Re: CBM 3032 (PET 2001N-32), no video?

On Sat, Feb 24, 2018 at 3:02 PM, Sherry Haibara <v.castelli92@gmail.com>
wrote:

> Hello everybody! Just acquired a beautiful CBM 3032 (PET 2001N-32) today,
> and
> I'm already running into problems... Which was kind of expected, given its
> age!
> I managed to get a first successful boot of the machine with crisp video.
> BASIC initialised correctly and I was able to execute the classic "PRINT
> 'Hello world'" command with no problem.
> I then powered off the machine as I had to go away for a while. When I came
> back, I tried to turn it on but to no avail. I hear a slight humming noise
> from the power supply and sometimes, but not always, there seems to be a
> sound right after flipping the power switch that reminds me of degaussing,
> but I'm unsure if that's really what's going on.
> I don't hear any other noise, including the usual pitched noise that comes
> from CRT monitors when they're working. I also didn't hear any obvious
> "failing noise", like crackling or pops, and I didn't see any smoke coming
> from the machine. The fuse is fine. I can see the electron gun of the CRT
> from the back of the case, but it's staying off - while on the first
> successful power on I could see it glowing in orange.
> There doesn't seem to be any obviously burnt component on the main board,
> and I've also already reseated the ROMs. I checked the +5V voltage on the
> user port and it's correct. I also checked the voltage on the main power
> connector (J8?) and it shows -9 V, which as far as I understood should be
> the correct value. The +12V rail also seems fine.
> The symptoms seems a little suspicious to me, in that - if I'm not mistaken
> - if there was a problem with the ROMs or the CPU, I should at least get a
> garbage screen of some sort, which I'm absolutely not getting. There just
> doesn't seem to be any sign of life from the CRT.
> So my question is - where should I begin troubleshooting? I don't have an
> oscilloscope, but I do have a multimeter and some basic soldering
> experience. I'm not too comfortable with going around the high voltage CRT
> video circuitry, but I know a person that may be able to perform
> troubleshooting on that part.
> Thanks!
>


For now rule out the CRT and connections within.

I have the same system and had the same issue.  A bonk on the side of the
display brought my video back....It may be a loose connection moreso than a
CPU or logic issue..


Bill

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