Auto reset question, Wurlitzer 2700.

Greetings, I am new to PhonoLand and I have a technical question regarding my ’63 Wurlitzer 2700 series. I have read the thread regarding the testing of switches and it left me with more questions than I previously had. My automatic reset switch tests good, I have continuity when closed and none when open, but the behavior is erratic. The adjustment is correct but when the switch is in place an album will change for no reason after working properly for a short time. The input of the switch has 24vac but when the switch is made the voltage disappears and no leg shows voltage. Is this switch in control of a relay that might be causing this behavior due to it warming up? I would like to eventually find a wiring diagram or service manual but I came across this forum first and thought I’d throw it in the ring.

Thank you, Chris.

This is a new one for me. What is the "auto reset switch"?

Rob-NYC

I may be using the wrong term for the switch, when an album is finished playing and the arm reaches it’s lowest point, this switch is made and prompts the next selection or ends the play function. Basically the same action that is accomplished by pressing the skip button on the rear of the machine.

Edit - A service manual is on order.

Ok, you are talking about the "trip switch". Inside the upper mech behind the tonearm pivot is a switch actuated by a tailpiece from the tonearm assembly:
http://s1192.photobucket.com/user/Rob-N ... ort=2&o=70

Shown is the older style switch. If this switch is failing, sometimes people will try to get it to work more 'reliably" by adjusting the trip positioner screw at the bottom left in the shot.
Set machine to play a record and turn power off. Connect some sort of continuity meter and move the arm through it's arc to trip off. It should trip at the same place each time.

Another often overlooked area that can cause this are the two over-center switches at the rear under the deck of the machine. If one of these is misadjusted (don't recall which) the machine can stop with the switch's actuator too far up on the cam lobe and the switch can spontaneously pop to the opposite mode which will start the change function.
With mech in play mode and power-on, lightly tap at the switches and see if they snap over. The action here is very positive and not at all sensitive. Again, if the switch contact points are pitted and erratic, someone may have tried to fix it be 'adjusting" the screws which flip the switch paddles. BTW: Make sure the spring is present in both switches.

This sort of problem is caused by someone tinkering and pretty much a matter of observation and common sense.

Rob

Thanks for the reply Rob. As I said above, the mechanical adjustment is correct and the switch tests fine. This is a problem that seems to happen after an hour or so of listening which is why I suspect the device the switch controls when tripped.

This still looks more mechanical than electrical. There isn't much of an electronic natire in the junction box that controls the mech. There are two non-polarized capacitors that provide phasing for the two AC motors; search and changer. The large (black?) one is for the changer. these and the other small caps should be changed for reliable operation, but I don't think they'll fix this problem
Given that this occurs after the machine has warmed-up I suspect that the mech is coasting to a point where one of the switches just barely falls off the cam lobe and thus the motor starts.
Another area is the motor itself. After a period of use check the knurled screw on the bottom of the rotor shaft on the mech motor. I can't recall if there is any form of dynamic breaking or just friction. See if the manual covers this.

Rob

That really helps Rob, thanks once again. I've ordered a new switch and I now agree that it is more than likely the culprit. I am really out of my element here and I appreciate your help. I will report my progress once I get the switch.

Where were you able to find THAT switch ?
Ron Rich

I just had to cross reference the original part number through Hubbell to get a current one (a benefit of working for UL) but they are readily available, I got mine through Digi-key for $18.