LPC PIckup Balance Adjustment / Trip Lever

it's me again! i figured i would post a new topic for each issue i encounter on my LPC resto. but let me know if it's better for the forum to just make it one long thread. i'm still quite new around here...

i'm doing the Pickup Balance Adjustment, as i'm trying to get a handle on some sporadic tracking/distortion issues with my new T-needles.

i am trying to set the arm in the area of the record cut-off groove (Pickup 12, page 2501), but there is a definite resistance and push back toward the outer edge of the record. the resistance is not present for the first inch or so from the outer edge. i've been rotating the counterweight, but it doesn't seem to overcome the resistance in the last third of the record that skates the arm backward.

it appears that the Trip Lever is exerting at this point. but the records have always tripped and ejected properly, only at the cut-off groove. so, i'm reluctant to mess with it. but i'm not getting a free floating arm later in the record.

cheers,
eric

Eric, looking at this pic:
http://s1192.photobucket.com/user/Rob-N ... ort=3&o=38

There is a an anodized gold colored bracket around the trip switch. On it there should be a spring that is straight vertical and connects to the notch hook in the trip whisker. that is there to adjust the trip bias and lighten the loading of the trip switch on the tonearm
Loosen the screw in the center of the bracket just enough to let you push the arm downwards. If you lower it too far the phono will be prone to tripping off with any vibration --but it should be as low as possible.

For reference, D-L and look at the short trip video here:
viewtopic.php?f=3&t=6428

As you can see, the trip switch whisker should not touch the trip opening except as the arm enters the spiral at the end of the record. Realistically, the precision in this area is not that good and often there may be some slight loading at either the lead-in or before the trip off but never enough to cause skipping or excess wear patterns.

Check also the pickup arm lead dress. Be sure it isn't causing binding.

Rob-NYC

Or, You could follow the very clear instructions in the service manual ??
One hint--almost all of the pick-up adjustments are interdependent on each other--therefore if one "messes" with any, all must be at least checked, and most people need to have a gram gauge to do this properly ! Once again, IMHO, **** NO "mechanical "adjustment" on a Seeburg mechanism "changes, by itself", once made correctly after changing a part **** Ron Rich

Rob-NYC wrote:Eric, looking at this pic:
http://s1192.photobucket.com/user/Rob-N ... ort=3&o=38

There is a an anodized gold colored bracket around the trip switch. On it there should be a spring that is straight vertical and connects to the notch hook in the trip whisker. that is there to adjust the trip bias and lighten the loading of the trip switch on the tonearm
Loosen the screw in the center of the bracket just enough to let you push the arm downwards. If you lower it too far the phono will be prone to tripping off with any vibration --but it should be as low as possible.

For reference, D-L and look at the short trip video here:
viewtopic.php?f=3&t=6428

As you can see, the trip switch whisker should not touch the trip opening except as the arm enters the spiral at the end of the record. Realistically, the precision in this area is not that good and often there may be some slight loading at either the lead-in or before the trip off but never enough to cause skipping or excess wear patterns.

Check also the pickup arm lead dress. Be sure it isn't causing binding.

Rob-NYC

brilliant - thanks Rob! i can see that adjustment in "Pickup 9 Trip Switch Pressure Adjustment" on page 2498. i'm glad you mentioned it's influence on the skating of the arm, as by the manual description i didn't glean that. indeed distortion will set in at this area where the arm meets an increased lateral exertion. very well could be this trip lever. this only became consistently apparent when i had to back off on the tracking weight (needle pressure) to accommodate the new T-needles.


oh - your video link from the thread you linked here has expired. i was excited to see it, but i think i get it form your deft description and photo.

cheers,
e

Ron Rich wrote:Or, You could follow the very clear instructions in the service manual ??
One hint--almost all of the pick-up adjustments are interdependent on each other--therefore if one "messes" with any, all must be at least checked, and most people need to have a gram gauge to do this properly ! Once again, IMHO, **** NO "mechanical "adjustment" on a Seeburg mechanism "changes, by itself", once made correctly after changing a part **** Ron Rich

oh, i hear ya Ron!! the interdependence thing was looming in my mind as i started working BACKWARDS... i had to intervene for the life of my costly new T-needles, indeed the needle pressure had been quite heavy in previous service, enough to grind copious amounts of vinyl around the old needle. easing the pressure then introduced some left/right distortions, i figured i would take a step back and check the balance adjustment. the manual is quite good at letting you know when a previous "adjustment should be correct before making this adjustment" but here it did not associate the balance adjustment and how the trip switch pressure might have influence. but yes - if yo do it from the beginning...

yeah - i wish i had a proper gram gauge. i am somewhat physically familiar with tonearm weights on my forefinger. this felt HEAVY. and the cantilever would flex under the pressure, allowing the housing to ride closer to the record. is that OK??
i figured i should back it off. i use my modern turntable tonearm as a reference, set to 3 grams (that's the max setting...) and try to judge a similar weight on my finger for the Seeburg arm.

hey... i'm a musician by trade, and merely an amateur tech. i know what *feels* right

should there be any flex at all when the cantilever is set on the record while playing? i know it's hard to see, but it looks wrong to me when it gets close to bottoming.

cheers!

your video link from the thread you linked here has expired. i was excited to see it, but i think i get it form your deft description and photo

.

Sorry about that, time does fly.

Here is the updated link:
http://www.fileconvoy.com/dfl.php?id=g8 ... 496587dea0

Once you have the trip loading as low as possible, make sure the arm is properly balanced and not biasing. This can be tricky given the old style springs which exert some influence even on the side which is not being used.

And then there is the issue of that dumb damping......

BTW: Do you gauge for tracking pressure?

Rob

Rob-NYC wrote:

your video link from the thread you linked here has expired. i was excited to see it, but i think i get it form your deft description and photo

.

Sorry about that, time does fly.

Here is the updated link:
http://www.fileconvoy.com/dfl.php?id=g8 ... 496587dea0

Once you have the trip loading as low as possible, make sure the arm is properly balanced and not biasing. This can be tricky given the old style springs which exert some influence even on the side which is not being used.

And then there is the issue of that dumb damping......

BTW: Do you gauge for tracking pressure?

Rob

thanks - i can see that yours is biased a little differently than mine.

THOSE SPRINGS... tell me about it. i made the mistake of removing the screw for the needle pressure springs, as my eyes aren't good enough to see the spring hook for removal (the mech is still in the cabinet)... in the process of removal THE SCREW AND THE LUG AND THE SPRING WENT FLYING IN ALL DIRECTIONS!!!

i recovered the spring, but the lug and screw are NOWHERE TO BE FOUND.

any idea if i can procure those two bits? ironically, i have seen the springs for sale, but that's the one piece that i recovered... i'm somewhat dead in the water here. i do have access to a spare mech, though i'll have to look and see if the tonearm parts are all there. it would be a shame to raid it though, if it is complete.

FUG!!!

oh - and no, I don't have a proper gram gauge. I noticed the one at Victory for sale, but I can't justify the cost for such rare usage on my part. anybody got a recommendation for something that works horizontally? ever tried placing a standard gram scale sideways onto the cartridge edge 'sideways'? sounds dubious, I know...

any idea if i can procure those two bits? ironically, i have seen the springs for sale, but that's the one piece that i recovered... i'm somewhat dead in the water here. i

If often screws that looked like they flew up and away actually fell straight down. If you have a strong magnet you can crawl around and see if you can catch it that way.....fun, I know.
If those fail, PM me, I have tons of those bitty pieces.

As for tracking force, a general rule is that there should be no deflection of the cantilever on any types of stylus. Since these are obviously different than the originals it may be difficult to attain that state and some -slight- compression may be unavoidable given the arm-cradle mass and that stupid damping.

Once you have it back together place the ear hooks on the tonearm at bottom, turn off power with the stylus on a record and closely examine the amount of cantilever compression.
When I used that pickup commercially I set them for 2- 3gm and this showed no compression.

Rob

aye - by that general rule, my arm had been tracking excessively heavy for sure. I'm glad I intervened... even though I lost some bits in the process. I'll get a look at my 'parts mech' this weekend, mebbe I can raid those bits for now.

I haven't yet considered the damping business...???

2-3 grams sounds quite civilized for a commercial jukebox! that would be great - I have a few treasured 45's that I haven't introduced to the LPC until I can achieve something like that.

cheers, and thanks!
eric

I don't see that a jukebox tonearm really has to track as light as a super-duper high fidelity home turntable.
Sure, 2-3 grams is nice, but only with a free-floating gimbal pivot system, as on quality home turntables.
As far as I recall, jukeboxes use crude tonearm pivots, pretty sloppy and crude adjustments and insensitive spring/weight counterbalances.
I've never seen a jukebox tonearm yet that used ball-bearing pivots, silicone clad super flexible wiring, or critically designed counterbalance systems,.... but then again I've not serviced them a lot either.
Therefore, I'd go with at least tracking at 3-5 grams - and at that setting, surely it won't "wear down" a record, as long as the stylus, pivots, and other adjustments were properly serviced.
The idea is to keep a solid reliable contact with the groove, to minimize skipping and wear due to mistracking and tonearm friction of these beasts.
I've got records dating to the early 1960's, played quite a bit over the decades on a console stereo at 5.5 grams.
And these same records play and sound great today, even on a quality turntable/system.
Of course, I'll get some flack on here for the post, and that's ok, because at 62 years old, and servicing phono's of all kinds for decades, I've learned that tracking "hype" (the less the better) is just that, up to a point.
You have to consider the equipment, and avoid pushing things to the limit of their capability.

Matt, I am not going to give you "flack" -just a bit of information.

In the 1950s jukeboxes had fairly crude arm bearings and idiotic spring schemes to adjusting VTF.
In the case of pre-Rowe AMI the arms could be substantially improved with the addition of a counterweight:
http://s1192.photobucket.com/user/Rob-N ... ort=2&o=13 -Added to this are new pickup cable and reduced pressure trip switch. These arms will then reliably track at 3gm.

Rock-Ola had a similar setup and can be modded to run at the same weight.

Wurlitzer had massive arms and crude bearings: http://s1192.photobucket.com/user/Rob-N ... rt=2&o=115

About the only thing you can do here is to replace the tonearm cable and mod the trip switch. A magnetic pickup rated for changer service and running @ 3-4 gm is how I always sent them out.

Of the '50s machines only Seeburg had the potential for 2gm tracking --but this was obviated buy fairly non-compliant pickups and heavy magnet structure.
However, needle-point bearings, high resolution pressure springs and gentle trip switch meant that with a better pickup and careful cutting down of the counterweights, and later, design arm and cart can be used and will reliably track at 2-3gm:
http://s1192.photobucket.com/user/Rob-N ... rt=2&o=169

Once stereo became standard and pickup tech improved in the early 1960s jukebox arms improved dramatically.

In 1962 what was now Rowe-AMI introduced its 1100 mech: http://s1192.photobucket.com/user/Rob-N ... ort=2&o=99
This new arm used a simple post bearing that sits in a well of light oil and on a single ball bearing. tonearm vertical are needle bearings Tracking was set via a counterweight and the assembly in inherently balanced. A magnetic reed trip switch was used and magnetic anti skate was adopted. The original Shure M77 was too crude to make full use of the new capabilities but when the M44 was introduced in the MM-1 in spring 1966 2gm tracking was specified. In fact these arms will track reliably at 1gm. I use 2gm for hideaways where no one will jostle them and 3gm for floor models.

Seeburg introduced 2gm spec with the SS160 in summer 1966. Here is one of those arm assemblies retro'ed into a 1956 VL :http://s1192.photobucket.com/user/Rob-NYC/media/VLmech_zps8abc5f4b.jpg.html?sort=2&o=69
The pickup was based on Pickering V-15 series which came out about 3 years earlier. The main difference for the juke version was the use of a thicker, high output cantilever. I have 9 old Seeburgs of this approximate vintage -all tracking at 2- 2 ½ gm. Most use the original trip switch.

I've got records dating to the early 1960's, played quite a bit over the decades on a console stereo at 5.5 grams.
And these same records play and sound great today, even on a quality turntable/system.

Have they been played upwards of 4000 times? This is common for a popular record over several years.
This is why you can not make a direct comparison between a home record player and a commercial phono.

Sorry to write an essay here, but the proper setup or modding of the tonearm is the first and most critical part of restoration and determines the quality of signal that we have to work with 'down the chain". As a matter of business, it also determines the longterm useability of an operator's stock; the records.

Rob-NYC

Great detailed post.
Rob, my statement about playing records at 5.5 grams in home use was not meant to compare with jukebox service.
In fact, it was merely to state that at 5.5 grams record wear was insignificant over years of "normal" play.
So with that said, I see nothing wrong with equipment using forces of 3-5 grams.
However, surely playing a tune 4000 times with ANY equipment is an extreme thing reserved for commercial use.

Cantilever compliance, pivot friction, etc, all figure into the mix.

Hi guys--
4000 plays???--I would hazard a guess that the hidaway I just up graded to a Seeburg SMC model, using my new Gen 2 MCU, has records in it that are at least 50, or more, years old, and have never been changed. Some of the records are Italian made, and probably ir-replaceable ? This jukebox, along with 12 wallOmatics has been in this Italian Restorante, in Sa Francisco, for about 60 years, in one form or another. It originally was a Seeburg M100 B or C, then was moved into the men's restroom (inside a closet) in a hideaway version, of some nature. It was up-graded last time in the early 60's to a model HLPC-480. I did a total restoration of this unit--I re-used the LPC record rack and base frame as I had a SMC that had been shipped somewhere without proper bolting, and had a bent main frame and record rack. I removed everything from the cabinet-cleaned the cabinet, re-installed rebuilt SMC stuff I wanted, along with the wall box power transformers, and moved the whole thing outta da men'z john, and I hope it plays on for the next 50 or so years--(I won't ever know ) !! Ron Rich

Ron Rich wrote: .................... and I hope it plays on for the next 50 or so years--(I won't ever know :lol: ) !! Ron Rich

So... now you're offering your services with just a 30 day warranty?
Just in case you kick the bucket?