Beomaster 4400 Type 2417 - Australia Project - Initial Checks

Here is a really nice example of a Beomaster 4400 Type 2417 receiver.

This one has been sitting patiently in my backlog of Bang & Olufsen restoration projects for a while.

It is the first Type 2417 unit I have seen.  All of my other Beomaster 4400 restorations have been Type 2419 units.

The Beomaster 4400 Type 2419 receivers have a transformer for the US market.  Their transformer is for 117 V, 60 Hz and has two switched AC outlets in the back for connecting other audio components.  I never liked having those switched AC outlets as it means more current through the Beomaster 4400 receiver's power switch when it is turned on.

The Beomaster 4400 Type 2417 does not have any additional AC outlets and it has a voltage selector switch so the transformer can be configured for markets that have AC voltages of 110 V to 240 V. 
Much nicer.

Like so many of the Beomaster 4400 receiver cabinets, the four rubber feet are worn down and there is corrosion around where they mount to the bottom, metal plate.  I will have to replace those and clean off the rust.

The procedure to open the top of the Beomaster 4400 cabinet for access to the internal components is pretty easy.
Two screws need to be loosened in order to move two cabinet latches out of the way.
Four screws have to be removed to allow the wooden cabinet to slide back and up for removal.
A couple of those screws are partially hidden by Beomaster 4400 heat sinks.

With the cabinet opened up I am pleased to see that the internal components look like they are the original factory components.

This photo shows the space between the Beomaster 4400 voltage selection and the transformer.
In the Type 2419 units, this space is crammed with the wiring for the two switched AC outlets.

Normally I jump straight to cleaning and replacing the electrolytic capacitors.

This time I decide to try some basic testing on the Beomaster 4400.

The first thing I did was to check the no-load bias current per the service manual.
Both channels (Left & Right) were low so I adjusted them to about 10mVrms across their respective emitter resistors.

Next, I set up my audio tester.
As in other Beolover Blog posts where I test my restored Beomaster amplifiers, I am using my two 8.1 ohms dummy loads for the speakers.

These dummy loads are made up of a 4 ohms resistor + a 0.08 ohms sensing resistor + a 2 ohms resistor + a second 2 ohms resistor.  In series these measure 8.1 ohms.

The different resistor segments allow me choices of where to place my differential measurement probes to measure the power/frequency/distortion of the output amplifier.  My QuantAsylum QA401 Audio Analyzer can only handle a maximum of 26 dBV (50 W across an 8 ohms load) so the resistor segments let me choose a measurement point that is friendlier to the analyzer. 

In the case where I was going to measure 50 Watts out of the amplifier across my 8.1 ohms dummy load, I would place my differential probes across the 2 ohms sensing resistor of my dummy load.
The maximum dBV across the 2 ohms resistor for the 50 Watts output would be around 14 dBV.

On this pre-testing of the Beomaster 4400 Type 2417 output amplifier, I don't expect to get to a very high output.

The output of the Audio Analyzer uses two single-ended signals for the Left channel and the Right channel.  I typically connect them to the Tape 1 or Tape 2 source input.  The most common test signal I use is a 1kHz sine wave of 0.316 Vrms.

This photo shows the test connections underneath the Beomaster 4400 cabinet.

For my initial testing of the Beomaster 4400 Type 2417 I started with the volume at zero and observed the distortion measurement as I increased the output across the dummy load resistors to 1 W.

The THD measurement was surprisingly good at 1 Watt output from the amplifier.

Things went bad for the Right channel when the output amplifier went just past 7 Watts.

Here is what the workbench looks like during the audio analyzer testing.

So a bit of pre-restoration testing just to have as a reference when the restoration is complete.

My next task is to begin moving/removing some of the Beomaster 4400 internal components to make way for the electrolytic capacitor replacement.  I will also change the trimmer resistors in the amplifier section and rework the thermal insulation of the transistors on the Beomaster 4400 heat sinks.

There are also some transistors on the main PCB of the Beomaster 4400 that get really hot.  I will look at attaching some thermal protection to them as well.

As I do on all of the Beomaster 4400 restorations I work on, I will install an arc suppression device for the power switch.  

Beomaster 1900 Type 2904: Assessment of a New Beomaster Restoration Project

Here is the start of a new Beomaster 1900 restoration project. 

This Beomaster unit has been patiently waiting for me to retool my workshop for Beomaster restorations after a lengthy stint of Beogram restorations and repairs.

I have several different Beomaster units in my backlog at the moment and it is time to start getting them working again.

So here is the first look at the latest Beomaster 1900.

The Beomaster 1900 is in really nice cosmetic shape.  I would rate it excellent except that it is suffering from a common problem with these models.  The thin veneer trim is separating from the plastic side panels the trim is mounted to.  I have seen this before with the Beomaster 1900 and 2400 receivers.

The plastic side panels and single, front panel do remove from the cabinet though.  Removing them (carefully so as not to break their mounting tabs) will make it easier to fix/reattach the veneer.

I moved on to the disassembly of the Beomaster so I can prepare it for replacing the electrolytic capacitors inside.  There are quite a few electrolytic capacitors to replace.  Around seventy.

I started removing the panels of the Beomaster 1900 first.

This photo shows the control panel (with the touch buttons) and the front, plastic trim piece removed.

The next four photos show removing the Bass, Treble and Balance indicator masks from the slide controls so the control panel PCB can be removed.

I was happy to see that the indicator masks were is great shape and the slide controls appear to be intact and working.

Two press-to-fit connectors are all that connect the control panel PCB to the rest of the Beomaster components.  I disconnected those and removed the control panel PCB.

With the control panel PCB out of the way I continued on and removed the indicator panels (the volume indicator, the Bass, Treble and Balance indicators and the source selection indicators).

Here is the volume indicator panel being removed.

Here is the indicator panel for the Bass, Treble and Balance being removed.

Finally, here is the source selection indicator panel shown already removed.

Here are the two plastic side panel (trim pieces) removed.

In order to free up the main PCB I removed the four output amplifier transistor heat sink assemblies.

I cleaned off all of the old white thermal paste from the transistors and heat sinks.
I will be replacing the thermal paste with SIL-Pads.

The Beomaster 1900 is now in a position where I can access all of the electrical components I need to access in order to start replacing old capacitors.  A while back I started making the parts for a jig to support the disassembled Beomaster 1900/2400 structure.  I used the pieces I have completed so far to put the Beomaster 1900 into a service position for working on.

Beogram 8002 Type 5633: A New Beogram Project From Idaho

This is the first post of another Beogram restoration project.  A very nice Beogram 8002 that belongs to the original owner's family.  It is amazing how many restoration projects are requested by people that have this type of personal connection to the audio component. Of course the Beogram 8002 is also a great turntable and one of my favorites.  Definitely worth restoring.

Here is the initial inspection and assessment of the Beogram 8002 as I disassemble it for the restoration.

The Beogram 8002 arrived with a lot of the original B&O packing.
You can see a bunch of black debris on the surface of the cabinet though. 
It looks worse than it is.
That debris is from deteriorated double-sided tape that B&O used to secure various pieces of the Beogram cabinet.  

Aside from being dirty from the deteriorated tape debris this turntable is actually in great shape for a successful restoration to its full glory.

Here is a look at the underside of the metal lid over the tonearm compartment.
It is the source for a lot of the debris.
You can see how the detached lid has double-sided tape remains on the lid hinge as well as the lid itself.

The owner dodged a fatal mistake with the MMC-2 phono cartridge though.
As you can see in the photo, this Beogram 8002 was shipped with the MMC-2 cartridge attached to the arm.
This is a big risk for damage to the phono cartridge because jerky movements during shipping could cause the tonearm to bounce in the vertical direction resulting in the stylus striking the deck of the Beogram.

While the MMC-2 phono cartridge is missing its plastic stylus guard, it looks to be intact.  A lucky break.  I think I might have an old, broken MMC cartridge of this type that has a stylus guard I can transplant on this one.

This next photo is kind of cool.  The owner still has the original insert that reminds the person unpacking the Beogram 8002 to unlock the floating chassis.  I think this is the first Beogram 8002 I have come across that still has this original shipping insert.

Just like the problem with deteriorating attachment tape on the tonearm compartment lid, the Beogram 8002 deck plate is also loose.

This photo shows a small, metal spring that helps remove static electricity build up on the metal deck of the Beogram.  It is loose (held in place when the deck plate is secure) so I will put it in a bag containing other loose parts that I need to take care of during the restoration.

Note that the Beogram 8000 turntable does not have this spring.  It was added when the Beogram 8002 was produced.

A maintenance feature of the Beogram 8002 turntable is that it can be opened up into a service position.

When doing basic maintenance on a Beogram 8002, like changing the servo belt, it is handy to open the Beogram cabinet into its service position.  

During a restoration however, I prefer to disassemble the components and remove everything from the cabinet. The reason for that is because the Beogram 8002 doesn't have any support of its own to remain open in the service position. That leaves it vulnerable to an accident if you have to leave it open for the whole restoration...meaning the raised top part of the cabinet can come crashing down. 

In addition, when the cabinet has loose pieces and a grimy dust cover, it needs working on by itself and those tasks are easier to manage if all of the turntable components are removed.

One of the first things I like to do in disassembling the cabinet is to remove the dust cover and the tonearm door assembly (the lid over the tonearm).

My preferred way of removing the dust cover and metal lid assembly is to pull the long bar that makes up the hinge and holds them to the cabinet frame.

This method works nicely because it doesn't disturb the rear, plastic plate that fits onto the back of the cabinet. Attempting to remove that plate often results in the plastic mounting tabs breaking.  I have seen cases where all of the mounting tabs were broken off so the solution then is to add screws to reattach the plate. The screws work but it would be better to avoid that whole scenario.

Those woes can be avoided by just pulling the hinge bar and lifting the dust cover and lid hinge off.

Before completely pulling the bar out, you have to disconnect the dust cover from the damping spring assembly.  I disconnect those components using a plastic prying tool and leveraging the dust cover hinge down (and off the mounting hook bracket).

Note: The mounting hook bracket shown above on the underside of the dust cover is another component that was originally attached with the B&O double-sided tape that eventually deteriorates.
I will remove that bracket, clean the old tape residue off and epoxy the bracket back on.

Here is the hinge bar fully removed.

...and here is a photo of the dust cover and lid hinge removed.

The next step is to remove the turntable components from the cabinet.

With the dust cover and lid hinge removed it is easier to maneuver the cabinet into the service position.

I don't show it in the photos but on the left side of the cabinet (when looking at it from the front), there are two M3 screw under the edge of the cabinet frame that must be removed so the top part of the cabinet can open upwards.

After removing the two screws the floating chassis must be detached from the cabinet leaf springs.
For the floating chassis attachment near the tonearm compartment the deck floor piece must be removed.

It is another assembly that typically has deteriorated double-sided tape ... as this one has in the photo below. 

To release the three floating suspension mount points I use a special hook tool.  It fits under the bend in the clip so I can press down on the leaf spring and disconnect the clip.

IMPORTANT: The Beogram 8002 cannot be lifted into the service position with the floating suspension springs attaches.

Once the suspension is dropped down off of the leaf springs the floating chassis can be maneuvered so the top section of the cabinet can tilt up. 

Before tilting the cabinet up I like to remove the Beogram 8002 Control Panel assembly and Transformer assembly.

Now to lift the Beogram 8002 cabinet into the service position.
A caution here is that the edge of the cabinet that lifts up will hit the left side of the fixed arm unless the floating chassis is slid to the right a bit.

With the Beogram 8002 cabinet finally up in its service position I can remove the PCB 1 & PCB 2 assemblies and pull out the whole floating chassis.

Lately on my Beogram 800x restorations I have been applying some tape to the underside of the floating chassis as I remove it to keep the clips for suspending the chassis from falling out.

The tape makes it easier to reassemble the components later.

Here is the empty Beogram 8002 cabinet.  
It can be put aside in a safe place along with the dust cover, metal tonearm compartment lid and other loose cabinet components.
I can work on the restoration of those parts separately from the main turntable components.

...and here are the main turntable components.

The floating chassis components, the circuit boards, the transformer and the control panel.

I really like that these components can be worked on then connected together outside of the cabinet for testing and adjusting.

In the next post I will begin restoring these main turntable components.
All of the electrolytic capacitors will be replaced.
All of the circuit board connectors will be checked and re-flowed with solder.
I will install my usual test connector under the control panel for measuring the left and right scanning LDR devices.
The tangential arm assembly will be disassembled some more for cleaning and lubricating.
During that task I will check (and likely add) a thin strip of Dura-Lar plastic where the tonearm rests against the lowering mechanism.  I will explain that when I get to that task.

A new belt will be installed on the tangential arm servo motor pulley.
Inside the microcomputer (uC) metal box (PCB 2) I will remove the processor IC and replace the 40 pin socket with a newer (and better) one.