optical switch/sensor

[stingman]

I have a Rowe/AMI R90 juke and all is well except it plays one record beyond the selection; all adjustments have been checked and double checked a dozen times. I need a way to check/test the optical switch onboard and a spare.

I hate to purchase a new optical switch if the problem is elsewhere.

I thought this or a similar problem might exist across all makes of jukes.

Can an optical switch partially fail or since it is solid state, is it either good or bad with no in between?

stingman

[Ron Rich]

Hi Stingman,
Check the rubber "grommets" in the sprag unit--if they are still good, replace the whole plastic sprag gear. Which "mech controller" is installed on that phono--with, or with out, the two adjustment pots ? Which "opto" is installed-- white, or red plug type ? Did you just get this phono, or has it been working well for a long time-- ?? Ron Rich

[stingman]

Thanks Ron,

I have had this juke for about one year; it has always had this issue. The rubber grommets and the sprag wheel have been replaced. The mech computer has the two adjustment pots which I have adjusted properly a dozen times with no joy. Originally the optical switch had the white connector and now has one with the later red connector.
Very frustrating, when I make a choice, it usually plays one record beyond selection but frequently two or three after the desired record and never the correct one. That is why I would like to know if the optical switch could be at fault. The latest red connector optical switch was an EBAY purchase (used) so I still have my doubts. Both switches act the same when interchanged.
I would like to test the optical switches to eliminate them as suspect. I still don't know whether I have a component issue or an adjustment problem.

Stingman

[Ron Rich]

Hi Stingman,
That adjustable model mech control, should have the red plug --however I have seen them operate fine with the white plug too.
Remove the Sprague assembly, check for "burs" or anything that could slow down that operation. I have found "dirt" inside the coil/plunger area, and worst of all, sloppy motor bearings. Has that motor been properly oiled, with 20 wt,. ND oil ? Ron Rich

[stingman]

Hi Ron,

I had the whole mech assembly out last year when I replaced the sprag gear and bushings. I lubed the motor as directed in the manual and cleaned everything. Actually, the whole insides were remarkably clean to start. I didn't check for sloppy motor bearings; how is that done?

Stingman

[Ron Rich]

Hi Stingman,
You remove the assembly, and see if you can move the shaft(s) on the motor "sideways"-- Lack of proper oil will cause the "brass" bearing(s), to become "egg shaped" rather then round. Ron Rich

[Ron Rich]

Stingman,
I just thought of this-- You do have the basket loaded with all records ? Rowe's will not work correctly with uneven baskets ! Ron Rich

[stingman]

Hi Ron,
Yes all records are present.

Stingman

[stingman]

Problem solved!!
I just purchased a used sprag assembly from Ebay. The first thing I did was to put a drop of oil on the motor shaft and by holding the sprag assembly in my hand and with the detent mechanism out of the way,gave the sprag wheel a good spin with my fingers. The wheel spun about one and a half revolutions before coming to a rest. I then took the original sprag assembly from my R90 and did the same thing. The wheel did not even spin a whole revolution and required more force when spun. I put the new (used) assembly in my R90 and after making adjustments, selected a record. Lo and behold, the chosen record was placed on the platter! Next, and for the first time since I acquired this unit over a year ago, I poked in a bunch of random choices and each and every one was correctly selected.
Up to this point, I had swapped in three different optical switches, a new sprag wheel and bushings, a different mech computer, lubed the motors de-oxed all the connectors, checked all voltages and made dozens of adjustments; all with the same result.
So apparently, the problem was the sprag motor having excessive drag even though it appeared to be fully functional. Without having another to compare, I never would have suspected the motor was the guilty party.

Stingman

[Ron Rich]

Hi Stingman,
Yes, In My Humble Opinion, ( and that of a couple of Rowe engineers, and the engineers at the company that made the motors, I spoke with), despite what is written anywhere--ALL, motors NEED, to be oiled ! Glad it's working for you- did you fill the oil wicks, on that new motor's armature (and on the "gripper motor's too !) ?? Ron Rich

[stingman]

Hi Ron,
I put a drop of oil on both ends of the motor shaft. I didn't see any oil wicks.

Stingman

[Ron Rich]

Hi Stingman,
Both of the motors Rowe used have a 'fly clutch" on the armature.
This design allows for an instant stop, upon removal of power, as the whole armature "pops out" of the gear box. MOST of the basket motors I have seen have an oil hole in the round stamping that holds the bearing. I have seen some of them with no oil hole-- but you can ( and IMHO, should) get oil into the oil wick behind that stamping. On the gripper motors, the oil fill hole is in the pot metal casting-- it's a "big" rectangular opening on both top and bottom-BOTH ends- do not over oil it or it WILL get on your records ! Ron Rich

[stingman]

Hi Ron,

I decided to look further into why my original sprag mechanism was acting so sluggish when compared to its replacement.
Originally I thought the motor had excessive drag but upon separating the motor from the gearbox, it is the gearbox that that is more difficult to spin. I took the cover off the gearbox and it was full of very old and very stiff orange grease that was mostly pushed away from making contact with the gears. My plan is to clean out all the old grease and re-lube with fresh. That being said, what type of grease should be used on the gearing and after scooping most of the goop out, what kind of solvent would be best to remove the residual?
I would like to get this sprag assembly operating proper again for backup.

Stingman

[Ron Rich]

Hi Stingman,
Try contacting the motor company- They were still in business several years ago, and they were very nice--Post if you find out -- ! Ron Rich

[stingman]

Did the motor company also make the gearbox too?

Stingman