I've been tied up with other things this week and finally got a chance to look at the Beomaster 6000 volume problem tonight. In the attached picture I have put the related schematic pieces for the volume control. To the right is a table of step and voltages from the service manual that show the approximate voltage levels for each step of the volume

Okay. My plan now is to first trouble-shoot the volume control problem that popped up. I have to have that working. Once that is solved I think I will run through the tuner checks described in the service manual.

I agree. I don't want to rock the boat. The 74 flip-flop that is in there right now is the last one I had tried before when the display was not working. So adding the resistor did something it likes. The only visual thing I can see is that it interacts with what is already there and the IC4 side of the resistor has a clean, square signal. If you

So you are wanting me to try something like a 100 ohm resistor in parallel with the 1k or replace the 1k with a 100 ohms and check that result? I guess now would be the opportunity to do that. I think this Beomaster is going to insist I go through every type of adjustment on this project. After I lowered the lid and have just the area of the 02 Module

Tuner performance is much improved! I tried to retrace my steps back when I messed with the tuner board. What I had tried to do back then was verify the 08TR2 transistor and see if I could measure the FM reference signal from that circuit. Of course I realize now that was dumb because there wasn't anyway my 25MHz scope would see anything and even

I performed the next step....and I might be back in business. One thing you can see on the previous postings with the oscilloscope pictures is that the scope probe on the side of the 1k resistor that goes to the IC4 pin 38 is cleaner than the scope probe between the 1k resistor and the flip-flop output. I have both probes set to X10 range so they should

I made another discovery. In thinking about how I am substituting the Beomaster tuner board FM reference to the 02 Module prescaler (so it can prepare the signal for measurement), I really have no idea what the Beomaster is expecting in terms of amplitude and load. I removed the ammeter from the circuit and have the flip-flop output now going to the

Well, this is kind of interesting. While I had the test setup with the signal generators, the ammeter, oscilloscope, 1k ohm resistor and the flip-flop to IC4 pin 38 wire opened up, I decided to see what happens if I removed the TTL/CMOS signal generator (which as been driving the IC4 pin 38 through the 1k ohm resistor) and in place of that signal generator

I decided to check on what frequency I have to set the TTL clock signal on the TTL/CMOS signal generator to get a display of 80 on the Beomaster 6000. It was around 178KHz. Here is the picture. The CH2 (yellow) probe still shows that the 80MHz FM signal through the prescaler and dividers produces a clock of around 156KHz. So something is off there.

I forgot to mention that I also left the TTL/CMOS signal generator on for over an hour and the display did not freeze up. It still moves when I change the frequency of the square wave. Back when I tried the higher output flip-flop the display worked for a while, then eventually stopped working. I agree with Mika about needing to get a signal coming