CBM 8032 - What does the startup chirp actually mean?

[daver2]

Hi Mike.

Wait until you get my PETTESTER image from dave_m and drop that in place of the EDIT ROM and see where that gets you.

You never know - the screen may burst into life and we start to track down the RAM faults...

Dave

[MikeP]

OK, Thanks Dave.

[daver2]

I see you are now mod. free...

Dave

[Hutch]

Hutch - good point.
...
Perhaps someone ought to post an audio clip of what a 'correct' PET 8032 chirp sounds like for comparison...

Dave

I happen to have a recording of the startup chirp from my 4032 that I did a while back for other reasons. I don't think the 8032 sounds any different.
https://drive.google.com/file/d/1D4Y...up6A25Chv/view

[MikeP]

OK, That's good, that is exactly what my 8032 sounds like

[dave_m]

Hi Dave,

I do have the tools to de-solder it and put in a socket, however I have only done that once before, so I think I would want to do it a few more times before I touch the PET's board. I have a dead C64 board that I can practice on.

Right, replacing a 40 pin part is not for the feint hearted. The real worry of course is putting too much heat into the PCB and lifting tracks, etc.

Let's hope that won't be necessary.

If it turns out you must replace, please consider sacrificing the part by cutting off all the leads close to the body of the chip before unsoldering leaving the pins sticking out of the board. Then you can remove one lead at a time with minimal heat and allowing the board to cool down between pins if necessary.

I was so terrified that I bought a Hakko Fr-300 Desoldering tool, but that is a too-expensive solution for very occasional use. It does a great job though of quickly removing all the solder from one pin at a time, and allowing one to save the part.

But solder wick or a simple solder sucker tool will do to clean the holes after the pins are removed.

[dave_m]

I happen to have a recording of the startup chirp from my 4032 that I did a while back for other reasons. I don't think the 8032 sounds any different.
https://drive.google.com/file/d/1D4Y...up6A25Chv/view

Thanks for posting. That will help Pet troubleshooters.

[MikeP]

please consider sacrificing the part by cutting off all the leads close to the body of the chip before unsoldering leaving the pins sticking out of the board. Then you can remove one lead at a time with minimal heat and allowing the board to cool down between pins if necessary.

Good idea, I would definitely feel better about taking that approach.

[dave_m]

Mike installed the Daver PETTESTE2KV4 EPROM but saw no screen activity at all. What would be the next step before replacing the 6545. I told him to check video sync signals but have not heard back. He uses a NOP Generator he could check all chip enables to the 6545, VIA and PIAs.

[MikeP]

HI Dave,

Sorry for the delay, got suddenly swamped with work.
After installing PETTESTE2KV4, I put the probe onto the CRT connecter (J7) again. Here are the results...

Pin 1: Active, but different from before, the probe shows Square wave <200Hz (Previously, it was Logic low with positive single pulses)
Pin 3: Low (same as before)
Pin 5: High (same as before)

You mentioned a NOP generator, but I have no knowledge of this.
Any thoughts on next steps?

Thanks
Mike