Thrift store SL-65B -- Initial questions

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amagasakii
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Re: Thrift store SL-65B -- Initial questions

Post by amagasakii » 14 Mar 2018 08:11

After about a month of other projects taking precedence, I've finally made some repairs to this deck.

It turns out I really was over-thinking how to repair the cam post. Rather than clamping it down to the deck, I put the cam back on, flipped the whole thing over, and let the weight of the cam pull down on and centre the post. While I know it's not ideal, I used a thick gel super glue that allowed me to build up a slight "dome" of glue on the rivet on the underside, but still left plenty of room for the auto trip link to move freely. The cam itself still has a small amount of wobble, but the cam post is solid...for now. I'll see how the glue stands the test of time.

The lifting shaft, which I thought was held in place with a spring-and-washer assembly, is not. With the mechanics underneath disassembled, I flipped the deck over and the lifting shaft simply fell out. #-o Even though the service manual says to apply damping fluid to the upper portion of the lifting shaft, it had no effect. I was over-thinking this as well; 500,000 cst damping fluid directly on the lifting platform where it enters the upper casting worked wonders, and now the tonearm drops gently when the cueing lever is dropped.

One thing I noticed putting it through its paces tonight: the auto return trips about 1/8" before the run-out groove on the album I'm using for testing. I noticed the set-down point is right at the beginning of the lead-in groove, so I'm hoping a minor adjustment will fix that. It could also just be the album.

The only things left to do are a proper re-greasing of the top side and soldering some new leads to the sled. Fingers crossed!

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Re: Thrift store SL-65B -- Initial questions

Post by DSJR » 14 Mar 2018 08:50

The auto return trips may begin to engage in one particular place, but slow arm movement should cause the top pawl to be pushed back slightly on the friction plate underneath until the arm moves more quickly and engages the mechanism.

Link here - https://www.vintage-radio.net/forum/sho ... php?t=8936

For the millionth time for me ;) - both pawls on the cam MUST be free to rattle like the leaves on a tambourine. PLEASE DON'T LUBRICATE these parts... Other decks may have different instructions, but the Autoslim derived trip pawls work best totally dry - and I care not what Garrard might have done on the assembly line!

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Re: Thrift store SL-65B -- Initial questions

Post by DSJR » 14 Mar 2018 08:52

PLEASE leave the pawls on the main cam free and rattly...

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Re: Thrift store SL-65B -- Initial questions

Post by DSJR » 14 Mar 2018 10:31

I'm not sure I'm able to post the link, so I'll quote the relevant text on how velocity trips work if that's ok... My extra words in brackets!

"The trip is intended to operate either manually, or when the stylus reaches the run-out groove on the record; this moves the large cam gear by rotating it slightly; this rotation causes the gap in the teeth to move so they engage with the turntable hub gear, thus starting the trip cycle.

The cam gear has two pivoted levers - the trip (friction) pawl below and the trip lever uppermost.

There is a sliding lever that operates the trip lever by either the arm moving inwards, or by the manual reject knob.

The turntable hub has a projection to arrest (catch) the trip pawl. The trip lever rests lightly on the trip pawl and can rotate slightly.

Operation:
Deck is running, and about 5mm before the end of the record, the sliding lever pushes the trip lever, which, by gravity, pushes the trip pawl inwards so a projection on it encounters the hub projection.

Every time this happens, the stylus has moved by a groove-width, and the trip pawl moves a minute amount each time, so the hub projection pushes it back out of the way, the friction on the trip lever allows this to happen.

When the runout groove appears irrespective of where on the record it is the trip pawl is moved far enough in to be arrested (fully caught) by the hub projection, starting the trip cycle.

After the pickup arm has swung out near the end of the cycle, and the sliding lever moves away from near the trip lever and trip pawl, a ramp on the trip lever encounters a stop on the deck and pushes it and thus the trip pawl as well, back to their resting position.

The main problems are due to (hardened) grease or oil ending up on the trip pawl and lever - they should be completely clean and dry."

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Re: Thrift store SL-65B -- Initial questions

Post by amagasakii » 15 Mar 2018 04:09

I did make sure to reassemble the trip pawls dry (and yes, I even did the rattle test! :-)), but I will check that I haven't contaminated it with grease with all my manhandling.

Let me see if I understand how a velocity trip works:

Towards the end of a standard 12" LP, the tonearm has moved far enough that the auto trip link is slowly pushing the trip pawl towards the hub of the platter. Each time the platter makes a full revolution, the projection basically "knocks" the trip pawl out of the way. Eventually, the run-out groove pulls the tonearm (and trip link) in so quickly that the trip pawl is caught by the hub projection, thus turning the cycle cam far enough to engage the teeth starting an automatic cycle.

Therefore:

A velocity trip works through velocity and a predetermined tonearm position. You can't put a run-out groove at the start of a record and expect it to trip the auto cycle. Conversely, you also can't cut a track right up to the spindle, because eventually the trip pawl will simply be pushed out so far it engages a return cycle.

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Re: Thrift store SL-65B -- Initial questions

Post by Spinner45 » 15 Mar 2018 04:44

amagasakii wrote:I did make sure to reassemble the trip pawls dry (and yes, I even did the rattle test! :-)), but I will check that I haven't contaminated it with grease with all my manhandling.

Let me see if I understand how a velocity trip works:

Towards the end of a standard 12" LP, the tonearm has moved far enough that the auto trip link is slowly pushing the trip pawl towards the hub of the platter. Each time the platter makes a full revolution, the projection basically "knocks" the trip pawl out of the way. Eventually, the run-out groove pulls the tonearm (and trip link) in so quickly that the trip pawl is caught by the hub projection, thus turning the cycle cam far enough to engage the teeth starting an automatic cycle.

Therefore:

A velocity trip works through velocity and a predetermined tonearm position. You can't put a run-out groove at the start of a record and expect it to trip the auto cycle. Conversely, you also can't cut a track right up to the spindle, because eventually the trip pawl will simply be pushed out so far it engages a return cycle.
That is basically correct.
At a predesigned "inner" diameter of the tonearm, the linkage starts to push (or pull in some cases) and contacts the trip pawl assembly.
Since the arm is only moving inwards, a groove-per-revolution, it's too slight, too small, to activate the change cycle.
The little "tap" backs it off until as mentioned, a large movement causes activation of the cycle.
The styles and materials will vary depending on the unit, but the application is the same.
Delrin, a slippery "plastic" material, was used on finer machines, allowing for a very light and sensitive tonearm to be used.
A Ball bearing in a "track" also makes less friction of the activating link.
Teflon washers are another "friction reducing" material.
The older, crude changers and inexpensive models naturally were not designed to track at say, 1 gram, due to the design.
The SL-65 would be happy at 2 grams or more, it was designed that way.

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Re: Thrift store SL-65B -- Initial questions

Post by amagasakii » 15 Mar 2018 07:37

Spinner45 wrote:That is basically correct.
At a predesigned "inner" diameter of the tonearm, the linkage starts to push (or pull in some cases) and contacts the trip pawl assembly.
Since the arm is only moving inwards, a groove-per-revolution, it's too slight, too small, to activate the change cycle.
The little "tap" backs it off until as mentioned, a large movement causes activation of the cycle.
The styles and materials will vary depending on the unit, but the application is the same.
Delrin, a slippery "plastic" material, was used on finer machines, allowing for a very light and sensitive tonearm to be used.
A Ball bearing in a "track" also makes less friction of the activating link.
Teflon washers are another "friction reducing" material.
The older, crude changers and inexpensive models naturally were not designed to track at say, 1 gram, due to the design.
The SL-65 would be happy at 2 grams or more, it was designed that way.
Excellent, I'm happy to have a general understanding of how this works. I'm really enjoying this project and all the learning that comes with it. (I've grown quite fond of the Autoslim design because, as intricate as it is, it's also been very sturdy and forgiving.)

As I understand it, then, there isn't much I can do if the return cycle starts before this particular LP's last cut ends. If, potentially, the last cut extends beyond the "inner" diameter of the tonearm, it's going to trip the return cycle.

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Re: Thrift store SL-65B -- Initial questions

Post by Spinner45 » 15 Mar 2018 15:59

amagasakii wrote:
Spinner45 wrote:That is basically correct.
At a predesigned "inner" diameter of the tonearm, the linkage starts to push (or pull in some cases) and contacts the trip pawl assembly.
Since the arm is only moving inwards, a groove-per-revolution, it's too slight, too small, to activate the change cycle.
The little "tap" backs it off until as mentioned, a large movement causes activation of the cycle.
The styles and materials will vary depending on the unit, but the application is the same.
Delrin, a slippery "plastic" material, was used on finer machines, allowing for a very light and sensitive tonearm to be used.
A Ball bearing in a "track" also makes less friction of the activating link.
Teflon washers are another "friction reducing" material.
The older, crude changers and inexpensive models naturally were not designed to track at say, 1 gram, due to the design.
The SL-65 would be happy at 2 grams or more, it was designed that way.
Excellent, I'm happy to have a general understanding of how this works. I'm really enjoying this project and all the learning that comes with it. (I've grown quite fond of the Autoslim design because, as intricate as it is, it's also been very sturdy and forgiving.)

As I understand it, then, there isn't much I can do if the return cycle starts before this particular LP's last cut ends. If, potentially, the last cut extends beyond the "inner" diameter of the tonearm, it's going to trip the return cycle.
A 7 inch 45 RPM record has a smaller lead-in diameter, and one with only 10 millimeters of lead-in should not trip the cycle until the song is finished.
If the automatic set-down adjustments for both LP's and 45's is correct and proper, this should be the case.
However if the setdowns are correct, and the changer trips prematurely, particularly on a 45, then the trip link is bent.
The "pushing end" at the tip of it can sometimes be carefully bent a tiny bit to allow more "time" before a cycle is started.
I don't recommend this usually because careless bending can cause the link to bind, or miss touching the trip pawl.
It is, after all, delicate lightweight aluminum.

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Re: Thrift store SL-65B -- Initial questions

Post by A70BBen » 15 Mar 2018 17:28

Spinner45 wrote: The styles and materials will vary depending on the unit, but the application is the same.
Delrin, a slippery "plastic" material, was used on finer machines, allowing for a very light and sensitive tonearm to be used.
A Ball bearing in a "track" also makes less friction of the activating link.
Teflon washers are another "friction reducing" material.
The older, crude changers and inexpensive models naturally were not designed to track at say, 1 gram, due to the design.
The SL-65 would be happy at 2 grams or more, it was designed that way.
In later years, Garrard quoted two grams as the lowest recommended for the SP25 Mk IV which had the same tonearm and trip as the SL65.

Garrard incorporated Delrin in the slot for the trip slider of the UK/Australian AT6 Mk II but not the USA version...America's AT6 did not get the Delrin insert and antiskating until it was superceded by the AT60. Although one could buy the Delrin insert cheaply from Garrard, Delrin could not be retrofitted because a different cutout in the steel chassis was required. The Delrin insert worked, reducing minimal tracking force from 2 1/2 grams on the AT6 to 2 grams on the AT60; and had Garrard added Delrin or Teflon washers to the other end of the auto trip slide, that may have worked, too.

Experimentally, on my my junkbox-rescue USA version AT6 Mk II, I will try lubricating the trip slider and trip levers with dry graphite powder and with dry Teflon powder, if I can source some. No wet lubricant. Even some so-called "dry" lubricants in spray cans seem to leave a residue as their volatile carriers evaporate.

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Re: Thrift store SL-65B -- Initial questions

Post by DSJR » 15 Mar 2018 18:29

Sorry to come in yet again. My AT6 is a very early one with original suspension and I wanted to see if I could reduce the sliding friction in the trip 'sliding lever.' Nothing to be done at the cam end because the stud lightly 'slides' on the painted deck plate and if the tiniest smear of sewing machine or clock oil is there (and I mean the tiniest smear), you can't do any more. HOWEVER, I experimented with adding a thin nylon washer at the other end between slider and screw head, as the slider acts directly on the fixing screw at this end. I *thought* the friction was slightly lower and because the washer was very thin, free movement wasn't impeded..

Fortunately, most modern cartridges track at 1.75 to 2g these days and suitable cartridges like the AT91, related Rega carbon and AT95E, are quite happy at a smidge under 2g. Price may be an issue and the sound is a bit bass-ripe and old fashioned, but the Sumiko Oyster might be a fun thing to try. I believe Tonar do a version of this as well with elliptical tip (Diabolic E) and I've just seen they do their version of the AT91 and also the elliptical Dual 251E which is sold by Thakker too for around forty quid in UK money... many cartridges are/were made by one or two companies in japan for many third parties... Through all this, the AT95E continues and if anything getting better as time passes (diamond finish I think is improved these days) and so many are made, the price is silly-low compared to everything else which used to be around the same money (yes Nagaoka, I'm looking at you!!).

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Re: Thrift store SL-65B -- Initial questions

Post by amagasakii » 17 Mar 2018 03:51

DSJR wrote:For the millionth time for me ;) - both pawls on the cam MUST be free to rattle like the leaves on a tambourine. PLEASE DON'T LUBRICATE these parts... Other decks may have different instructions, but the Autoslim derived trip pawls work best totally dry - and I care not what Garrard might have done on the assembly line!
Thanks for this hint— even though I left everything dry when I first disassembled the cam, the constant manhandling had indeed contaminated the pawls with grease. A minute amount of it on the post of the lower trip link created enough friction to pull the upper pawl out early. Even though they still rattled freely, I cleaned off the offending grease, put everything back together, "et, voilà", the return cycle now starts just before the tonearm hits the overload spring. :)

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Re: Thrift store SL-65B -- Initial questions

Post by amagasakii » 17 Mar 2018 05:20

I'm on the home stretch now! Just a couple questions:

[*] What is a good modern equivalent to lubricate the spindle? Chainsaw bar oil? That's adhesive and cheap.
[*] The auto cycle visibly slows down halfway through the cam cycle (when the tonearm is drawn out of the way). Can I fix this? This seems like it's the most stressful part of the cycle.

(Apparently BBcode bullets are broken.)

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Re: Thrift store SL-65B -- Initial questions

Post by A70BBen » 17 Mar 2018 08:19

I use chainsaw bar oil and it works fine on these machines.

The auto cycle WILL slow down at points of maximum load on the motor (it drops out of synchronism under heavier loads than while playing a record). I can't see your turntable as it does this, but it could be normal.

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Re: Thrift store SL-65B -- Initial questions

Post by amagasakii » 17 Mar 2018 10:21

A70BBen wrote:I use chainsaw bar oil and it works fine on these machines.
Excellent! $3.99 a litre; I can keep this thing going for decades.
A70BBen wrote:The auto cycle WILL slow down at points of maximum load on the motor (it drops out of synchronism under heavier loads than while playing a record). I can't see your turntable as it does this, but it could be normal.
That's exactly what it does. There's a point in the auto cycle where you can see the motor slow and struggle. I ran it through several cycles with a strobe disk and you can watch the strobe marks briefly drop back quickly. If that's normal, I don't mind.

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Re: Thrift store SL-65B -- Initial questions

Post by Spinner45 » 17 Mar 2018 14:32

amagasakii wrote:
A70BBen wrote:I use chainsaw bar oil and it works fine on these machines.
Excellent! $3.99 a litre; I can keep this thing going for decades.
A70BBen wrote:The auto cycle WILL slow down at points of maximum load on the motor (it drops out of synchronism under heavier loads than while playing a record). I can't see your turntable as it does this, but it could be normal.
That's exactly what it does. There's a point in the auto cycle where you can see the motor slow and struggle. I ran it through several cycles with a strobe disk and you can watch the strobe marks briefly drop back quickly. If that's normal, I don't mind.
People who aren't familier with these machines overlook key areas to service.
That little "stud" that follows the cam groove is actually a little roller that usually seizes to its shaft from dried grease.
And when that happens, it creates substantial extra friction inside the cam groove, causing stalling or excessive slowing down.
Flush, clean, two drops of oil.
And a light "smear" of super lube inside the cam groove.