Scope Choice for Vintage Computer Troubleshooting

From: Tothwolf <tothwolf_at_concentric.net>
Date: Fri Oct 11 00:09:00 2002

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.

> 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 :)

> Indeed. And on some of the more complex 'scopes, like my 555, there's a
> little spool of the special solder (it contains about 3% silver, like
> the stuff now used for SMD assembly) mounted inside. To be used for
> repairs, of course.

My 561 also has that little spool of solder. I'm not sure if I saw it in
one of the modules or if it was inside the main chassis. There was a
warning label near the solder that indicated solver bearing solder was
required to prevent damage to the silver-ceramic bond.

> Unlike modern instruments, you were expected to repair the 500 series.
> Not that they need it very often.

I need to eventually track down manuals for the 561 and it's X/Y modules,
but I've just got way too many projects right now ;)

Do you know if the 561 will require genuine Tektronix probes like the
newer 60MHz analog Teks I mentioned before?

Thinking about it now, I believe I also have a 502 and 502A buried
somewhere, currently in unknown condition.

-Toth
Received on Fri Oct 11 2002 - 00:09:00 BST