Walthers Cornerstone 130' turntable (1st gen) help request

[nickelplate759]

I have a 1st generation Walthers Cornerstone 130' turntable (model 933-2613, not the newer 933-2618) ;I got it second hand and have been fixing it up.

Once I figured out how to wire up the control board (thanks Peteski!) it works, but it runs a little rough and  I've noticed sometimes it will just stop -- and not start again until I power cycle it.  When it stops, the status lights don't change - the power light stays on and the position light stays off.  It's not at an official stopping point - in fact this can happen when I start the "find zero point" function - it sometimes stops before it gets to the zero point.

I'd appreciate it if anyone with experience with this board could tell me if this is a current overload safety feature, or just a sign that it's on it's on its last legs?

Also - it has code 80 rail - has anyone successfully swapped that for code 55?

[peteski]

George, assuming that 2 leads form the controller go directly to the motor, hook up a voltmeter to the motor leads (at the controller connector) then take voltage readings when the motor is running and when you think the motor should be running but it is not.  That will let you know what is going on.

[rodsup9000]

George, assuming that 2 leads form the controller go directly to the motor, hook up a voltmeter to the motor leads (at the controller connector) then take voltage readings when the motor is running and when you think the motor should be running but it is not.  That will let you know what is going on.

  I don't think that will work, Pete, cause I'm pretty sure the bridge is driven by a stepper motor.

 George, look to see if the gear on the bridge that rides on the pit floor is cracked. If not, you'll need to take the motor out and check the rest of the gears. I know of 3 that has had gear problems.

[peteski]

  I don't think that will work, Pete, cause I'm pretty sure the bridge is driven by a stepper motor.

I thought it was a standard DC motor with a a photoelectric revolution counter. 

[nickelplate759]

I thought it was a standard DC motor with a a photoelectric revolution counter.

When I opened it up to clean it I got the same impression - there's something that looks like  a fan attached to the non-gear end of the motor shaft, and it appears to spin in front of a photoelectric cell.   

I don't think a cracked gear is the problem - I thought it was at first but after decrudding the gear train the distinctive clunk-clunk doesn't happen - the table just stops if before it can do a full revolution. A power cycle gets it going again, which suggests that it isn't physically jammed. 

In another thread Pete asked for a picture of the reverse of the board - I'll get one tonight.

[rodsup9000]

I thought it was a standard DC motor with a a photoelectric revolution counter.

You're probably right, Pete.  I was just told wrong by somebody.   

[peteski]

You're probably right, Pete.  I was just told wrong by somebody.   

There are turntables out there which use stepper motors.

[alhoop]

I thought it was a standard DC motor with a a photoelectric revolution counter.

It is!
Probably need to clean the wiper fingers and what they make contact with and if they are not making
contact for the complete circle some bending will be required.

Al

[nickelplate759]

It is!
Probably need to clean the wiper fingers and what they make contact with and if they are not making
contact for the complete circle some bending will be required.

Al

Checking the contacts is a good idea.  I need to test and see if the problem happens in repeatable locations or is sort of random.

[nickelplate759]

The problem isn't due to contacts, although there is a little hitch in the bridge's motion when it goes past the dead area in the ring rail that suggests a little interference from a contact.

I'm thinking I may have missed a cracked gear after all - running clockwise is fine, but counter clockwise is clunky at a frequency of around 8-10 ticks per second.     It's too high a frequency to be the gear that engages the pit (and I can see that one really well and it looks fine) - I'm suspecting it's in the area of the gear train close to the worm (there are a couple there that are hard to see, and also well covered in grease).  I'm beginning to wonder if this particular example of this turntable is going to be worth the effort to restore.

[peteski]

The problem isn't due to contacts, although there is a little hitch in the bridges motion when it goes past the dead area in the ring rail that suggests a little interference from a contact.

I'm thinking I may have missed a cracked gear after all - running clockwise is fine, but counter clockwise is clunky at a frequency of around 8-10 ticks per second.     It's too high a frequency to be the gear that engages the pit (and I can see that one really well and it looks fine) - I'm suspecting it's in the area of the gear train close to the worm (there are a couple there that are hard to see, and also well covered in grease).  I'm beginning if this particular example of this turntable is going to be worth the effort to restore.

You know George, I have a fuzzy memory of someone here mentioning a source of (3rd party?) replacement gears for this turntable. Maybe do a forum search for that?

[rodsup9000]

 George, Here is a thread on replacement gears
https://www.therailwire.net/forum/index.php?topic=39946.0
 

[nkalanaga]

If the gears are "well covered in" grease, there may be a small piece of ballast, flash, or other hard material in one.  Cleaning all of the gears well may solve the problem.  I've had that problem with diesel trucks, especially on my Nn3 diesels.  They seem to collect debris even without a lot of grease...

[nickelplate759]

George, Here is a thread on replacement gears
https://www.therailwire.net/forum/index.php?topic=39946.0

I'll have another go at disassembling the drive train. Last time I couldn't figure out how to life the motor out safely, but I wasn't terribly motivated.   Unfortunately that thread has lost its photos.

[alhoop]

I'll have another go at disassembling the drive train. Last time I couldn't figure out how to life the motor out safely, but I wasn't terribly motivated.   Unfortunately that thread has lost its photos.

They should be back.
Al