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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.

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