Date   

Tektronix TM500, TM5006 Plug in Pull TAB latch replacements available again

 

Hi all...
I have started manufacturing these again so have a look:
https://www.ebay.com/itm/132933760409
Please keep any queries off-list.


Re: 465 minor repairs - help requested

bbortnick@...
 

It's definitely a 465...


Re: 7A26 attenuator compensation problem

 

Not sure about your method.

- I really wouldn't want to use an FG504 for adjusting the step response of a 7A26, be it for the slope or the post-slope time. I don't know what Tek 7000-model you have; did you try observing its calibration waveform and does it look identical to the FG504's at attenuation settings above 10 mV/div?
- I wouldn't call what I see straight overshoot. There seems to be some overshoot but your time scale is too slow to really see it well. After the overshoot, which itself seems to contain some fast "ripples", the level dips to almost the flat level but rises again not too steeply to a bump and then "slowly" falls off. I see that in your 7A24 pictures as well, also at larger input voltages (and attenuations).
- I guess you compared with another 7A26. "Consistent" misadjustment could explain the consistent behavior of both channels in your problem module. If the wave shape with another 7A26 and the same 7A24 setup is ok, the following doubts about the FG504's behavior don't apply of course.
- Things may look OK driving the 7A24 but without a 50 Ohm feed-through terminating the signal into your amp who knows what shape the signal really is, so what does the waveform via the 7A26 mean in that case? It looks like you did use a 50 Ohm feed-through on the 7A26 for all your photographs (on-screen amplitudes are equal) and that's ok but it could be misleading:
At 10 mV/div with the feed-through, the input voltage follower circuits are fed by a low impedance (your feed-through). In that situation, C130, C133 and C134 have relatively little influence.
At all greater attenuations, the series resistors in the attenuators make for a much larger impedance driving those voltage followers and the influence of C130, C133 and C134 is much larger.
If you didn't yet, have a look at the waveform on the 10 mV setting using a well-compensated (!) 1:10 10 MOhm input resistance probe. Obviously, you'd need a larger input voltage.
If the shape differs a lot from the 50 Ohm feed-through situation, I'd suspect a problem in the voltage follower circuits or an earlier misadjustment of those circuits in both channels, explaining why they are both wrong to the same amount. Again: C130, C133 and C134 and components around them (but these C's are the only adjustable components in the area).

The failure mode of the nylon-topped attenuation blocks leads to jittery behavior and finally, complete loss of adjustment influence by the problem-block; internal solder connections are bad and contact is lost.

Raymond


Re: Tektronix 575 help

Dan Cordova <danny_cordov@...>
 

It's alive... it's ALIVE... IT'S ALIVE!!!

Thanks for the help from the group! 
I replaced all the paper capacitors in the CRT Circuit using silver bearing solder. Replaced two neon lamps and one resistor in the CRT Circuit. The neon lamps glow while the curve tracer is on. 
Fired it up and the trace looks beautiful as it ever did. 
Going to do a little calibration, check voltages, then check some tubes with the fixture I made. 
Dan

On Thursday, January 24, 2019, 8:17:13 PM PST, John Griessen <john@ecosensory.com> wrote:

On 1/24/19 9:50 PM, Dan Cordova via Groups.Io wrote:
On 1/24/2019 8:35 PM, Dave Seiter wrote:
    The only "shelf life" limit would be from a change to the rosin, or more likely, surface corrosion.
I agree.  I bought a big  4lb roll of rosin core 60/40 about 14 gauge thick with really old
looking markings at the thrift store fifteen years ago -- older than the 60's.
Works great for sheet metal soldering with big irons.


Re: 2400 series Test 4 Fail 3,13, 2

Craig Cramb
 

With the scope off it should be about 0.1V less then the keeper battery, and when on close to +5V.

Did the test of the values listed Pin 28 and I'm at 3.5Vdc power off and 4.97 Vdc power on.
If this is considered failed is there boot data that will have to be captured before replacing and downloaded to the replacement?

Craig


Tektronix 2440 Cursor failure does not stop the selected line

ernestodigitals@...
 

Hello, I am Ernesto from Argentina, sorry for the translation, it is with google, my problem is the following one I have a Tektronix 2440 which when I activate the cursor function, the lines that fit with the knob located at the top appear in the panel where it says cursor and delay since thank you very much to the one who can provide an idea for your solution Greetings !!!


Re: Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

 

TO get free shipping that is ...

-----Original Message-----
From: David C. Partridge [mailto:david.partridge@perdrix.co.uk]
Sent: 28 January 2019 21:24
To: 'TekScopes@groups.io'
Subject: RE: [TekScopes] Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

Mouser is OK but they (like Digikey) have a non-trivial MOV (about GBP35
IIRC)

Cheers
David


Re: Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

 

Mouser is OK but they (like Digikey) have a non-trivial MOV (about GBP35
IIRC)

Cheers
David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ovidiu
Popa [Business]
Sent: 28 January 2019 19:01
To: TekScopes@groups.io
Subject: Re: [TekScopes] Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

https://www.mouser.co.uk/ProductDetail/Central-Semiconductor/2N5189?qs=%2fha
2pyFadugIgCYia8CQ8sKj0cBA2t1rGTg7FfnkB9M%3d


Re: 7A26 attenuator compensation problem

Nenad Filipovic
 

Thank you all for your hints, but still no go.

the 20mV or whatever highest sensitivity range is THE reference. Get that
flat first. After that then deal with the attenuator(s). The key is still
the most sensitive setting which bypasses all that attenuator stuff.
Literally. What is it 5mV on that ? And also no X10 probe, 1;1. Eliminate
ALL sources of frequency abberations, then you are down to the amp itself.
If that ain't right nothing else will be right

Yes, 10mV and 20mV are pass-through, and at these settings 7A26 and 7A24
are identical, you can see it on the photos I posted. Ignore the corner
overshoot, it comes from the FG504 when you reduce its output to milivolts.
I believe 7A24 to be correct as I compared it to another instrument, so if
7A26 is identical to it at 20mV I'd say the amplifier part is OK. And yes,
swapping amplifiers in mainframe slots makes no difference.

I think those little modules plug in. That means you can switch them
channel to channel. Once you are flat at the highest sensitivity you can
tell which modules are the problem. To make sure switch them channel to
channel, they should act the same. If not, you KNOW someone was in there
diddling without knowing what they're doing.

The most annoying fact is that both channels behave identically, as you can
see from the photos. For that reason I don't think I'd get any info by
swapping atten. modules. The original calibration was pretty decent,
however I repeated it (using normalizer) and it went very well (see photos
on 1kHz).

Clean all of the resistor leads and the attenuator module pins with a
good contact cleaner and work them in and out of the board sockets a few
times...

I did a thorough IPA session (CH2 only, so that I can compare with "dirty"
CH1) on the front PCB side where the switches and sockets are (front side
only though, it was pretty clean already). Also scrubbed all pins of
attenuator modules, as well as resistor leads. No contact noise, no
intermittent DC levels (even before the cleaning). CH1 and CH2 still
identical, and showing the same aberration.

This thread was my 7A26 with one of those resistors cracked in half.
There are some pictures that show how bad the rise time was
https://groups.io/g/TekScopes/topic/19243444#148067

I've read that post, and I also hate carbon composite resistors. I measured
mine and all of them were off the specified value by +10% to +20%. I
immediately replaced them all with metalfilms (temporarily, just to see if
I that was the problem), however there was no improvement after the
replacement :(

At this point I'm out of ideas. It could be the back side of the PCB
(hiding some residue dirt?), but I'm not sure since the device is in good
general condition. Some corrosion trace here and there (from moisture most
likely), but not excessive. If the attenuator modules deteriorate by
themselves (age, corrosion, or if you can partially damage them by signal),
than it's going to be a sour lesson. Will need to think about this some
more.

Best Regards,
Nenad FIlipovic


Re: Anyone have a Tek 555 interconnection cable for sale

widgethunter <tubesnthings@...>
 

I may be able to help

-----Original Message-----
From: Matt Russell <statesomattr@gmail.com>
To: TekScopes <TekScopes@groups.io>
Sent: Thu, Jan 24, 2019 9:58 pm
Subject: [TekScopes] Anyone have a Tek 555 interconnection cable for sale

I just purchased a 555. It has had someone poking around that shouldn't have been! Not that I am the best candidate either!! However, I am in need of either the interconnection cable in whole, or some of the ends with the clasps, I am having trouble sourcing these, and I am starting to think about all of the horrible things I could do to defile this amazing piece of equipment, any help would be very much appreciated by myself and my 555! thank you all.-Matt


Re: Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

Ovidiu Popa [Business]
 


Re: 7904A Vertical Output Chip 155-0178-05

 

Fred,

I have one new factory boxed 155-0178-05 version left, not too pricey. Please email me off line.

regards,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.


Re: Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

 

david,

I have some new Tek 151-0260-00 and -02 parts, TO-5 cans.
I can get them to you cheaply in the UK by padded bag, email me off list, please.

-walter (walter2 -at- sphere.bc.ca)


Re: [TekScopes2] Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

dnmeeks
 

FYI, and sorry if you already have this info, that should be a 2N3724A.

-----Original Message-----
From: TekScopes2@groups.io <TekScopes2@groups.io> On Behalf Of David C.
Partridge
Sent: Monday, January 28, 2019 11:47 AM
To: TekScopes <Tekscopes@groups.io>; TekScopes2@groups.io
Subject: [TekScopes2] Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

Hi folks,

While working on my troublesome 7854 supply, I found that Q46 (151-0260-00)
was dead (open collector), so I'm looking for a replacement.

Can anyone help with one (or even a few) of these, or a suitable cross as I
scavenged the last of these I had from a 7904 LV regulator board a while
ago? I saw a few in the UK, but not exactly cheap :( Plenty in USA of
course but stupid shipping charges ($3 part >$200 shipping).

Thanks
David


Re: 7A26 attenuator compensation problem

Brendan
 

On Mon, Jan 28, 2019 at 10:18 AM, Jeff Urban wrote:


On Sun, Jan 27, 2019 at 10:15 AM, Cliff Carrie wrote:


Even at the 5mv setting, you are depending on switch contacts at each
attenuator stage to pass the signal through without adding series
resistance.
That's why the vertical instability check is so important.
Agreed.

Don't try any frequency compensation adjustments until you get DC stability
in all >attenuator settings, including 5mv.

Very agreed.

Cliff Carrie
Jan 26 #153944

There are small resistors on the board between the attenuator modules. The
resistors >and the attenuator modules are both pluggable.

The RESISTORS are pluggable ? That might be my problem. If it turns out to be
you saved me some time etc. thanks.
This thread was my 7A26 with one of those resistors cracked in half. There are some pictures that show how bad the rise time was.
https://groups.io/g/TekScopes/topic/19243444#148067


Re: Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

ppppenguin
 

Nothng special about that transistor. The 2N5189 is in the Mouser catalogue so even with the small order surcharge it won't be ludicrously expensive: https://www.mouser.co.uk/ProductDetail/Central-Semiconductor/2N5189?qs=Ypxpq5eNvNUfgtR9aTq9Kg%3D%3D

I don't know the circuit configuration but there are likely to be many parts that will do the job. This part in a different package will handle the power and voltage with ease: https://uk.rs-online.com/web/p/bjt-bipolar-transistors/1687288/

It's even possible that a commonplace BFY50 or 2N2219 will do the job.If it was my instrument I'd probably stick one in (I have them in my stock at home) and see if it worked.

Cricklewood Electronics have the 2N5859 listed: https://www.cricklewoodelectronics.com/2N5859.html

Incidentally, all of this was found with simple google searches on the part numbers. The Mouser link gave the spec of the device. Not trying anything clever.


Re: 2400 series Test 4 Fail 3,13, 2

Mark Litwack
 

I would double check the voltage on the RAM Vcc, U2460 pin 28, with the scope off and then on to make sure it's ok. With the scope off it should be about 0.1V less then the keeper battery, and when on close to +5V.

If you completed all the cal steps, including the steps for any options you have, I think what you're seeing is odd. The scope does a read/write test of each RAM location on boot and it would stop there if if found a problem with the RAM.

It could still be the RAM, maybe not holding data at 3.6V, but I would check around a little bit more before pulling it out.


Re: Looking for a scope mobile 202-2

Dave Brown
 

Where are you located? We'll check to see what we have at the vintageTEK museum.


Wanted 151-0260-00 (aka 2N3724A, 2N5189, 2N5859)

 

Hi folks,

While working on my troublesome 7854 supply, I found that Q46 (151-0260-00)
was dead (open collector), so I'm looking for a replacement.

Can anyone help with one (or even a few) of these, or a suitable cross as I
scavenged the last of these I had from a 7904 LV regulator board a while
ago? I saw a few in the UK, but not exactly cheap :( Plenty in USA of
course but stupid shipping charges ($3 part >$200 shipping).

Thanks
David


Re: 7A26 attenuator compensation problem

 

On Sun, Jan 27, 2019 at 10:15 AM, Cliff Carrie wrote:


Even at the 5mv setting, you are depending on switch contacts at each
attenuator stage to pass the signal through without adding series resistance.
That's why the vertical instability check is so important.
Agreed.

Don't try any frequency compensation adjustments until you get DC stability in all >attenuator settings, including 5mv.
Very agreed.

Cliff Carrie
Jan 26 #153944

There are small resistors on the board between the attenuator modules. The resistors >and the attenuator modules are both pluggable.
The RESISTORS are pluggable ? That might be my problem. If it turns out to be you saved me some time etc. thanks.

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