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Saturday, May 12, 2018

Beogram 4002: From Oil Cleanup to First Operational Test

My restoration plan for this Beogram 4002 project encountered a detour. After restoring the main board I intended to do the reservoir capacitor replacement and the output board. However, the rust and corrosion I found when starting the project got me thinking that I need to address that first. Applying rust neutralizer and painting takes time because you have to let the parts dry between applications.

Here are a couple of pictures of the worst rust spots again.























This Beogram is interesting in that it has some really nasty looking rust damage but the overall condition of the turntable is actually really good.

I decided to apply three coats of the rust neutralizer.























After 24 hours I painted the parts with black, oil based paint.





























Now I can proceed with the normal restoration. Since I had to disassembly the chassis to get to all of the rusty areas I discovered there were a few puddles of oil in the Beogram. People often make the mistake of applying thin oil to the Beogram turntables...and too much of it.




























Thin oil applied to the moving turntable parts end up being slung against other turntable parts. My next step was an oil clean up job.

I had removed the floating chassis to get to the first oil spill.

The tangential arm assembly needs going over anyway so I moved those steps up in my project schedule.

There is a lot of wet oil around the spindle bearing nut. That means thin oil instead of grease was used on the tangential arm drive spindle.























The tangential arm drive spins as it moves the tonearm and you can imagine how that would really throw loose oil like this around.

There was quite a bit of oil on the surface of the floating chassis but I found the most gathering of oil in the tangential drive sensor housing.






















The oil could interfere with the sensor preventing it from working properly.
I cleaned all of this area up and put the tangential drive sensor assembly back together.
























The tangential arm sensor should be in good shape now when I get to the record tracking adjustment procedure.

I moved on to the arm lowering damper. It was in good shape but I cleaned it and applied some light grease to its piston.






















I discovered the tangential drive pulley had small, hairline cracks as most do by now. That makes the pulley deform when the set screw tightens to the spindle shaft. The result is a wobbly running spindle.






















I am still amazed that the transport bushings on this Beogram are still really good. That is a rare sight.
Here is the new pulley. It is one of Nick's aluminum pulleys and it works as great as it looks.
























I also performed and initial tonearm tracking force calibration. It is easy to work on the tonearm assembly when it is removed like this.
























Note that I installed the usual Beolover mod where a small locking nut is added to insure the tonearm counter weight stays where the calibration put it.

That takes care of the initial tangential arm mechanical restoration tasks. Now I can get back to the electrical step of replacing the reservoir capacitor.  Here is the original one as pictured before I started the rust and oil clean up.






















Here is one of my favorite Beolover replacement parts. The 3D printed housing with the new reservoir capacitors.
























Before this nice assembly I use to glue the new reservoir capacitors to the cabinet floor. This is so much nicer and it uses the original Beomaster clamp.

I am getting close to running an operational test on this Beomaster. First I went ahead and changed the capacitor and muting relay on the output board. I still need to add the grounding switch but I will come back to that.

Here is the before picture of the output board.





















...and here is the after.































Now for some reassembly. I have to re-install the rust repaired chassis components so the floating chassis can be put back. I also have to re-install the DC platter motor that Beolover restored for me.

Here are some pictures of various components as they are fitted back into the Beogram chassis.




















































































Whew. It is looking like a Beogram again. I should be able to install the sub-platter, belt and top platter then give this Beogram a test run.












































I love it when things work the first time.

Even though this Beogram thinks it is ready I don't trust it enough to try a record yet. I will run through the service manual checks first to make sure it is ready to play a record.


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