Columbia AH brake and speed control alignment issue solved

[jboger]

I write this with the hope that people might find it (1) interesting and (2) useful if they've encountered the same problem with the Columbia AH. This earliest model has a very different motor, speed control, and braking system from later models with plunger-type brake/speed controls. Unlike Victor, it seems Columbia tried to combine the two functions (speed control and braking) into a single function, not separate discrete functions. I have found Columbia's solution not very satisfying, but I believe I have found an easy solution to an alignment problem.

The first photo shows the top plate to the Columbia AH. The second photo concentrates on the speed control screw and the brake lever, so indicated. if these are not properly aligned to either stop the governor from rotating or to adjust its speed, then the turntable will dangerously rotate at high speed. What controls the alignment is a single screw. If this screw is not down tight, the alignment can easily be off because the screw becomes a pivot point. What rotates is a lever underneath.

You can see that someone probably in the long ago had buggered this screw, not by untightening it, but by tightening it, as indicated by the screw slot. I too tried to tighten down on this screw (I use gunsmith screwdrivers for all my machine work) but could not get it tight enough. When I operated either the brake lever or tried to adjust the speed, I would throw the alignment off and the turntable would race out of control. (This is easier to understand if you look underneath.)

After pondering how to solve this problem for a day or two, it struck me to try tightening down on a washer. So the washer you see in the photo is one that I added, not one that came with the machine. I have now run this machine, many. many times and fiddled with the speed control; I thus far have not thrown off the alignment. I believe I have solved the problem in a satisfactory way.

[jboger]

Attached is the underside of the motorboard. You can see various parts labeled. There is the brake lever and the speed adjustment screw. This screw makes contact with the lever that operates the governor. This lever is spring-loaded. When one tighten downs on the screw, it makes contact with the lever and pushes the lever down to slow the governor and consequently the rate at which the turntable spins. Raise the screw, the lever lifts, and the turntable spins faster.

You can see that the width of the lever is about 3/16 inch. If the lever moves just a little bit to the left or right, the speed adjustment screw won't make contact. And because the lever is spring-loaded, it rises to the maximum and the turntable spins wildly. When this system fails, it fails open. It could be designed to fail closed, that is, stop the turntable from spinning. But Columbia did not design its brake/speed control system that way.

Columbia designed a brake and speed control system that both operated on the governor. Victor kept these functions separate: the speed control operates on the governor, and the brake tsops the turntable. I think that's a better system.

Anyway, this is why I tightened a screw down on a washer up above. That washer stops the lever from moving left or right--or at least so far has. We'll see.

John

[phonogfp]

Columbia designed a brake and speed control system that both operated on the governor. Victor kept these functions separate: the speed control operates on the governor, and the brake tsops the turntable. I think that's a better system.

The brake/speed control you show was used only on the earliest AH Graphophones. When the Type 1 motor (with horizontal mainsprings) was discontinued, a new brake/speed adjustment device was introduced, using a plunger to set/release the brake. It was a better design than this early model.

George P.