Beogram 4002 Type 5513: Results of Platter Motor Test 2 - Beolover Rebuilt Motor

As were the results of other Beolover rebuilt DC Beogram platter motors, I expected much more consistent speed readings from this second twenty-four hour speed test. That is the case here but it is impressive to actually run and record the test results myself.

To restate this second motor test - I took a Beogram 4004 platter motor that Beolover already re-infused the bearings with oil. That motor is now in this Beogram 4002 and I recorded the platter speed for twenty-four hours with the Beolover RPM Measurment Tool. This Beogram hasn't had any of its electronics restored yet so they are still as I received them and as far as I can tell still operating with the original 1976 parts (perhaps 1975 as that is the date marked on the motor).

Here are the test results:

Quite an impressive improvement and it leaves no doubt in my mind the importance of this restoration service on Beogram 4002/4004 DC motors that are over forty years old now.

That is very consistent speed for twenty-four hours straight and all with an analog control system.

The next steps in this project are to send the 1975 DC motor to Beolover for that part of the restoration and I will continue on with the electronic restorations. I will work on the main circuit board next then run another motor test to check the speed stability again. That test isn't really necessary but I am curious to record the improvement provided by each step.

Beogram 4002 Type 5513: Results of Initial Platter Motor Test

After a little over twenty-four hours running I stopped the Beogram and loaded the measurement logging data into my analysis software. The previous post yesterday showed that the Beolover RPM Measurment Tool logs a timestamp HH:MM:SS and an RPM measurement every ten seconds. Plotting this on a graph of RPM by time gives the following result.

The top level speed for the selected 33 1/3 RPM turntable speed stayed pretty level but you can see quite a few dropouts down to a lowest speed value of 30.324 (at the three and a half hour mark).
Note that this result is consistent with measurements that Beolover typically gets on his initial testing for one of these motors.

Like Beolover's other Beogram DC motor tests, it will be interesting to see the result of this Beogram with a DC platter motor whose bearings have recently been re-impregnated with oil. I would also like to do that before doing any other restoration work on this Beogram so I can see the incremental effect each restoration task has on the motor stability.

Luckily I happen to have a spare Beogram 4002 motor that Beolover treated the bearings on already. So I'll install that motor in the Beogram and run the speed test again.

Beocord 9000: Identifying Repairs

The disassembly of the tape transport allows me to get to various nooks and crannies for cleaning and locate hard to see places that need repair. This makes sense from a restoration stand point but you pretty much have to disassembly a majority of the transport anyway to replace the rubber wheels.

NOTE: Don't disturb the part of the transport where the tape heads are mounted. Chances are they are still in alignment or, at least very close. There is no need to remove them at this point unless you know they are defective.

Here is a picture that identifies the four rubber wheels that will need to be replaced.

The replacement wheels and the rubber belts I will use are parts I get from Martin Olsen. He has done the research to make sure these replacement parts are accurate reproductions for the Beocord 9000.
Here are the replacement parts for the belts and wheels.

This picture shows the tape heads and the pinch roller (or thrust roller). The picture also shows what type of dust and dirt builds up inside these machines.

One of the rubber wheels to be replaced is part of the Beocord clutch assembly. Every clutch assembly from a Beocord 8000 to 9000 deck I have seen has cracks in the plastic where the pulley shaft mounts (via small brass inserts in the plastic).

I went ahead and disassembled the clutch assembly to apply the fix for the cracked plastic. I cut sections from a brass tube and epoxy into place so the brass sleeves prevent any more damage. The tubing I used is 8.73mm (11/32 inch) x 0.355mm (0.014 inch). I got mine at a hobby store that specializes in parts for remote control airplanes and cars. I used a Dremel tool to cut sections off then file off any burrs. When mounting the brass sleeves I remove the brass mounts the clutch shaft fits in to.

The final repair to identify is the repair of the tape head transport leaf springs. I already know there is one broken spring mount. I need to also check for any other places there are cracked or loose plastic pieces. I found these bad spots by the gears that dampen the cassette holder open/close function.

I will repair those spots with some epoxy when I fix the leaf spring mount here.

I wanted to get the epoxy step done and cured so I could continue with the tape transport. I actually did the cleaning and epoxy step last night so I could continue working today. This picture shows the re-installing of the leaf springs that hold down the tape head transport. Some new TriFlow Red Grease, the 2.5mm ball-bearings and the springs are complete. Next it is on to installing the new wheels and lubricating the moving parts. That should mean the tape transport will be ready to reassemble and test.