A500 black screen

[necronom]

I've just got a cheap oscilloscope (a FNIRST DSO153), and since I have an A500 (Rev 5) that was given to me about 20 years ago I thought I'd have another look at what might be wrong.

I was giving a red screen, but when I temporarily changed Denise I'd get a black screen. I've just cleaned Denise's legs and she's not giving a red screen now, so that part might be fixed. The screen gets a sync, so it's outputting a black screen.

So I'm now looking at other things. I tested the clock and instead of getting 28.375, I'm getting around 1.6MHz (it jumps slightly above and below).

Am I doing it wrong (I'm a beginner at this), or do I need a new oscillator?

I checked the clock pin (15) on the 68000, and that's showing about 2MHz. I'm seeing 5v on the Vcc pin, and I can see activity on the RAM chips, other CPU pins, Gary, etc.

[pipper]

Make sure your Oscilloscope is capable of capturing >28Mhz, otherwise you may just see phenomena just as this

[necronom]

I think that's it. I was wondering about that after posting this. I get the same on the 14, and 7 MHz pins. I think the limit is about 1.6.

I'm seeing continuity between the Odd CIA and the CPU (as mentioned here: https://www.retrosix.wiki/odd-cia-amiga-500 ), and I did swap all the chips from my working A500 several years ago and still had a black screen.

I've noticed that after pressing the caps lock key about 12 times it's filled the buffer then doesn't respond anymore, so it's not getting out. Resets all seem to work okay. I've seen the reset signals getting to various chips.