1. TekScopes@groups.io
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Re: Oscilloscope Operator Training Kit - TNGTDS01

ebrucehunter
 

Thanks Brian. 

Searching online for information on the Velleman boards, I see that Jameco https://www.jameco.com/z/EDU06-Velleman-Oscilloscope-Tutor-Kit_2175568.html offers them for $29.99 .  Although inexpensive, the signals these boards generate are generally available from instruments on the bench top.  My interest in the Tektronix board is for the glitched signals it offers as a way to demonstrate the capture and storage capabilities of these DSOs for catching transient waveforms.  I have never owned a storage scope before, but on several occasions could sure have used one. 

Bruce, KG6OJI
Re: SC502 With Display Issues

Stephen
 

On Wed, Aug 19, 2020 at 05:48 AM, Dave Wise wrote:


To replace 2N3565 in the SC502 power supply, BC639 is better than 2N2222A,
100MHz vs 300MHz. Under a dollar at Mouser. But the best choice is KSC1008.
It's only 30MHz - perfect to avoid oscillation - and even cheaper. Mind the
pinout.
Ooh ok. Now I understand. You were talking about oscillation. This is the thing I didn’t grasp before from your previous post. Thank you for clearing that out. Do you think that could bean issue in the low power supply section?

On a side note, I’m trying to find parts that are readily available at my local shops because it’s just a 20min ride from my place.
And I know that if something fails, I can easily go and get them without having to order, and wait for (sometimes) a week to 10 days to get them. Yes, it’s terrible, I know.
BC639 is available. Not the KSC1008. I’ll try that.
Re: SC502 With Display Issues

Dave Wise
 

To replace 2N3565 in the SC502 power supply, BC639 is better than 2N2222A, 100MHz vs 300MHz. Under a dollar at Mouser. But the best choice is KSC1008. It's only 30MHz - perfect to avoid oscillation - and even cheaper. Mind the pinout.
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Stephen via groups.io <stephen.nabet=gmail.com@groups.io>
Sent: Wednesday, August 19, 2020 8:00 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] SC502 With Display Issues

On Wed, Aug 19, 2020 at 03:49 AM, Ke-Fong Lin wrote:

I just don't like the idea to spend that much money for these "nothing
special" transistors, which should be replacable by equivalent ones.
I know Mouser ships to Paris. There is even a Mouser France, or Farnell, and many others like RS Parts.

But this my point exactly. It’s just not financially worth it to pay $5 for a transistor when other alternatives work just as well. I can locally buy 7 to 12 2N2222A or BC639C for the price of just one 2N3565 (without shipping)...
Re: Tek 465: CH1 No signal, CH2 signal reads a fraction of input, V Pos distorts signal

Greenpitu@...
 

Hi Roger,

I have the IC based Y amplifier.

I will proceed today with your instructions.

Thanks a lot!
Luis
Re: Little ceramic trimmer caps that always break... A fix.

Stephen
 

On Wed, Aug 19, 2020 at 04:54 AM, Carsten Bormann wrote:

(Earlier in my life, I experienced the eyesight of my father deteriorate over
a span of a decade. Something I wouldn't wish my worst enemies, if I had any
to wish something bad onto.)
My father has ARMD (81yo), so I should be careful too.

Let me just say that your posts are highly enjoyable on so many levels.
Any nits don’t distract from that.
I concur!
Re: Little ceramic trimmer caps that always break... A fix.

Carsten Bormann
 

On 2020-08-19, at 17:35, Chuck Harris <cfharris@erols.com> wrote:

my brain fills
in whatever word it can think of that fits the space.
I think that is a problem fundamentally every proofreader has.
Confirmation bias in the small.

My retina specialist says not to worry, it will only
get worse... especially if he tries to fix it.
(Earlier in my life, I experienced the eyesight of my father deteriorate over a span of a decade. Something I wouldn't wish my worst enemies, if I had any to wish something bad onto.)

I know you want perfection out of each of us, but I for
one, am not up to it anymore.
Please don’t take my comments as personal criticism.
They were directed to the list (or I would have sent them personally to you).
And, yes, I do like some attention to detail; perfection is not a very useful goal for informal messages like these...

I do this gig for fun, and it is becoming less and less
fun as the nits get picked.
Let me just say that your posts are highly enjoyable on so many levels.
Any nits don’t distract from that.
(Too bad that telling more about your tractors would be off-topic on this list.)

Grüße, Carsten
Re: Little ceramic trimmer caps that always break... A fix.

Chuck Harris
 

Well, the key to good proofreading is to be able to see
the mistakes. And since my retina was damaged by my
vitreous humor pulling away... a present I got for my
53rd birthday..., I can't do that very well anymore.

I see a tiny magnified spot right at the center of vision
on my right (dominant) eye, that darts around as I read,
or inspect things.... So, when I read, I cannot always
tell the difference between a "n" and an "h", or an "i"
and an "l", or an "o" and a "b" or "d", g", ... without
serious study.

It's worse, of course the smaller the print. And, my brain,
and good vocabulary isn't helping me much, as my brain fills
in whatever word it can think of that fits the space.

My retina specialist says not to worry, it will only
get worse... especially if he tries to fix it.

I know you want perfection out of each of us, but I for
one, am not up to it anymore.

I do this gig for fun, and it is becoming less and less
fun as the nits get picked.

I think I'll go play with my tractors...

-Chuck Harris

Carsten Bormann wrote:

On 2020-08-19, at 14:58, Chuck Harris <cfharris@erols.com> wrote:

FG504 can become FG540, Chuck can become CHuck…
WElcome to the clbu.

As was pointed out, it is useful to get model numbers, part numbers, measurements etc. right, so as Barry reminded us, proofreading is king for those.

(And wrt to the measurements, if someone gives a timebase setting in nanosiemens per division, I cringe, but maybe it’s normal that a lot of people simply don’t know how to type measurements and any correction will be seen as nitpicking, so there is no learning either.)

Grüße, Carsten
Re: SC502 With Display Issues

Stephen
 

On Wed, Aug 19, 2020 at 03:49 AM, Ke-Fong Lin wrote:

I just don't like the idea to spend that much money for these "nothing
special" transistors, which should be replacable by equivalent ones.
I know Mouser ships to Paris. There is even a Mouser France, or Farnell, and many others like RS Parts.

But this my point exactly. It’s just not financially worth it to pay $5 for a transistor when other alternatives work just as well. I can locally buy 7 to 12 2N2222A or BC639C for the price of just one 2N3565 (without shipping)...
Re: Last Call - Tek 222/224 Battery Charger Project

Henry Martinez
 

Sorry if I'm late to the party,
Just wanted people to know the kits are still available on eBay and they work great. I just put one into my Tektronix 224 and it is performing exactly as advertised. Thanks Jeff for pulling this all together.
Re: Oscilloscope Operator Training Kit - TNGTDS01

Brian
 

Only available training board i know of. 
https://www.amazon.com/dp/B00BY8LJA2/ref=cm_sw_r_cp_apa_i_3PQoFb224SN58
On Sat, Aug 15, 2020 at 7:37 PM, ebrucehunter via groups.io<Brucekareen=aol.com@groups.io> wrote: Roy,
Thanks,
Thanks; looking in the appendix; I see there's a comprehensive description of the generated signals included there.  While the 465 is a great scope,I am looking forward to the increased bandwidth and digital displays of frequency, voltage, and timing offered by digital models.  My expected applications will include both analog and digital signals.  Although most of the test signals provided by the training board can be quickly generated with instruments on the bench, the Tek training module seems to provide a rapid, and rather complete, introduction to these DPOs for folks like me that spent the latter portion of their career in administrative, rather than technical positions.
Bruce, KG6OJI
2246A Power supply failure turning on / off

JorgeTop
 

Hi!

Some time ago I got a used 2246 oscilloscope which was working quite well until recently. First it began to show a single point on the screen and then it would return, or you just had to turn it off and turn it on again.

Soon after, it started to cycle on and off and sometimes I needed to turn it off for a moment and turn it on again to get it working again.

Now it kept turning on and off cyclically without stabilizing. So far, I have changed things like some electrolytic capacitors (I read right here that it is a common fault), however I have not found all. I have also changed zener diodes and some transistors without success.

With the service manual I have tried to measure some points however since it turns on and off the voltage is erratic. I have not yet found a similar power supply for sale so at the moment it is not an option and I would like to be able to repair it.

Any suggestion?
Re: Little ceramic trimmer caps that always break... A fix.

Carsten Bormann
 

On 2020-08-19, at 14:58, Chuck Harris <cfharris@erols.com> wrote:

FG504 can become FG540, Chuck can become CHuck…
WElcome to the clbu.

As was pointed out, it is useful to get model numbers, part numbers, measurements etc. right, so as Barry reminded us, proofreading is king for those.

(And wrt to the measurements, if someone gives a timebase setting in nanosiemens per division, I cringe, but maybe it’s normal that a lot of people simply don’t know how to type measurements and any correction will be seen as nitpicking, so there is no learning either.)

Grüße, Carsten
Re: SC502 With Display Issues

Ke-Fong Lin
 

Just out of curiosity, Mouser.com in the US does not ship to Paris? I know
there is a Mouser.eu, but it should be easy to get around that limitation if
need be.
Mouser ships to Paris and any place in Europe. It's actually my favorite source for electronics component.
Free 2 days fedex for any order above 50 euros, they handle import/custom fees, so you just pay on additional 20% sales tax, which is the usual amount in Europe.
Vast choice of components, only a few times I had to order stuff on digikey.
Prices are very good, makes me wonder why there are people buying parts on ebay to make marginal savings, when you can buy from an authorized dealer.

Only drawback is that you have to "batch" an order for 50 euros, otherwise shipping & handling is 20 euros.
So if you have a single repair and no other project along, that's certainly not economical.

My main issue with these transistors from Central Semi, is that they are 4 or 5 euros a piece.
There are a few other companies (Rochester electronics) specializing in these (expensive) obsolete parts (used by aeronautics, medial, and military).
I just don't like the idea to spend that much money for these "nothing special" transistors, which should be replacable by equivalent ones.
Re: Little ceramic trimmer caps that always break... A fix.

Chuck Harris
 

Perhaps, but Dennis is a geezer too, and there is nothing
we have said that he doesn't already know all too well.

I'm done.

-Chuck Harris

pdxareaid wrote:

we are going to get slapped for this geezer fest, but now in my late sixties i exhibit all of the above annoyances when typing with
one addition. i am basically a touch typist but developed some bad habits over the years (coding does that) and tend to look at the keyboard when composing. i find i
will use a word like "composed" or "composing" correctly in my mind but in reading what i typed, i will find "compose".
lately on the fly grammar checking has been flagging some of these.
as far as dexterity, i have the same problem with the guitar. the fingers are not working like they used to.
We're all like old electrolytic caps. If we don't blow our tops, someday we'll eventually leak out. Regular use does stave off
an early demise.
DID vs DIDN'T: yes the sign bit gets a bit sticky at times too.
i have no problem with the shift key, however, as is plainly obvious in this posting :-)
Re: Little ceramic trimmer caps that always break... A fix.

Chuck Harris
 

No, it's age.

We have the benefit of self introspection, and a memory that
can remind of us of how things were, and how they aren't anymore.

My heart and lungs are good, but I cannot run a 4 minute mile
anymore.

For a while, you can brush these things off as just little nothings,
but at a certain point, for me, it became clear that changes were
afoot.

-Chuck Harris

Stephen wrote:

I’m mid 50’s and I just realized I missed a word on my last post. I meant “when he DIDN’T find it”, but wrote “when he DID find it”... See? It’s not only age, it’s also that we’re trying to do things faster and faster, in order to keep up with a world that constantly demands speed and responsiveness.
Re: Little ceramic trimmer caps that always break... A fix.

pdxareaid
 

we are going to get slapped for this geezer fest, but now in my late sixties i exhibit all of the above annoyances when typing with
one addition. i am basically a touch typist but developed some bad habits over the years (coding does that) and tend to look at the keyboard when composing. i find i
will use a word like "composed" or "composing" correctly in my mind but in reading what i typed, i will find "compose".
lately on the fly grammar checking has been flagging some of these.
as far as dexterity, i have the same problem with the guitar. the fingers are not working like they used to.
We're all like old electrolytic caps. If we don't blow our tops, someday we'll eventually leak out. Regular use does stave off
an early demise.
DID vs DIDN'T: yes the sign bit gets a bit sticky at times too.
i have no problem with the shift key, however, as is plainly obvious in this posting :-)
Re: Little ceramic trimmer caps that always break... A fix.

Stephen
 

I’m mid 50’s and I just realized I missed a word on my last post. I meant “when he DIDN’T find it”, but wrote “when he DID find it”... See? It’s not only age, it’s also that we’re trying to do things faster and faster, in order to keep up with a world that constantly demands speed and responsiveness.
Re: A possibly sick 7904A

Chuck Harris
 

Indeed, but that didn't stop the tek engineers from trying
to make FOCUS a universal control that worked equally well
on both beams, and the readout.

They failed, of course, but got a pretty good compromise that
worked on most normal intensity levels.

You have to get the internal controls adjusted right, though...

-Chuck Harris

teamlarryohio wrote:

If focus stayed constant irrespective of beam intensity, there would have been no need for a front panel focus control.
-ls-
Re: SC502 With Display Issues

Stephen
 

On Wed, Aug 19, 2020 at 02:20 AM, <tekscopegroup@miwww.com> wrote:

|
Just out of curiosity, Mouser.com in the US does not ship to Paris? I know
there is a Mouser.eu, but it should be easy to get around that limitation if
need be.
They probably would ship to Paris. But honestly, it’s not financially worth it at all.
It works just fine with the 3904’s, and I could put some higher current handling ones like the 2222A if need be.
but so far it’s been functioning perfectly.
Re: A possibly sick 7904A

teamlarryohio
 

If focus stayed constant irrespective of beam intensity, there would have been no need for a front panel focus control.
-ls-
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