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Friday, June 16, 2017

Beogram 4002 Type 5513: Service Manual Adjustments

The rebuilt platter motor from Beolover arrived so I will be testing it out soon. In the meantime I have the service manual adjustments mostly complete on this Beogram.

The longest part for me on these turntables is the platter height and leveling adjustments. This Beogram was out of level and the height of the platter to the top of the fixed arm was less than the required 23mm distance.

To make the adjustments the platters are removed and the center, threaded bearing is adjusted up or down as necessary. There is a large nut designated "A" in the service manual. It is loosened in order to move the bearing. There are three other bolts around the bearing that are used to level the platter.

I use a number of measurement tools to check the platter position. Including some small levels. Getting everything right takes me quite a few iterations of small adjustments.

I also check if the fixed arm is level.

When I had the floating chassis removed from the cabinet I like to remove the small set screws for the tangential carriage rails and flip them around so they screw in from the top. I guess they are installed from the bottom to discourage owners from adjusting them. However, when it is necessary to adjust them it is much easier to do when you can just lift off the end of a rail and make an adjustment. Otherwise you have to remove everything from the chassis again.

Normally I use a small, digital scale to check the cartridge tracking weight but due to some untimely dead batteries I reverted to the Beogram's manual check.

That will do for now.  I will recheck it when I get the digital scale powered up again and calibrate the tonearm counter-balance.

To check the travel path of the cartridge on the tonearm I use a string from the platter center to the edge of the cabinet.

I adjusted the tonearm lowering limit where it is just above the first rib. This will prevent accidental damage to the stylus and cantilever if the platter detection ever fails.

Last is the record tracking adjustment. All of the tests so far were made with the platter belt removed so the platter won't turn. On this record tracking test the platter will be manually turned by hand while observing the tangential arm motor turning to keep the tonearm tangent stylus travel path. Any adjustments necessary are performed with an eccentric screw at the base of the tonearm.

The tonearm checks are done. I will revisit the tracking force and calibrate the counter-weight later. This turntable is almost ready to try out with a preamp.

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