Date   

Re: Choosing the right replacement cap

adesilva_1999@...
 

The latest is that a kind soul on EEVblog has decided to send me two of those Attn. Cap blocks from his old collection of parts. I have to pay only the postage. Such nice guys are still around! Should have it late next week.

Meanwhile, I will poke around some more and see what else I can find before placing an order for a few caps I like to replace. Have a great Thanksgiving everyone!


Re: worst condition Tektronix scope?

Dave Peterson
 

I had no idea: I thought the 475 was the one with the vertical input to the right of the screen. I had to go and check myself - have I been calling my scopes 465 by mistake!? No, they really do look identical - the 465 and 475. What's the difference between 465 and 475? Is the 465B and the 475A the same too? Is the difference bandwidth? Doesn't seem that it'd be release date as the 465B seems more advanced than the 465. I seem to recall we preferred the "B" and thought it was the newer more advanced model.
Learning engineering minutia AND history and product lines.Dave

On Thursday, November 26, 2020, 11:16:48 AM PST, Jeff Dutky <jeff.dutky@gmail.com> wrote:

Here is a parts scope I got from eBay https://groups.io/g/TekScopes/album?id=257163

Most of the knobs are smashed, it's been spattered in something gray that won't come off with soap or IPA, but when I powered it up it appears to be in almost perfect working condition (I say "almost" because I didn't really try to test it in any complete way, just fed the cal signal into both channels, twiddled what knobs could be twiddled, and tried the different button positions. Everything I tried seemed to be working perfectly).

I'd like to turn this from a parts scope into a second bench scope, but I'll need to completely replace the front panel and knobs, unless I can find a way to clean them up. Whatever is spattered all over it won't wash off with either detergent and water or IPA, and I haven't tried any stronger solvents or vigorous brushing. Any advice on how to clean the front panel and remaining knobs, techniques or safe solvents, would be appreciated.

-- Jeff Dutky


Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.

Don Bitters
 

Have you tried the VCF organization (Vintage Computer Fair)? They have branches in the US - NE, SE, SW, West, and Midwest, also Europe. I have been to the Midwest one and prices were pretty reasonable - not $1200, more like $50 -$250 - for working items. I would contact them for your closest org., and ask the moderator whom among their membership might have what you are seeking. I saw a working PDP11, many Commodores, TRS-80’s, IBM’s, Altair’s, IMSAI’s, MAC’s, etc. Plus you will have access to people that can readily fix all of the above, and have all of the required accessories needed to make them work.
Don Bitters


Re: worst condition Tektronix scope?

Carsten Bormann
 

Here we go…

https://dilbert.com/strip/2001-01-02

Grüße, Carsten


Re: Delay Time Position Vernier

 

Dave,

I'd also be interested in people's practical experience using both the delayed timebase and the vernier control.

The oscilloscope operators instruction manuals for the 475 and 2213 (as well as The XYZs of Oscilloscopes) have some discussion of how to use the delayed timebase to perform different measurements, but I've had trouble wrapping my head around the discussions without concrete examples to try out myself. Here is the discussion on page 29 from The XYZs of Oscilloscopes (1981, for the 2213, which has neither a full dual timebase nor a vernier for the delay):

"Dual time base scopes offer you all the measurement capabilities of single time base instruments, plus:

• convenient comparisons of signals at two different sweep speeds
• jitter-free triggering of delayed sweeps
• and timing measurement accuracy of 1.5%

Most of this increase in measurement performance is available because you can separately control the two sweep speeds and use them in three horizontal operating modes. These modes — in a 2215 — are A sweep only, B sweep only, or A intensified by B as well as B delayed. The HORIZONTAL MODE switch controls the operating mode and two SEC/DIV switches — concentrically mounted on a 2215 — control the sweep speeds.

When you use the ALT (for alternate horizontal mode) position the HORIZONTAL MODE switch, the scope will display the A sweep intensified by the B sweep and the B sweep delayed. As you set faster sweeps with the B SEC/DIV switch, you'll see the intensified zone on the A trace get smaller and B sweep expanded by the new speed setting. As you move the B DELAY TIME POSITION dial and the change where the B sweep starts, you'll see the intensified zone move across the A trace and see the B waveform change."

My father replaced a 475 (which has a vernier) with a 2213 (which has merely has a blank knob) as his daily use scope in the early 80s, after having used the 475 for 6 or 7 years. He had the choice between the 2213 and the 2215 (which has a proper dual time base and a vernier to control the delay) so I can only conclude that he didn't feel that those features were useful in his work (he was a service technician working on laboratory mass analysis equipment — mass spectrometry, spectroscopy, chromatography — and the computers that were connected to that equipment).

-- Jeff Dutky


Re: worst condition Tektronix scope?

Colin Herbert
 

My awful tryping (sic) strikes again. I should have written "garden shed near the river Trent?
I don't really see it as very ornamental either, even if cleaned up, it really is a mess. I don't think I would take it away if the seller gave me the money he is asking for it.
Colin

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Colin Herbert via groups.io
Sent: 26 November 2020 19:25
To: TekScopes@groups.io
Subject: Re: [TekScopes] worst condition Tektronix scope?

There aren't many tropical jungles in Stoke-on-Trent, but maybe it was stored in a garden shed neat the river Trent? The price is well-above any sane person would pay, surely?
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Sparky99
Sent: 26 November 2020 18:27
To: TekScopes@groups.io
Subject: [TekScopes] worst condition Tektronix scope?

Just saw this on ebay in the UK : https://www.ebay.co.uk/itm/Tektronix-Type-545-Oscilloscope-Vintage-Antique-Collectors/353290325095?hash=item5241be8c67:g:-GYAAOSwBPZfvDOx

Looks like it's been stored in a tropical jungle for a few years!

Anyone got any worse examples?


Re: worst condition Tektronix scope?

Colin Herbert
 

There aren't many tropical jungles in Stoke-on-Trent, but maybe it was stored in a garden shed neat the river Trent? The price is well-above any sane person would pay, surely?
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Sparky99
Sent: 26 November 2020 18:27
To: TekScopes@groups.io
Subject: [TekScopes] worst condition Tektronix scope?

Just saw this on ebay in the UK : https://www.ebay.co.uk/itm/Tektronix-Type-545-Oscilloscope-Vintage-Antique-Collectors/353290325095?hash=item5241be8c67:g:-GYAAOSwBPZfvDOx

Looks like it's been stored in a tropical jungle for a few years!

Anyone got any worse examples?


Re: worst condition Tektronix scope?

 

Here is a parts scope I got from eBay https://groups.io/g/TekScopes/album?id=257163

Most of the knobs are smashed, it's been spattered in something gray that won't come off with soap or IPA, but when I powered it up it appears to be in almost perfect working condition (I say "almost" because I didn't really try to test it in any complete way, just fed the cal signal into both channels, twiddled what knobs could be twiddled, and tried the different button positions. Everything I tried seemed to be working perfectly).

I'd like to turn this from a parts scope into a second bench scope, but I'll need to completely replace the front panel and knobs, unless I can find a way to clean them up. Whatever is spattered all over it won't wash off with either detergent and water or IPA, and I haven't tried any stronger solvents or vigorous brushing. Any advice on how to clean the front panel and remaining knobs, techniques or safe solvents, would be appreciated.

-- Jeff Dutky


Re: worst condition Tektronix scope?

Dave Seiter
 

Awfully high price for an "ornament"; and you'd need quite a substantial Christmas tree to hang that from!
-Dave

On Thursday, November 26, 2020, 10:26:46 AM PST, Sparky99 <jnolan@iprova.com> wrote:

Just saw this on ebay in the UK : https://www.ebay.co.uk/itm/Tektronix-Type-545-Oscilloscope-Vintage-Antique-Collectors/353290325095?hash=item5241be8c67:g:-GYAAOSwBPZfvDOx

Looks like it's been stored in a tropical jungle for a few years!

Anyone got any worse examples?


worst condition Tektronix scope?

Sparky99
 

Just saw this on ebay in the UK : https://www.ebay.co.uk/itm/Tektronix-Type-545-Oscilloscope-Vintage-Antique-Collectors/353290325095?hash=item5241be8c67:g:-GYAAOSwBPZfvDOx

Looks like it's been stored in a tropical jungle for a few years!

Anyone got any worse examples?


Re: Delay Time Position Vernier

Dave Peterson
 

I checked my working scope this morning. I wish we could do inline pictures. I reviewed my tear down pictures and found that I had a shot of the DTP knob before I took it off, and am 99% certain that it's in the full ccw position. The new (parts) one is SN 29XXXX, the "old" working one is 31XXXX. The 29XXXX is at 0.35, the 31XXXX is at 0.25. Interestingly the 29XXXX has the fine dial setscrew at the "1" position. The 31XXXX has the setscrew at the "3.5" position. That's funky, but not really relevant?

I also wonder about the history behind these "min" settings. There's got to be some engineering behind it.

I don't recall them being non-zero back in my Army days. My experience, in general, is that there's not a lot of use for the B-delayed trigger. Perhaps more so in broadcast TV? (As another aside: in my profile picture I'm using the B-delayed function to examine a GHz radar transmit pulse triggered from a 20kHz system clock. Funny the things you remember). In any case, I don't recall the zero or values on the knob were of any interest. It was just a device to move the B-delayed signal under examination. This could be entirely my experience and use case only. I would be interested in learning what use cases in which values from this pot are needed.

Is this style of multi-turn pot just a means of obtaining fine delay control over a very large range? The ability to have nano-second resolution over a micro-second (or mili-second?) range. 1000-1 is a pretty large range.

Also interestingly, the other scope visible in my profile pic is a Tek 491 spectrum analyzer. I recall that it had a crank-knob on it. I was reviewing replacement knobs on the sphere site and came across that knob and all these memories came flooding back. I remember cranking on that thing to slew the spectrum analyzer across several orders of magnitude of frequency. So I wonder if these are just devices for handling fine control over a large range.

Dave


Re: Delay Time Position Vernier

 

Colin,

Oh, I had expected some kind of calibration process, but it's just a bunch of constant offsets for different models.

I see that I am lucky to only be concerned with a model that is always set to 0.0 (the 475 and 475A). Good to know, however, since I would surely have been led astray on my 2215.

Thanks

-- Jeff Dutky


Re: Why you now Paypal

Vince Vielhaber
 

I've gotten it occasionally. I usually go there from what Firefox calls a private browsing window. Cookies aren't saved there and the first time going after restarting the browser is when I would get it, if I get it. Like I said, it's occasional.

Vince - K8ZW.

On 11/26/2020 12:09 PM, Frank DuVal via groups.io wrote:
Weird. I NEVER have a Captcha / Not A Robot screen or button when using
PayPal....

I do not save my password. Have to enter it every time, my choice. Works
for me.

I do not understand the "how far along in the buying process you are"
comment. All the screens on PayPal seem logical to me. And there are not
many when sending money, either on their website only or through a
vendor link to send funds.

So far it works well for me! Both as buyer and sending money to friends.
Even for Tek supplies, to keep it on subject.😉

Frank DuVal

On 11/26/2020 1:01 AM, Jeff Dutky wrote:
I don't have particular issues, other than complaints about this
particular process (not being offered the options that would have made
this process easy), and about the quality of their buyer interface
(every time I have tried to log into their web interface I have had to
do the "I'm not a robot" dance, and every time the site has responded
with "something went wrong on our end" throwing me back to the "I'm
not a robot" screen, so that I get to do the dance again, and maybe a
third time. That's shoddy UX on PayPal's part, and I haven't got any
patience for that sort of thing. Also there's no indication of how far
along in the buying process you are, so you just have to keep clicking
Continue until suddenly the process is over. That's also shoddy UX).
My only other complaints about PayPal are mere hearsay, but I've heard
too many stories of sellers having their funds frozen over the years
to think that maybe there isn't at least a little bit of fire behind
that smoke.
That said, I understand why people want to use PayPal: they fill a
niche that, even today, has very few players. If you want to accept
payment over the web you just don't have many choices, and the
established choices (credit card merchant accounts) are not well
suited to small players. When PayPal got started they were basically
the only game in town for people who couldn't afford to set up a
merchant account, and that benefit can not be overestimated. Still,
I'm a grumpy sort, and this is one of the things I'm grumpy about.

-- Jeff Dutky



Re: Why you now Paypal

Frank DuVal
 

Weird. I NEVER have a Captcha / Not A Robot screen or button when using PayPal....

I do not save my password. Have to enter it every time, my choice. Works for me.

I do not understand the "how far along in the buying process you are" comment. All the screens on PayPal seem logical to me. And there are not many when sending money, either on their website only or through a vendor link to send funds.

So far it works well for me! Both as buyer and sending money to friends. Even for Tek supplies, to keep it on subject.😉

Frank DuVal

On 11/26/2020 1:01 AM, Jeff Dutky wrote:
I don't have particular issues, other than complaints about this particular process (not being offered the options that would have made this process easy), and about the quality of their buyer interface (every time I have tried to log into their web interface I have had to do the "I'm not a robot" dance, and every time the site has responded with "something went wrong on our end" throwing me back to the "I'm not a robot" screen, so that I get to do the dance again, and maybe a third time. That's shoddy UX on PayPal's part, and I haven't got any patience for that sort of thing. Also there's no indication of how far along in the buying process you are, so you just have to keep clicking Continue until suddenly the process is over. That's also shoddy UX). My only other complaints about PayPal are mere hearsay, but I've heard too many stories of sellers having their funds frozen over the years to think that maybe there isn't at least a little bit of fire behind that smoke.
That said, I understand why people want to use PayPal: they fill a niche that, even today, has very few players. If you want to accept payment over the web you just don't have many choices, and the established choices (credit card merchant accounts) are not well suited to small players. When PayPal got started they were basically the only game in town for people who couldn't afford to set up a merchant account, and that benefit can not be overestimated. Still, I'm a grumpy sort, and this is one of the things I'm grumpy about.

-- Jeff Dutky


Tek 2xxx and 3xxx 56x series plugins available

Jim Reese
 

Hello to all,

I should have many 3A1/3A6 and other 56x series plugins in my stock.  The problem is they are on the other side of Ohio at my other house.
Let me know what you want and I can look for them in a few weeks. Figure $20-$40 range plus shipping for most.  They will be complete (and most were tested/working years ago), but as-is now.

I also have many letter and 1xx series plugins.

You can email me direct at: jreese7010@aol.com

or phone: 740-947-7103

Regards,

Jim

Jim Reese
Waverly, OH

On Tuesday, November 24, 2020, 12:05:25 PM EST, Brenda via groups.io <brendda75=yahoo.com@groups.io> wrote:

Hello Dave, The 3A1 plugins that I have come across ends up not only the 6DJ8 tubes missing, there are 2 8233 tubes that end up missing as well.  There are 4 7586 nuvistor tubes in the front end, but seems like the tube pickers pass over these from my experience. I am in the market for a few 3A1 and 3A6 plugins myself...at a reasonable price, $400 is just way too much!!


Re: 7A26 no signal

 

Thanks for the guidance,

I suppose I have to take the cleaning challenge first as there are couple of suggestions for it.
As I didn't get any signal to R130...

I am also getting another unit to facilitate part swapping.

Regards,

Jouko


Re: A Couple Restorations

-
 

Bob,

Where are you located? there is a small handheld Tektronix scope in a
surpus store near me and that I can probably get cheaply. As best as I can
remember it is a 2xx model but I don't remember the complete model number.

On Wed, Nov 25, 2020 at 10:09 PM greenboxmaven via groups.io <ka2ivy=
verizon.net@groups.io> wrote:

My main pleasure with equipment is finding inoperative or basket cases
and restoring them. I just finished a 2230 and an R-631B. This is an
account of the projects, skip now if you aren't interested.

The R361B was obtained from a member of this group, and I was quite
pleased with it when it arrived. I replaced the power cord, and tried it
out. It came alive, had a trace, then a loud snap was heard and it went
dead. I feared the worst, but continued with the work. It needed a bath,
and got it, followed by about ten hours in a hot box to dry it out. I
wanted to see if I could get the power supply working before I put the
jug back in after the cleanup. First tests were aweful. None of the
voltages were correct. The negative 100 volt supply is the reference for
everything else, and it was producing about 115 volts. All of the others
were very low. After a few hours of round and round circuit tracing, I
found the key problem- a partially shorted ceramic condenser. It was one
of the square red Erie brand ones, rated at 200 volts. There were two on
the board, I replaced them with 600 volt ceramic discs. There were two
other old electrolytics, I changed them out as well. The fuse protecting
the high voltage supply was gently blown, not fried and flashed all over
the glass tube. After finding and replacing two fried transistors in the
positive 125 volt supply, everything came alive and right on what they
should have been. I put a fuse in the high voltage supply, it came alive
with an output nearly 4KV, it should have been 3300. I turned the HV
adjustment all the way down, but could not get it below 3500. Both of
the transistors in the HV regulator are "special selected", and tested
good. After studying the manual, and not having exact original
transistors, I added a 12 meg resistor in parallel with the 2.2 meg
resisator coming from the moving contavt on the HV adjust pot. That
allowed me to adjust down to 3300 volts. I cleaned all the switches and
pots in both the mainframe and plug ins, re-installed the jug, and tried
it out. With adjustment of the sweep and position controls, I was
rewarded with a good bright trace. External signals and the built in
calibrator were displayed quite well. The vertical plug in I have is a
single trace differential, not especially useful to me, so I have a 72
dual trace on order. I will let the scope cook on the bench for another
day or so before I put it aside waiting for the dual trace preamp to
arrive. It will probably be used in my RTTY setup, the vertical response
is only about 600 KC.

The 2230 was a genuine basket case, almost entirely dismantled and
filthy with carbon dust. It was a freebee with another purchase at the
Rochester hamfest. I was quite skeptical until I got it home and found
that except for many screws, it was complete. It wasn't stored in the
dirt, it was operated in the filth because the knobs and front panel
were almost unreadable, and the focus pot was completely covered in
fuzz. Getting the front panel and control label plastic sheet off took a
bit of exploration, but WD-40 and a blow dryer softened up the adhesive
on the sheet, and it came off with very little damage. Now I could
remove the front panel to give it the cleaning it needed. Now fully
dismantled, everything got a bath. The cleaner and rinse water were
black as night, but everything cleaned up very well. After re-assembly,
cleaning and lubing switches and pots, it was time to see if it would
come alive. Turning the power on did nothing for a second or so, but the
pilot lamp blinked and the cooling fan moved. I remembered a similar
problem with broadcast waveform monitors and vector scopes, and replaced
all of the smaller low voltage electrolytic condensers in the circuit
that drives the inverter. Now, the same delay but the fan started and
the pilot lamp lit. There were some bright green blobs on the screen,
adjustement of the focus control produced brilliant menu text. After
exploring the controls, I found that one of them had to be pushed in to
display waveforms. I spent an hour or so exploring the locking action of
the pushbuttons, and there was no was to get two of the switches to
latch in, even if I borrowed the latch pins from other switches. The
others that were supposed to latch did. Because the buttons are plastic
stems on the switches, I filed a notch in the bottoms of the two that
would not latch. This allowed them to latch in, a gentle lift released
them. Everything seemed to work fine, the scope has many features I will
probably never use, but it displayed waveforms and would store them.
After several hours of cooking, I put the shield cover over the power
supply section and the brace that supports the top circuit board back
in. I turned it on, and was met with a total disaster. The only thing I
could get on the screen was blobs bouncing around. I shut it off
instantly, and started looking for bad solder joint on the bottom board
where the power supply is located. A solder splat was found and removed,
the scope came on and performed fine. After a few more hours of cooking,
I put the case and back panel on and ran it on test for a few more
hours. It performs very well, it will probably be used mostly in my
shack to troubleshoot RF circuits and monitor transmitter outputs
because it has a 100 MC. vertical bandwidth.

These are examples of the kind of projects I really like. Now, does
anyone have a 224 handheld scope project they would like to find a home
for? 73.

Bruce Gentry, KA2IVY




















Re: Resistor in series

Chuck Harris
 

Hi Tom,

You must have done that calculation before the thread caught my
attention.

I've checked everything I wrote, and I don't see anywhere that I
have said, "but they might still have made a mistake" as you appear
to be attributing to me.

When did I write that, or are you simply making up quotes for effect?

Tektronix had excellent engineers. Way better than most, but in
terms of reliability, they very often compromised the quality of
their designs in production by using poorly specified parts, and
cheese ball fixes for their mistakes. Their "tented" parts are
legion, and some are very embarrassing to see as an engineer.
(See 2465 A1 board for plenty of examples...)

That said, it is a fool who changes the arrangement or parts
selection, of an RF circuit he does not understand.

-Chuck Harris

Tom Lee wrote:

Well, I've presented quantitative calculations explaining why capacitance matters in
this circuit, and thus why series combinations are helpful. In rebuttal, you provide
"but they might still have made a mistake." That's moving the goal posts, Chuck.

I am happy to concede (for the nth time) that Tek's engineers were not flawless. But
the series resistors in the 475A are that way because of capacitance, not incompetence.

--Tom


Re: To pay for Peter Keller's Book ...

Lawrance A. Schneider
 

Thanks

larry


Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.

Michael A. Terrell
 

I have a pile of old IBM and Telex terminals from a local school system
when the state moved away from old IBM mainframes. They are stored in my
garage, but I am unable to get to them without help. The IBM terminals are
color, but I don't rember the model number. I believe they are RS232. Most
of the Telex were dead, but I had swapped enough bords to get some of them
to wake up. I am in North Central Florida.

On Tue, Nov 24, 2020 at 2:03 PM cheater cheater <cheater00social@gmail.com>
wrote:

Thanks everyone. Not really bothered about the dependency on a control
unit for two reasons. First of all, finding /anything/ of this era will be
difficult, whether it's the rarer RS232 kind, or less rare control unit
based type. Second of all, emulating the bus will likely be part of an
interesting challenge and a good way of figuring out the inner workings of
the display and input device, which is what I want to do, so rather than a
problem it's a positive thing for me. A $10 computer nowadays will be able
to do the job. My current biggest problem is locating those older terminals
in the first place. My assumption is they're mostly in defunct computer
graveyards, warehouses, university store rooms, or bank or utilities store
rooms, dusting and decaying away.





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