Beogram 8000 (Type 5613): Installation and Test of the New Tracking Sensor LED Light Source for Beogram 8000 and 8002

About three weeks ago I replaced the tracking sensor light bulb in a Beogram 8000 with a prototype LED assembly. Based on this experiment I designed a dedicated LED board. The first batch just arrived from the manufacturer and is now available via the DKaudiolover store. After soldering on two leads the boards look like this:

So I put the Beogram 8000 back on the bench and set out to implement this new component. This shows the tracking sensor compartment under the arms:

This is how it looked originally after removing the cover before I started playing with it:

The bulb and the photo resistor are both soldered to a small board that is situated in a slot in the back of the compartment. This board connects with four leads to the ribbon cable of the carriage. These wires can be seen when the carriage is lifted up: 

Lifting up the carriage as shown in the above picture requires these steps:

• Remove the encoder PCB and the carriage belt. 
• Pop the shorter stainless steel rod on which the carriage travels out from its plastic bases and pull it out.
• Liberate the threaded rod from its 'bearings' while carefully lifting the carriage up (take extra care that the white plastic 'nut' does not pop out from the black plastic 'fork'. It can be a bit challenging to get things back together)

Here a detail shot of the wiring:

After removal of the two plastic rings that hold the wiring in place

the wires can be pulled out from around the solenoid housing:

This gives enough slack that the board with the bulb and photo resistor can be pulled out from its slot:

Then the bulb can be removed and the LED board installed. For this it is best to bend the leads right at the edge of the small board:

Then it can be stuck through the bulb orifice with its narrow end, and the leads can be soldered to the pads around the orifice:

Care needs to be taken that the LED board is about perpendicular and that the LED side of the board is facing the photo resistor.

Once the board has been put back into its slot the four wires can be put back around the solenoid and secured with the two plastic rings:

After the carriage is put back down, the board can be tested:

This is how it looks with the tracking sensor cover back on.

Of course, the tracking feedback needs to be adjusted after this exchange. This can be done with the screw that goes into the sensor housing. Turn it clockwise and the sensor gets more sensitive, i.e. the carriage moves sooner when the needle advances towards the record center. Turn it counterclockwise to make the carriage move a bit later. Ideally, the carriage should start moving after the record made two full turns after the needle hits the groove.