Tonight was a little better. Earlier today I found out that another option is to use a different version of the flip-flop chip...one with better drive capabilities. So I ordered a couple 74ACT74 and 74HCT74 flip-flops from Mouser (didn't have time to drive over there). They are scheduled to mail out tomorrow so, hopefully, they will arrive on Saturday

It will have to be tonight before I can measure it again but when I made the earlier measurements I did cycle through to the ground coupling to check where that line was. I will need to re-measure the other logic signals to know where they all are. Last night though I was just measuring the 74LS74AN chip and noticed the offset. That offset is from the

When looking at the measurement on the oscilloscope, if I set the probe input to use DC coupling then the clock signal inputs I see on pin 8 and 9 shift up about 3.5v on the display. When I set the probe to use AC coupling the DC offset is ignored and I only see the clock signals on the display. I was just wondering if that is what is expected.

That is correct about never seeing a real working frequency display on this unit. When I first got the 6.5v problem fixed where the Beomaster would start working (prior to the issues with the reset line), I briefly was able to tune stations and see the proper value in the display. But just like now, that only lasted a short bit before the display started

No real breakthroughs tonight but I did get some additional information. As Mika suggested I rechecked the wiring on the 8002562 mod board. I didn't find anything wrong but with a lack of solid leads I decided to rewire it (carefully and with anti-static protection). When I was done my first attempt was to pull the P26 connector at the 08 tuner

Good idea mika. For this test I used the FM signal generator again to supply a 90MHz signal to the J7-2,1 connector on the 02 module. I also put the original 74LS74AN IC back in and verified that it too had too low a Vout on pin 9. It did. The complement Vout, Pin 8, is a nice 4v p-p square wave though. So I removed the wire from pin 9 to the processor

Did a quick test and got an answer. After removing the 74LS74AN chip (B&O mod IC) from the socket, I injected a 3.5v square wave in the socket - pin 9 (output to the IC4 pin 38 frequency counter input). That gets the display working again! I can vary the frequency on the generator and monitor it on the Beomaster display. Whew! So here is where I

I am wondering about the clock signal into the processor frequency counter input (2IC4 pin 38). In that last picture of the scope measurement the 2IC4 pin 38 signal looks like it has the correct frequency for the 90MHz signal being generated (to simulate the tuner). The voltage level looks like it could be a problem though. The IC that sends that signal

I should have shown the signal generator lines in my picture. They were applied across P7 pins 1 and 2 going 2L14 to simulate a signal coming in from the tuner board. I am brain dead though...The reason I am never reading a signal from the tuner board is because I only have a 25MHz oscilloscope. I put that out of mind thinking that I wasn't going

Here is what happened today - A step or two backwards. At the start of the day the Beomaster was operational except for the FM tuner display and the volume level lamps not being bright enough. At the end of the day the FM tuner is out of alignment. To take care of the lamps I ordered replacements from Dillen. I also ordered some other LEDs to try out