Lead in groove length.

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chenry57
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Lead in groove length.

Post: # 27313Unread post chenry57
Mon Sep 30, 2013 1:37 pm

Hey all. I'm noticing that my 12" lead in grooves are pretty small. Not the pitch of the grooves, but the actual distance that the lead in gets written. I've used calipers and a compass to determine that My drop down is RIAA accurate, but my program start time is at a tad higher radius than is optimal. I do not have any info in my manual pertaining to this, but I'm assuming its a micro switch thing, as it is identical on both 45 and 33 12" cuts. My 7" cuts are fine at both speeds btw. If anyone can shed some light on this I'd appreciate it. Or if you have the proper manual pages (as my purchased CD manual has omitted all info for programmers, plus other omissions) I'd love to get that info. I'm using a VMS-70 by the way.

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jjgolden
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Re: Lead in groove length.

Post: # 27315Unread post jjgolden
Mon Sep 30, 2013 4:48 pm

Hi,

Yes, there are 2 little screws that lock each of the little trigger fingers in place.
These can be moved forward and back to trigger the micro switches sooner or later & extend the lead in area by whatever amount you want.
It may be helpful to put up a few current pressing from various pressing plants on your neumann platter and see where your at in relation to the groove guard(s).

JJG

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opcode66
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Re: Lead in groove length.

Post: # 27316Unread post opcode66
Mon Sep 30, 2013 5:03 pm

Careful making adjustments. Those are nut locking screws (not sure of the proper terminology).

Two of them determine when the groove starts. The third in the middle will determine the length of time the microswitch is depressed. This is the one you want to adjust. I think the rounded head of it on the bottom side needs to be a bit lower and closer to the microswitch assembly so it depresses the microswitch longer. But, don't adjust too much. You don't want to kill the switch! Just make minor adjustments and then see what the results are.
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chenry57
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Re: Lead in groove length.

Post: # 27318Unread post chenry57
Mon Sep 30, 2013 5:38 pm

Thanks a bunch. I assumed this was the case, as the middle screw on my 12" was 1 thread "higher" than the others, but didn't want to mess with anything without a second opinion. I've since tweaked it down just a bit and it took care of my problem.

The difference was subtle, but 1 out of every 4 or 5 turntables with auto needle drops would place the playback stylus right into the track, which annoyed me.

Thanks!

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opcode66
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Re: Lead in groove length.

Post: # 27319Unread post opcode66
Mon Sep 30, 2013 6:15 pm

There is also the Safety Groove switch in the PS66 programmer boxes. You set set that to on for a nice nearly locking groove to start, then lead in, then set lpi.

What is interesting to note is that Neumann used a combination of timing mechanisms: physical as well as electrical. The timing of the length of the lead in groove is physical. The timing of the Safety Groove (which is initiated by the prior physical microswitch triggering) is governed by an RC circuit (Resistor Capacitor combination) because that timing is dependent on rotational speed (45/33/whatevs). Therefore each programmer box has a different RC combo to achieve the proper delay for Safety Groove (making a nearly locking outer groove).
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Re: Lead in groove length.

Post: # 27325Unread post chenry57
Mon Sep 30, 2013 9:44 pm

Yeah, I was able to find all of that info. It was just bugging me because the lead in issue is the one "problem" that isn't addressed in the manual. Thanks again for the help. It's always nice to have a second opinion on what I assumed to be true. I don't ever want to touch those micros witches without being totally sure first.

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opcode66
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Re: Lead in groove length.

Post: # 27326Unread post opcode66
Mon Sep 30, 2013 9:49 pm

There are a number of them used on the back plate as well as within the suspension boxes. I know of a place to order them from if you even need replacements. I order a bunch.
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Re: Lead in groove length.

Post: # 27331Unread post concretecowboy71
Tue Oct 01, 2013 5:00 pm

I agree the one screw maybe needs to come down a bit to make contact a bit longer.

There is a special tool you are supposed to use to adjust those screws. Paul Gold has a set from what I remember.

FYI. Not every suspension has micro switches. Both of mine have reed style switches inside. Not sure when the change was made.
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gold
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Re: Lead in groove length.

Post: # 27333Unread post gold
Wed Oct 02, 2013 2:58 pm

I have the tool for the round nuts. It's available from PB Swiss Tools. It sounds like you need to adjust the Fast mode pitch. That's the "f" pot on the programmer(s).

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opcode66
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Re: Lead in groove length.

Post: # 27334Unread post opcode66
Wed Oct 02, 2013 4:00 pm

Adjusting the speed at which the Fast motor rotates will not increase the overall length of time that it is run for while the machine is cutting the lead in groove. It will only affect how wide the grooves in that time period are cut. The time period is determined by the length of time the microswitch in the back is depressed. That is determined by adjusting the height of the plunger on the plate that is connected to the carriage arm.
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opcode66
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Re: Lead in groove length.

Post: # 27335Unread post opcode66
Wed Oct 02, 2013 4:07 pm

What size round nut are used????
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chenry57
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Re: Lead in groove length.

Post: # 27336Unread post chenry57
Wed Oct 02, 2013 9:39 pm

concretecowboy71 wrote:I agree the one screw maybe needs to come down a bit to make contact a bit longer.

There is a special tool you are supposed to use to adjust those screws. Paul Gold has a set from what I remember.

FYI. Not every suspension has micro switches. Both of mine have reed style switches inside. Not sure when the change was made.

Ah, well, I was able to use a tweak tool for the tape machine and it worked very well.

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chenry57
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Re: Lead in groove length.

Post: # 27337Unread post chenry57
Wed Oct 02, 2013 9:41 pm

opcode66 wrote:Adjusting the speed at which the Fast motor rotates will not increase the overall length of time that it is run for while the machine is cutting the lead in groove. It will only affect how wide the grooves in that time period are cut. The time period is determined by the length of time the microswitch in the back is depressed. That is determined by adjusting the height of the plunger on the plate that is connected to the carriage arm.
I'll have to pull my compass out again, however. Since the screw head is lower, it's also triggering the drop down a tad earlier...sweet.

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gold
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Re: Lead in groove length.

Post: # 27348Unread post gold
Thu Oct 03, 2013 5:07 pm

chenry57 wrote:
opcode66 wrote:Since the screw head is lower
The microswitches are delicate. If you want to alter the position, the way to do that is to loosen the ring and physically move it. The height of the actuator should be set for least stress.

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gold
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Re: Lead in groove length.

Post: # 27349Unread post gold
Thu Oct 03, 2013 5:53 pm

That last post wasn't very clear. If you want to alter the height of the actuator loosen the ring and turn the screw. If the ring was loose it should be tightened. The height of the actuator shouldn't be used to alter the position. The microswitches are delicate and will break eventually if the actuator is too low. If you want to move the position you should move the whole screw/nut/actuator assembly.

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gold
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Re: Lead in groove length.

Post: # 27351Unread post gold
Thu Oct 03, 2013 9:16 pm

opcode66 wrote:What size round nut are used????
It says M3/M3.5 on the screwdriver handle. The part number is PB 196/5. I went to the website and it's kind of confusing. The part number matches the screwdriver I have but the description says it's "size 5". It doesn't say M5 but calling it size 5 for an M3 screw is pretty confusing. I actually bought the whole set to figure it out the correct size.

http://www.shop.pbtools.us/Classic-Round-Nut-Screwdriver-size-5-1965-90.htm

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opcode66
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Re: Lead in groove length.

Post: # 27352Unread post opcode66
Thu Oct 03, 2013 9:36 pm

Thanks Paul. Yes, I just bought all but size 9 and 10 yesterday. Thanks for pointing out who has them. I used a hack before...
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gold
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Re: Lead in groove length.

Post: # 27353Unread post gold
Thu Oct 03, 2013 10:32 pm

They are really fine tools. The official Studer maintenance kit came with them. They make the best flat head screwdriver hands down. The head shape prevents the screws from getting marred.

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opcode66
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Re: Lead in groove length.

Post: # 27354Unread post opcode66
Thu Oct 03, 2013 11:16 pm

I downloaded their catalog. Really fine tools.

Mr. gold is correct in that you absolutely dont want to apply too much downward force to the switch. I also warned of this earlier.

However, there is some millimeters of play there. It does affect how long the switch is depressed. Which affect the overall length of the lead in. You'll notice if you crank the carriage while leaving the halfnut disengaged to the pount where the switch is depresseed Spiral will illuminate. The SP potentiometer is actually the one that determines the pitch of the grooves here. Not F as previoisly indicated.

If you leave the carriage there Spiral will stay illuminated and will not turn off until you move it such that the switch in back is no longer depressed. You can hear the clicks as in gets closed and opened. Immediately after the carriage is past the switch, the Spiral light goes off and we are back to you set LPI pitch. There is no delay. Therefore the length is entirely physically determined. No delay circuit.

Since the bottom of the screw is a sort of rounded plunger the further it goes down, the earlier it stiked the switch mechanism. Because it is spherical on the bottom. That accounts for why you notice the lead in staring earlier. As stated, the other two normal screws can be loosened and the entire striker assembly can be adjusted left or right to move the point where the lead in starts. I had to do this for my 12" one because it was starting a hair too early and it was causing issues for the pressing plant.
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chenry57
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Re: Lead in groove length.

Post: # 27369Unread post chenry57
Mon Oct 07, 2013 7:34 pm

Thanks for all of your info. The reality is (had I taken pictures) is that the actuator screw was sitting very high 2 "threads" higher than all of the other actuator screws. So the issue was that it had been moved at some point & wasn't holding the microswitch down for a long enough duration.

When I finally acquired a compass and force gauges, I noticed that my drop down time was a bit shallow (too far "in" as a diameter), so I moved the actuator assembly slightly outside until my dropdown was to spec. This is when my program start time was becoming an issue. The actuator screw's height was probably my problem all along, but I just didn't know it (experience is something you get right after you need it, sometimes). Oh well, all's well with the world. I guess there isn't a way to tell if I'm applying too much pressure to a microswitch or not. However, my actuator screws seem the same height as all of the others.

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