Technics SL-1600 MK2 platter problems

[kim1965]

I got a problem with a Technics SL-1600 MK2 turntable.

Everything works except for a slow spinning platter.

When I press start 9 out of 10 times the platter starts slow. I can accelerate it by a push to the platter, and it will get into the right speed and stay there with no problems. The 10.th time it just starts as it should.

It is fully cleaned and got a new o-ring for the arm so nothing wrong there. It also had the problem before I did the deep clean.

Anyone had this problem on a Technics SL-1600 MK2 TT?

 

[EngineerNate]

Either:

1. Weak capacitor somewhere hampering startup torque.

2. Gummed up spindle bearing. Does the 10th time come usually after it's been running for a while or is it random?

 

[kim1965]

Either:

1. Weak capacitor somewhere hampering startup torque.

2. Gummed up spindle bearing. Does the 10th time come usually after it's been running for a while or is it random?

Thank you for the input.
I will try to look at the capacitors. The 10th time is random and could as well be first time i use it. So it does not depend on a "warm" TT.

 

[vincei]

When the platter is running, is the torque less than normal? There may be a cracked solder joint on the motor board.

I believe there is a cap that affects torque, but can't remember which off hand.

 

[kim1965]

When the platter is running, is the torque less than normal? There may be a cracked solder joint on the motor board.

I believe there is a cap that affects torque, but can't remember which off hand.

Thanks for the answer
Yes the torque is less than normal. It is a bit funny that if i just let it spin, it runs a little uneven, but once in a while it picks up the pace to normal speed. When it reach normal speed it runs rock steady at the correct pace.

I think I will try to go through the solders first to se if anything looks fishy

 

[MitsuMan]

Thanks for the answer
Yes the torque is less than normal. It is a bit funny that if i just let it spin, it runs a little uneven, but once in a while it picks up the pace to normal speed. When it reach normal speed it runs rock steady at the correct pace.

I think I will try to go through the solders first to se if anything looks fishy

I have an SL-1700 (not a Mk II) so I'm not sure if the speed control pots are the same, but I had to take it apart and access the 33 and 45 rpm speed pots and clean them with Deoxit before it would run at a consistent speed. If you're already under the hood, it wouldn't hurt to make sure the pots are clean as well.

These may help. https://www.flickr.com/photos/nall/sets/72157622856641166/

Edit: According to a user on Vinyl Engine, the Mk 2 only has one speed pot vs. the earlier version.

 

[losthorizon]

I hope you find the problem as I also have an sl 1600mk2 that started to lift off the record after a short time of playing and that progressed to it not starting, It now does a sort of stop/start motion, I sent it to a Technics repair chap who has had it for months and can't work out what's wrong with it.

 

[douglasman]

I have picked this thread to post my issue . Is this a good way or starting a new thread ?
In any case, I've been trying to restore three 1600Mk2(s). There're now in various condition(s).
1. The worst one is one that was working fine except that the lever would not lower the stylus back on the record surface. It's just shy of all the way down .
Thurs, I have assumed it was the sluggish of the arm lifting rod spring combination issue. The cueing buttons at the front works fine. The armlift travels different amount of up and down distance between using the cueing buttons and lever. What I have done was to dissembled the arm drive mechanism to cleaned and lubed the arm lift.
Upon reassembled and re-installed it back into the table. The platter would spin as soon as power on and that auto-start as like STOP but the arm was still at rest . So, it'd go up and down while the platter is still spinning. Manually place the stylus to play a record is fine ( even repeat would work) . It's just that the whole time platter never stops.
If it's not a repeat auto-return or pressing the stop button , the arm would lift itself and return the rest. The platter, then , would stop briefly while the arm was still at up but rest position. As soon as the arm was rest down completely, the platter started spinning again. I 've deduced that the issue is with the arm assembly because I could install the problematic arm assembled on any of the three units, it'd behavior the same while my other working arm assemblies are perfect on any of the unit base.

if anybody on here knows and care to share how the photo sensors ( i suspect they are the source of this issue) work in details such as if power (+5v) disruption could cause this. ( i am hoping it's a wire gotten loose during re-assemble) But logic suggests that when power is applied to the sensor ( as long as power on assuming) the lights are being blocked by the arm bottom plate for all three sensor. It'd be as if all sensor were off and the platter doesn't spin. That means that fact that platter spins by itself seems to suggest that it thinks the arm is out of rest position ( meaning stop/start sensor are getting light ?)

2. Second turntable while works fine but has a start hesitation. I've observed that if I power on after off for a long while, hitting the start button will cause the platter to spin quarter turn and stop. I'd have to hit it three four time for the spin to stay on. Or, if i play with cueing up and down before hitting the start button, it'd spin up right a way with one push to the start button

3. Third turntable seems to be perfect ( none of these three have i test if the muting is optimized). But the rubber mat is hard as a rock


Any idea for any of these three are welcome. By the way, please don't suggest to replace the arm drive belt. I am absolutely certain that has nothing to do with my issues

 

[losthorizon]

I have picked this thread to post my issue . Is this a good way or starting a new thread ?
In any case, I've been trying to restore three 1600Mk2(s). There're now in various condition(s).
1. The worst one is one that was working fine except that the lever would not lower the stylus back on the record surface. It's just shy of all the way down .
Thurs, I have assumed it was the sluggish of the arm lifting rod spring combination issue. The cueing buttons at the front works fine. The armlift travels different amount of up and down distance between using the cueing buttons and lever. What I have done was to dissembled the arm drive mechanism to cleaned and lubed the arm lift.
Upon reassembled and re-installed it back into the table. The platter would spin as soon as power on and that auto-start as like STOP but the arm was still at rest . So, it'd go up and down while the platter is still spinning. Manually place the stylus to play a record is fine ( even repeat would work) . It's just that the whole time platter never stops.
If it's not a repeat auto-return or pressing the stop button , the arm would lift itself and return the rest. The platter, then , would stop briefly while the arm was still at up but rest position. As soon as the arm was rest down completely, the platter started spinning again. I 've deduced that the issue is with the arm assembly because I could install the problematic arm assembled on any of the three units, it'd behavior the same while my other working arm assemblies are perfect on any of the unit base.

if anybody on here knows and care to share how the photo sensors ( i suspect they are the source of this issue) work in details such as if power (+5v) disruption could cause this. ( i am hoping it's a wire gotten loose during re-assemble) But logic suggests that when power is applied to the sensor ( as long as power on assuming) the lights are being blocked by the arm bottom plate for all three sensor. It'd be as if all sensor were off and the platter doesn't spin. That means that fact that platter spins by itself seems to suggest that it thinks the arm is out of rest position ( meaning stop/start sensor are getting light ?)

2. Second turntable while works fine but has a start hesitation. I've observed that if I power on after off for a long while, hitting the start button will cause the platter to spin quarter turn and stop. I'd have to hit it three four time for the spin to stay on. Or, if i play with cueing up and down before hitting the start button, it'd spin up right a way with one push to the start button

3. Third turntable seems to be perfect ( none of these three have i test if the muting is optimized). But the rubber mat is hard as a rock


Any idea for any of these three are welcome. By the way, please don't suggest to replace the arm drive belt. I am absolutely certain that has nothing to do with my issues

If you find the solution to the problem, please post an answer on this thread, I have given up on my SL1600mk2 for the moment as I have run out of ideas.

 

[douglasman]

If you find the solution to the problem, please post an answer on this thread, I have given up on my SL1600mk2 for the moment as I have run out of ideas.

I am thinking that the photo sensors behave like a transistor where in this case a short has been developed such that even where there were no light, a current is flowing through such that to cause the platter to think the arm is out of REST position. I was hoping that it would not be the case. After all, the turntable was working before I disassembled.

It's true that this beast is complicated in that many thing could go wrong with it


By the way, does anyone know if the mat of a SL Q33 could be used for 1600Mk2, not that it's any easier to find ....
or if any of the parts of the arm mechanism, gears, photo sensors, could be used for 1600Mk2 ?

 

[losthorizon]

I am thinking that the photo sensors behave like a transistor where in this case a short has been developed such that even where there were no light, a current is flowing through such that to cause the platter to think the arm is out of REST position. I was hoping that it would not be the case. After all, the turntable was working before I disassembled.

It's true that this beast is complicated in that many thing could go wrong with it


By the way, does anyone know if the mat of a SL Q33 could be used for 1600Mk2, not that it's any easier to find ....
or if any of the parts of the arm mechanism, gears, photo sensors, could be used for 1600Mk2 ?

I hope you find a solution, I have sent an amp to a firm called " Get it fixed " to have some work done, and if the work is good and the price reasonable, I will send the 1600mk2 to them as well, I am okay with practical jobs but out of my depth with electricals.

 

[douglasman]

Any body knows the spec of those photo sensors ?

 

[douglasman]

I've disconnected the output of the rest sensor to the output . The platter is no longer spinning on power up since with no power from the rest sensor, it's thinking the arm's at rest. That means the rest sensor is faulty that it's always outputting an voltage regardless if the LED is blocked or not. If i don't know what to replace it with, i will try using a sensor from that of a 1700mk2 rest sensor. It looks the same

 

[losthorizon]

I've disconnected the output of the rest sensor to the output . The platter is no longer spinning on power up since with no power from the rest sensor, it's thinking the arm's at rest. That means the rest sensor is faulty that it's always outputting an voltage regardless if the LED is blocked or not. If i don't know what to replace it with, i will try using a sensor from that of a 1700mk2 rest sensor. It looks the same

Please let me know if it works.

 

[douglasman]

I've found a logical explanation to the problem i was having and i think i have it solved since it seems to be working now.
1. The table/arm has been working until after i disassembled the arm to clean the arm lifter.
2. The behavior is that of the platter spin as soon as power up, which indicates the Photo sensor for the rest detection is sending power to the platter. That means the arm was not able to detect the arm's been rested and that the power to the platter from photo sensor should be off.
3. When after assuming the photo sensor for rest detection is faulty, i was about to replace it with a spare from a 1700mk2. Then, i have noticed that when the arm 's lock in the rest position, the blade from the circular bottom plate of the arm was not completely blocking the led of the photo sensor. I could not explain but I have all along failed to pay any attention the alignment of the bottom plate with the photo sensors. That means...
4. That because of out of alignment LED from photo sensor for rest was able to illuminated the sensor and thus turning the power to platter on all the time.
5. carefully loosen the the two black screws securing the bottom plate to arm and re-align the blade with the photo sensors. The issue has gone away.

 

[losthorizon]

I've found a logical explanation to the problem i was having and i think i have it solved since it seems to be working now.
1. The table/arm has been working until after i disassembled the arm to clean the arm lifter.
2. The behavior is that of the platter spin as soon as power up, which indicates the Photo sensor for the rest detection is sending power to the platter. That means the arm was not able to detect the arm's been rested and that the power to the platter from photo sensor should be off.
3. When after assuming the photo sensor for rest detection is faulty, i was about to replace it with a spare from a 1700mk2. Then, i have noticed that when the arm 's lock in the rest position, the blade from the circular bottom plate of the arm was not completely blocking the led of the photo sensor. I could not explain but I have all along failed to pay any attention the alignment of the bottom plate with the photo sensors. That means...
4. That because of out of alignment LED from photo sensor for rest was able to illuminated the sensor and thus turning the power to platter on all the time.
5. carefully loosen the the two black screws securing the bottom plate to arm and re-align the blade with the photo sensors. The issue has gone away.

I am not as technically minded as you but I understand what you are saying, is there any possibility you could take a picture to point out the parts you are referring to so I can see if this is what caused mine to have the same fault?

 

[douglasman]

This picture shows the arm is out of rest

 

[douglasman]

Apologizing for not knowing how to send multiple pictures in one reply ...
The second picture shows that the arm is at rest. Tell me if you can spo
t the difference