Tektronix T921 15Mhz scope, basic tools needed to test proper function? - Page 1
Forum section: electronics / testgear

author: WolfmanTech
author_rank: Contributor
timestamp: November 25, 2016, 05:50:03 am
content: Yup, me again! How should I go about testing proper function of this unit? This scope I have kept inside since I want it to keep working, but I don't have any proper probes for it ATM (I think... Might have 2-3 new-in-bag 1X/10X or some such somewhere! Maybe after some cleaning I'll find them again!). I have a coax cable with a BNC on it from a broken 1/10X probe of some kind, as well as the internal board from said probe, might be able to bodge it back together in an empty pen casing or something. Also have a pice of coax with BNC at one end and a mono audio jack at the other, was considering playing music through that, what do you folks think? Will also get pictures in next few days somewhere, with shiny new family camera. Thanks for reading!

author: oldway
author_rank: Super Contributor
timestamp: November 25, 2016, 04:50:24 pm
content: http://www.logwell.com/tech/oscilloscopes/index.html

author: David Hess
author_rank: Super Contributor
timestamp: November 25, 2016, 06:28:16 pm
content: Please rephrase in the form of a question.A function generator, AC voltmeter, frequency counter, and appropriate adapters are sufficient for checking basic operation and performance. Attenuators will be needed to check the more sensitive vertical ranges.

author: WolfmanTech
author_rank: Contributor
timestamp: November 26, 2016, 01:24:14 pm
content: Oldway- Yup, already downloaded the manual, just have to devote the time to sit down and read through it! May be easier if I print off a physical copy though. Thanks!David Hess- Aside from the question in the topic header? I can do that. I have an Elenco GF-8026 Function Generator (which needs some new alps switches and upper case half as well as possibly some electrical repair), I also have various Multimeters (one digital, a couple analog, and an EICO 232 VTVM that needs recapping), don't have a frequency counter (yet), and adapters should be fairly easy to come by or build my own. Depending on what I use the scope for/on, I may not need too fine a range, but we'll see. Thanks!Just to warn everyone, I'm a bit slow on getting things done (due to being depressed and unemployed), but I'll try to post new progress as often as I can!

author: WolfmanTech
author_rank: Contributor
timestamp: November 29, 2016, 07:46:58 am
content: Small update, I hooked it up to the radio and played music into it, no screen output on any settings.I could get a dot with the beam-finder, and it pulsated larger/smaller+brighter/darker with the music.It was at this point that I noticed the vertical position knob was missing and I can't recall whether this was the case when I got it or (more likely) I removed it at some point, possibly for repair.So, I'll have to see about finding that and the knob with the broken clear skirt, which I do recall removing for repair.

author: tautech
author_rank: Super Contributor
timestamp: November 29, 2016, 07:58:51 am
content: You might be able to find a replacement knob at Sphere, should be easy if you have the part #.http://www.sphere.bc.ca/test/tek-parts/tek-knobs.htmlTheir Tek troubleshooting guide is pretty much the universal guide for repairing CRO's.http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

author: tggzzz
author_rank: Super Contributor
timestamp: November 29, 2016, 09:45:23 am
content: Quote from: WolfmanTech on November 25, 2016, 05:50:03 amWhat's the pass/failure criteria? Don't forget the scope's spec is probably 2%, but see the manual.Timebase: either an accurate frequency generator (e.g. a DDS) capable of generating one cycle per horizontal division, or an inaccurate frequency generator and a frequency meter.Vertical: either a variable power supply or a fixed power supply and a potentiometer, plus an accurate voltmeter.Pulse response: a source with acleanrisetime less than 10% of the scope's risetime (presumably 23ns), plus appropriate terminations to avoid reflections. (Definitely not a scope probe with a 6" ground lead)