The only think I can think of that is "special" about
Tek probes is the 1X/10X switch grounds the small ring
around the BNC connector, so that the unit will switch
and the appropriate 1x/10x lamps will light
automatically. Other good quality probes rated to the
response of the scopes work fine other than that
feature.
--- Tony Duell <ard(a)p850ug1.demon.co.uk> wrote:
 
 On Fri, 11 Oct 2002, Tony Duell wrote:
 > RM-xxx is the Rack Mount version of the xxx. So 
 the RM503 is a rackmount
  > 503 (IIRC, that one doesn't take
plug-ins at 
 all), the RM561 is a
  > rackmount 561 (later, smaller 500 series,
taking 
 plug-ins for both X and
   Y).
 Right, I knew about the RM-xxx meaning rackmount, 
  but I wondered if the
  500 series might have shared a common design.
 Some did. The 53x, 54x, and (most of) 55x have
 similarities in mechanical
 construciton (and circuitry to some extent). The 53x
 were the
 low-bandwidth models and the 55x dual beam, of
 course. All took the same
 plug-ins.
 The 58x (100MHz bandwidth, with a beautiful CRT with
 distributed
 deflection plates and a built-in delay line) were
 similar but took
 different, higher-bandwidth plug-ins. You could use
 the plug-ins from the
 53x, etc if you had a type 81 adpater between the
 plug-in and the 'scope.
 The above series had plug-in Y preamplifiers, but in
 general the
 timebased (and X deflection system) was built into
 the 'scope. There are
 certainly 2 exceptions to that -- the 536 took 2
 'normal' plug-ins (one
 for each of X and Y -- there was a thing called a
 type T which was a
 timebase unit) and the 555 has plug-in timebases,
 but they're special
 modules, not interchangeable with anything else. The
 only reason they
 were plug-ins was to allow access for repairs,
 really.
 The 56x were the odd ones. The insturments
 (non-rack-mount versions) were
 a lot smaller than the other series. The plug-ins
 were totally different,
 and all 'scopes took plug-ins for X and Y.
 > If the brightness control section is still good, 
 is there any reason not
  > to bypass the switch on the back of it, and
just 
 use an external
  > double-pole switch in series with the mains
 input? It would at least
   give you
a working 'scope... 
 Thats kinda how I found it when I got it...except 
  that the wire that was
  used to jumper the switch had obviously gotten
 very hot. Since the wire
  had been tack soldered across the terminals, one
 side seems to have acted
  like a fuse. I imagine the power switch was
 probably damaged due to the
  same problem. Oh, and I found that someone had
 installed a much higher
  rated fuse in the scope than should have been
 installed... Needless to
  say, there is something else that needs to be
 fixed in the 'scope too :)
 Hmm.. Why do idiots persist in over-rating fuses
 when they blow???
 OK, you've probably got a serious short somewhere in
 the PSU section. A
 smoothing capacitor if you're lucky, shorted turns
 on the transformer if
 you're not. Tekky used to claim that these
 transformers have a lifetime
 warranty, but apparently their definition of
 'lifetime' is not the same
 as mine -- you will not get a free (or any other)
 replacement now :-(.
 Do you know if the 561 will require genuine 
 Tektronix probes like the
  newer 60MHz analog Teks I mentioned before?
 I wasn't aware _any_ Tektronix 'scopes needed
 special probes (apart from
 the plug-ins that came with integral probes). On
 later 'scopes the probes
 will do things like set the on-screen readout, but
 that doesn't apply to
 the 561.
 Provided the probe can match the input impedance of
 the 'scope, it will
 work fine.
 -tony
  
 
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