--- In TekScopes@..., "Stan and Patricia Griffiths"
<w7ni@...> wrote:
Hi Andy,
Others may call me careless in my approach to firing up an old 555,
but I
would just plug it in and turn it on. It is pretty well fused and I
would
not expect any to blow anyway.
Probably will soon... Visual inspection shows nothing suspicious at
least... I could put the L and CA in, but now I feel obliged to at
least try to recalibrate or fix the D (was marked "broken" but seems
to work except that the gain is too low and the CMRR is lousy... Most
of the switch trouble vanished after applying some Tuner 600) ...
whoever designed it had money in the plugin extender business I guess
:) And something with the idea of operating a 500 series lying on its
side strikes me as very odd... same with sawing a hole in the table...
Are the connectors needed to make an extender cable as rare as those
in the 551/555 PSU cable are said to be? I noted the pitch is
different....
You can not test the power supply disconnected from the scope and your
reason is correct. It must have a proper load on it and, yes, you
will need
all plugins in place to put a proper load on the power supply. Both
timebases and both verticals.
On old Tek scopes, I never bother to reform the electrolytics. A
shorted
one is very rare and an open one will show up as too much ripple
somewhere.
I have never seen a shorted one do serious damage.
Over the past 46 years, I have probably turned on more than 1000 of
these
old scopes. I have lost count but I have at least six or seven
555's in my
collection . . . maybe more.
How many blew up? :)
I think when originally shipped from the factory, the serial number
of the
power supply will match the serial number of the mainframe.
Sometimes in
the field, mainframes and power supplies get swapped around, but I can't
remember any serious incompatibility problems, even with mismatched
serial
numbers.
Stan
_____
From: TekScopes@... [mailto:TekScopes@...]
On Behalf
Of faustian.spirit
Sent: Friday, December 29, 2006 12:16 PM
To: TekScopes@...
Subject: [TekScopes] Bringing up a 555
Hi all,
recently got my hands on a 555 System in unknown working condition
(probably been stored 10+ years). Can anybody here give me good hints
from experience on bringing this up without risking unnecessary damage?
Especially, can the PSU (these things are [expletive deleted] heavy!)
be bench-tested separately, or will there be unexpected effects
(underload)? I am aware that I will probably need to take out and
reform all the lytics....
What happens if I operate the unit with only one vertical, or only one
horizontal, or one only each...? Don't want to switch on and fry
everything in one session :)
I can work on the verticals with the 545B (doing so at the moment...
an extender cable would help with the Type D, it would.... I'd rather
avoid turning the scope on its side... oh well...)... BTW, does anyone
of the history buffs here know why a Type L has such a big honking
filter cap on board?
Oh, and BAMA does not have any 21A/22A schematics... oh well again...
And finally... what ARE the differences between different serial
numbers of the PSU? It is often claimed they are not
interchangeable... why?
Cheers,
Andy
[Non-text portions of this message have been removed]
