RoweAMI MM3 search unit

[stagemanagerjeff]

Hi all,

I have a Rowe AMI MM3, When I Make a selection, the pushbuttons latch in, search unit motor starts, but runs continuously.I have a Service Manual- Parts Catalog.

The service manual states 2 probable causes.

1. Open circuit in selector assembly, wiring from pushbutton switches to search unit printed board segments. - I checked and cleaned all contacts with in wiring harness.

2. Contacts on mechanism control relay R dirty, broken, or out of adjustment.- I can not seem to find mechanism control relay R. I found relays, R1, R2, R5, Sprag relays 1&2, but no R.  I have put external power to each of the relays and they all work.

Now, as the search unit is spinning I can see and hear sprag relay 1 move, and as I time it when it is engaging I can quickly hit it down with my finger,and at that point the search unit stops, buttons unlatch, a record is chosen, played and put back.  record chosen is the correct letter, but the number may be correct, or off by one. I did this for every letter using the test combination stated in Page 4-3, it was always the correct letter.

So, I assume, that it is sprag relay 1 not going all the way down, or fully engaging? Any ideas on a fix or what i am missing?

Thanks

Jeff

Music City USA

[Ron Rich]

Hi Jeff,
Yep-- got a couple of ideas--
1. Either somethin's wrong with your book, as all "relays" are called out as "R", + a number, or you are miss-reading it.
2. One or more of the CONTACT points, on the "R" relay is not conducting current as it should. See our FAQ's on "contacts"--
Ron Rich

[stagemanagerjeff]

Hi Ron,
Thanks. I have the first printing of the MM3 service Manual Nov 1968from Rowe International. I kinda thought just stating "R" meant any of the relays since all the other places mention a number.
I'll check all the contacts, I assume it is not getting enough current and not pulling down as fast or strong enough for the sprag to fall into the notch.
Back at it.....
Jeff

[wdln]

I would also double-check that the letter and number wipers on the search unit are aligned. The book tells how to do that. There's also a procedure for checking the contacts in sprag relay 1 to make sure they're not bent too far apart. If your finger can help it engage far enough to make it stop, maybe they're too far apart. In a nutshell, the book says to position the tooth over a notch and make sure the contacts engage about halfway through the travel into the notch.

Ron... my MM5/6 manual also refers to checking "Mechanism Control Relay R" (with no number) in the troubleshooting section for this problem. In the mech block diagram under Principles of Operation it shows "Mechanism Control Relay R" as the enclosed (non-serviceable) precision multi-conductor relay mounted near the cam switches. If this is bad, there's no re-bending the contacts... you'd have to find a replacement.

[Ron Rich]

Hi Dave,
OK-- I do recall it now-- I have replaced a couple of them with "Ice Cube" relays--same as Rowe did on later model production mechanisms. Ron Rich

[wdln]

One other thing to check, Jeff... I had an issue similar to this on my MM6 where the search unit would spin and spin, but only on selections involving the number 1, and it was inconsistent. I ended up figuring out (using the schematic) which color wire the #1 button went to on the big edge connector on the search unit, and sticking a voltmeter on that lead, grounding the other side of the meter. An analog meter works better for this if you have one... it's easier to see short pulses. Running it and making a selection, I was able to figure out that the #1 button was only making intermittent contact on one of the circuit closures, and if you wiggled it around as the button was bottomed out, the voltage would get sent to the #1 contact on the search board, the search unit would quickly find it and stop, and it would play the right record. I ended up having to pull apart the button assembly and fix some bent contacts on the #1 button.

Since you're (presumably) having this problem with all selections, I think I'd start by verifying that 30VDC is making it down to the search unit on the correct wires for the selection you're making. If it's not, then the search unit isn't at fault. You could have an issue in the buttons, as those are all daisy-chained together. Perhaps voltage is not even making it TO the daisy-chaining on the buttons, or one button early on in the chain is not passing it on to the others.

[stagemanagerjeff]

Thanks for your input, Dave! I will check those ideas out.
I pulled the power supply out today and will take it to work tomorrow to check for all the proper voltages, and I will remove the old 14/3 power cord and replace it with a 12/3. If I am getting correct voltages, I'll trace it down the line.
Jeff

[Ron Rich]

Jeff,
As far as I know, all UL approved jukeboxes, had to have a 6 ft.long, 16/2, or 16/3 ( depending on when made)In power cord. 14, or 12 gauge would be awful thick --?? Warning, In some states, it is illegal to swap a 2 wire cord for a 3 wire cord, or vise versa.
Ron Rich

[stagemanagerjeff]

Thanks Ron,
When I acquired the machine, 20 years ago,the cord was 2' long, and did not have an end on it. I put a new end on and besides placing glass, and cleaning that was all the work I did on it (except for regular maintenance). Now that it has stopped I am getting into it a bit more. The cable has quite a few cracks.
The schematic calls for a 3 wire, no gauge listed, but it was a 14 gauge that was in it, so I replaced it with a 6' 14/3 with a molded edison end. When I get home from work I will double check the specifications.
Jeff

[wdln]

If you want to get fancy (or closer to original), they also usually had a right-angle plug on the end, so the jukebox could be shoved against the wall as close as possible. I don't usually bother with that. However, I have had to replace the end on almost every jukebox I've bought, as the ground pin has usually been unceremoniously removed, probably so it could be plugged into 80-year-old ungrounded knob and tube wiring in some dive bar! As Ron has indicated, the ground is important for safety.