Date   

Re: TEK176 fixing a shorted wet tatalum capacitor

 

On Sun, Dec 20, 2020 at 10:37 AM, donald collie wrote:


I am told that one method is to spray all the tantalums with "freeze" until
they are all frosted, apply power, and look for the first one to burn off
the frost - there`s your culprit. Cheers!...Don C.
In contrast with dipped (epoxy coated) tants, which go through all levels of leakage and at times burn up like fireworks, metal-encased tants seldomly fail, if treated correctly, and they tend to fail dead short (pun intended), limiting their power consumption. I'd say you need to run a significant amount of current to warm them up enough to have this trick work.

Raymond


Re: TEK176 fixing a shorted wet tatalum capacitor

 

On Sun, Dec 20, 2020 at 07:02 AM, Roy Thistle wrote:


I see what I think is a glass seal, in one of the pics (... is that a
distinguishing feature of a wet type tant?)
Wet tants are not hermetically (glass) sealed, as I wrote earlier, so no. Solid tants are hermetically glass sealed and those is what you see in the picture. A "distinguishing feature" of wet tants as I mentioned used to be the Ta anode wire.

Raymond


Re: 500 scopes n stuff

William Rice
 

Copy. Will do.Thank you Dennis!~BSent from my Verizon, Samsung Galaxy smartphone


Re: Looking for an *original printed* version of a Tek Measurement Concepts book

Dave Daniel
 

Do an author/title search on bookfinder.com. There are some copies listed there. Prices are all over the map.

DaveD

On Dec 20, 2020, at 02:04, sdturne@q.com wrote:

Hi all,

I am looking for an original copy of the Tektronix Measurement Concepts series book entitled "Semiconductor Device Measurements" by John Mulvey to add to my library. I do know of the scan available on TekWiki but this scan suffers legibility issues, so I would prefer to find a printed version.

If you have one you are willing to sell, please contact me off list.

Thanks!

Sean





Re: TEK176 fixing a shorted wet tatalum capacitor

Miguel Work
 

As always Raymond has the reason, THF is the original capacitor, Hermetically Sealed Axial Lead Solid Tantalum Capacitors

https://www.cde.com/resources/catalogs/THF.pdf

Where I can find a similar specs capacitor?


Re: Found Option 7 board DC-508

Miguel Work
 

Hi, yes, this option is for use the counter in a tracking generator/ spectrum analyzer system, for frequency cursor measurament.


Re: TEK176 fixing a shorted wet tatalum capacitor

donald collie
 

I am told that one method is to spray all the tantalums with "freeze" until
they are all frosted, apply power, and look for the first one to burn off
the frost - there`s your culprit. Cheers!...Don C.

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On Sun, Dec 20, 2020 at 9:45 PM Miguel Work <harrimansat@hotmail.com> wrote:

https://passive-components.eu/wet-tantalum-capacitors/

There is some trick to find wich capacitor is shorted, (very shorted), in
a low impedance system like that with all capacitors in parallel?









Re: TEK176 fixing a shorted wet tatalum capacitor

Miguel Work
 

https://passive-components.eu/wet-tantalum-capacitors/

There is some trick to find wich capacitor is shorted, (very shorted), in a low impedance system like that with all capacitors in parallel?


Looking for an *original printed* version of a Tek Measurement Concepts book

Sean Turner
 

Hi all,

I am looking for an original copy of the Tektronix Measurement Concepts series book entitled "Semiconductor Device Measurements" by John Mulvey to add to my library. I do know of the scan available on TekWiki but this scan suffers legibility issues, so I would prefer to find a printed version.

If you have one you are willing to sell, please contact me off list.

Thanks!

Sean


Re: Found Option 7 board DC-508

Larry McDavid
 

Miguel, I have a DC508. Please explain what that Resolution Multiplier and Option 7 mod kit does.

Larry

On 12/19/2020 10:15 AM, Miguel Work wrote:
I modified my DC508 time ago, I have some photos in photos in our gallery:
https://groups.io/g/TekScopes/album?id=86699...
--
Best wishes,

Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)


Re: 500 scopes n stuff

 

Hi Bill,
There are no rules. When you have your list prepared post it with specific instructions on how interested parties can contact you OFF -LIST. Be sure to say they should contact you OFF-LIST at the top of your list of equipment. If the best way is to contact you is via email be aware that Groups.io scrambles email addresses to protect us from spammers. The way around this is by spelling out your email address as
"bill at ricemail dot com". So at the top of your list be sure to say something like
Please contact me OFF-LIST at bill at ricemail dot com if you are interested in any of my items.

Dennis Tillman W7pF
TekScopes Moderator

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of William Rice
Sent: Friday, December 18, 2020 11:08 AM
To: TekScopes@groups.io
Subject: [TekScopes] 500 scopes n stuff

Is there any info on how to conduct oneself if one wants to list some older Tek scopes n bits to let go of?

Is this prohibited on this list? Where can I find the rules for such please?

Thank You All,
Bill
W4MXT







--
Dennis Tillman W7pF
TekScopes Moderator


Re: 475A Chop Blanking and a Theory Question

 

Harvey,

What I currently do is, apparently, fix broken scopes. I've bootstrapped myself up to a point were I have enough reliable equipment that I can triangulate on almost any measurement (with the exception of observing bandwidth rolloff, but that will change in a couple weeks when my TinaSA arrives). I'm going through the calibration process on my 475A using cobbled together equipment. I have a cheap old signal generator, and I calibrate it's output amplitude using a Tek DMM916 and a 2236. The signal generator isn't really good above about 1 MHz, so that's a significant limitation for the 475A calibration process, but I think I'm doing pretty well emulating what the PG506 and SG502 would do at lower frequencies. I'm also working on a DIY calibration source that will produce square waves at several frequencies with amplitudes ranging from 5 mV to 50 V, which would make some of the work I've been doing with with the signal generator and the 2236 a little easier.

Oddly, I feel that the multiple instruments give me greater confidence in what any one of them tells me. I've got three relatively nice DMMs that I've been using the make comparative measurements, as well as a programmable power supply, and the cheap signal generator. Combine those with some TCXOs and I feel as if I can actually make some pretty good measurements of voltage, resistance, and frequency. From there I should be able to bootstrap myself into at least a couple decimal places of accuracy. For the kind of things I'm doing, I'm not sure I care about anything more than that.

What I want to be doing in the short term is investigating and documenting the display protocol for an old laptop that has a gas plasma display, so that I can then replace the innards of the laptop with a Raspberry Pi. Also, I'm working on building a 6809 microcomputer, and a homemade minicomputer using 74181 ALU slices. I've also got a couple other old pieces of equipment of my father's and grandfather's that I'd like to spend some time fixing up.

It's all just hobby stuff that has interested me ever since college, and the pandemic has given me enough extra hours in the week to actually pursue it. I suspect that I don't need much more than a 200 MHz scope to do most of this work, though I'm sure a logic analyzer would be a nice addition. At some point I expect to buy a modern Chinese DSO (probably a Siglent 1204xe), but the old (70s and 80s era) analog scopes are what really interest me, both because of my history with them, and because it feels "closer to the metal" than a DSO. I know too much about the limits of discretely sampled signals to really trust a DSO, and maybe not enough about analog amplifiers to know where my trust in analog scopes should stop.

-- Jeff Dutky


Re: Firmware for Tektronix 492/496 spectrum analyzer

Steve Dench
 

There are a number of 24 to 28 pin adaptor boards on eBay as Ye Old
Commodore 64 computers have the same issue. I used some in my 468 some time
back with the usual Mostek Rom failures. Some of these adaptors are very
slim and fit the 468 well.

On Sun, 20 Dec 2020, 2:11 pm vk2bea via groups.io, <vk2bea=
yahoo.com@groups.io> wrote:

I have a 492 Spectrum Analyzer that has developed a fault with the ROM
(self test indicates a checksum failure).
The test blinks 14 times which, according to the manual, means that U2012
fails checksum. I do not have this ROM populated on the board (just U2023
and U2028)

Does anyone know what's going on here?

The ROMs are 8K x 8 one time programmable (it appears) part. (its also
possible that it is an ee programable part but that is unlikely I think).
The chip markings are custom - 160-0839-00 & 160-0838-00 (Tek #) and
SCM92217CR (with Motorola logo) & data code of 8343 and 8402.
8K 24pin DIP parts seem scarce (Although I found a Motorola MCM68766 thats
pin compatible ... I just don't see how I'll program it 8-( )

What is the standard practice for this repair? Use a 28 pin package and
add the appropriate mod wires ?
I found the firmware binary here ..
http://w140.com/tekwiki/wiki/ROM_images






Interfacing 576 Curve Tracer to 7633 Storage Scope

RellikJM
 

Hello all!

I'd like to interface my 576 Curve Tracer to my 7633 Storage scope. It would be nice to have the features of the 577D1 Curve Tracer available to the 576. I have the 176 High Power Fixture for it and it doesn't trace anything but DC points. I'd also like to do push pull matching and true 0 bias point measurement.

Is the best way to grab the deflection signal right from the CRT pins and only use 1/2 of the differential signal that the deflection plates need or do the differential signals need to be integrated some how? I was thinking that if I used the (+) side of the horizontal and vertical deflection plate signals I'd be able to feed that into the storage scope in X-Y mode. My concerns are I don't want to do any damage to the 576 and I'm thinking it would be smart to use some sort of coupling capacitor from the deflection plate signal so I'm not coupling to the +225VDC that powers the deflection plate transistors. If I couple to the deflection plates should I leave the 576 CRT in circuit with the intensity turned down while feeding an external storage scope or should the CRT be disconnected and suitable load resistors connected to substitute for the disconnected 576 CRT?

Thanks in advance,

Jay


Re: Firmware for Tektronix 492/496 spectrum analyzer

vk2bea
 

I have a 492 Spectrum Analyzer that has developed a fault with the ROM (self test indicates a checksum failure).
The test blinks 14 times which, according to the manual, means that U2012 fails checksum. I do not have this ROM populated on the board (just U2023 and U2028)

Does anyone know what's going on here?

The ROMs are 8K x 8 one time programmable (it appears) part. (its also possible that it is an ee programable part but that is unlikely I think).
The chip markings are custom - 160-0839-00 & 160-0838-00 (Tek #) and SCM92217CR (with Motorola logo) & data code of 8343 and 8402.
8K 24pin DIP parts seem scarce (Although I found a Motorola MCM68766 thats pin compatible ... I just don't see how I'll program it 8-( )

What is the standard practice for this repair? Use a 28 pin package and add the appropriate mod wires ?
I found the firmware binary here .. http://w140.com/tekwiki/wiki/ROM_images


Re: 475A Chop Blanking and a Theory Question

 

On Sun, Dec 20, 2020 at 02:09 AM, Jeff Dutky wrote:


You say that they are less attractive, but the screens are big, and if all you
want to do is play oscillofun through it, then the big screen is the important
part. If I could find a 5440 or a 5444, it would be nearly as fast as my 2213
and 2215A, but with a much larger screen.

My problem with the 5000 series is that they don't follow the same control
patterns that I'm used to with the portables: it's not at all clear how I
would set the scope into X-Y mode, for example, with a 5440 configured with
two 5A48 vertical amplifiers and a 5B40 horizontal timebase.

Hi Jeff,
The screen of a 7603 is as big as that of a 5000-series 'scope, that's why I mentioned it.

With a plug-in 'scope, like a 7000 or a 5000, much of how you set it up depends on the plug-ins used.
For versatility and "orthogonality", i.e. consistency in setting up, a 7000 mainframe is better.
I'm sure it would appeal to you, having followed your way of thinking in this group.
I'll give a very short description of some main points below.
The standard 7000 mainframe has four locations (slots) for plug-ins. The two left-hand ones control vertical deflection, the two right-hand slots control horizontal deflection.
For X-Y display, you may just put a "vertical amplifier" in one of the "vertical" slots and another one in one of the "horizontal" slots. No time base involved. You select the slots with buttons above the slot area.
The 7603 only has three slots: two vertical and one horizontal.
Should you want a "normal" 'scope with its display rotated over 90 degrees, just put a time base plugin in a vertical slot and a vertical amplifier in a horizontal slot. Just an example of versatility/orthogonality.
All 7000 mainframes are single-beam, suitable for showing a maximum of four input channels concurrently, with the exception of the 7844, which is a true dual beam 'scope, with dual vertical *and* dual horizontal plates and amplifiers! That's essentially two 'scopes in one frame! Switches provide all possible variations of setups for the plugin configurations.
In practice, there isn't much that you'd need a 7844 for, except maybe showing two unrelated signals with extremely different frequencies at the same time.

Raymond


Re: 475A Chop Blanking and a Theory Question

Harvey White
 

I have both portable and 7000 series (and a few 5000 series, too).

They each have their uses.  My 7904 is the go-to bench scope, I have enough plugins to make most of what I do (no RF and SA work, although I can....) workable.

Normally, I use the 7A26 plugin and a 7D13 (at times, does peak measurements).  I have 7A22 and 7A13 (LED) plugins for audio/low bandwidth/low voltage measurement.

Sweep wise, I normally use a 7B92A (mixed sweep good enough for the scope's bandwidth), and a 7D15 digital plugin which adds frequency readout on an input waveform.

Those combinations will generally get you enough that you can nose around for 0-200 Mhz.  The advantage of other plugins (and I've got a few), is that the 7A29 and 7A24 extend the scope bandwidth to 500 Mhz or so, but you need 50  ohm probes.  Most CMOS chips can drive a 10x 50 ohm probe (giving 500 ohms input impedance, but the higher bandwidth).

I do a bit of digital, microcontroller, power supply, and some signal designs, so  YMMV for what you want.

Once you see a scope with on screen readout, you may not want to go back.

Now, for the 400 series, I have a pair of 468's.  The main advantage of the 468 is that it has digital storage to 10 Mhz. Often, I need to look at a low rep-rate digital waveform, not fast, not sub-microsecond pulses, but slow stuff.  The 468 will do that, and be portable.  Of course, I have an earlier acquisition, a 2430A, and a Kenwood (analog, non digital, but CRT readout), analog scope.  My goto, not sitting in lab with project, sitting in front of TV in library, scope is an HP54622D, which is digital, has a few interesting triggering modes, and 2 channel 100 mhz.  If I need to go and look at the innards of some moderately complex stuff, I'll use my logic analyzer (HP 16702B).

But what you buy is dependent on what you actually do.

CRT readout is a nice thing.  High bandwidth?  I think I need it, and you may or may not.

Multiple channels?  2 is a minimum, 4 is better (IMHO), if nothing else, trigger view is a big plus....

for the rest of it?  I like 100 Mhz at a minimum, 200 to 500 much better.  I'd rather have more than less when I need it.  Yes, have 7000 series mainframes with less bandwidth, and more bandwidth; but I'm talking what I use day to day.

With enough scopes, you may want calibration equipment....

<misquote>  " the man with multiple scopes never knows what the wave form is, the man with one scope always does....."

You may eventually want calibration equipment, depending on what you do and do not.  I have 6 figure DC voltage standards, PG506, SG502 and SG503 and TG501 calibration equipment, as well as a few counters....  I should be ok.

Harvey

On 12/19/2020 7:14 PM, Jeff Dutky wrote:
Raymond,

Okay, I'm watching a couple of cheap 7603s on eBay, maybe I can score a deal (and if it's not working, then I score a project).

I'm hesitant to go down the path of the mainframes (7000 or 5000) as that seems like a way that I could waste astonishing amounts of money, and consume even more space and power than I already do with my modest menagerie of portable scopes.

-- Jeff Dutky





Re: 547 front panel 100V source

Harvey White
 

Oddly enough, they do the same (set to 100 volts output) arrangement for the PG506.

Harvey

On 12/19/2020 6:49 PM, snapdiode via groups.io wrote:
It's shorted out when the switch is in 100VDC mode. Actually I never knew the 100VDC position forces 5mA DC through the front panel current loop!
A new discovery for me.
In any case, in the 100VDC position, the negative power supply to the multivibrator is cut, so half a 12AU7 is powering the calibrator through 225V through 250 ohms. I think I'm OK.





Re: 475A Chop Blanking and a Theory Question

 

Raymond,

You say that they are less attractive, but the screens are big, and if all you want to do is play oscillofun through it, then the big screen is the important part. If I could find a 5440 or a 5444, it would be nearly as fast as my 2213 and 2215A, but with a much larger screen.

My problem with the 5000 series is that they don't follow the same control patterns that I'm used to with the portables: it's not at all clear how I would set the scope into X-Y mode, for example, with a 5440 configured with two 5A48 vertical amplifiers and a 5B40 horizontal timebase.

-- Jeff Dutky


Re: 475A Chop Blanking and a Theory Question

 

On Sun, Dec 20, 2020 at 01:14 AM, Jeff Dutky wrote:


I'm hesitant to go down the path of the mainframes (7000 or 5000) as that
seems like a way that I could waste astonishing amounts of money, and consume
even more space and power than I already do with my modest menagerie of
portable scopes.
Going the 5000-way could well be safer, since they are so much less attractive...

Raymond

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