[ARC5] Scope Question

[Tom Lee]

Most of my scopes arrived with no trace. I own over 100 (possibly as 
many as 200); don't ask why. Of those, only two have had anything 
seriously wrong with the HV supply -- one Tek 465, and one Telequipment 
something-or-other. The 465 had a bad multiplier, which I was able to 
replace with a modded multiplier from an old color TV. Not pretty, but 
completely functional.

I love older analog scopes precisely because their general lack of 
unobtainium parts gives me a fighting chance at repairing them. With 
modern scopes, if anything other than the power supply is the problem, 
they're often basket cases.

I have also fixed many 22xx scopes (the switching supply seems to have 
many failure modes). I am not sure why someone would consider those 
particularly hard to repair. Except for the front end, everything is 
pretty accessible.

--Cheers
Tom


-- 
Prof. Thomas H. Lee
Allen Bldg., CIS-205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu
650-725-3383 (public fax; no confidential information, please)

On 3/20/2018 2:12 PM, K5MYJ wrote:
> When I buy old scopes  won't buy one that does not show a trace. 
> Replacing the HV(CRT) power supply can be difficult and expensive.
>
> I've been warned that the Tek 22XX and 24XX scopes can be difficult to 
> repair.
>
> I also find early HP digital test equipment can be a CRAP SHOOT! And I 
> do understand why, The earlier analog stuff is usually not a big problem.
>
> Bob Macklin
> K5MYJ
> Seattle, Wa.
> "Real Radios Glow In The Dark"
> ----- Original Message ----- From: "Kenneth G. Gordon" 
> <kgordon2006 at frontier.com>
> To: "Michael Hanz" <aaf-radio-1 at aafradio.org>
> Cc: <Arc5 at mailman.qth.net>
> Sent: Tuesday, March 20, 2018 9:59 AM
> Subject: Re: [ARC5] Scope Question
>
>
> On 20 Mar 2018 at 12:16, Michael Hanz wrote:
>
>> I've seen that procedural step sometimes used on the later solid state
>> scopes to reduce the chances that you will start a measurement with the
>> sensitivity switch set at, for example, .01v/CM, when you are about to
>> measure say 800v p-p. Transistors don't like that. It's a last "do you
>> really want to do this?" check before you make the measurement.
>
> Yes. That makes complete sense, but then why didn't the manual follow 
> that with advice to
> 1) set the vertical sensistivity to "such and such", then
> 2) set the input to AC or DC to take the measurement.
>
>> The
>> older tube input scopes are pretty immune to such errors.
>
> Yes.
>
>> Or, it may be a manual error, as you suggest.:-)
>
> Yes. Well, I am also working on a couple of Tek scopes, a 2465B and a 
> 2467B (which had
> been left out in the rain for at least a year before I got it), and I 
> am finding periodic small
> errors in the documentation.
>
> BTW, the 2467B works just fine after I let it dry out for a month or 
> two. The 2465B doesn't
> "work" at all, but it appears that the trace-blanking is locked on 
> permanently.
>
> Ken W7EKB
>
> ---
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