Beomaster 2400 Type 2902: Another restoration project begins

An owner of a Beomaster 8000 restoration I did last year sent me a nice Beomaster 2400 unit that needs some work. Today I was finally able to put it on the bench and check out what condition it was in.

The outside cosmetic condition of this Beomaster 2400 is quite nice. With it plugged in I can get sound from the FM tuner testing the Beomaster output with some headphones. I can see however that the Treble indicator lamp is burned out. In addition, the Bass and Treble controls do not work. The slide control knobs are loose which is a symptom of broken sliders.

As you can see, a handsome Beomaster 2400 unit. It didn't arrive with a remote control so I used mine to check that the remote control functionality works...it does.

Now it is time to open the Beomaster up. I know that it partially works so that is good. However, the problems it shows from the initial testing indicate that typical problems for this receiver exist.

The disassembly begins by removing screws on the underside of the Beomaster. I have circled the screws that I remove with red circles in the pictures.

This is an early production Beomaster 2400 unit. The Phono DIN jack is the 5-pin type of DIN jack. Later Beomaster 2400 units were fitted with 7-pin DIN jacks to go along with the added support of remote control functionality of the Beogram 4004 turntable. Bang & Olufsen produced a modification kit that included a 7-pin DIN jack and wires to add the Beogram 4004 remote control support to these early models.

Here is the schematic diagram from that mod kit.

We will decide later in this restoration whether this mod kit will be applied. Interestingly, there are 7-pin DIN jacks available for the Beomaster 2400 from later model Beomaster 1900 units. Because the Beomaster 1900 and 2400 share the same main board Bang & Olufsen started installing 7-pin DIN jacks on both the Beomaster 2400 and the Beomaster 1900 units...even though the BM1900 receivers do not have remote control circuitry. Swapping a 5-pin DIN jack from an early Beomaster 2400 with a 7-pin DIN jack from a later model Beomaster 1900 would not result in loss of functionality for either unit.

Continuing on with the Beomaster 2400 disassembly I loosened the rear panel for removal.

That step allows the bottom panel that was loosened earlier to now be removed.

Next is the removal of the tone control and FM tuning control panel. Two screws are removed on either end of the panel to allow it to slide out.

Now for removal of the bottom control panel (volume control and source selection).

With the control panels removed I can see the inside components of the Beomaster 2400. I spot some problems with the Bass and Treble tone controls as well as with the display indicator masks for Bass, Treble and Balance.

The indicator masks have started to deteriorate from the heat produced by the indicator lamps. I have seen this before on the Beomaster 1900 (which as I said before, is essentially the same receiver...minus remote control).

I have new replacement masks I can fix the deteriorating ones with. In this restoration I will also change the Bass, Treble and Balance display lamps to LED lamps which run way cooler and should not repeat this problem.

Be careful removing the little brass clips that hold the display mask to the slider bridge. If done wrong the lip of the brass clip can easily be broken off.  The ends of the clips need to be pressed inward then up as shown here.

The Bass and Treble adjustment sliders are loose and do not function. This is usually because small, plastic clips on the plastic slider bridges have failed. I can see that is the case here.  Martin Olsen produces replacement bridge parts to fix this problem so I will be installing those here.

To continue the disassembly of the Beomaster 2400 I need to loosen and remove the tone control and tuner control board followed by the removal of the three indicator lamp modules (volume, tone control and source selection).

Now all that is left is to loosen the large, main board so I will be able to get to the majority of capacitors that need replacing in this restoration project.

The FM tuner box (the shiny silver box) and the FM antenna jack must also be loosened.
Finally the main board can be lifted up for access to all of its components.

I can also get to the two reservoir capacitors easily now for replacement of those.

The initial evaluation is complete on this unit and the Beomaster 2400 is opened up where restoration work can begin.