Beomaster 4400 Type 2419: Continuing the Reassembly of the front panel switches

Continuing on from the previous post with the reassembly of the Beomaster 4400 front panel switches, I will also continue showing the differences in the switch panel components between early serial number units and later serial number units.

I did look up the B&O service manual addendum on the change with the switch panel.
According to that documentation the "early serial number" switch assemblies are for Beomaster 4400 serial numbers prior to SN 1524001.  Units with serial numbers 1524001 and on have the new switch assemblies.

That bears out on the Beomaster 4400 units I have seen.  The serial number for the Beomaster 4400 of this project is 1510043.

Here are some photos of the Beomaster 4400 front panel for both versions side by side.

From the front the difference is in the way the slider controls mount to the front panel.
The later serial number panel mounted the controls with screws from the front while the early serial number panel used metal spring clips. For that reason the early serial number front panels included a narrow mounting bracket for the slider controls to rest on.
The metal button panel frame that the switch assembly mounts to also changed due to the different style of switch actuators.

This picture shows the type of slider controls the Beomaster 4400 uses for the early serial number and later serial number units.

On two the circuit boards and wiring.
Both types of front panels have a small LED glued in place for the Stereo Indicator.
It is difficult to detach that LED assembly when disassembling the front panel so I started cutting the two wires that connect to the LED assembly.  When reassembling the panel I install a small 2-pin connector for the cut wires. That makes it a little easier in servicing the front panel.

The switch assembly is mounted to the front panel on a metal, button panel frame. 
It is secured with two screws.
The important thing here is to make sure all of the plastic switch actuators are pressed against their respective push buttons.

Now that the switch assembly is secured onto the front panel it is a good idea to double-check the mechanical operation of the switches again.

While I was working on the front panel assembly I took a little detour to replace the two 10,000uF electrolytic capacitors for the ±35 VDC output amplifier rails.  These are the two capacitors that are mounted on a bracket just to the side of PCB 5.

I also took a little time to install the two 100Ω trimmer resistors for the no-load current adjustment of the output amplifier. On those two trimmers I always go with multi-turn trimmers as they are easier to fine tune.

Here is the left channel trimmer.

Here is the right channel trimmer.

Returning to the reassembly of the front panel I decided to prepare the new incandescent lamps in the front panel wire harness.

Three of the five original lamps still worked but since I have to replace two I am going ahead and replacing all five with proper lamps from Martin's Beoparts store.

Here are the original lamps removed.

Here are the new lamps installed.

The next step of the front panel reassembly is to re-attach the circuit boards that mount to the switch assembly.  They are how the switches electrically connect to the Beomaster.

First is the PCB 6, 2-piece board.  
It has a normal, rigid PCB part and a flexible part to connect to the FM tuner preset dials.

The next PCB to attach to the switch assembly is PCB 9.

Here is a picture of the circuit boards reattached to the switch panel.

The front panel reassembly has gone smoothly so far.  
It is at the point where the wire harnesses get reattached.
In some cases that just means plugging in some connectors but unfortunately for me it also means quite a few loose wires that do not have a connector.  
That is the reason you have to take a lot of photos during the de-soldering of those wires when the front panel is being disassembled. 
I have those of course and my task for next time is to gather all of that information and carefully solder all of the individual, loose wires back in place.

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.

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.

Beogram 4004 From Canada: Restoring the keypad

The keypad on this Beogram 4004 functions without any issues.  It is still a good idea to take a look at the contacts, clean them with Deoxit and a fiber brush. That will ensure that they continue working properly for many more years.

Another decision has to be made regarding the cosmetic restoration of the Beogram.
Most Beogram 4002 and 4004 turntables have some visible wear on the keypad button surfaces. Oil from human fingers wears away the original coating on the metal buttons over time.

This Beogram 4004 shows some of that type of wear.

The area of the panel where the buttons are is a polished steel plate that has been sprayed with a matte finish that gives it a brushed look. The contrast look of the design is a distinctive and classic look that makes the Beogram 4002 and 4004 turntables so great.

The owner of this Beogram wants that look returned as part of this restoration so I will exchange his keypad with one I had professionally recoated prior to lock downs.

I stripped off the remaining, original matte coating on the button plate then masked off everything else on the panel. I sent the keypad to a paint shop that could spray the button plate with an automotive grade, matte clear coat finish. It is a very tough finish that is used on automobiles so I expect it to last for a very long time in this application.

The keypad came back looking beautiful.

The two horizontal gaps between the button panel and the keypad frame was originally painted black. That needed touching up so I used some matte black paint for that.

Now on to the button contacts.

I began with taking off the Start button contacts first. 

After cleaning the two contact pieces with Deoxit and a fiber brush I reinstalled them and continued with the remaining buttons.

Contacts cleaned and treated, the button panel is ready to be reinstalled in the keypad frame.

The keypad is installed back in the Beogram 4004 and works like new.

I will replace the two lamps in the speed indicator displays next.