Rock-Ola 1485

viewtopic.php?f=3&t=6750&p=35641#p35641
I posted to the above link in error; sorry about that.

Hello...I am new to the forum and am experiencing a similar problem with my project Tempo II 1485, the 200 play version of the the 1478.
Let me start out by saying I bought this thing years ago and it's been in dry storage for the last 20. Now that I have retired I can tackle some of my lingering projects. I was totally surprised to see this thing power up and actually produce some sound after sitting so long. I did a visual on electrolytics and transformers for oil or fluid leaks and then ran a power supply check and a filament check on all the vacuum tubes. I manually cycled the grabber and drum motors and decided it was safe enough to spin up the ferris wheel. But before I did that I burnished and cleaned every open relay or contactor I could find. The scan control panel works ( except the scan solenoid does not engage) and I can manually select pins and observe the grabber is right on the mark for handling the vinyl....I cannot make a selection from the switches. In this thread I saw reference to the pulse from the accumulator that controls the reset coil. I believe I have the same problem; I haven't located a dual electrolytic capacitor. It is a Sprague 14416; 300mfd and 150 mfd @350 WVDC. Can someone steer me to a suitable sub or a source. I know it is obsolete so what substitutions are permitted here. I can bridge a second capacitor across the suspect 300mfd but not sure of value required to give the proper time constant for driving the solenoid.

In the meantime I am prepping to clean the carriage assembly and the selector assembly...... with the least impact on present alignments and adjustments. Any advice here will be greatly appreciated. I could use a schematic of the power control chassis too....it is not included in my instruction manual. Today I manually set 5 random pairs of odd and even pens and manually pulled the scan solenoid; the machine played all selections and shutdown normally. During this free play exercise I was able to quiet down some nasty vacuum tube noise due to dirty pins in the tube sockets; and I got rid of intermittent noise in a dirty switch contact in the bass and treble adjusts....the amp is doing a great job at a reduced listening level. These old Jensen's have held up remarkably well....I was sure I would have to replace them but now I want to concentrate on getting the scan solenoid, and the reset coil working. I'm hoping the select and arrow buttons are not working because of the accumulator capacitor.


As an aside...years ago my dad passed and left me a favorite carbine, a 30 cal M1 built by Rock-Ola. 1st block, Serial number, 1,662,520 - 1,762,519| November, 1942 - November, 1943. I did not know that about David Rokola -Approximately 228,500 total Carbines were made by Rock-Ola: About 3.7% of M1 Carbines made. Me and My Rock-Olas......let's make some noise.

Thanks for a great site and thanks for the wealth of knowledge.

Ed

Hi Ed,
Replacement for the dual cap is two "regular" caps--I believe voltage is shown on the dual can?--don't recall it being very high ? Ron Rich

...About the pulse forming cap. You're right on the mark, it is 35 working volts instead of 350 and I tested with a bridged cap and a discharge resistor. IT turned out the capacitor was not bad, there was resistance in the coil circuit which weakened the RC duty cycle. An interesting note;
At the octal connector for the scan solenoid I decided to reseat the plug. While doing this I noticed a leaf spring a couple of inches long; maybe 3/8 inch wide with extra sharp points on each corner. It looked like it was supposed to be wedged between the main chassis and the scan control module....maybe to insure a good ground or for hum reduction. Anyway I flexed the spring to make sure it was a good connection and reseated the connector...the scan coil circuit started working with the original pulse forming capacitor. I am running this thing in short selection and play cycles until I am comfortable with the mechanics; amp disabled for reduced load and heat. A new problem has surfaced. After a few cycles of select, scan, play, select, scan, play, and return to parade rest something loses connection in the select function. The scan relay doesn't energize, the selection coils don't get pulsed, and nothing happens. The arrow switches, and the selection buttons cease to function. I have never seen a "select" light on; maybe a bad bulb. But if I move through the arrow selects and slowly move through the select buttons....when I get to 18 the scan solenoid energizes, and a successful select, scan, play will complete. This has happened a couple of times and now I need a schematic...I have the parts and instruction manuals for operations and representative block diagrams. I am staging for making selection switch continuity checks; as soon as I can acquire a point to point schematic.

One other thing.....I am concerned about the TTM running too hot to touch; I noticed that when I rewired the phono arm and replaced grommets......it has plenty of oil and both platter and motor spin freely by hand. I don't recall ever seeing a phonograph motor run this hot!

Ed,
Think you are on the right track with the selection failures--open/poor ground, and an open in the series on the keyboard--
TT motor ? well, I never have checked on this ? I know Seeburg motors run 60 C above ambient temp., ( hot enough to burn human skin !!), but they do "everything" with one motor-- Ron Rich

Ron
I know the TTM is a synchronous motor; I will check for low input voltage.
About the switches (arrow and select)....I notice the arrow switches have a "latching" feel but the instruction block diagram says "release mechanism only HAS NO CONTACTS" which means I must have missed something in the sequence of selection. Dumb question: What do they release? Each other?

Also please comment on the selection buttons. Are these momentary ONLY (no latch on or latch off)? All four banks of switches are slaved with a common link from a single button. I think that may have been to deter an operator from trying to press two buttons at once. If this is the case, switches cannot lose pass through connectivity during the release cycle or the next selection might not get picked up. I think I have to remove the whole (front panel) assembly and do a visual and clean and continuity test.....if I can figure how to get this thing out!

Hi Ed,
Sorry, I don't re-call one RockOla model from the next. I THINK the drum buttons latch one down at a time, only ?
As for the schematics--IF, you purchased a "package" from one of the suppliers listed above, SCREAM at "him" for not including the schematics. If you purchased elsewhere (like on line)--well, --- Ron Rich

I have been wondering about that for some time now; the drum switches latching instead of being momentary. Guess it's time to poll the forum members for some one who owns one...thanks

Ron
Just an update for continuity on my progress. I removed the selector switch panel. On the bench I could tell the slide switches were not fully sliding for full contact across the group of 4 clusters. There was no mechanical latch, just a forty switch matrix with hundreds of places to lose a connection. It cleaned up real nice with contact cleaner. I re installed it and using a small pry bar was able to remove every bit of slack between the select switch buttons and the switch actuators. All the switches stand up flat and straight, and the sliders engage as designed.....You never see this in the manual!... After reassembly I select/play cycled a few times and picked up a new problem. An intermittent loss of power to the turn table motor and a faint chattering sound was coming from the scan switch panel. I removed the panel and cleaned and burnished and tightened grounds; It looks like that problem has cleared. And especially thanks for the posts on where to get pieces parts and docs; and how not to grind relay points of closure!.....good stuff to know.
Ed

Hi Ed,
Glad it's working--
Ron Rich