Hi,
Thought this might be of interest to members that own a Linn Axis TT.
I was asked to have a look at one of these recently, it was suffering from variable speed issues, and also it was not able to select the 45rpm speed (was locked on 33rpm).
It had been looked at by a repair shop, and the advice was that it needed a new motor.
A bit of searching revealed that the likely culprit for the speed problems were the 33uf 250V motor capacitors, but on opening the unit up, these had been replaced sometime in the past. Given the fact that there were known problems with capacitors in this TT I decided to check the other electrolytics. There are three different electros - the 33uf 250V mentioned above, two 47uf 250V power supply caps, two 220uf 16V caps and seven 22uf 50V caps. The 22uf are used for various functions in the circuit.
As it turns out, all of the 22uf caps were at various stages of failure, values measured ranged from 7uf to zero. Two of these caps are used to feed signals to the motor drive circuit and they measured 5uf and 3uf respectively. The two 220uf caps measured 93uf and 78uf. The two 47uf power supply caps measured out OK, and so did the 33uf motor drive caps.
The 220uf and 22uf were all replaced with high grade 105 deg C caps, and the unit tested. Motor start and speed were now functioning correctly, and 45rpm speed could now be selected.
A photo of the control board showing the caps in question
One of the 22uf caps
One of the 220uf caps
This shows the degradation that can occur in electros in older gear, and the reason for suggestions that recapping vintage audio should be considered.
A word of caution.....
The circuit board in this TT is double sided construction, and without experience and the correct tools it is very easy to damage such a board when removing components. I have a top of the line vacuum desoldering station for such work, and without one of these it can be difficult to replace components without casing damage.
Hope this is of some benefit to anyone with a Linn Axis TT !!!!
Cheers
John
Thought this might be of interest to members that own a Linn Axis TT.
I was asked to have a look at one of these recently, it was suffering from variable speed issues, and also it was not able to select the 45rpm speed (was locked on 33rpm).
It had been looked at by a repair shop, and the advice was that it needed a new motor.
A bit of searching revealed that the likely culprit for the speed problems were the 33uf 250V motor capacitors, but on opening the unit up, these had been replaced sometime in the past. Given the fact that there were known problems with capacitors in this TT I decided to check the other electrolytics. There are three different electros - the 33uf 250V mentioned above, two 47uf 250V power supply caps, two 220uf 16V caps and seven 22uf 50V caps. The 22uf are used for various functions in the circuit.
As it turns out, all of the 22uf caps were at various stages of failure, values measured ranged from 7uf to zero. Two of these caps are used to feed signals to the motor drive circuit and they measured 5uf and 3uf respectively. The two 220uf caps measured 93uf and 78uf. The two 47uf power supply caps measured out OK, and so did the 33uf motor drive caps.
The 220uf and 22uf were all replaced with high grade 105 deg C caps, and the unit tested. Motor start and speed were now functioning correctly, and 45rpm speed could now be selected.
A photo of the control board showing the caps in question
One of the 22uf caps
One of the 220uf caps
This shows the degradation that can occur in electros in older gear, and the reason for suggestions that recapping vintage audio should be considered.
A word of caution.....
The circuit board in this TT is double sided construction, and without experience and the correct tools it is very easy to damage such a board when removing components. I have a top of the line vacuum desoldering station for such work, and without one of these it can be difficult to replace components without casing damage.
Hope this is of some benefit to anyone with a Linn Axis TT !!!!
Cheers
John
