you are dealing with. If you need a schematic I have a copy.

[bubbamc119]

Thank you ever so much for your help.

tkwou: I would love a copy of the schematic and anything else you have axis related, I'll pm you my email now. I've been looking all over the net for service info for this turntable.

I'm finishing my electronics eng degree this year and am pretty handy with a soldering iron so I'll have a crack and I'll let you know how it goes.

[bubbamc119]

btw what kind of motor does the axis have? Is it an ac induction motor or a DC variant?

shallbehealed: I have tried another belt but that didn't work, sometimes on startup the platter will even spin backwards.

[stoolpigeon]

AFAIK the Axis uses the same motor as the LP12 which is a 2 phase synchronous type.

A motor spinning backwards is a sign of a faulty phasing capacitor which in LP12 is about 0.22uF.

Now the Axis has an electronic power supply so there may not be a phasing capacitor but similarly the drive to one of the motor phases may be dodgy.

[bubbamc119]

While we're on this subject does anyone know where I can find a counterweight for a Basik LVX tonearm?

[tkwou]

I have the schematic but I will need to email it to you. It's too large to post. If you are familiar with trouble shooting things should be pretty easy. If the red and green led's still light up the signal gen portion of the board is still working. The other thing that goes are the 22uF electrolytic caps which act as signal coupling caps between the opamp low pass filters stages for the sine wave. There are about 4 of them. You can change them one at a time until you get an equal output from the output quad opamp. Also check the bias supply resistors for the output circuit. Sometimes they blow. The output circuit is Class A with constant current load on both leads of the motor. If you have a blown output transistor then the smaller transistor of the CCS will also blow along with the emitter resistor.

[tkwou]

As far as the counterwight is concerned you see them on Ebay from time to time.