NSM City II - Rotation Speed adjustment?

[jbnyc341]

Hi Everyone - I acquired a City II 2 years ago that I restored but I have one last small problem which is that the vinyls play just a tad too fast.
Does anyone know of a solution to adjust the speed of the playing motor?
From the Electrical Schematics (208 550 B - Electrical Scheme) it seems to me that RV1 and RV2 (on the left side above "SPM" - SpielMotor) must be some variable resistors that should play this role - one for each direction of rotation.
However I have been unable to locate them on any of the electronic boards.
Any help will be very appreciated - Thanks in advance!

[Hildegard]

Hi jbnyc341,

what does "a tad too fast" mean in detail? How much rpm does the City II make? Mark a point at a record and count the rpm in one minute.
Does your City II use the Ortofon cartridge? I am asking because you refer to the schematic for that version. Or is it Shure 17CM?

Hildegard

[jbnyc341]

Hi Hildegard - Thank you for your appreciated response - The cartridge/needle is definitely on Ortofon.
Regarding the RPMs, I will measure these tonight when I get home. I suspect it must be in the 48-50 range. Will confirm that.

Julien

[jukenorman]

NSM turntables normally tend to run slow due to lack of lubrication so yours is an unusual problem. It's a synchronous motor so it shouldn't run fast. Could it be that a 50Hz motor is fitted? The motor body should be marked.
Norman.

[jbnyc341]

I just verified the RPMs and they are at 47+
Norman, thanks for the contribution. The stamp on the motor reads "901 3520 007 - 42V 60HZ" so it looks like it's the right motor.
Not sure what else to check.

[jukenorman]

How worn is the rubber ring on the turntable - that would make it run fast, if it was worn? As I said, NSMs usually tend to run slow from lack of lubrication, could somebody have trimmed it down (it wouldn't surprise me!)? Although to get 47rpm, I think it would need to be right down. Jukebox World has replacement rings. The only other thing I can think of - could somebody have put a piece of heat shrink sleeving on the motor shaft? That actually might be more likely!
Norman.

[jbnyc341]

Rubber seems fine, along with the motor shaft (attaching pictures for visual check).
The unit came to me in near mint shape (minus a few issues due to aging), so it does not look like anyone played around trying to fix it.
Thanks for the appreciated help on this. 

Julien

Attachments:

[jukenorman]

That looks all OK to me. I don't actually have the drawing you refer to above in my mish mash of NSM documentation; I only have 208 550 A. I'm afraid I always find NSM documentation a bit of a nightmare! When I'm really struggling for the correct schematic, I send an SOS to Hildegard and Oliver and they send the drawings I need so I'm very grateful for the service they provide! Looking at the drawing that I do have, there's not actually much in the playmotor circuit to fail. I'm at a loss, I'm sorry to say - faulty motor? Does it run hot?
Norman.

[jbnyc341]

Don't be sorry! I am very appreciative of the time and help that you'be been providing trying to find a solution - Thank you for that!
Motor feels cold on touch, just like the rest of the frame. I am attaching the schematics that I was referring to (difficult to get something crystal clear with the 1MB limitation - but it is decently readable). I have a lot more documents that came with the Jukebox but this one seems the most straight forward to read the wiring of the playing motor (SPM). Also adding the schematics of the carriage plate in case it can add value. Thanks again!
Julien

Attachments:

[jukenorman]

The circuit is exactly the same as I had looked at and it's quite simple - 43V AC, a motor run contact, a changeover contact for motor direction and a motor run capacitor. What else can it be?

[jbnyc341]

... that's the mystery that I have been dealing with for over a year. I read a few threads on the net and saw some references to NSM jukeboxes having a tendency to turn a little fast anyway. I'm just floored that there is apparently no adjustment available to resolve a problem like this. Not a huge deal, just annoying, especially after the first time you notice it.
Thanks for the help trying to resolve this, Norman!

[Ron Rich]

Norman,
Why are you "floored" at this ?? Radio stations, all over the world played them "fast"- jukeboxes did the same-- all for the same purpose.
Don't understand yet--please read, "Hi Newbies" in our FAQ's section -- Ron Rich

[jukenorman]

I have put a strobe disc in my Dropbox here
www.dropbox.com/s/90xft6klj0qigt9/Strobe_45_60hz.pdf?dl=0

This was made by one of the members of our British Jukebox Forum (thanks John). Paste it to an old 45 and it will give you a better idea of how the turntable is behaving speed wise and also whether the speed is fluctuating. I still can't get my head around why your machine should run so fast - you're not by any chance on some private electricity supply that might be operating slightly above 60Hz.?

[Ron Rich]

Hi Norman,
Great point !!
AND--one of the reasons our "rules" (introduction section !) ask people to show their locations in their PROFILE.
Ron Rich

[jbnyc341]

Hi Rich - Thanks for replying to my post. I had included my location in my profile, but only in the location section. I added it in my status so that it's now visible in my ID tab.

Thanks Norman for the strobe disc. I just tried it and the speed shows between 46.15 and 47.06 (closer to 46.15 though, which moves very slowly in in opposite direction to 47.06). Also, I do not use a private electricity supplier. I also checked the frequency of my power outlet and it reads exactly 60Hz.

Rich, I read the "Hi Newbies" section which is quite interesting. I understand that these machines were made primarily to make money, although I am not sure about the incentive for the radio broadcasts to play the records "fast". If this is how the jukebox was tuned at the factory, then be it. It's not a big deal - just annoying noticing it, especially when switching to MP3 mode on the same song to compare the audio quality of my vinyls.

Thanks again to you both for your appreciated inputs!