LPC mech gets snagged all the way left

[robnyc]

Eric, what happens if you flip the reversing sw paddle at some point other than at the ends? Does the mech instantly reverse as it should? If it fails to reverse or is sluggish in doing-so that can indicate either a bad motor cap or shorted turns in the motor.

I suggest measuring the motor stator coils. For the typical Bodine KCI-42 motor you should see approx 300 ohms between GREEN and YELLOW wires and around 100 ohms from RED to BLUE. Since the LPC switches direction via a relay on the mech you'll need to slip paper between the "made" contacts to isolate the motor so as to prevent the other electrical circuits from distorting the results. Remove power plug as well.

What is the state of the mech cable, is it free all the way to the left side?

I've not followed the whole discussion here but, does this "bucking" happen after a selection has played at any point? Or just when the mech tries to reverse at the left end even if no selection has been player at that end. Bucking coming out of play into scan is classic clutch failure though as the condition worsens it can buck just as it scans.

Rob

[Ron Rich]

Hi Eric,
Normally, you purchase a "whole" cap--

[Ron Rich]

Rob, Eric,
Flipping the reversing switch back and forth is a "BIG RED FLAG", if not done VERY carefully-- On phono models thru the LS-3 series, it can result in the "switch stops" being bent, and eventually causing broken "center blades" in the switch. Starting with the USC series they used a "new style" white Nylon contact block that used "fingers" under the Tormat. On these phonos, "flipping the reversing switch", can and often times results in a fatal failure of that finger (bends it over), along with the previously mentioned, reversing switch problem. BTW-- The "Rubber bumpers" attached to either the record rack, on the SAU type mechs, or the adjustable types, attached to the base, on later, TMU models, are there to prevent a reversing switch from being "overtaxed" ( wished working people had that "protection"--lol !) Ron Rich

[babycat]

noted, Ron - i'll be extra careful when gently flipping the paddle switch

Feb 22, 2017 13:23:28 GMT robnyc said:

Eric, what happens if you flip the reversing sw paddle at some point other than at the ends? Does the mech instantly reverse as it should? If it fails to reverse or is sluggish in doing-so that can indicate either a bad motor cap or shorted turns in the motor... <cut>...



Rob

thanks for jumping back in Rob!   yes - so far, manually flipping the paddle results in an immediate and decisive reversal.


 <<robnyc Avatar
 Feb 22, 2017 5:23:28 GMT -8 robnyc said:

 I've not followed the whole discussion here but, does this "bucking" happen after a selection has played  at any point? Or just when the mech tries to reverse at the left end even if no selection has been player  at that end. Bucking coming out of play into scan is classic clutch failure though as the condition  worsens it can buck just as it scans. >>

the bucking only happens on the reversal at the left end while scanning.  it has not happened coming out of play.  

there was a new development last night, however  - coming out of play from a B-side, the relay released but the mech did not scan, just sat there, and the TT did not turn.   i could see (and actually slightly hear in the speakers) some tiny arcing on the relay contact (that i had just cleaned).  i shut it down for the night.  the next day, powering up, still no movement.  until i gently flipped the reverse paddle, and it all came back to normal.


 

[Ron Rich]

Hi Eric,
If you heard that arching, your "cleaned" contacts--aren't,correctly cleaned / adjusted, or the fiber blade support is loose on the relay armature--VERY common occurrence, on that relay (see earlier post--this thread). (see above in FAQ's "how to clean contacts" ) Ron Rich

[babycat]

aye - i'm still getting a moderate degree of arcing - especially on the "J" contact, which is in the rear of the stack. i usually don't hear the arcing, except that one time i mentioned above, when i was sitting right in front of the relay with the amp turned up, and the motor wasn't running.

i'd like to do a proper adjusting, and probably filing and burnishing of the G and J contacts, but the J seems especially out of reach.

can the relay be removed from the mech without a lot of fuss, to gain better access to the J contact?

cheers,
eric

[Ron Rich]

Eric,
"FILE" contacts--?? LAST thing you should do, IMHO--see FAQ's above !
Yes--relay can be removed, subject to length of wires. Easiest way is to remove the screw on the bottom of the coil.
Ron Rich

[robnyc]

"yes - so far, manually flipping the paddle results in an immediate and decisive reversal."

"the bucking only happens on the reversal at the left end while scanning. it has not happened coming out of play."

One thing I'd check is the position of the reversing cog that actuates the rev sw. I bought a BL where the mech bucked occasionally at the right. the reversing switch had been replaced and apparently, the replacement switch was formed just slightly further away so that actuator didn't hit the switch in time. One VL I bought had a similar problem though it didn't buck, the mech turned slightly as the readout arm hit the end support on the record magazine.

You never know what has been done to these things over the years until you light em'up.

Rob

[babycat]

Feb 25, 2017 0:08:44 GMT Ron Rich said:

Eric,
"FILE" contacts--?? LAST thing you should do, IMHO--see FAQ's above !
Yes--relay can be removed, subject to length of wires. Easiest way is to remove the screw on the bottom of the coil.
Ron Rich

are they gold contacts on the reversing relay?   i still haven't gotten a goof eyeball on them.   maybe i'll pull the mech (sigh...) and get a closer look.

[babycat]

Feb 25, 2017 8:44:58 GMT robnyc said:

"yes - so far, manually flipping the paddle results in an immediate and decisive reversal."

"the bucking only happens on the reversal at the left end while scanning. it has not happened coming out of play."

One thing I'd check is the position of the reversing cog that actuates the rev sw. I bought a BL where the mech bucked occasionally at the right. the reversing switch had been replaced and apparently, the replacement switch was formed just slightly further away so that actuator didn't hit the switch in time. One VL I bought had a similar problem though it didn't buck, the mech turned slightly as the readout arm hit the end support on the record magazine.

You never know what has been done to these things over the years until you light em'up.

Rob

indeed i've been tempted to sneak the left side actuator a little bit to the right and see if that helps... but i'm afraid it could bend or damage the switch if it goes too far.   when i shut down after it starts bucking, the reversing switch is always in the correct position.  but i haven't been able to confirm that the relay engaged and made good contact.  

do you think there's a little 'wiggle room' to tweak the actuator.  i assume the mech is bucking against the rubber stop - though i can't see it.

[Ron Rich]

No "tweaking' allowed--it MUST be set as per the manual's instructions ( unless you like replacing switches)! Ron Rich

[robnyc]

Eric, at the risk of arousing the ire of Ron, I'll outline how I set them up when either building up a mech or replacing the reversing sw.

With power off: bring the mech over toward the reversing point, in this case the left side. The switch paddle should be pointing toward the left as it hasn't been actuated yet. Continue to turn the motor coupling to advance the mech to the point past where the actuator has flipped the sw and the mech is now stopped firmly against the bumper. At this point the actuator can still be touching the paddle but there should be little (1/8 in or less) or no deflection at the bottom of the paddle. The idea is to keep the mech inertia from stressing the spring steel in the switch itself. Check also that the mech is clearing the last record slot but not moving so far as to allow the readout arm to hit the magazine support.

None of this would normally be necessary but if things have been tinkered or the switch replaced over the years, you have to at least check it. I goofed up in early 1994 when I was working 20 hr days to get a wallbox system ready for a diner. The machine (a 201) was filthy and tampered with so I should have checked for this sort of thing when reassembling it...but I didn't. About six years later the reversing switch literally fell apart and blew the main fuse but thankfully did no other damage. Had I checked the reversing actuator & bumper setup I might have prevented that mess.

RobNYC

[Ron Rich]

Hi Guyz,
No "ire" here ? The only thing I would say is, RTFM, for your model phono, as this set-up varies by model number !
One addition--in ALL cases, the inverted "V arms" on both sides of the Rev. switch, MUST be formed so that the "paddle" is just touching them--EVENLY, when on the flipped side. These are there to prevent "overtaxing" the spring steel paddle "arms". These are OFTEN "bent" by improper adjustment on the adjustable type rubber bumper phonos, or by a bad motor cap add circuit on all phonos, or by "hand flipping" !
When "flipping" the Rev. switch at either rack end. The mechanism in no way,should be able to travel far enough at the end, to touch the paddle to the adjustable stop, AFTER it has been flipped !
"Adjustment" of the V is accomplished when, if flipped, the paddle rests against the pair of V's on each side, and the switch section has totally "flipped".     Ron Rich

[robnyc]

For the sake of clarity here, the way I set them up (when necessary) is based on the fact that a normally functioning mechanism will reverse with little or no overtravel of the reversing switch paddle against the actuator. The bumpers are there to provide a hard limit and should not get more that the light "bump" if the mech has normal torque.

The primary difference in importance of these bumpers is related to the scanning speed in the later models. Obviously, the post VL-R-j models run faster and thus may overtravel and stress the switch more if not limited. There is also a consideration of the much heavier mech covers adding to the forward mass beginning with the Q.

Rob

[babycat]

that all makes sense to me - thanks fellers. i'm not yet convinced that i need to adjust the stop or actuator, but i like the procedure to look at it manually. since cleaning the relay contacts again last week, the symptom is coming up much less frequently. but i'm still getting some arcing on G and J... i finally snuck my camera and flash into the tight space, and in the photo i can see some slight pitting in the center of the disc-shaped contact (on the lower blades of each pair).

Ron - you mentioned 'no filing' above, but in the FAQ you mention using a point file and burnishing tool. i'm inclined to do that lightly on the G and J contacts as seen below:

whaddaya think?
cheers,
e