Phonoland

Rowe Model JAN 200 Diplomat (1965) skips past selection.




I have owned this wonderful Rowe Jukebox for 20 years and have always been able to keep it running with a little effort but this current problem has been difficult. The changer is the original Model 1100.

The unit started skipping past the wanted selection and playing the next record on occasion. Slowly, it has come to be 100% of the time. I can see what is happening. The Selector Mechanism works perfectly striking the correct pin and the search arm detects that pin correctly.

The Magazine Detent Coil drops out when the search arm detects the pin and applies the lock to the record magazine. Immediately, the Magazine Detent Coil activates a second time just long enough for the detent to unlock and magazine skip to the next record. The magazine then locks at the next position and the unit plays the unwanted record correctly. The Annunicator also follows and displays the position of the record being played.

Something is causing the Detent Coil to react properly but then receive a second unwanted pulse and the total mechanism skip to the next record. As a result, the arm on the pin wheel assembly stops on the correct pin but then climbs up the pin because of the extra pulse and turn of the magazine. It does not jump over the pin.

The motion does not have this second unwanted pulse when it stops after the last record and it also operates correctly when stopped with the manual Mechanism Service Switch.

My service manual says that this may be due to a defective C2 cam switch and that the switch should be replaced. It is not obvious to me that C2 is causing this problem.

My questions are as follows:

1. Is the C2 switch the most likely problem?
2. Where in the USA can I purchase a C2 switch?
3. Can I remove the outside switch plate with Cam switches C1, C4, C6 and C7 to get to C2 on the inside plate without having to adjust all these switches upon reinstall? Any hints?
4. Is there something else that could be causing my problem?


Thank You,

Donald Rodeman
Kokomo, Indiana USA

Hello Donald,

Yes the problem could be CS2 but it could be also the detent switch or the Mechanism Control Relay.
My advice is to change the relay first to see if this is the issue folowed by adjusting the detent switch as per the manual and if none of the above works then change CS2.

Regards
Alan Hood
ami-man
UK

Thank you, Alan.

I see how to adjust the Detent switch and I can also inspect Mechanism Control Relay but I do not have a spare to try a replacement. If you know of a source in the US, please let me now.

Donald

Hi Donald,

The relay should be the same as the one on the Search Unit, also on some of the later amps it was the same used as the mute relay, it should be available from a number of outlets in the USA.

Regards
Alan
Alan Hood
ami-man

Donald,
That is what is called an "ice cube" relay--I do not recall if it has an AC or DC coil--DC I think, but it should be marked on it's cover, and be available at any good electronics store--or for a temp. check/fix--carefully pry off the cover, remove the "swing" blade set and clean the contacts-- depending on how well you do this, it should operate for awhile. Ron Rich

Hi Donald,

Ron is correct the relay is 24 volt DC. I have known situations where this relay has burnt off the insulation on the some of the links of the swing blades thus shorting out the relay.
So when you take it apart for cleaning check it out, I use paper pulled through the contacts to clean them but also using those fibreglass pencils.

Regards
Alan

Alan Hood
ami-man

I removed the Mechanism Control Relay (R) and gave it an inspection. It is not an enclosed relay so I did not have to open a cover. It is labeled Potter Brumfield KR-3140-2. I cleaned all the contacts using the typing paper technique and removed a normal amount of black stuff. I reinstalled but the record selection skip to the next position problem remained unchanged.

I looked at the Magazine Detent Switch and the Stopping Switch and the adjustments required. Both have a friction nut surrounding the allen wrench opening. I wondered if that friction nut must be loosened before the allen wrench adjustment can be made. It seemed very tight and the action seemed correct without actually making the adjustment.

I also looked at the action of the Magazine Detent coil and can see that when the Stopping Switch activates the Mechanism Control Relay telling the Magazine Detent Coil to drop out and lock the Magazine there is a second pulse on the coil that unlocks the detent again and allows the Magazine Motor to move on for one more position before dropping out the second time.

Donald Rodeman
Kokomo, Indiana USA

Donald,
I do not have a schemo or remember--but, a WAG is, that is a ("drop-out") time delay circuit for the relay coil. If so, the RC circuit may be failing ?
Also, did you examine the contact points for "burns"/"pits" ? Ron Rich

Ron,

The Mechanical Control Relay contacts seemed smooth when I cleaned them. I did not take them apart to inspect.

Also, I don't see any RC time constant for either the Mechanical Control Relay or the Magazine Detent Coil that drops out when the stop switch is activated.



Donald

Check the stop switch adjustments.

John,

Ref: Adjusting the stopping switch.

I know how to rotate the Magazine and lock it at U-0 top center.

I know how to manually set pin B-1.

I know how to set the switch pawl on pin B-1.

I am not sure how to turn the allen wrench. Do I need to loosen the friction nut first? Do I need to loosen the head of the screw first? Both the friction nut and the allen screw are very tight and I am concerned about doing damage while trying to follow the procedure. They both don't want to turn.

In general the stopping switch seems to be doing its job but I guess it could be actuating late and missing the first and correct stop and then slipping over to the next stop causing the selection of the incorrect record. Everything happens so fast that it is hard to see exactly what is happening. I know that the stop pawl rides up on the pin after it first hits the stop pawl but I have been thinking that is because of motor run on and the second pulse to the Magazine Detent Coil.

Donald

Donald,
What you have just written brings on another guess--
Is the motor "over running" ? If so, and it's the type with a "fly out clutch" it may be having that problem due to lack of, or improper oil.
Motors of the above type require oil, as the clutch MUST dis-engage at the instant power is removed.
Easy check is to put a drop or two. of SAE 20 wt. motor oil, on the armature shaft, as close to the bearings as possible, and see if that improves the situation.
If so, there is most likely an oil wick on each end of that shaft that needs to be soaked. Ron Rich

Ron,

I have noticed that this extra record magazine motion does not occur after the last record is played and the magazine turns, stops and parks normally.

I also know that the magazine stops normally when the service switch is released.

It does have that extra jump where the detent is immediately released after the stop switch is met and then the magazine turns one more notch before the detent again stops it and plays the incorrect record successfully. This started to happen occasionally but is now 100% of the time in the normal play mode.

So there is something different between the three modes.

I could email you a schematic but it is too large to post.

Donald

Hello Donald,

I have had a look at the Diplomat manual the Magazine motor switching circuit is completed by the switching of the magazine dedent switch and the closed contacts on cam switch 3.
The magazine detent coil is controlled by a normally closed switch (7, 10) on the mechanism control relay the detent switch and C3 also through a 33 ohm resister and C7.
Check out SM-204 in the manual.

Regards
Alan

Alan Hood
ami-man

I made some progress today working on the Rowe Diplomat skipped record problem. I put an oscilloscope across the Magazine Detent Coil and found that immediately after the coil drops out at the stop it is reenergized again by a 100 millisecond pulse which releases the detent and allows the Magazine Motor to turn to the next record. I moved the scope to the Magazine Motor and again saw the voltage come back on for 100 milliseconds before shutting down completely. That says the pulse is coming through the Magazine Detent Switch.

Moving on one step, I confirmed the pulse at the Mechanism Control Relay coil also.

That is where I had to stop for the day. From the Mechanism Control Relay, the source voltage goes thru the C2 Cam Switch, the Stopping Switch fingers, the Stopping Switch and to the +30 volts DC supply.

It is not easy to find nodes to check these additional locations and I still don’t know what is causing the pulse.

Right now I am discounting the SS fingers since this always happens at the stop pin in the full 360 degrees and does not sound like one spot on the fingers. I don’t believe the C2 Cam Switch is programmed to open at this point in time. That leaves the Stopping Switch and the power supply.

If it is the Stopping Switch, I would like some advice on how to turn the allen wrench as it is very tight and I don’t want to strip it. Do I need to loosen the friction nut first or put a drop of oil on the adjustment threads to free them up?

Thanks

Donald