Removing PVA from a CRT

Alan Perry aperry at
Mon Nov 19 19:12:38 CST 2018

On 11/19/18 1:48 PM, Paul Koning wrote:
>> On Nov 19, 2018, at 4:01 PM, Alan Perry via cctech <cctech at> wrote:
>>>     Finally, a VR201 specific question. I booted the Rainbow over the
>>>     weekend and, looking through broken-down PVA, I could see the
>>>     Rainbow has booted and I could enter DOS commands. I could also
>>>     see white retrace lines. What is the likely cause of that on a
>>>     35-year-old CRT?
>>> Pics?
>> Here is an attempt to use Facebook for image hosting here. If it doesn't work, I will put the image up on a real image hosting site.
>> alan
> It looks like you turned the intensity up so far that the retrace didn't get blanked fully.  Not much choice about that given the bad screen, I suppose.

Actually, the intensity is turned all of the way up because that is 
where it happened to be when I connected everything up. I was so focused 
on whether DOS had booted that it didn't even click in my head that I 
could adjust the monitor to make it easier to read. I didn't notice that 
I had things turned all the way up or even notice the retrace lines 
until later when I looked at that picture.


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