So you are saying that if the waveform doesn't make it through the digital circuit that would cause the processor to not function properly? -Sonavor

I do get a triangular type 3.975MHz signal from the oscillator (on one side, the other side was 5v I think). It isn't a nice, perfect triangle wave. I'll try and get a picture of it from the oscilloscope. But even so, I think there is a lot of evidence indicating the processor is dead. If so, I had to have zapped it with static when the board

Here is what I make of the Beomaster 6000 - 02 Module frequency counter circuit. The top frame is from the service manual schematic. The bottom frame is from tracing the paths on my BM6000 with the 74LS74AN flip-flop on the 8002562 mod PCB. Note that I didn't include all of the +5V filtering components on my schematic. I also didn't show all

Yeah, I see that now. I checked the oscillator and pin 1 of IC4 and there is a signal there. So with a clock signal going to IC4 and +5V power, the processor does not respond to the reset line. The display output is stuck on "P". I think IC4 is dead. Is the IC4 processor component still available or is this receiver now a spare parts unit

After removing the mod PCB with the 74LS74AN IC it looks like this is an official Bang & Olufsen mod. The little mod board has a number: 8002562 that fits the B&O PCB designators. I traced out where the wires went that attach to the small board. I will try and trace out the whole circuit to compare it to the old IC6 4-bit counter. It looks like

I have studying the unknown IC and the wiring it uses to the trace side. It looks like it is a replacement for IC6 (which is underneath it). IC7 and IC9 are 74LS93 4-bit binary counters (Decade Counter; Divide-By-Twelve Counter). IC6 is a 74LS393...slightly different? The replacement on the little home-made board is a 74LS74AN Dual Edge Flip-Flop. The

Here is a picture of the 02 Module microcomputer components front-side and back-side. Note: The back-side was photographed prior to replacing the IC8 component. I have a question about the unknown IC that is mounted on top of IC7 and IC6. That looks like some sort of retrofit mod. I don't see it in the schematic. The IC components I have identified

I think I have found the problem. The IC4 MicroComputer has no clock. IC4 pin 15 is supposed to be the timebase for the processor and it is dead. So without a clock nothing can change state. Here is a picture of the 02 Module circuitry involving the timbase and microcomputer. The red line is the connection that is supposed to be supplying the clock

I ran a test where I forced a reset - connected the base of TR5 (TP1) to the ground of the board. I was monitoring the reset line (Pin 39 of IC4) and saw it go to its "0" state. Nothing changed during or after the reset regarding the display. It remained at "P". Is there an output pin for IC4 that I can monitor to see if the reset

Another oscilloscope measurement at BM6000 power up. This is IC4 pin 40 (power) and pin 19 (fault switch).