Record Changer Model W750 - Continuous Trip Problem

I am working on a Record Changer Model W750, that I think was built by Collaro. It is a W700/W800 Series unit, that was made in England, and is out of a Magnavox Combination Unit.

Problem with the record Changer is that it continually trips a stack of records. The motor runs and spins the turn-table when turned on. The tone arm goes thru part of its cycle and will lay down on the record. However, before it can start playing the record, the tone arm will pick-up and will start a new cycle again and another record will trip and fall on the turn-table. This entire cycle continues again until all records are ejected off the spindle. However, this even happens without any records on the spindle. The tone arm will just go back and forth and will not play a record. Also, the unit will not automatically shut down with or without out a record on the turn-table.

The turn-table is level, I already checked that, so that is not a problem.

Any suggestions on where to look or what to do to repair this problem ???

Thanks ..... Jim

I'm trying to identify this changer. The number is not familiar. But there are two basic types:

Type 1. There are two rubber drive wheels under the turntable.

Type 2. The turntable has gear teeth on the hub.

These troubles have different causes for the problems you cite.

For type 1:

- The cause is usually that the right-hand drive wheel is mounted too low on its shaft. When the change cycle ends, the wheel is supposed to move away from the motor shaft. But if it contacts the 78 rpm step, it keeps driving. The correct step is the 45 rpm step.

If the change cycle drive wheel was just replaced, this it is. But it does not explain the absence of automatic shutoff. Check for the other causes before adjusting this. (Note: if power is applied to the yellow wire instead of the black, it would explain that)

- I think this is it: If the whole change-cycle assembly is loose on its mounting screws, it can cause the wheel to be too low. There are five mounting screws holding the change unit in place. Three are equally spaced around the spindle above the plinth (under the turntable). The other two are on opposite sides of the tonearm shaft on top of the plinth (visible when changer is being used). The lowering of the change unit also keeps the shutoff tab on the change cycle cam from striking the switch lever to turn off power.

If the arm sets on the rest post after each cycle with no records, this is probably it.

Look for a wire trapped between the change unit frame and the plinth. It kept the screws from fully tightening.

- The same symptoms also occur if the circlip holding the change cycle cam in place came off. On the oldest ones, the circlip is under the turntable, where the change cam stick through a hole in the plinth. On newer ones, the circlip is on the bottom of the change-cycle assembly. Note that, in the first case, you will find the circlip loose under the turntable or on the cam. But in the second case, the circlip could be gone, lost in shipping.

Hardware stores cell circlips. There are several others in the works yolu can use for comparison, but none the correct size.

- Another possibility is that the trip arm is bent, or the trip finger has jumped out of the slot in the trip arm. This is under the change cam. This causes the changer to trip again. It also causes the arm to be blocked on the size scan, causing it to set on the record even with no record on the spindle.

If the arm returns to the middle of the last record repeatedly, this is it.

- Another possibility is that the record pusher activation roller came loose from the change cycle cam and is fouling the trip arm. But, unless you radically readjusted the pusher linkage to the spindle, records would not drop. The cam has to be removed to put this back, and the change unit has to be removed to remove the cam.

For type 2:

- Check first to see if the circlip holding the change-cycle cam on its shaft has come loose. This causes both the repeated cycle problem and the failure to shut off power.

It is the only cause on the new unit if the arm repeatedly returns to the rest post.

- If the arm repeatedly returns to the middle of the last record, check for a damaged trip finger or slide, or a wire trapped in the trip mechanism.

Thank You very much for all the info you sent me. I appreciate the response.

The type of turntable that I have is the TYPE 2 that you spoke about with the gear teeth on the hub. And yes, the arm repeatedly returns to the rest post. I worked on it today ( I am retired) and it appears as though the control for the automatic position is not doing its thing. It doesn't appear as though it is controlling the unit or the change cycle. When you start up the turntable it just automatically goes into an eject mode and continues in this mode indefinitely as long as I keep power on the unit, with or without records. It seems as though it has something to do with the nylon gear that connects the turntable to the large gear that is used to control the tone arm and used to cycle thru the turn-table operations. I just can't figure out yet how this turn-table really works.

Any suggestions on how this turntable operates ??

Regards... Jim Z.

Check to see if the linkage to the automatic control is jammed.

Check to see if the shipping hold-downs are engaged. These are little slides on the edges of the plinth which say LOCK on them. Move them to the position which floats the changer on its springs.

I posted this last week, but it failed somehow.

Glad I found this post. I just purchased a record changer of the same model, and have been having the exact same problem. The arm continuously returns to the rest post. Did you ever fix it? Also, I am not very experienced with turntables, so I'm having trouble figuring out what's what. How do I identify the change cycle cam, and how would I fix the circlip if that's the problem?

Pfau - i'm in your boat. just got a console with an A940 Zenith changer in it, and it is doing the same thing.

The Magnavox unit does this if you forget to unlock the transit locks. It jams the reject link in the reject positon.