Beogram 4004 Type 5526 - California Project - Completed, Tested and Ready to Ship

This post continues from the last post where the initial power on and start play operations were tested on this Beogram 4004.

Even though most of the functions I tried appeared to work I still needed to finalize moving the new trimmer for the platter sensor circuit to its final position.

Here is the DC voltage check of that platter sensor circuit as measured at the collector of 1TR3.
The new trimmer is adjusted to get 4 VDC at the collector with no platter in place.

That was easy to dial in but when I examined the platter sensor signal with an oscilloscope I could see quite a bit of noise on the signal.  The signal was the expected shape but the noise wasn't expected.

I checked the 21 VDC rail voltage for the circuit and could see noise there as well.

The voltage was good but the noise wasn't.

To remove the unwanted noise on the 21 VDC rail voltage I changed the filtering capacitor I had added to a 10uF value, then remeasured the rail voltage and platter sensor signal.

Much better now.

Even though the sensor circuit appeared to be working correctly, I have seen where noise like I was getting cause strange things with the Beogram control circuit.  

I installed the new Beogram platter speed indicator lamps next.
These are the Beolover LED replacement lamps from the DKaudiolover.com store.

Here are photos of the cleaning and Deoxit treated Beogram control panel contacts.
This Beogram 4004 will be getting the Beolover Remote Commander installed but I want to make sure the manual control button operation is perfect.

This picture shows a couple of contacts cleaned and treated on the left while the other contacts have yet to be cleaned.

...and this picture shows the full set cleaned and treated.

I used the Beolover RPM measurement tool to calibrate the 33.33 and 45 RPM platter speeds of the Beogram 4004.  This Beogram 4004 has a Beolover restored DC platter motor so it must be calibrated to the correct speeds.

Next is the installation of the Beolover Remote Commander (one of my favorite additions to any Beogram 4002 and 4004 turntable).

The installation of the Remote Commander to a Beogram 4004 is slightly different from a Beogram 4002 as the Beogram 4004 has a basic, no-frills remote control circuit that must be tied in to.

A drawback of the built in Beogram 4004 remote control circuit is that it is only functional when the Beogram 4004 is paired with a Beomaster 2400 receiver.  And...the remote control of the Beogram is just play, pause and stop.  The Remote Commander provides all of the Beogram 4004 control panel functions.

Now the Beogram 4004 is ready to be reassembled and some records played on it.

The final step of this restoration project was to replace the original dust cover with a brand new one from DKSoundParts along with a new aluminum trim piece.

The first step is to center the new trim piece and mount the trim onto the top portion of the new dust cover.  The two ends that bend down over the left and right sides are left straight at this point so the dust cover can be mounted onto the metal hinge assembly.

Here is one side of the metal hinge assembly and dust cover attachment screws.

After the dust cover is attached to the metal hinge assembly, the left and right sides of the new aluminum trim can be bent into place.

Note:  This attachment of the trim can be a little tricky. I found that I had to clamp the top and sides in place to make sure the double-sided tape bonded the trim securely (without pulling away).

The new dust cover assembly is now ready for installation on the Beogram 4004 frame.

There are two of these spring loaded mounting clamps that screw down on the dust cover assembly.

I am leaving the protective plastic wrap on the dust cover and Remote Commander remote so the owner of this Beogram can be the first to open them up.

I will listen to a few more records on this Beogram before shipping it back to its owner.

After that, I have another Beogram 4004 to begin restoration on.

Beogram 4000: Installing a New Carriage Motor and a New Hood

Yesterday, I finally received the first batch of my new custom manufactured Beolover Carriage Motors for Beogram 4000, 4002, and 4004. They are a direct drop-in replacement for the original motors, which also suffer from dry oilite bearings, similar to the DC platter motors of the later Beogram 4002 and 4004.

Unfortunately, these motors cannot be opened up very easily for oil infusion of the bearings and therefore I had a suitable replacement motor designed. Since they use modern coreless technology they draw less current than the original motors at the same mechanical performance. This is great news for the often failing power transistors in the H-bridge of the carriage drive. They also vibrate less. Read about the motors here, where I describe my tests of these motors in comparison with an original motor.

This was good news for the Beogram 4000 from Australia that I recently restored. My customer had opted for upgrading his carriage motor and so this project was on hold until I would receive the motors. This shows the original motor still installed:

I extracted the motor:

This shows the upper half of the housing removed and the new motor for comparison:

The new motor is slightly shorter and so the leads can conveniently be fed through the bottom cutout of the housing:

This shows the new Beolover motor installed:

I positioned the motor inside the housing making sure the carriage belt sat straight between the two pulleys. This is easily done since the motor is held in place by two vibration insulating EPDM rubber rings, i.e. the motor can be laterally shifted within the housing if necessary to achieve perfect fit.

This Beogram also still needed a new hood installed. This shows the new hood from the dksoundparts store in Denmark together with a reproduction aluminum trim:

I used the my alignment aids to center the strip

and marked the position with a pencil:

After installing the re-painted hood hinge and glueing in the aluminum trim I installed the hood on the Beogram:

Beolovely! I will play this deck a bit more, and then it will be time to send it back to Australia!

 

Beogram 8002 From North Texas: Reassembled and Ready for Testing

After a short break from the workbench I am ready to wrap up this Beogram 8002 project.
I left off with all of the Beogram 8002 functions tested out successfully.
In this post I will re-install the Beogram floating chassis back into the cabinet and reattach the dustcover and metal lid.

First however, I need to remove the test leads I installed for the oscilloscope measurements and I need to close the microcomputer metal box.

The lid for the microcomputer shield box contains a heatsink bar that requires some fresh thermal grease before closing it back up.

The two board assemblies are then re-installed back into the Beogram cabinet. The repaired post for mounting the board comes into play here.

Next is the power supply transformer box. It slides into place from the top and the connector mates with PCB 1.

The Beogram cabinet can now be closed from its service position and the floating chassis suspended from its three hangers.

So far so good.  

Now is a good time to recheck the Beogram 8002 operation. It is easy to open the Beogram back up for any fix if needed at this point.

I get the Standby light when the Beogram 8002 is plugged in.

Pressing Play results in the Beogram scanning the platter for a record. It correctly changes the platter speed from 33.33 to 45.00 RPM when it reaches the 17 centimeter point.

That demonstrates to me that everything internally is still good.

Now I can move forward with the install of the dust cover and metal lid.

For that I inspect that back of the Beogram 8002 cabinet.
This photo shows the damped hinge mount for the metal lid.

This photo shows the right end of the cabinet back...where the phono cable connection is.

This is the time to inspect and check the mounting of the dust cover spring mechanism (that holds it up and controls its slow lowering operation).

I test fit the dust cover spring mechanism while it is easy to get to everything for adjustment.

The fit was perfect so I was able to continue on and mount the dust cover assembly.

I adjusted the tension on the leaf spring for the dust cover assembly so it would hold position when the dust cover was partially closed (or open).

Here is the dust cover closed.

I believe this Beogram is ready for some test play of record albums.

While I am doing that I will fashion some bumper pads for the metal lid and the front part of the dust cover as the original bumpers are long deteriorated.

Next time I should have the bumper pads installed and will be listening to records on this Beogram.