Just to follow up for those if any who also got the bug to change ceramic capacitors without just cause. I managed to replace c226, c227, c228 with the values stamped on the capacitors (c227:220pF is correct that isn’t a typo in this manual). Outside of tracking moving by 1msec I found absolutely no difference after swapping with MLCCs, which calls for a toast to 40+ year old ceramic caps - since these were still within their tolerances. Also +1 percent speed increase persists. I decided against swapping out c227 with a 330pF MLCC after reading more and understanding less about crystal load capacitance and given this crystal is no longer available. Thanks all for your help.
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I've seen this a hundred times before, and with customers in the shop through the decades as well.
A concern with speed accuracy on turntables-record changers with fixed speed settings.
And this is what I tell them all....
Depending on whether they're "pitch sensitive" individuals, or just annoyed by slight inaccuracies in platter speed not attributed to belt or drive system problems, if they want absolute "perfect" speed, then they should purchase a machine that allows the user to adjust speed to their liking.
That's primarily what those types of machines were made for.
Because a trivial 1% or even a few percent is typical of mass-produced machines - it's called a "tolerence level" in the industry.
Just like parts (caps/resistors/etc) have a certain tolerence.
A concern with speed accuracy on turntables-record changers with fixed speed settings.
And this is what I tell them all....
Depending on whether they're "pitch sensitive" individuals, or just annoyed by slight inaccuracies in platter speed not attributed to belt or drive system problems, if they want absolute "perfect" speed, then they should purchase a machine that allows the user to adjust speed to their liking.
That's primarily what those types of machines were made for.
Because a trivial 1% or even a few percent is typical of mass-produced machines - it's called a "tolerence level" in the industry.
Just like parts (caps/resistors/etc) have a certain tolerence.
I think that error might be me lol. Thought I'm not yet sure. I'm coming from a SL-1700 where my phone strobe app (50 hz) synchronized with that TT's strobe. Now when I shine my strobe at the 1301's there's a beat frequency (~.5 hz). The strobes synchronize (platter removed) when I set the strobe app to 50.5 hz. Perhaps there's something else aloof. I'm going to print out a strobe disc and check. I've verified Parts A, B and C check out per service manual.
Question when checking tracking on an oscilloscope do you recommend AC or DC coupling? As I understand it AC coupling introduces a capacitor in the signal. I'm seeing longer To section in AC vs DC coupling.
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Thanks for the help
. I’ve adjusted using AC coupling with the 10x probe. Turns out I was short by 1.5 msec using DC coupling with 1x. And the verdict is in! I’ve tested the turntable speed using a printed out strobe pattern. The speed is dead on 33 and 1/3! I was wrong
. I can see the stove pattern slowly migrate to the left or right when I decrease and increase the strobe app frequency by .6Hz. I think the discrepancy might be explained by the fact that the TT’s strobe LEDs blink sequentially rather than in unison, and I was seeing is that artifact. Well all is well thanks for everyone’s help and suggestions! I’m just glad I didn’t break anything along the way.Attachments
And the verdict is in! I’ve tested the turntable speed using a printed out strobe pattern. The speed is dead on 33 and 1/3! I was wrong
And there you have it!
All due respect...
Using those dumb "apps" which seems to be what everyone depends on these days is for fools.
Living everything by an "app" - the masses are dumbified, it's their whole world these days.
Bottom line, it's just not normal, nor reliable.
But if people insist that "it's the new normal", I feel sorry for them.
And I've seen and heard plenty of discussions from others complaining about turntable speed inconsistencies by using some dumb app.
You'd think they'd learn from it, but the millenial crowd is insistent on using such modern technology.
It's been drummed into their heads - that cellphone is relied on for everything.
Using technology as a crutch is not new to the millennial generation. Its as old as technology and each generation has said what you say about the current millennials. Phone apps are not unique to that cycle. Radio, TV, Internet etc… Does certain tech not belong? I’m not a millennial. The phone app I’m using is accurate. The mistake I made, a mistake anyone can make, is jumping to the conclusion that the turntable strobe being off by 1% meant the turntable speed is off. I didn’t account for the strobe dot spacing… Hence the turntable speed being spot on. I used the same phone strobe app to verify that on printed strobe pattern. Thank god for phone apps! Lol.
Turntables are a 1960's/70's era thing, and using technology/tools from the same era was and still is the most reliable way IMO.
Aquiring a paper or other strobe disk and placing it on the platter, then viewing with a neon or other 120V 60Hz AC source while playing a record's outer band was and still is the trusted way to confirm speed accuracy.
Any slight "drag" from stylus friction or loading is taken into acount of course.
Nevertheless, the world is full of variables, including discrepencies in the production process of records, and the manufacturing tolerances of mass production of consumer products.
This is something I don’t understand. Math and physics don’t belong to a certain vintage IMO.
Yes I agree older consumer products in my experience are better made and I’m glad this community here exists. It’s a marvel this technics so-1301 still plays beautifully, I hope it lasts another few decades.
This is not focusing on math or physics, it's how you go about something just like you would if you were back in the day.
People back in the 1970's didn't have cellphones, etc.
At the time, they perfected diagnostic procedures to fit their equipment.
Thus, they use the,.. as it's now referred to,.. "old school" methods of a neon lamp and strobe disk.
Even turntables were made that way with a strobe on or under the platter.
It was just the way things were done.
Technics, among some others, stepped forward, out of the box, with crystal-controlled flashing illumination of their strobes, causing some confusion to the situation.
People started relying on a common 60Hz common neon flashing if the internal LED died, and wondered why they couldn't get a correct speed reading.
I've seen threads on sites like vinylengine.com, among others, that discussed this.
Ah ok, I see. Yeah and here today I made the same mistake relying on a 60hz strobe app to check a crystal controlled strobe (101.11hz). I used to own a SL-1700 mk1 and routinely used my strobe app at 60hz which did match that 50/60hz strobe, which is a non-quartz locked turntable.