Re: TEMPEST update

It's starting to sound like a bad focus/screen pot assembly OR an
overload on the focus line. Either way the output of the screen pot is
dropping.

If you put a meter on the output of the screen pot (grid 2 of the CRT)
you'll see the voltage drop when the picture goes dim (make sure you use
a meter that can handle as much as 400 volts).

vernimark@vernimark.com wrote:
> Hi,
> Following Roger suggestions I did new experiments.
> turning focus pot clockwise I've the right focus but
> brighteness drop down in few seconds, then if I turn focus
> pot counterclockwise screen loses the focus but the
> brighteness grow up.
> in order to have the right focus, i have to turn clockwise
> the focus pot near the end of its run.
> :(
> What can I test in order to understand which component
> doesn't work in the right way?
>
> Thank you,
> Marco
>
> PS Colin, did you receive my email about G05?
>
>
>
>
>
>
> vernimark@vernimark.com wrote:
>
>> Hi all,
>> I tested HV with my HW probe and I can understand that HV
>> goes from 19.5 to 20.1 kv. when HV reach 20.1 then the
>> screen become dark.
>>
>> Is it normal that during normal operation I've a range
>>
> (19.5
>
>> - 20.1 Kv) so large?
>>
>
> Seems like a reasonable range to me. The voltage is going
> up because
> you're loosing brightness, not the other way around.
>
> You're loosing brightness because, most likely, the screen
> supply from
> the screen/G2 pot is dropping OR grid 1 is drifting negative
> due to a
> bad connection.
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Received on Tue Jun 10 06:47:28 2008