Date   

Re: Push-push switch repair (need some theory of operation)

EJP
 

Well I did this yesterday and it was even easier than expected. Removal was just a matter of solder-sucking and wicking. Heat gun didn't work a damn. If my desoldering gun had been working it would have been even easier, but it wasn't. Insertion was just a matter of tack-soldering a pin at each end with the PCB vertical, then fllipping it horizontal and going over each hole. Plenty of solder in each hole, as some of them have connections on the top side, and the holes aren't through-plated. Did the switches one at a time so I could inspect the topside soldering of at least one of them on the inside where they meet.

I didn't bother with the green spacers as they wouldn't fit on the flat pins on the new switches. Fit to the switch shafts was perfect.

I sourced the switches for about $A6.50ea from X-On, which is the Australian version of Mouser. They used to have an MOQ of 25 on them but it dropped bo 2 between the two times I looked.

Only remaining issue with the 7CT1N is that with PNP selected the dot is at bottom right, not top right. Am I right in thinking this is controlled by S70D, which is the part nearest the latch? All connections look OK and seem functional considering things like resistance to ground that should and shouldn't occur in the two positions. It's actually not a showstopper, as I can always adjust the vertical offset myself, but it's annoying.

EJP


Any known issues with the 577?

Eric
 

So along with the 576’s that I am trying to rebuild It seems that a 577 D1 and decided to call my lab its resting place for now. It is in pristine condition given its age and the chips are date coded 91 so it seems to be one of the very late models. The good news is the tube is nice and bright with good visibility at about ½ intensity. They only issues I have found with it so far was the storage switches were slightly gummy and needed to be cleaned so they have been drenched in and exercised. Also it seems the looping capacitor in the 177 has locked complete solid other then that all the controls “feel” free and mobile. And there is 0 dust in the unit it looks like it has sat on a shelf for 30 years. Is there any known faults in a 577 like there are in a 576 that I need to worried about for this unit to be serviceable for the long haul? If there is noting there and I can repair the 177 I am going to run it through the performance check and Cal procedure then learn how to maximize its potential on the bench.


Re: Tek 576 Curve Tracer USB port to a cpu ... ?

 

Hi Garp,
<SNIP> His Tek 576 plots on the laptop screen seem quite convincing and useful...

There were many comments about this a month ago. The 576 plots on the laptop are the most plausible aspect of whatever this person was attempting to demonstrate. It is a very primitive display. At a minimum he could have calculated and displayed the voltage and current of each graticule division along the left and bottom axes, overlaid the base current next to each step of the characteristic curves, and added useful information. Instead it adds nothing. It simply repeats the info from the 576 readouts and switch settings. It is nice documentation if you are keeping a lab notebook, but if you are a casual user of the curve tracer the axis scales and the overlays makes understanding the results easier.

I would also add:
* Every aspect of this is so crude and amateurish that you could not even call it a "prototype". The kindest thing I would say about it is that it was done as "a proof of concept".
* Alarm bells were going off in my head as I looked at this and the other web site pictures and info because they were deliberately being secretive.
* In order to capture all the information they show on the laptop they have to make connections to many places inside the 576.

Conclusion: Given the extremely amateurish nature of everything I can see they did and the secrecy I wouldn't touch one of these things.

I do admire the person who had the idea. It is a very good one and he should keep at it. I think he will have a very bright future in electronics. He reminds me of myself when all I wanted to do when I was 20 was to design my own oscilloscope.

Fortunately I did not know that when Barrie Gilbert was about the same age he showed up at Tek with a SAMPLING OSCILLOSCOPE he designed. Finding out things like this is a very humbling experience.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of garp66
Sent: Tuesday, February 11, 2020 8:26 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek 576 Curve Tracer USB port to a cpu ... ?


The eBay seller of the Tek 576 with USB is still listing ....
perhaps he has multiple units...

His Tek 576 plots on the laptop screen seem quite convincing and useful...

(eBay search " Tektronix 576 USB " ):
https://www.ebay.com/itm/Tektronix-576-Semiconductor-Curve-Tracer-1-Yr-Warr-Calibrated-USB-interface-CRT/302445112576?hash=item466b222d00:g:E5MAAOSw-0xYhVJm

I did not get a reply *when* I queried the Seller for more information about his interface to the Tek 576.

-- Did anyone else try to get a reply ?







--
Dennis Tillman W7PF
TekScopes Moderator


Re: 11301/11302 in the Bay area

Jerry
 

ha, for the heck of it, I looked for the service manual again and I found one! A preliminary service manual for the 11301/11302. Go figure.


11301/11302 in the Bay area

Jerry
 

Hello, Every now and then I post that I'm looking for an 11302 in the SF bay area. I don't need any plug-ins, just a functioning frame. I have one that is defective and I'm unable to figure out the issue. The symptoms are that I get double traces so there is a problem in the triggering or something. All the power is fine. No ripple to speak of. I think at a minimum it needs new NVRAM, assuming it has such. If anyone has one they would like to unload, please send me a note. Or if anyone has the service manual, again, I'd appreciate a copy or a pointer to the same.

Jerry


Re: Installing CRT into Tektronix 531A

Chuck Harris
 

It doesn't much matter. Add a splash of vinegar to a cup of
water.

As to the tubing spacer, I just warm the tubing, and stuff
a piece in that is a little larger OD than the gap.

If you split the tubing down the middle, it allows you to
handle spaces that are between two walls thick and one wall
thick. The former curvature adds springiness.

-Chuck Harris

Brenda via Groups.Io wrote:

Thanks everyone for your suggestions! I really like Chuck's suggestion and I would see no reason why it won't work. I just have to find one with the right thickness and split it and cut it to size. Chuck, if I may ask, what ratio should I use for the mix for the water/vinegar soak? I would really like to reuse that ring for my 533A.

However, I thought that I would just be able to throw that CRT into my 531A and power it up but that's not going to happen right away sadly to say. I have found that the screw that secures the rear of the shield has been sheared off, (Probably why the original CRT shattered), and after more vacuuming I found that 4 electrolytic caps are leaking a white substance where the leads go through the bottom, so I am considering these caps to be bad. On top of that, the fan barely turns so I need to figure the best way to clean it and the right oil. But I will bring this oldie back to life!

Brenda




Re: Installing CRT into Tektronix 531A

Brenda
 

Thanks everyone for your suggestions! I really like Chuck's suggestion and I would see no reason why it won't work. I just have to find one with the right thickness and split it and cut it to size. Chuck, if I may ask, what ratio should I use for the mix for the water/vinegar soak? I would really like to reuse that ring for my 533A.

However, I thought that I would just be able to throw that CRT into my 531A and power it up but that's not going to happen right away sadly to say. I have found that the screw that secures the rear of the shield has been sheared off, (Probably why the original CRT shattered), and after more vacuuming I found that 4 electrolytic caps are leaking a white substance where the leads go through the bottom, so I am considering these caps to be bad. On top of that, the fan barely turns so I need to figure the best way to clean it and the right oil. But I will bring this oldie back to life!

Brenda


Re: WTF: TDS3000 Blank option modules.

Magic_Smoke
 

I had considered that project, but living a few blocks from Tek HQ I managed to end up with an original that has "ENG" scrawled on the front and turns on all the goodies, so I may not need to for my own benefit. It would, however, be a pretty simple thing to design the new piece with a snap-in home for a SIM-card connector...hmm! Easy to see how the scope of these projects can really start to inflate.


Re: Tek 576 Curve Tracer USB port to a cpu ... ?

garp66
 

The eBay seller of the Tek 576 with USB is still listing ....
perhaps he has multiple units...

His Tek 576 plots on the laptop screen seem quite convincing and useful...

(eBay search " Tektronix 576 USB " ):
https://www.ebay.com/itm/Tektronix-576-Semiconductor-Curve-Tracer-1-Yr-Warr-Calibrated-USB-interface-CRT/302445112576?hash=item466b222d00:g:E5MAAOSw-0xYhVJm

I did not get a reply *when* I queried the Seller for more information about his interface to the Tek 576.

-- Did anyone else try to get a reply ?


Re: WTF: TDS3000 Blank option modules.

Oz-in-DFW
 


Re: Help with a Tek 7A26

Jim Ford
 

LOL at the 7D1X "conspiracy"!Best laugh I've had all week!Thanks, William!Jim FordSent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: k6whp <@k6whp> Date: 2/10/20 7:58 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Help with a Tek 7A26 Dennis,Absolutely fascinating! Tek scopes of that generation amaze me because of their performance and the fact that some semiconductors can be replaced with lowly 2N222s or 2N3094s. I had a Tek 484 whose A7 board revolted and part of the regime my friend taught me was to re-socket as well as remove AND CAREFULLY CLEAN the IC pins by scraping toe oxidation off. Could have knocked me over with a feather when we "fixed" it with a 2N3904! I have a 7D14 and a 7D15 that I dearly love and both are misbehaving at present. One craps out after 60 seconds and the other starts functioning after the same amount of time. I personally think they talk to one another and plot to confound me. My sincere thanks for your advice and the Tek lore. Chat with you again soon!-- William, k6whp"A friend told me to cheer up, things could be worse.So I cheered up and, sure enough, things got worse!"


Re: Anyone needing parts from Tektronix 310A, 531A or 533A scopes?

Keith Erickson
 

I have working 531A and 533A scopes available in MN TC.

Keith,
Wayzata, MN

On Feb 10, 2020, at 9:03 PM, Phil Cirocco <filter@...> wrote:

Wow, thank you for getting my hopes up and than passing along the frustration.



Re: Help with a Tek 7A26

k6whp
 

Dennis,

Absolutely fascinating! Tek scopes of that generation amaze me because of their performance and the fact that some semiconductors can be replaced with lowly 2N222s or 2N3094s. I had a Tek 484 whose A7 board revolted and part of the regime my friend taught me was to re-socket as well as remove AND CAREFULLY CLEAN the IC pins by scraping toe oxidation off. Could have knocked me over with a feather when we "fixed" it with a 2N3904!

I have a 7D14 and a 7D15 that I dearly love and both are misbehaving at present. One craps out after 60 seconds and the other starts functioning after the same amount of time. I personally think they talk to one another and plot to confound me.

My sincere thanks for your advice and the Tek lore. Chat with you again soon!
--
William, k6whp
"A friend told me to cheer up, things could be worse.
So I cheered up and, sure enough, things got worse!"


Powering Up 577 Curve Tracer without 177

Gary Robert Bosworth
 

Does anyone know FOR SURE if it is safe to power up the 577 Curve Tracer without the 177 device adapter installed?

Gary


Re: Anyone needing parts from Tektronix 310A, 531A or 533A scopes?

Phil Cirocco
 

Wow, thank you for getting my hopes up and than passing along the frustration.


Re: WTF: TDS3000 Blank option modules.

Magic_Smoke
 

Hmm, this sounds like a good candidate for 3d printing...should I mock one up?


Re: Help with a Tek 7A26

 

Hi William,

Glad to hear you have a working 7A26. You figured out a very useful technique (by yourself) of removing and reseating all parts that are socketed. Tek did use sockets liberally but not always. They make repair much easier but they also contribute to an increase in failures since a soldered connection is much more reliable than a press-in connection. Tek, and most other companies discovered this the hard way.

One of the socket brands Tek used for many ICs was later discovered to have a serious flaw. These are the infamous Texas Instruments (TI) IC sockets. Their logo is an outline of Texas and/or the capital letters TI on the socket.

TI tried to design a socket that would not violate the existing patents other companies had on IC sockets. The right way to make contact to each pin of an IC is for the flat IC lead to slip between two flat springy contacts that press against it from both sides of the ICs flat lead.

That idea was already patented. TI decided to make contact with the lead of the IC with two flat spring contacts that pressed against the narrow edges of each IC pin. It turns out the flat side of an IC pin is very smooth because the pins are stamped out from a single thin tinned strip of metal. The stamping die punches out the all the excess metal between each pin. It is a very quick, cheap, reliable way to form the IC leads during manufacturing. The flat side of each pin is undamaged because the die doesn't touch this part of the pin. Unfortunately the die leaves the edges of each pin very jagged and irregular where the shearing of the excess metal takes place. As you insert the IC into one of the TI sockets the jagged edges of each IC pin damages the springy connector fingers. After a few insertions and removals of the IC the socket becomes unreliable.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of k6whp
Sent: Monday, February 10, 2020 12:28 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Help with a Tek 7A26

Dennis, et al,

The 7A26 is back in the land of the living. Bottom line was (disappointingly) that it was "Lazarus'ed by re-use" meaning that in my inspection, I cleaned, twisted, flipped, and otherwise manipulated the controls and retaining screws so the poor beast regained life, straightened up, and is flying right. It was a mechanical resolution. But there is more to it and may be of benefit to others, so here goes:

(1) Borrowed a working 7A26 from a friend.
(2) Used the 7704A square wave standards -- mainly the 4.0 Vpp.
(3) Checked voltages on the bad 7A26 and 15 VDC was good.
(4) At first the bad 7A26 exhibited the following:
(a) difference of 50-75% reading versus good one. (4.0 Vpp signal 4 divisions on good one and 3+ divisions on bad one.)
(b) bad on top channel ONLY. (Differs from my initial observation.)
(c) as vertical position changed, amplitude varied on bad top channel.
(d) top and bottom of CRT position were accurate. Middle position inaccurate per above.
(e) at middle, square wave trace exhibited drastic overshoots -- to almost one division.
(5) Re-tightened the attenuator retaining screws on both upper and lower channels.
(6) Pulled and carefully cleaned pins on attenuators on both channels.
(7) After manipulating the attenuators through their ranges the mid-position inaccuracy disappeared.
(8) Compared bad versus good 7A26 and both displays were accurate for the standard as well as input 10 MHz, 100 MHz signals.

Thus I am forced to conclude that it was a mechanical fix. Sorry to waste time reporting this but a long time ago, I was told by someone here that all requests for help should be followed up by a resolution report so that others my benefit from the thread.

Makes sense.

Should this problem creep back in, I will resolve it (hopefully) and pass the results along.

Sincere thanks for the great support!.



--
William, k6whp
"A friend told me to cheer up, things could be worse.
So I cheered up and, sure enough, things got worse!"





--
Dennis Tillman W7PF
TekScopes Moderator


Re: Help with a Tek 7A26

k6whp
 

Dennis, et al,

The 7A26 is back in the land of the living. Bottom line was (disappointingly) that it was "Lazarus'ed by re-use" meaning that in my inspection, I cleaned, twisted, flipped, and otherwise manipulated the controls and retaining screws so the poor beast regained life, straightened up, and is flying right. It was a mechanical resolution. But there is more to it and may be of benefit to others, so here goes:

(1) Borrowed a working 7A26 from a friend.
(2) Used the 7704A square wave standards -- mainly the 4.0 Vpp.
(3) Checked voltages on the bad 7A26 and 15 VDC was good.
(4) At first the bad 7A26 exhibited the following:
(a) difference of 50-75% reading versus good one. (4.0 Vpp signal 4 divisions on good one and 3+ divisions on bad one.)
(b) bad on top channel ONLY. (Differs from my initial observation.)
(c) as vertical position changed, amplitude varied on bad top channel.
(d) top and bottom of CRT position were accurate. Middle position inaccurate per above.
(e) at middle, square wave trace exhibited drastic overshoots -- to almost one division.
(5) Re-tightened the attenuator retaining screws on both upper and lower channels.
(6) Pulled and carefully cleaned pins on attenuators on both channels.
(7) After manipulating the attenuators through their ranges the mid-position inaccuracy disappeared.
(8) Compared bad versus good 7A26 and both displays were accurate for the standard as well as input 10 MHz, 100 MHz signals.

Thus I am forced to conclude that it was a mechanical fix. Sorry to waste time reporting this but a long time ago, I was told by someone here that all requests for help should be followed up by a resolution report so that others my benefit from the thread.

Makes sense.

Should this problem creep back in, I will resolve it (hopefully) and pass the results along.

Sincere thanks for the great support!.



--
William, k6whp
"A friend told me to cheer up, things could be worse.
So I cheered up and, sure enough, things got worse!"


Re: Dead 2430

Szabolcs Szigeti
 

Hi,

Check the psu caps on the secondary side, especially the one for the
startup supply for the pwm circuit. I had a 2430, a 2440 and a 2432 all
having these caps gone dead, some even leaked and the symptom was the same,
no startup, no fan. It is running off the psu, so if it doesn't work, you
won't even get the fan running.
(But, i was able to buy these cheap as not powering up at all :-) )

I also replaced all other caps on the secondary side, as most of them were
leaking and had high esr an low capacitance. If you remove the psu, best is
to replace all.

koralrf via Groups.Io <koralrf=btinternet.com@groups.io> ezt írta (időpont:
2020. febr. 8., Szo 12:53):

Hi

I tend to run all my instruments periodically just to ensure that they are
OK.

Today, I turned on my old TEK 2430 - and it was completely dead - no fan,
nothing!

I have checked the power lead - OK, plus the 5 amp quick blow fuse and
that is OK too..

So I presume that it has a fault in the Power Supply A16 board?

Any suggestions as to the best place to start looking please?

Thanks in advance

Tony




Re: Installing CRT into Tektronix 531A

Eric
 

I used a high voltage electrical silicone tape. This was not electrical
tape at it stuck to its self but was not adhesive backed. Scotch electrical
tape 70. It has a breakdown of 35Kv. If I remember correctly it way
expencive 12.50 for a really small roll. However I also remember I did not
need much.

Eric

On Sun, Feb 9, 2020, 7:35 PM Leon Robinson <leon-robinson@...>
wrote:

Brenda
Try a few wraps of felt.

Leon Robinson K5JLR

Political Correctness is a Political Disease.

Politicians and Diapers should be changed
often and for the same reasons.

On Sunday, February 9, 2020, 3:40:53 PM CST, Brenda via Groups.Io
<brendda75=yahoo.com@groups.io> wrote:

Hello everyone,

I apologize if I am making too many posts, I figured that this would fall
into a new topic. Anyways, since I was able to remove the CRT from the
trashed 533A, I am ready to install the CRT into my 531A, however, I have
run into a problem that I am hoping that someone on here will have a simple
solution. When I removed the remains of the shattered CRT from the 531A,
the rubber or nylon ring that was around the CRT socket has totally fell
apart. Is there anything that I could use that would be a proper thickness
to secure the end of the CRT? The one on the trashed 533A is still good,
but I want to save that one for the other 533A that will be a long process.

Brenda