I have came across a very strange looking diode during the restoration of HMV STEREO 666 Record Player. The machine is 40 years old, the diode of interest also has the same age. The marking of the Diode became very faint due to its age. After a great trial I can read the marking as 'BEL OR23'. A strange nomenclature. I could not get any explanation of this name, also could not find any datasheet of this component. I am assuming it as a diode because the silk screen layer of the PCB where the diode was fitted denotes it as a diode and I know that this component was company fitted.
The circuit where the diodes were fitted is a Sound Level Monitoring Circuit, where 3V light bulb glow according to the sound output level of the amplifier. Lights does not glow in its full capacity if these diodes are being used. The circuit works, but the bulbs lack brightness, even in the 100% volume.
Preliminary checking of this component with digital multi-meter (assuming it as a diode) reveals the following results:
Diode Name = OR23
Forward Bias Voltage (Vf) @1mA = 168 mV
Forward Resistance = 900 Kilo-ohm
Reverse Resistance = 900 Kilo-ohm
Maximum Current Handled (I-max) = 1A (assumed from the study of circuit schematic)
I am attaching two pictures of the diode here......
Here is the schematic diagram of the circuit where the diodes were used. I have shown the diodes as Schottky Diode in the schematic
My questions are as follows -
1. If it is a diode, then is it in healthy condition? (the circuit where the diode is attached is operating at its sub optimal condition, same reading of forward and reverse resistance confused me)
2. If it is a diode, is there any replacement can be suggested keeping the specification in mind? (it will be good if a Schottky Diode can replace this diode)
3. If it is not a diode then what is it and what can be the probable replacement of it?
Statement: This post is only the personal view of the author and does not represent the opinions of ALLPCB.com.