Beomaster 5000 Type 2323: [UPDATED] Solving a troublesome mechanical door latch problem

 I have seen owners of Beomaster 5000 receivers complain on various forums about problems with the control panel door. The door either won't respond to the "Open" button command, is slow to open or won't close properly.

This Beomaster 5000 receiver had all of those symptoms. Pressing the "Open" section of the front press-bar would often do nothing. No click from the internal door latch solenoid could be heard.  Sometimes it would seem to magically engage the solenoid but then the door would either not open or just slightly open.
Then, finally, closing the control panel door would often result in the door not latching closed.

If the door never operated the solenoid I would suspect the electronics as there is a ribbon cable from the main electronics of the Beomaster 5000 to the control panel door. Sometimes that ribbon cable fails over time and has to be replaced.

In this case the ribbon cable is still functioning and the problem was a mechanical issue.

Here is a picture of the Beomaster 5000 turned on with the control panel door closed.

Pressing the open part of the control panel bar (shown highlighted in the photo) would bring disappointment (and frustration) in the door not opening.

With the Beomaster top cover removed I could observe some of the activity that goes on when the door is being operated.

This photo shows some of the key components and how far the door would try to open during the times that the "Open" button got the control solenoid to engage.  It didn't have enough force to open fully.

I checked several things first.

The control panel door damping mechanism controls the opening of the door so that it slowly and gently opens up.  I checked that the damping mechanism wasn't hanging up and was correctly configured.

In this case it was good.

The photo below shows the door open actuator that the door bar presses against to release the door.
That actuator is spring activated and simply presses a rod that moves the metal door inward.
When the press bar is released the spring returns the bar to its normal position.
Pushing on the press bar also moves a plastic actuator to press against a flat, metal contact located on the keypad circuit board (PCB 5).
That is the actual, electrical button component that operates the door latch solenoid.

This photo shows what a disassembled Beomaster 5000 control panel door looks like from behind the "Open" press bar.

I noticed that when I applied pressure to the back of the control panel door (the black plastic frame) as I pressed the "Open" section of the press bar that the solenoid would always engage.

So electrically it appeared that everything was good.

Another issue with the door opening is that the door would not fully open up when it was unlatched.
Once the door is unlatched there is a center spring in the center of the door hinge rod that presses against the cabinet base and causes the door to flip open.

Here is what that spring looks like.

The spring is intact and it is pressing against the metal part of the cabinet base so that is not the source of the door not fully opening.

Checking the attachment points of the panel door hinge rod along the bottom of the door I discovered that there are two key mounting/pivot points.  It also looked like those two pivot points were sticking.

I worked in some dry lubricant and the door panel became much easier to rotate open.
Now an unlatched door rotated completely open.

That left the "Open" function intermittent operation and the problem with latching the door closed.

It turns out that those were related.

Here is a look at how the Beogram 5000 control panel door latch/unlatch mechanism works.
This is a photo of a disassembled Beogram 5000 front panel.  It shows the solenoid and the lever that latches and unlatches the control panel door.

Here is a closer look at the solenoid that operates the unlatching.

Looking at the catch for the door here are photos from the top looking down at the door latched and unlatched.

When observing these mechanics operating during latching and unlatching I initially thought there were two problems.

One of course was the unlatch solenoid operation being intermittent.
The second was the plastic door catch would often not move well enough to latch and to unlatch the door.

After many iterations of operating the door I found that if I helped the door panel "Open" actuator by holding the back of the panel firm, the solenoid would engage and unlatch every time.  It wasn't intermittent under that condition.

The door catch would also sufficiently move to unlatch and let the door open.
Surprising the latching function also improved.

Re-examining the "Open" push bar operation and comparing this Beomaster 5000 with the photo of a disassembled Beomaster 5000 control panel I realized this Beomaster panel has a missing plastic tab.

Here again is the photo of a disassembled control panel.

Here is a photo of the Beomaster 5000 door with the intermittent operation problem.
Notice the missing tab.

That explains why the door works when I manually hold the black plastic frame in place when pressing the "Open" press bar.  When the missing tab or my finger is not keeping the plastic frame secure it will move with the press bar and fail to engage the open door button contact.

The next problem was how to fix the faulty door mechanics.

After some more testing iterations I decided that I would try supporting the control panel door compartment behind the left side of the panel, where the "Open" actuator is, with a cut-to-fit rubber block.  I considered just gluing the keypad circuit board (PCB 5) where the missing tab is but rejected that idea because I wanted to keep PCB 5 where it can be easily removed if future repairs are ever necessary.

There is plenty of room behind the panel door for a rubber block and it would be like my finger in supporting the back of the panel.
Here is the rubber block glued in place.

The result is a success. 

So far the door opening mechanism works 100% of the attempts.
The door latch operation also works properly now.

I believe that too much flex developed on the left side of the control panel door, press bar over time.
That caused the mechanical operation to become unreliable.
The rubber block is providing needed support when the press bar is engaged so the latch/unlatch lever can fully travel and complete its task.

Here are a couple of photos of the working control panel door.

A few important things to note after wrapping up this issue...

1. A completely non-functioning door unlatching problem (solenoid not working) could be an electronic problem involving the ribbon cable.
2. When working on the door latch/unlatch mechanics, avoid the temptation to try and solve the problem with oil or other lubrication. The solenoid and its lever assembly work better dry.
3. There could be a need to lubricate the mounting/pivot points of the long, door hinge rod. In that case use a dry lubricant like Tri-Flow Dry Lube.

Now back to my listening tests.