Adjustment #5: Carriage Assembly (w/video)

Carriage Assembly Adjustments

A few Posts back I mentioned that, as a kid, the jukebox we had "ate" records, and I distinctly recall records scraping along the sides of the Record Keepers as they were going into, and out of, the Record Magazine. I'm almost certain that this adjustment, had it been performed properly, would have saved most, if not all, of the 45's I had as a child.

According to the IOM, the Carriage Assembly has three functions:

1. Search for a Selector Lever in the "Play" position, and upon finding one, stop the rotation of the Record Magazine motor,
2. Align (or "index") the Gripper Arm to the proper record,
3. Return the Selector Lever (see item #1) back to the normal position.

There are two rows of Selector Levers located around the circumference of the Selector Unit, the levers in the front row correspond to odd numbered selections, and the levers in the rear row correspond to even numbered selections. Regardless of row, a lever in the innermost position is considered to be "Off", while a lever in the outer position is considered to be in the "Play" position, as seen here:

On the bottom of Carriage Assembly are two spring-loaded contacts- one for the odd (front) levers, and one for the even (rear) levers (circled in yellow):

As the Carriage rotates over the Selector Unit, it will immediately stop the Magazine Motor when a contact finds a Selector lever in the Play position by short-circuiting the Magazine Motor armature (the Selector Lever in "Play" electrically "grounds" the motor). In the IOM this is referred to as "Indexing the Gripper Arm".

Also note in the picture above that these contacts are mounted in separate "blocks" that can be moved left to right independently. I will refer to these blocks as the "front/odd block" and the "rear/even block" in a minute.

On top of the Carriage are 4 screws that hold these blocks in place- the two towards the front (yellow) are for adjusting the odd selections, and the two at the rear (red) are for adjusting the even selections.

Also, there are allen head bolts located on each side of the Carriage (no picture, see video) for making minute L-R adjustments.

The adjustment procedure is a little tedious, and one must be finicky when performing it, otherwise damage could occur to the records. Be thorough and take your time here.

The procedure:

* If the Carriage Assembly has been replaced, rebuilt, cleaned, or in any other unknown condition, the "rough" location (L-R) will have to ascertained. Doing so requires removing all of the records, powering-up the unit, and making various selections, both odd and even numbered. The idea is to adjust the 10-32 bolts on either side of the Carriage so that the Gripper Arm is located roughly on the centerline of the record slot in the Magazine when in the rest/home position. You don't have to be exact here, just try get a good "average".

* Once this is set-up, leave the bolts alone! You won't be touching them again. 

* After this is accomplished, the Odd selections (only) need to be adjusted. First step is to install some old records, and then select record #1. Note the Magazine rotates in a CW direction when making odd selections (this matters when making the adjustments, and under normal Play conditions the records will Play from #49 down to #1). When the Gripper Arm begins to remove the record form the magazine (maybe about half-way out), shut the unit Off at the Service Switch and note the location of the record with respect to each side of the Keeper on the Magazine. Take notes ("tight LH side", etc), and then repeat this process for the #49 record, as well as one of the middle selections (23, 25, etc). The results should be somewhat consistent.

Here's what I was able accomplish with Record #1 (performing "odd" adjustments):

Note how the gaps on both sides are almost identical.

Depending on where the record is at (too far left or too far right) will determine which way to move the Carriage Assembly, as you are either picking up the record "too soon" in the Magazine rotation, or "too late". See below.

If the alignment is off (the record is not centered in the Keeper), you can correct for this by loosening the two front screws on top of the Carriage (yellow, above), and moving the "front/odd block" either left or right accordingly, as per my notes below. Note that the allen head bolt is to be used for this adjustment, and my advice would be to make small, incremental changes (one-half turn on the allen head bolt) AT MOST before re-checking!

Once the adjustment is set-up for the odd numbered selections, DON'T TOUCH THEM AGAIN!

* The procedure for the even numbered selections is the same, only now the Magazine will rotating in a CCW direction (under normal Play conditions the records will Play from #2 up to #50) , and you will be working with the two rear screws (red, above) on top of the Carriage assembly. Start with record #2, take notes, go to record 48 or 50, take notes, go to record 24 and take notes (etc.) Again, make small changes, be patient, and go slow.

At the end of the video I promised I would post the following information to help clarify this procedure. If you watch the video, here's the info I promised:

Odd Selections:
  - Front set of Selection Levers
  - Carousel rotates CW, from #49 down to #1

Record tight to the left side of Magazine opening:
- Carriage picking-up contact "too late"
- Adjust carriage to the right

Record tight to the right side of the Magazine opening:
- Carriage picking-up contact "too soon"
- Adjust carriage to the left


Even Selections:
- Rear set of Selection Levers
- Carousel rotates CCW, from #2 up to #50

Record tight to the left side of Magazine opening:
- Carriage picking-up contact "too soon"
- Adjust carriage to the right

Record tight to the right side of the Magazine opening:
- Carriage picking-up contact "too late"
- Adjust carriage to the left

After everything above has been accomplished, Best Practices would dictate that all Selections are checked (odd selections and then even selections), and VERY SMALL changes made to the Carriage so that a "best fit" is achieved for all records.

Be patient. Do this "right", not "right now"!


Link to video: https://youtu.be/QmWMJI2Lm8I