Kenwood GE-87 disturbed signal on display

[dariuxzy]

Hi, I have this spectrum analyser Kenwood GE-87 (EQ) and the displays are disturbed by a dirty signal as you see in the attach video...

What could it be? I also attach the diagram wiring

[CapLeaker]

Open it up and post high resolution, straight shot pictures of the boards. I assume that is happening with nothing hooked up to the EQ?

[dariuxzy]

Open it up and post high resolution, straight shot pictures of the boards. I assume that is happening with nothing hooked up to the EQ?

No, the video is an example with the signal. With zero signal, nothing happens.

[dariuxzy]

assume that is happening with nothing hooked up to the EQ?

As you can see in the first picture, even the non-involved bands are slightly illuminated, like a ghost effect. In fact, only the bands/frequencies produced should light up, not all of them.

In the second picture (i take it online), there's an example of what it should look like, the frequencies/band not involved are totally black, there's no "ghost" effect

[CapLeaker]

Does it do that on both sides, Left and Right channels, or just one?

I would go over all the power supply rails and see that all voltages are correct. You can poke around with an oscilloscope and see what happens. Maybe with the FIP Driver IC's, a display issue, or maybe something has gone conductive, bad ground solder joint, etc.

[redwire]

Always start troubleshooting by checking the power supply rails. Don't slip with your probe.
+/-14V, +6.2V IC9, VFD -30V, +5.6V

It seems to be an analog drive and mux to the VFD. There are some VFD annunciators always on, so they are dim as well which might mean it's not the driver IC.
Is it my browser of that PDF schematic clipped off on the right side? I can't see the mux portion.