technics sl-dl1 linear turntable repair questions

turning japanese
stanwebber
junior member
junior member
Posts: 20
Joined: 29 Nov 2011 19:07

technics sl-dl1 linear turntable repair questions

Post by stanwebber » 27 Aug 2018 02:51

i got a hold of a non-working technics sl-dl1 that i'm working on to restore to operation. it was missing the repeat and cuing buttons and there was a loud clanking sound coming from the upper cabinet when raised. i removed the tonearm dustcover to investigate and found the tonearm belt off and the clanking sound resulting from the larger brass belt pulley loose off the shaft. a small washer was still stuck to the pulley on one side while the other side had a hardened translucent substance covering the shaft hole. i cleaned up the worm drive shaft with alcohol, applied a little locktite to the end then reassembled the washer and pulley and let it set. i reapplied some super lube grease between the washer and pulley and also hit the plastic worm gear and large gear wheel. while i was at it i used some super lube ptfe oil on the drive rails.

i put on a new drive belt and powered everything on, but the tonearm would only return to the rest position and nothing else. after a few moments i realized the reset switch on the lower cabinet wouldn't be depressed unless i reattached the tonearm dustcover at which point i discovered the manual record size selector was hanging with a broken tab. i poked thru the selector openings with a toothpick and got everything aligned and screwed back on. this time everything started working, but i still have some concerns and questions for someone else who has had this turntable.

1. my primary concern is an audible clicking sound when the tonearm is manually cued forward. the belt/drive rope is not slipping as the speed is dead constant at both slow & fast cue speeds. the clicking sound is at regular half second (or faster) intervals completely synced to the cue speed. the sound is totally absent when cuing backwards. this can't be normal can it? what could be causing the noise?

2. while lubricating the tonearm mechanism i noticed 4 or 5 stiff points (near the middle of travel) when moving the drive pulley by hand. i added additional grease and ran the worm gear back & forth over them, but the stiff points stubbornly remain. the drive rails were completely free of debris...only dry lubricant had ever been used on them before i added ptfe impregnated oil. could the large plastic gear wheel be damaged--visually the gears look unblemished? where else to look as this has to impact the smooth operation of the tonearm?

3. do the front panel buttons just pop out? despite the button being missing i can still operate the repeat and cuing functions with a stick.

4. what's the deal with no 45rpm adapter?

stanwebber
junior member
junior member
Posts: 20
Joined: 29 Nov 2011 19:07

Re: technics sl-dl1 linear turntable repair questions

Post by stanwebber » 27 Aug 2018 19:34

i taped over the reset switch and record size sensors and was able to observe the tonearm cuing in action close up. the clicking sound is actually the tonearm being jerked forward. i can visually see the tonearm carriage rhythmically bouncing up & down as it is being pulled along. i don't understand what could be causing this as the carriage action is butter smooth going the other way so the guide rails aren't out of alignment.

the drive rope is uniformly covered in a thick black substance, but i've seen mention of this in numerous other forums so i'm thinking whatever it is is factory. in any case it absolutely causes no problems when the tonearm cues backwards.

also, is there something weird about the t4p cartridge screw? mine sort of looks like part of the threads closer to the tip are stripped, but it looks so uniform i'm not sure. i also notice there are threads on both sides of the cartridge socket which i've never seen before.

stanwebber
junior member
junior member
Posts: 20
Joined: 29 Nov 2011 19:07

Re: technics sl-dl1 linear turntable repair questions

Post by stanwebber » 06 Sep 2018 20:22

at this point all old lubrication has been cleaned off/replaced and the forward cuing jerking/vibration still remains. the only possible culprit i can point to now is the stiffness of the tonearm cables causing an imbalance with the forward motion of the tonearm sled--flexing on forward cuing and unwinding when reversed. the cables don't contact any surface until near the end of the tonearm movement where the contact point is freshly lubricated with grease.

if this is indeed the case then everyone who owns these turntables (sl-7/dl1/ql1) must experience this behavior to some lesser or greater degree and not notice or realize it or just not care.

fscl
vinyl addict
vinyl addict
United States of America
Posts: 7598
Joined: 05 Aug 2004 07:51
Location: CT, US

Re: technics sl-dl1 linear turntable repair questions

Post by fscl » 10 Sep 2018 15:46

Very interesting......... :-k

Finally back at home base after some much needed down time on the "Left Coast"........ :lol: :lol: Spent an overnight in Campbell and couldn't even walk / didn't have time to visit the Rasputin Records right across the street....... :shock: #-o ](*,) Hopefully, there'll be a next time...... [-o<

Anyway, have you tried running the tonearm drive motor both directions with a 9VDC battery....... :-k :-k :-k Unhooked from the drive system, for like a constant 1 + minute at a time then change polarity and run again. Repeat this several times...... :-k :-k :-k This should revive the motor for smooth driving as under LP play conditions it kind of steps forward incrementally when tracking grooves.

Then reinstall the motor and then use the battery to drive the motor to see if there's any mechanical interference causing hangups while the tonearm sled is moving to the left....... :-k :-k :-k Careful, as the travel of the sled is pretty fast, you may want to make up a 3VDC battery source...... :-k Are the audible clicking sounds due to some mechanical interference :-k :-k :-k Did you check the tonearm drive rope / wire, is it routed / wrapped correctly on the rope pulley according to the service manual(s)....... :-k :-k :-k

Hopefully, running the drive motor will solve your problems. I'm thinking that the motor, over years of just stepping, has to respond to more and more voltage input from the servo control system to the point where it has to severely offset before moving, hence jerking....... :-k :-k :-k

Good luck

Fred

stanwebber
junior member
junior member
Posts: 20
Joined: 29 Nov 2011 19:07

Re: technics sl-dl1 linear turntable repair questions

Post by stanwebber » 10 Sep 2018 23:35

no luck. took off the drive belt and ran the motor off a battery as suggested and there was no appreciable difference in behavior. the drive rope is routed correctly...i matched it to both the service manual and images others have posted of their sl-dl1/ql1 units online.

fscl
vinyl addict
vinyl addict
United States of America
Posts: 7598
Joined: 05 Aug 2004 07:51
Location: CT, US

Re: technics sl-dl1 linear turntable repair questions

Post by fscl » 11 Sep 2018 15:56

When running the sled on battery in both directions, did you hear / find the source of the interference / thumping in the drive...... :-k :-k :-k

Was the thumping in the drive left direction only, so under inward pulling, does any of the drive components shift causing a tight(ening) clearance problem....... :-k :-k :-k

Fred

stanwebber
junior member
junior member
Posts: 20
Joined: 29 Nov 2011 19:07

Re: technics sl-dl1 linear turntable repair questions

Post by stanwebber » 11 Sep 2018 17:15

the source of the clipping sound is the tonearm sled momentarily sticking & jerking forward on the guide rail. this only happens when traversing left (inwards towards record label). going the other direction is butter smooth although i can very faintly hear the same clipping very briefly at a single point on the guide rail--going left/inward the clipping is constant the entire length of the rail. all of this behavior is observed while advancing the tonearm at slow & fast speeds with the cuing buttons. normal playback behavior appears smooth and sounds ok so far, but i'm thinking the jerking motion has to be having an effect at some sonic level.

the only shifting that occurs is the wormgear pulley when the motor changes direction. when advancing inward towards record label the pulley is furthest left; advancing outward butts the pulley up against the washer and stanchion holding the entire wormgear. the pinwheel on the other end is centered in the gap when advancing inward and offset right when going outward, but with plenty of clearance to avoid rubbing.

i own and operate an sl-3, sl-6, sl-q6, sl-j33 and sl-l25 and none have this issue. my thinking is this has to be an imbalance on either side of the tonearm sled that must affect all these units (sl-7/dl1/ql1) to some lesser or greater extent.

fscl
vinyl addict
vinyl addict
United States of America
Posts: 7598
Joined: 05 Aug 2004 07:51
Location: CT, US

Re: technics sl-dl1 linear turntable repair questions

Post by fscl » 11 Sep 2018 17:53

stanwebber wrote:the source of the clipping sound is the tonearm sled momentarily sticking & jerking forward on the guide rail......major snippage.......
Is the guide rod bent / slightly swelled / rubbed off / worn ...... :-k Have you tried reversing the direction / installation to see if the rod is causing this jerking in the opposite direction..... :-k Is the inner barrel bearing of the tonearm sled perfectly clean and smooth...... :-k I have wondered what the material / how this rod was fabricated, ie some sort of graphite coated metal rod ? When I've used my dry Teflon lube on this and the inner bearing barrel, I find that the sled mechanism is surprisingly friction free...... :-k

IIRC, I've seen this ^ post previously. Have you operated the tonearm drive with the lid up using the battery arrangement to drive the sled....... :-k :-k :-k I take it no jerking ...... :-k

Then, have you operated the tonearm drive with the lid down using the battery arrangement to drive the sled....... :-k :-k :-k It's a PITA, I think you may have to carefully remove plastic window which is glued in place to observe the motion.

I now have a feeling that gravity shifts / pulls / catches some tonearm drive component that doesn't clear perhaps the interior plastic cover and causes the this jerking motion.

This is truly perplexing........ :shock:

Fred and not doubting your extensive experience with Technics linear drives....... :wink: Just want to know what's causing this so the solution can be included in / linked from the "SL-7 Disassembly" topic...... =D> =D> =D>

stanwebber
junior member
junior member
Posts: 20
Joined: 29 Nov 2011 19:07

Re: technics sl-dl1 linear turntable repair questions

Post by stanwebber » 11 Sep 2018 23:29

the guide rod isn't bent, at least not to my eye. when i received the unit the rod was coated in a healthy layer of dry graphite. before testing i added some synthetic oil impregnated with ptfe to the rod as well as lubricating the wormgear and drive wheel with synthetic grease with ptfe. when i couldn't get things moving smoothly i decided to remove all the old lubrication and start over. when i had everything apart the rod could have been reversed upon reinstallation since each end is identical, but i don't really know. i also didn't see any visual defects on the inner barrel of the tonearm sled when i swabbed it out with a q-tip. i can't imagine that you MUST use dry lubricant on the guide rod...oil or even light grease should suffice.

clipping behavior when cuing inward is the same whether in a vertical or horizontal orientation. i've only ever hooked up the battery with the drive belt removed to let it run free in both directions as you suggested. i would be very reluctant to remove the glued on plastic window to try anything else. nothing is close to rubbing against the aluminum cover except the tonearm cables on the lower lip where it is liberally lubricated.

i've got the unit back together and am going to do some critical listening. i'm hoping someone can just verify this is the normal behavior and that my unit just suffers to a greater, noticeable degree due to manufacturing variances where most people don't even realize or care.

Spinner45
long player
long player
Posts: 2995
Joined: 01 Mar 2017 18:21

Re: technics sl-dl1 linear turntable repair questions

Post by Spinner45 » 12 Sep 2018 00:39

stanwebber wrote:the guide rod isn't bent, at least not to my eye. when i received the unit the rod was coated in a healthy layer of dry graphite. before testing i added some synthetic oil impregnated with ptfe to the rod as well as lubricating the wormgear and drive wheel with synthetic grease with ptfe. when i couldn't get things moving smoothly i decided to remove all the old lubrication and start over. when i had everything apart the rod could have been reversed upon reinstallation since each end is identical, but i don't really know. i also didn't see any visual defects on the inner barrel of the tonearm sled when i swabbed it out with a q-tip. i can't imagine that you MUST use dry lubricant on the guide rod...oil or even light grease should suffice.

clipping behavior when cuing inward is the same whether in a vertical or horizontal orientation. i've only ever hooked up the battery with the drive belt removed to let it run free in both directions as you suggested. i would be very reluctant to remove the glued on plastic window to try anything else. nothing is close to rubbing against the aluminum cover except the tonearm cables on the lower lip where it is liberally lubricated.

i've got the unit back together and am going to do some critical listening. i'm hoping someone can just verify this is the normal behavior and that my unit just suffers to a greater, noticeable degree due to manufacturing variances where most people don't even realize or care.
The intermittent clipping noise is likely due to a cracked gear or damaged teeth on it, or rough spot on the worm itself.
The plastic over time shrinks due to outgassing and causes a tiny crack to spread.

stanwebber
junior member
junior member
Posts: 20
Joined: 29 Nov 2011 19:07

Re: technics sl-dl1 linear turntable repair questions

Post by stanwebber » 12 Sep 2018 02:12

Spinner45 wrote:The intermittent clipping noise is likely due to a cracked gear or damaged teeth on it, or rough spot on the worm itself.
The plastic over time shrinks due to outgassing and causes a tiny crack to spread.
i do think there is some slight damage/irregularities with the drive wheel. there are a couple momentary stiff points when advancing the worm gear by hand; however, i'm skeptical of your hypothesis. the even rhythmic repetition of the jerking along the entire length of travel means it would have to be the worm gear and not the drive wheel. the fact it occurs only in one direction means the damage is narrowly localized to one side of the worm gear and not the other. i cleaned out the grease from the worm gear by hand with toothpicks and probes so i think i would have noticed/felt any irregularities given how central the worm gear is (vs the drive wheel where i easily could miss damage).

that being said, i can't rule it out and it still takes first place in leading theories.

AsOriginallyRecorded
senior member
senior member
Canada
Posts: 735
Joined: 26 Jun 2018 06:05

Re: technics sl-dl1 linear turntable repair questions

Post by AsOriginallyRecorded » 12 Sep 2018 03:58

Just jumping in here with a memory I have concerning technics linear tracking turntables in particular. Although the details fail me at the moment, I do recall that the sled does not move in a totally smooth movement, but the led in the arm reads two or three grooves at a time, sending a signal to a switch near the transit motor, which moves the sled across the record a few mm at a time. Depending on the frequency of the click you are hearing, it may be linked to this process. I wish I could elaborate further, but have no idea when or where I read this. Hopefully adds a bit of insight to possible future investigations. :idea: :)

fscl
vinyl addict
vinyl addict
United States of America
Posts: 7598
Joined: 05 Aug 2004 07:51
Location: CT, US

Re: technics sl-dl1 linear turntable repair questions

Post by fscl » 12 Sep 2018 19:34

stanwebber wrote:
Spinner45 wrote:The intermittent clipping noise is likely due to a cracked gear or damaged teeth on it, or rough spot on the worm itself.
The plastic over time shrinks due to outgassing and causes a tiny crack to spread.
i do think there is some slight damage/irregularities with the drive wheel. there are a couple momentary stiff points when advancing the worm gear by hand; however, i'm skeptical of your hypothesis. the even rhythmic repetition of the jerking along the entire length of travel means it would have to be the worm gear and not the drive wheel. the fact it occurs only in one direction means the damage is narrowly localized to one side of the worm gear and not the other. i cleaned out the grease from the worm gear by hand with toothpicks and probes so i think i would have noticed/felt any irregularities given how central the worm gear is (vs the drive wheel where i easily could miss damage).

that being said, i can't rule it out and it still takes first place in leading theories.
Hmmmmmmm.............. :-k

With all of the linears around do you have enough parts in the tonearm drive train for substitution to identify the culprit ..... :-k

Is the DL1 missing a washer / spacer / needs an extra washer spacer on either side of the worm gear opposite the side when the tonearm drives towards the left...... :-k

This was a non working DL1, how badly abused was this unit....... :-k

Fred and that's all I got...... :?

stanwebber
junior member
junior member
Posts: 20
Joined: 29 Nov 2011 19:07

Re: technics sl-dl1 linear turntable repair questions

Post by stanwebber » 12 Sep 2018 22:40

the worm gear pulley was detached & loose when i received the unit so it's possible a washer or spacer may be missing. the configuration i have is:

brass pulley - washer - stanchion - washer - plastic wormgear - stanchion - pinwheel

can anyone confirm if i'm missing an extra washer/spacer? otherwise, the sl-dl1 came complete except for the topside repeat and up/down cuing buttons.

the guide rod is distinctly different on this model. on all other technics linear trackers i've examined the guide rode is perfectly smooth coated steel always lubricated with a lightweight grease. the sl-dl1 guide rod has a slight texture to it and may or may not be coated. perhaps the texture facilitates the dry graphite since that is the only lubricant ever used on the rod. (i've since replaced with ptfe impregnated oil.)

the rhythmic clipping/jerking motion i'm referring to throughout this post comes about as the result of manually cuing the tonearm back & forth at slow & fast speeds with the front buttons. during normal playback the tonearm movement is so incremental that you can't visually identify any irregularities (and hopefully not hear any either).

stanwebber
junior member
junior member
Posts: 20
Joined: 29 Nov 2011 19:07

Re: technics sl-dl1 linear turntable repair questions

Post by stanwebber » 13 Sep 2018 22:21

well, my worst fears have come to pass. i can hear the tonearm movement thumping during playback which i assume is the sled sticking/binding. not every incremental movement is audible, but the pattern of sticking/binding follows what i've observed when cuing the arm forward manually with the buttons.

i also noticed a couple other anomalies which are of concern. the tonearm has significant problems in the lead-out section of the record. the tonearm isn't advancing fast enough so what ends up happening is the stylus pops out of the groove and skips 4 or 5 times (depending on length of lead-out) before the tonearm advances to the point where the auto-return kicks in. the tonearm has never skipped once anywhere outside of the lead-out area after playback of 6 records.

the other thing i've noticed is that the tonearm is particularly susceptible to slightly off-center records--more so than other linear trackers which as a group continually struggle with this condition. i don't know if this is just the result of tighter tolerances for this design, arm adjustment or something else.

Post Reply