Technics SL-QD33 turntable - some repair tips

[zaibatsu]

I had to repair one of these recently, and while searching for answers, there were ~20 threads of people wondering why the platter stopped spinning / tonearm stopped moving, or things would work intermittently. Many threads ended with no conclusion, so I suspect many tables were binned.

I had some time this morning to finish it off and thought I'd share, in case someone does a search in the future.

These points will likely apply to similar Technics turntables like the SL-QD22, SL-BD33, SL-BD20, etc, not just the SL-QD33. It's just a budget table but apparently decent enough.

• The first major problem is that Technics cheaped out and used Toshin Kogyo capacitors in these (they say TK on them). The particular ones that were bad were ALL the 47uF ones in my unit, down to 10uF or worse in some cases. I took the opportunity to replace them all, but if you are on a budget, I'd recommend replacing all the TK branded ones at least. Check all boards (function button board, power supply board, motor board). Generally the Panasonic/Matsushita (triangle logo) are fine. This will generally restore all electronic function, particularly the platter and tonearm either completely not working or only working intermittently.
• I replaced the main PSU capacitor (2200uF axial) with a slightly higher value 2700uF Panasonic FM radial, you can do whatever you want here - just make sure it physically fits. This one *just* cleared when mounted upright.
  
• The second "issue" most people notice is that the record size detection "prongs" that poke out of the platter are amiss, and that only one of them is poking up. They mistakenly think this might be a cause of a whole bunch of issues (as did I) - but actually - it's not a problem at all. I think these either broke really easily or were like this from factory (it's just the outer one), either way, if there are problems with your turntable then this isn't it. If neither of them pop up you *should* address it, but if the inner one is poking up and the outer one is down, don't worry about it - all functions of the table will still work normally.
• There are a lot of adjustments that need to be done as per the service manual. You can get them from vinylengine with a free account, the QD33 one is here: https://www.vinylengine.com/library/technics/sl-qd33.shtml
• Something confusing is that there are two adjustments performed through the same hole (under a rubber cap near where the tonearm enters the table). What happens is that when the tonearm is at rest, one screw is positioned under that hole, however when you move the tonearm onto the platter (as per instructions), it moves a different screw under that hole - hence two different adjustments. The other adjustments are straightforward and the manual is excellent - you have to set yourself up so you can work from underneath the table (without turning it upside down) though.
  
• The entire system is very sensitive to the initial positioning / setup of the parts inside the tonearm positioning mechanism. If the start/stop light flashes when you try to use the turntable, it means there is an error in the initial setting of something in that mechanism. This part is a royal pain, but my advice is just be gentle when you mess around with it so you don't break anything. The arm should be able to move to the center of the record freely from its rest position and back if you've positioned things right, without feeling like it gets "spring loaded" at any point (before you power-on the table).
• If everything works well but the start point or end point detections don't work, it's likely something to do with the initial setting of the plastic mechanisms described in the above point - particularly the plastic parts triggered by the large/small disc tabs on the platter.
• There are some tiny switches in the record size detection mechanism (a triplet of black cable runs to these switch boards from memory), they are depressed at different extremes of operation. If all else fails you can unscrew these boards and check that pressing the switches causes the matching terminals to short (I used my meter in diode test mode). You don't have to desolder anything to test them. Mine were fine.
• My knowledge of turntables is limited, but apparently the stock P-mount cartridge is decent (better than the cheapest replacements anyway), and you can just get a replacement stylus for it. Typing EPS30 or P30 stylus into ebay will get you going. I'm sure there are better cartridges if desired, but I'd replace the stylus on the original as a minimum - the stock one will have deteriorated damping rubber. The purple part just pulls off by hand, very easy.
  
• The stock hinges suck and the perspex tabs that slot into them are fragile (and probably cracked) so be gentle + remove the lot to work on it, if still intact.

The main problem is the capacitors. The actual mechanisms and motor in these tables seem to be quite reliable if someone hasn't messed around with them already.

This table didn't work at all initially, then after moving things manually occasionally I could get the platter to spin and arm to move a bit but that stopped again. After recapping, everything worked again, however the initial record size detection didn't (arm would move all the way to the middle on start). Then, after pulling apart the arm mechanism and resetting everything carefully, everything works perfectly - including record size detection, start/end points, cueing, and even the repeat function (which is kinda cool!).

Picture of recapped boards (I just used spare parts I had lying around, including a mix of film caps for smaller values):

(There's also some more caps to change under the control/button board visible in top left)

I also attached some pictures I saved from the internet of the various mechanisms that operate the arm - just in case people want to check for things like broken plastic tabs. These are not my pictures, I just used them to check for broken parts on the one I was working on (everything seemed to match).

 

[Balifly]

I had to fix one of these for someone, and while searching for answers, there were ~20 threads of people wondering why the platter stopped spinning / tonearm stopped moving, or things would work intermittently. Many threads ended with no conclusion, so I suspect many tables were binned.

I had some time this morning to finish it off and thought I'd share, in case someone does a search in the future.

I also attached some pictures I saved from the internet of the various mechanisms that operate the arm - just in case people want to check for things like broken plastic tabs. These are not my pictures, but seemed to correlate to my (now perfectly working) table. I used them to check for broken parts on mine.

Very nice of you to combine the fixes and pictures in one thread, your efforts are/will be much appreciated.

 

[JSahara]

Thanks for this, I need to tear mine down to find out why it stopped working. Great unit I ran it for years and now my son has it a college.

 

[80sGuy]

I have the same problem with mine. Bought it new from Circuit City back in '92. One of the best turntables I've ever owned. It's been a work-horse but problem started about 7-8 years ago. It would not 'auto-start'. I opened the unit up and somehow managed to fidget with something and now I can manually lay the stylus down play. Still works but once I hit that 'cue' button it just stops spinning. It was a pain to re-assembled/lined everything back up together. Great info here, might have to open her up again and do some soldering!

 

[Captgogo]

I have had mine since 2016, it has had intermittent problems which I had tried to address by resetting the motorised mechanical arm. It had the symptom, that many people have described of the Auto start not working.
I found out that eventually by turning it on with power switch and waiting for about 15 mins and then placing a record and pressing the auto start it would work just fine. It was like it needed to warm up( charge up a weak capacitor?)
This is how it has worked for the last 12 months. Until about a week ago, when no matter how long I waited it would not auto start , I could use it manually but the end of record auto shut did not work which was a pain.
So again I played around with the arm mechanism but was beginning to realise it most likely was a electronic fault which I dreaded cause I do not have enough experience fault finding microprocessor boards. I am confident the problem is isolated to the tone arm drive board and most likely a Capacitor?
After reading this Zaibatsu great post, I am going to attempt to replace the 3 TK branded plastic film cap first and hope I do not destroy the Integrated Circuits.
Before I do I was looking for any comments on whether my conclusion make sense and if anyone else has corrected this problem by replacing these Capacitors.

 

[Captgogo]

We'll I replaced the three TK caps on the Tone Drive Board, but the problem is still there.
Quite frustrating, the logic circuit is not working, so no response when start button is pressed the tone arm motor does not turn, though it works in both direction when external tested.
So at this stage I need to assume it is either the Integrated Circuits?, other caps or resistors gone faulty.?
Anyone who is familiar with this turntable that can help me pin point where to look next it would be most appreciated.

 

[JamVal]

We'll I replaced the three TK caps on the Tone Drive Board, but the problem is still there.
Quite frustrating, the logic circuit is not working, so no response when start button is pressed the tone arm motor does not turn, though it works in both direction when external tested.
So at this stage I need to assume it is either the Integrated Circuits?, other caps or resistors gone faulty.?
Anyone who is familiar with this turntable that can help me pin point where to look next it would be most appreciated.

I also have an SL-QD33 , that has an occasional failure.

I watched the mechanism very closely and after reading this thread, I would:
1. Find the switch that turns the platter motor on and make sure it is clean and working consistently.
2. Change the caps on the motor board and that big one on the power supply. I think there are some of those 47uF caps on the motor board, I had written them down, but lost my notes.

The mechanism that automatically sets the tonearm down at the proper location relies on the platter motor starting before the record size can be detected.

There are 2 mechanical detection slots/levers on the platter. Inner slot has a lever that is sticking up. The outer lever is down. The platter has to make at least one full rotation for a mechanism underneath to push the outer slot lever up.

There are 3 possible conditions:
1. No record on the platter. Inner lever is up means there is no record on the platter, tone arm does not advance, motor shuts down.

2. 7" 45rpm record on the platter. Inner lever is down, full rotation pushes the outer lever up. This means that a 7" or 45 is on the platter. The inner lever is down because of the 7" record, and the outer lever flips up with nothing stopping it. This sets the tonearm set down point for a 7" record.

3. 12" LP is on the platter. Inner lever is down, full rotation attempts to push the outer lever up, but the LP is blocking it. Both levers are down so a 12" LP must be on the platter. This sets the tonearm set down point for a LP.

I don't think there is a 'logic' circuit that drives the tonearm to the correct start point, it's all mechanical, dependent first on the position of those 2 levers.

I think the intermittent problem is when the motor doesn't start, and the platter doesn't turn, the system can't detect a record size and it stops. So, in my case, there is something electrically preventing the motor from starting - switch, power supply, motor board?

 

[Captgogo]

Hi Jam
I have mine working now and even though I change the caps it at first still had the problem. I did post my solution but it might have been on another site like Vinylengine I think.
Your description on the observed working is correct. But what no one else had discovered is that the worm screw on the tone arm motor due to some where does not properly engage. So what I did was remove the motor and check it was doing as it should based on the various logic circuits and if it is doing what it should then remount the motor but do not over tighten the three screws, the little bit of slack prevent the motor worm drive stalling.
Mine has been working like a charm for about 3 weeks with all functions including queuing and repeat.

 

[80sGuy]

I fixed my SL-QD33 yesterday from the infamous tonearm 'cue' lockup and flashing red lights. For years I've only been able to utilize the turntable manually by lifting its tonearm, to play and to stop. Any buttons I push would lockup and freeze! Replaced 13 capacitors - one big axial, 12 small radials (all same value) with Nichicon aluminum electrolytic caps on every board. All TK-branded ones are extracted, leaving 3-4 others intact. Also, I did not mess with any of the film caps. The turntable is working correctly now just like how it should when I first brought her home 26 years ago in 1992. Only thing needed was a slight adjustment to the 'auto start' positioning for 33/45 (7"/12") record lead-in. The needle landed a bit off to the outer grooves, especially with 7" 45rpm where it mostly misses and drops on the rubber mat! That was easy calibration, an approximate 3mm clockwise turn from a screw located by the tonearm brought it back to spec. All in all, only a mere $10 for parts.
A huge thanks to original poster 'zaibatsu'!

 

[80sGuy]

We'll I replaced the three TK caps on the Tone Drive Board, but the problem is still there.
Quite frustrating, the logic circuit is not working, so no response when start button is pressed the tone arm motor does not turn, though it works in both direction when external tested.
So at this stage I need to assume it is either the Integrated Circuits?, other caps or resistors gone faulty.?
Anyone who is familiar with this turntable that can help me pin point where to look next it would be most appreciated.

You'll need to align the tonearm mechanism back to specs for it to function correctly, or otherwise nothing will move. Follow the scheme exactly on page 5 under 'How to fit the mechanism board'. Here's the service manual.
https://data2.manualslib.com/pdf4/8...s/slqd33.pdf?312862bbadc4a1f1057abeadead15ab9

 

[bluemooze]

I fixed my SL-QD33 yesterday from the infamous tonearm 'cue' lockup and flashing red lights. For years I've only been able to utilize the turntable manually by lifting its tonearm, to play and to stop. Any buttons I push would lockup and freeze! Replaced 13 capacitors - one big axial, 12 small radials (all same value) with Nichicon aluminum electrolytic caps on every board. All TK-branded ones are extracted, leaving 3-4 others intact. Also, I did not mess with any of the film caps. The turntable is working correctly now just like how it should when I first brought her home 26 years ago in 1992. Only thing needed was a slight adjustment to the 'auto start' positioning for 33/45 (7"/12") record lead-in. The needle landed a bit off to the outer grooves, especially with 7" 45rpm where it mostly misses and drops on the rubber mat! That was easy calibration, an approximate 3mm clockwise turn from a screw located by the tonearm brought it back to spec. All in all, only a mere $10 for parts.
A huge thanks to original poster 'zaibatsu'!

 

[petersargent]

I had to repair one of these recently, and while searching for answers, there were ~20 threads of people wondering why the platter stopped spinning / tonearm stopped moving, or things would work intermittently. Many threads ended with no conclusion, so I suspect many tables were binned.

I had some time this morning to finish it off and thought I'd share, in case someone does a search in the future.

These points will likely apply to similar Technics turntables like the SL-QD22, SL-BD33, SL-BD20, etc, not just the SL-QD33. It's just a budget table but apparently decent enough.

View attachment 977650

• The first major problem is that Technics cheaped out and used Toshin Kogyo capacitors in these (they say TK on them). The particular ones that were bad were ALL the 47uF ones in my unit, down to 10uF or worse in some cases. I took the opportunity to replace them all, but if you are on a budget, I'd recommend replacing all the TK branded ones at least. Check all boards (function button board, power supply board, motor board). Generally the Panasonic/Matsushita (triangle logo) are fine. This will generally restore all electronic function, particularly the platter and tonearm either completely not working or only working intermittently.
• I replaced the main PSU capacitor (2200uF axial) with a slightly higher value 2700uF Panasonic FM radial, you can do whatever you want here - just make sure it physically fits. This one *just* cleared when mounted upright.
  
• The second "issue" most people notice is that the record size detection "prongs" that poke out of the platter are amiss, and that only one of them is poking up. They mistakenly think this might be a cause of a whole bunch of issues (as did I) - but actually - it's not a problem at all. I think these either broke really easily or were like this from factory (it's just the outer one), either way, if there are problems with your turntable then this isn't it. If neither of them pop up you *should* address it, but if the inner one is poking up and the outer one is down, don't worry about it - all functions of the table will still work normally.
• There are a lot of adjustments that need to be done as per the service manual. You can get them from vinylengine with a free account, the QD33 one is here: https://www.vinylengine.com/library/technics/sl-qd33.shtml
• Something confusing is that there are two adjustments performed through the same hole (under a rubber cap near where the tonearm enters the table). What happens is that when the tonearm is at rest, one screw is positioned under that hole, however when you move the tonearm onto the platter (as per instructions), it moves a different screw under that hole - hence two different adjustments. The other adjustments are straightforward and the manual is excellent - you have to set yourself up so you can work from underneath the table (without turning it upside down) though.
  
• The entire system is very sensitive to the initial positioning / setup of the parts inside the tonearm positioning mechanism. If the start/stop light flashes when you try to use the turntable, it means there is an error in the initial setting of something in that mechanism. This part is a royal pain, but my advice is just be gentle when you mess around with it so you don't break anything. The arm should be able to move to the center of the record freely from its rest position and back if you've positioned things right, without feeling like it gets "spring loaded" at any point (before you power-on the table).
• If everything works well but the start point or end point detections don't work, it's likely something to do with the initial setting of the plastic mechanisms described in the above point - particularly the plastic parts triggered by the large/small disc tabs on the platter.
• There are some tiny switches in the record size detection mechanism (a triplet of black cable runs to these switch boards from memory), they are depressed at different extremes of operation. If all else fails you can unscrew these boards and check that pressing the switches causes the matching terminals to short (I used my meter in diode test mode). You don't have to desolder anything to test them. Mine were fine.
• My knowledge of turntables is limited, but apparently the stock P-mount cartridge is decent (better than the cheapest replacements anyway), and you can just get a replacement stylus for it. Typing EPS30 or P30 stylus into ebay will get you going. I'm sure there are better cartridges if desired, but I'd replace the stylus on the original as a minimum - the stock one will have deteriorated damping rubber. The purple part just pulls off by hand, very easy.
  
• The stock hinges suck and the perspex tabs that slot into them are fragile (and probably cracked) so be gentle + remove the lot to work on it, if still intact.

The main problem is the capacitors. The actual mechanisms and motor in these tables seem to be quite reliable if someone hasn't messed around with them already.

This table didn't work at all initially, then after moving things manually occasionally I could get the platter to spin and arm to move a bit but that stopped again. After recapping, everything worked again, however the initial record size detection didn't (arm would move all the way to the middle on start). Then, after pulling apart the arm mechanism and resetting everything carefully, everything works perfectly - including record size detection, start/end points, cueing, and even the repeat function (which is kinda cool!).

Picture of recapped boards (I just used spare parts I had lying around, including a mix of film caps for smaller values):
View attachment 977645
(There's also some more caps to change under the control/button board visible in top left)

I also attached some pictures I saved from the internet of the various mechanisms that operate the arm - just in case people want to check for things like broken plastic tabs. These are not my pictures, I just used them to check for broken parts on the one I was working on (everything seemed to match).

 

[petersargent]

I have successfully done many of these with the cap replacement. Now I have 3 that have the same problem, the tonearm does not return at the end of the record. Attempting the adjustments per service manual, and the TP4 voltage stays at 11v when tone arm moves. Manual says it should move to 8 volts at middle, and then adjust vr1 ETC. These 3 with the same problem the 11 V does not vary with the tone arm movement . Any suggestions to look for next?

 

[petersargent]

We'll I replaced the three TK caps on the Tone Drive Board, but the problem is still there.
Quite frustrating, the logic circuit is not working, so no response when start button is pressed the tone arm motor does not turn, though it works in both direction when external tested.
So at this stage I need to assume it is either the Integrated Circuits?, other caps or resistors gone faulty.?
Anyone who is familiar with this turntable that can help me pin point where to look next it would be most appreciated.

I have done some of these. You must replace ALL the electrolytic caps. After testing the ones I replaced mostly 70% of them bad. So while you are there it pays to replace them all. After cap replace manually reset the motor moving it towards you as you look down at it. It will reach a stop point where the little tab nears the curve at the end of travel. make sure the size sensor is in the notch towards you.
that restores operations in most units, save those with sensor problems which are rare.

 

[petersargent]

I fixed my SL-QD33 yesterday from the infamous tonearm 'cue' lockup and flashing red lights. For years I've only been able to utilize the turntable manually by lifting its tonearm, to play and to stop. Any buttons I push would lockup and freeze! Replaced 13 capacitors - one big axial, 12 small radials (all same value) with Nichicon aluminum electrolytic caps on every board. All TK-branded ones are extracted, leaving 3-4 others intact. Also, I did not mess with any of the film caps. The turntable is working correctly now just like how it should when I first brought her home 26 years ago in 1992. Only thing needed was a slight adjustment to the 'auto start' positioning for 33/45 (7"/12") record lead-in. The needle landed a bit off to the outer grooves, especially with 7" 45rpm where it mostly misses and drops on the rubber mat! That was easy calibration, an approximate 3mm clockwise turn from a screw located by the tonearm brought it back to spec. All in all, only a mere $10 for parts.
A huge thanks to original poster 'zaibatsu'!

there are many different values of the caps to change only 5 are 47uf the rest are different all must be replaced.

 

[80sGuy]

there are many different values of the caps to change only 5 are 47uf the rest are different all must be replaced.

My apologies. What I meant to say was I replaced all the caps with the same values of the respective caps, not all same with one value.

 

[JSahara]

Thank you. You were absolutely correct. Switched out the purple caps and everything runs as new again. You can get a box that has 90% of them from Amazon for $12.

 

[80sGuy]

Yep! Got mine from Digikey. It was like $8. Exact values. These are the old ones.

 

[Vince A.]

I'm trying to verify and adjust the current adjustment. I get 11.31V when I turn it on and with the tone arm all the way to the center it only drops to 10.13V. Could the capacitors have a part of this? I haven't replaced any of them yet. Thanks for any suggestions!

 

[80sGuy]

I'm trying to verify and adjust the current adjustment. I get 11.31V when I turn it on and with the tone arm all the way to the center it only drops to 10.13V. Could the capacitors have a part of this? I haven't replaced any of them yet. Thanks for any suggestions!

Best to replace all the TK caps.