I offered to look at a Sugden SDT-1SE player for a friend, the problem appearing to be the well known issue of the loading gear on the tray mechanism.
This is a real heavyweight of a player both in terms of build quality and its audiophile heritage. The internal build quality is superb and Sugden gear is mostly hand built (I've actually had the privilege of being shown around the factory many years ago when this player was being replaced by the later CD21).
The DAC is the Philips TA1541 '1 Crown'
The PSU
Inspection showed the gear was well and truly annihilated. More of a surprise was that it was almost glued to the shaft by some mysterious green stuff. I can only think this is some remnant of old grease that has baked and dried solid. ISO wouldn't touch it and in the end it had to be scraped off:
A new gear was fitted and reasonably generous amount of a special plastics/metal compatible grease applied. The replacement was advertised as coming with the belt but the belt that arrives with it is only a fraction the size of the original which fortunately was still soft and supple.
The mech removed from the player:
And then a curiosity......
The tray operated smoothly and quietly but there was a little issue that was quite unexpected... the tray motor over ran for around a second and a quarter on each eject cycle. The loading part was perfect, just the eject with the issue. There is only a single micro switch that operates when the tray is either opened or closed and monitoring this showed it to be working correctly. So this was odd. Slipping the belt off and opening the tray manually by hand saw the motor behave correctly. Weird.
A long story short but I wondered if this could be either some contact bounce (unlikely and it didn't really fit because I would expect the tray to immediately reverse if that was happening). The other dark though was the firmware being programmed to run the motor for a set minimum time and only after that time elapses will the system control accept the electrical input state of the microswitch.
I added a 22 ohm in series with the loading motor. Perfect. Hmmm. How low can we go. Seems like around 5.6 ohms as a lower limit. I fitted a 10 ohm and for good measure added a bi-polar 47uF across the motor. It operates perfectly, the tray is smooth and fast and has plenty of torque. Any slow down in tray speed due to the lower voltage is imperceptible from a user point of view. It will also be much kinder on the gear not to be rammed into the end stop with the motor still powered.
I have asked Sugden if there is a known issue for this......
This is a real heavyweight of a player both in terms of build quality and its audiophile heritage. The internal build quality is superb and Sugden gear is mostly hand built (I've actually had the privilege of being shown around the factory many years ago when this player was being replaced by the later CD21).
The DAC is the Philips TA1541 '1 Crown'
The PSU
Inspection showed the gear was well and truly annihilated. More of a surprise was that it was almost glued to the shaft by some mysterious green stuff. I can only think this is some remnant of old grease that has baked and dried solid. ISO wouldn't touch it and in the end it had to be scraped off:
A new gear was fitted and reasonably generous amount of a special plastics/metal compatible grease applied. The replacement was advertised as coming with the belt but the belt that arrives with it is only a fraction the size of the original which fortunately was still soft and supple.
The mech removed from the player:
And then a curiosity......
The tray operated smoothly and quietly but there was a little issue that was quite unexpected... the tray motor over ran for around a second and a quarter on each eject cycle. The loading part was perfect, just the eject with the issue. There is only a single micro switch that operates when the tray is either opened or closed and monitoring this showed it to be working correctly. So this was odd. Slipping the belt off and opening the tray manually by hand saw the motor behave correctly. Weird.
A long story short but I wondered if this could be either some contact bounce (unlikely and it didn't really fit because I would expect the tray to immediately reverse if that was happening). The other dark though was the firmware being programmed to run the motor for a set minimum time and only after that time elapses will the system control accept the electrical input state of the microswitch.
I added a 22 ohm in series with the loading motor. Perfect. Hmmm. How low can we go. Seems like around 5.6 ohms as a lower limit. I fitted a 10 ohm and for good measure added a bi-polar 47uF across the motor. It operates perfectly, the tray is smooth and fast and has plenty of torque. Any slow down in tray speed due to the lower voltage is imperceptible from a user point of view. It will also be much kinder on the gear not to be rammed into the end stop with the motor still powered.
I have asked Sugden if there is a known issue for this......
Sugden to their credit have replied but only to say it was an issue they had never come across although they did say 'well done' 🙂 The player has been running all day with numerous open/close cycles and its been faultless with the resistor added.
I got curious and started searching the web for CDM 9 mech issues and a Bing search through up an old thread actually on diyAudio:
https://www.diyaudio.com/community/threads/cdm9-tray-motor-overrun.55089/
Some of the posts in that thread mirror my findings.
The special grease I used is super slick and the tray is now very free running. I wonder if that speeded it up beyond any minimum motor run time limits programmed into the firmware. I guess we'll never know.
I got curious and started searching the web for CDM 9 mech issues and a Bing search through up an old thread actually on diyAudio:
https://www.diyaudio.com/community/threads/cdm9-tray-motor-overrun.55089/
Some of the posts in that thread mirror my findings.
The special grease I used is super slick and the tray is now very free running. I wonder if that speeded it up beyond any minimum motor run time limits programmed into the firmware. I guess we'll never know.