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Beolover SyncDrive: DC Platter Motor Replacement for Beogram 4002 and 4004 (Type 551x and 552x)

Late Beogram 4002 and the 4004 (Types 551x and 552x), which have DC platter motors instead of the earlier synchronous AC motors usually suff...

Tuesday, March 29, 2022

Beomaster 4400 Type 2419: Reassembly of the front panel switches

The front panel switches are finally reassembled into the switch rack of this Beomaster 4400.
The switch contacts are clean and coated with Deoxit D100L contact conditioner. 

Reassembly of all the small contacts isn't too difficult but does require patience and tweezers.
You need to take care (and precautions) to keep the small contacts from jumping off the work table and into oblivion.  I made it through the reassembly without losing any.

I started with the far left switch, Speaker 1 Switch.  It only has two sets of the small spring contacts.

Once the fixed contacts are installed there are four metal tabs that must be carefully bent to secure the contact board to the switch actuator (white plastic part).

As I will show later, this early serial number Beomaster 4400 switch assembly is much easier to work with regarding the metal tabs.

Continuing on I inserted all of the spring contacts into the proper slots.
This photo shows my technique of using some good tweezers to angle in the spring contact pairs.

Here are all of the switch contacts in their proper slots prior to installing the top, fixed contact pieces.
Note that some switches have two sets of spring contacts, some have three sets and three switches have four sets of spring contacts.

I have labeled the switch functions in the photos.

Here is a repeat of the above sequence of switch photos with the top contact assemblies installed.
One other thing to note...The power (Off) switch assembly is sealed with plastic rivets.  I decided not to mess with that switch by attempting to disassemble it down to the contacts at this time.

Tip: The fixed contact top assemblies must be carefully slid into place. You have to make sure the fixed contacts align with the slits between the spring contacts. If you go too fast you risk a metal part not aligning and bending a spring contact where its shape deforms.  Not a good situation.

Before continuing on with any more front panel assembly this is a good time to test the operation of the switches.

While I have the switch assembly in this state I put a switch assembly from a later serial number Beomaster 4400 next to it in order to show some pretty major differences.

The switch assembly (and switch parts) are not interchangeable between these switch panels.
The switch assembly on the early serial number Beomaster 4400 units are more closely related to the Beomaster 4000 and Beomaster 3000 receivers that preceded it.

The switch assembly and switch parts of the late serial number Beomaster 4400 units is a different design as you can see in the next two photos.

Looking at just the AFC ST Switch there are some easy to spot differences.
The actuators are different (metal instead of plastic).
The AFC ST Switch went from two sets of spring contacts to four sets.
The spring contacts are shaped different.
The late serial number switch assembly has a plastic insert holder for the sets of spring contacts.
The metal tabs for the top, fixed contact part of the switch are much smaller on the newer switch assembly.
That is really a disappointment. There is no room for error and it is extremely easy to damage the newer tabs beyond repair. 
I haven't found a method of dealing with those new, tiny tabs that I am confident with.
My smallest and best pliers do not do a good enough job.

The PCB 6 board that the switch assembly solders to is different.

For this early serial number Beomaster 4400 project I will resume the front panel assembly and plan on having it back together in the next post.

Monday, March 28, 2022

Beomaster 4400 Type 2419: Cleaning & Polishing the 268 switch contacts

In a previous post for this Beomaster 4400 restoration project I mentioned disassembling the switches to clean and polish the switch contacts.

It took a while but I finally got all 268 front panel switch contacts completed.
I did take a little bit of a detour during the task to do some remodeling of the workshop but that is a different story.

With a much improved workspace the switch contacts are now polished and ready for reassembly.

Here is a picture of the start of the work with the switches all disassembled.

This photo shows a couple of the switch assemblies side by side.
The set on the left has not been cleaned and polished.  The set on the right has.

Here is a photo of the complete set of switch contacts after cleaning and polishing them all.

Here is a closer view.

This level of Beomaster 4400 disassembly for cleaning is not always necessary.
If the front switch panel is performing correctly then simply spraying some Deoxit contact cleaner/conditioner into the switch housings (and exercising the switches about 50 times) is enough.

However, I have run into one case where a Beomaster 4400 switch assembly operated correctly for periods of time but then had problems (making contact).

Also...on this Beomaster 4400 project there was a problem with the Off switch not functioning.
So in this type of scenario, since it is already a big task to disassemble the switches in order to fix the Off switch, I decided I might as well take advantage of the open switch assembly and clean all of the contacts manually.

The next post will reassemble the switch assembly and prepare the Beomaster 4400 for powering on.

Saturday, March 26, 2022

Beogram 4002 (5513): New Arrival from Arizona - A First Look

I recently received a Beogram 4002 (Type 5513) from Arizona for a complete functional restoration. The unit arrived without its hood. It came in a Beolover shipping container. An excellent approach for trouble-free shipping. 

This is the unit as extracted from the packaging:

A bit dirty, but overall not too bad, except for the completely worn keypad:
I hope we will soon be able to professionally restore these keypads. On the positive end of things, the plinth is in a pretty good condition. The corners are almost pristine:
I removed the aluminum plates and had a look below deck:
This unit looks mostly unadulterated, a perfect starting point for restorations. There are fragments of decayed transport lock bushings all over the place, nothing unexpected in this vintage:
As usual the plastic pulley on the carriage spindle is cracked and my customer said he glued it to the shaft (shudder!...;-). It will be interesting to remove it from the shaft for installing an aluminum replacement. The belt definitely also looks 'end of life':
I was told this unit did some traveling in an RV for a few years (that is what I call 'roughing it'!...;-). Maybe this is the reason that the floating chassis springs are pretty rusty:
This is nothing really worrisome, just looks a bit, well, rusty!...;-).
After this first inspection, I plugged it in and pressed START. The carriage sluggishly started moving and the arm found the LP setdown point and - nothing! No solenoid action. I pressed STOP and waited for the return of the carriage to its home position. Then I manually operated the arm lowering mechanism a few times and tried again. This time the solenoid acted. So it seems there are just the usual hardened lubricants at play, and a thorough cleaning and re-lubricating should do the trick. The DC platter motor made some noises while the above happened. This is also not unexpected. These motors usually have dry bearings and they need to be re-infused with oil before the deck can be used again.

In summary, this is a pretty decent starting point for a full restoration, and I expect this Beogram will soon play like-new, and hopefully also look like-new after installation of a refurbished keypad!

Friday, March 25, 2022

Beogram 4002 (5513): Complete Functional Restoration and Installation of the Commander Remote Control Module

This post is the follow up to an initial post I made about a Beogram 4002 (5513) that arrived from West Virginia a while ago. In the above post I discussed the overall condition of this unit. Here I will show what was done to the unit to bring it back to like-new performance.

This shows the unit as I received it:

As usual, I first rebuilt the carriage. Most Beograms of this vintage have hardened lubricants that need to be removed and replaced. I removed the moving components of the arm lowering mechanism, the rods the carriage slides on, and the threaded rod that drives the carriage:

This shows the cleaned parts:
The next step was to replace the tracking sensor light bulb with a LED based replacement. This shows the original setup:
I removed the original bulb housing and installed the Beolover LED replacement. It has a built in trimmer (blue) that allows regulating the brightness of the LED:
The trimmer is useful for fine-tuning the tracking sensor responsiveness.
Another 'carriage task' is the replacement of the usually cracked original plastic pulley. This shows the precision machined aluminum replacement:
Beolovely! On to the damper to arm linkage that has its often stuck pivot point on the sensor arm assembly. This shows the linkage on the removed sensor arm. It lacked the circlip that holds the linkage on its pin. 
I replaced the missing clip with a new one:
As usual, the small copper plate that is glued to the sensor arm base to reduce friction of the of the upper limit adjustment screw for the tone arm fell off when I worked on the assembly:
It is originally attached with degraded double sided tape. I cleaned the tape residues off and reinstalled it with a dab of epoxy:
The next step was to rebuild the PCBs. This shows the main PCB in original condition:
This detail shot shows the 'RPM section' of the board with the RPM relay and the corroded RPM trimmers:
I replaced these parts with modern ones, to ensure RPM stability and easy calibration with encapsulated multi-turn trimmers:
I also replaced all electrolytic capacitors and the sensor arm photodetector transistor:
I also replaced the power transistors: This shows, as an example, the replaced 24V rail TIP120 Darlington transistor:
Next in line was the output board with the output muting relay and its delay circuit:
I replaced the relay and the electrolytic capacitor that is part of the time constant of the delay circuit. I also implemented a switch that allows connecting system and signal grounds in case there is a hum problem (often the case with RCA versions, which this Beogram is):
When I took out the board I realized that the clamp that holds the output cable in place as well as the PCB upper end was cracked:
This happens frequently in these models, and so I have a replacement part available, which I installed:
While I had the boards out It was a good moment to have a look at the transport lock bushings, which are usually degraded in this Beogram vintage. This shows the left bushing after removing the upper part of the transport lock:
Since the fragments of these degraded bearings are often distributed all over the enclosure it is necessary to remove the floating chassis and clean out the debris. Otherwise they can get lodged beneath the floating chassis and impede its free movement, which is detrimental to the main purpose of the floating chassis: Vibration damping. I removed the chassis and also the original reservoir capacitor shown here:
This shows the emptied enclosure:
After installing the new bushings (3D printed replacements - this shows again the left lock as an example)
and re-installing the chassis it was time to put a new reservoir capacitor in place:
This Beogram is a version that is ready for CD-4 upgrade, i.e. it has a dual capacitance reservoir capacitor, which needs to be replaced with two individual modern capacitors, since dual capacitance models seem to have gone out of fashion these days.
The next step was the replacement of the two light bulbs in the RPM adjustment panel above the keypad. These bulbs illuminate the adjuster scales and have the potential to cause RPM variations since they heat up the potentiometers inside this panel. This shows the original bulbs installed:
I replaced them with the latest iteration of the Beolover RPM panel LED assemblies:
They solder directly to the wire terminals of the bulbs. Then it was time to replace the last of the 4 incandescent bulbs of this Beogram, the sensor arm bulb. This shows the original bulb in place with its replacement next to the arms:
This shows the LED assembly in place and 'in action':

Next came the various mechanical adjustments like floating chassis position, arm parallelism, platter alignment, and finally the adjustments on the tonearm. This shows the original circlip on the counterweight adjustment screw:
This arrangement is a bit flimsy and does not hold the counterweight firmly in position. Therefore, I usually replace the circlip with a M3 square nut:
Then it was time to calibrate the tracking weight with a digital gauge:
Once the weight was calibrated I adjusted the arm lowering limit:
This is an important adjustment since it ensures that there is no damage to the stylus should the arm drop on the empty spinning platter due to a malfunction in the record detection circuit.
Then I calibrated the RPM for 33 and 45 settings and adjusted the tracking feedback. At this point the only thing separating me from a test spin were the very corroded original RCA plugs:
I replaced them with nice all-metal gold plated units:
Then it was time to install the Beolover Commander remote control module, which was recently redesigned (see here for more info):
The Commander is an important addition since it enables operating the Beogram entirely without touching the precious keypad. These keypads often loose their coating due to contact with the acids and fats in the skin. The Commander uses an Apple remote and it mirrors all functions of the keypad, plus it adds a dynamic slow/fast scanning feature and an auto-repeat mode, similar to that found in the later Beogram 8000 and 8002. 
Then it was finally time for a test spin. I selected one of my favorite CTI recordings, "Cherry" by Stanley Turrentine and Milt Jackson (CTI 6017). It was recorded in 1972. A perfect period-correct match for this beautiful Beogram 4002! Of course this album was cleaned ultrasonically before play with on a CleanerVinyl ProXL setup. 

I will now play this Beogram for a couple of weeks aiming to make as sure as possible that there are no intermittent issues. Then it will be time to send it back to its owner in West Virginia!