Date   

Re: Delay Time Position Vernier

J Mcvein
 

There is a nut inside the fixed part of the counter dial. It takes a 2-pin spanner
wrench made by Kilo, or you can make one, or if you have very strong fingers
you can use a round nose plier in the slots at peril of marring the dial. GL -J-

-----Original Message-----
From: "Dave Peterson via groups.io" <davidpinsf=yahoo.com@groups.io>
Sent: Wednesday, November 25, 2020 4:12pm
To: TekScopes@groups.io
Subject: [TekScopes] Delay Time Position Vernier



Anyone know the trick to removing the Delay Time Position Vernier pot?

I have the fine adjustment knob off. Now what!?

Befuddled.


Re: OT - PCMCIA anyone?

Vince Vielhaber
 

Email sent. Check your spam folder.

Vince.

On 11/25/2020 01:19 PM, Dan Gillis wrote:
If no one has taken you up on the offer, I will take them off your hands.

Let me know.

Cheers!

-Dano

On Nov 25, 2020, at 10:07 AM, Vince Vielhaber <vev@michvhf.com> wrote:


I know some of you guys deal with older computers and PCMCIA cards so I figured I'd offer it up here first.

I have an ISA bus PC Card adapter (card that goes into the ISA bus and you can plug a PC Card card into it). I don't know if it'll take one card or two, it's new and sealed. Made by or for Lucent/Orinoco.

Second item is a Lucent/Orinoco PC Card wireless network adapter 11Mbps. Also new and sealed.

I have no use for either and before I bit bucket or recycle it, I figured I would offer it up here for the cost of shipping. CONUS only.

You can email me direct at either:

vev at michvhf dot com OR vev at cdupe dot com

Vince - K8ZW.
--
K8ZW http://www.metalworkingfun.com http://www.hamradio.fun




Re: Resistor in series

Terry Gray
 

In my >60 years experience with this type of equipment I have seen these two series resistors (modification?) in many different situations and I agree with Jeff 100%.  He has it right.     Terry

On Wednesday, November 25, 2020, 02:44:56 PM CST, Jeff Dutky <jeff.dutky@gmail.com> wrote:
  Chuck Harris wrote:

How do you know tektronix did this?  Most of the stuff we have hasn't
been at the factory for 20 or 30 years.
The main reasons that I think Tek did this are 1) that the two resistors appear in the schematic in the service manual, and 2) the resistors look like matches for resistors found elsewhere on the unit. Also, the method of vertically mounting the resistors and soldering their upward pointing leads together is found elsewhere on the unit, specifically on the vertical preamp board in the 3rd stage amplifier.

-- Jeff Dutky


Delay Time Position Vernier

Dave Peterson
 

Anyone know the trick to removing the Delay Time Position Vernier pot?

I have the fine adjustment knob off. Now what!?

Befuddled.


Re: Tek 3A1 Module

David Holland
 

Today, with that which shall not be named still around?

Ummm, FairRadio (in Lima, OH) has (had?) some of the more common ones in
back... - (No affiliation, just a customer).

IIRC, they were in what I would at least consider fair condition. They'll
probably be kind of expensive, but you should be able to stipulate that
they have all their tubes. You'll probably want to send them an email,
their website is not at all complete.

After that, I dunno, you're back to ePay...<shrug> If anyone has any
suggestions, I'd love to hear them as well. I have a few plugins I'd like
to find. (A 3B5 particularly.)

David

On Wed, Nov 25, 2020 at 2:38 PM David Kuhn <Daveyk021@gmail.com> wrote:

If not for FleaBay, then where else can one obtain these old scope modules?

On Wed, Nov 25, 2020 at 1:19 PM - <rrrr6789@gmail.com> wrote:

My rule of thumb when looking at electronic equipment on E-bay or
anywhere else is to look *closely* for signs that anyone has been into
it.
If it isn't *sealed* and it's not guaranteed to work then expect the
worst. I wouldn't pay more than a *minimal* price for anything that has
been opened and that isn't guaranteed to operate properly. I've seen far
too much equipment for sale by big time used equipment dealers such as
Tucker Electronics being sold in "as-is" condition that I'm sure have
already been stripped of anything useful.

On Wed, Nov 25, 2020 at 10:08 AM David Holland <
david.w.holland@gmail.com>
wrote:

Yeah, as Brenda said....

The manuals detail what vacuum tubes are in the plugins. I'd pay
close
attention to any photos as I've gotten burnt once or twice by not
paying
attention to them. I would presume if there's no photos, and no
statement
one way or the other, that the tubes are missing.

If you start getting into the advanced (sampling) plugins, I would pay
closer attention to the photos for the presence of the transistors, as
most
of them are socketed, long obsolete, and made from 99.95% pure
unobtanium.

A few plugins (ex: 3B3) use tunnel diodes, but as far as I've seen,
they're
generally soldered to the board. Tunnel diodes are also mostly made
of
unobtanium, and may be dead, but at least they'll likely still be
there...
:-)

Again, the various plugin manuals all have a relatively complete parts
list
in the back, if you wonder what should be in a given plugin.

David


On Tue, Nov 24, 2020 at 12:05 PM 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: Resistor in series

 

Chuck Harris wrote:

How do you know tektronix did this? Most of the stuff we have hasn't
been at the factory for 20 or 30 years.
The main reasons that I think Tek did this are 1) that the two resistors appear in the schematic in the service manual, and 2) the resistors look like matches for resistors found elsewhere on the unit. Also, the method of vertically mounting the resistors and soldering their upward pointing leads together is found elsewhere on the unit, specifically on the vertical preamp board in the 3rd stage amplifier.

-- Jeff Dutky


Re: Choosing the right replacement cap

Dave Peterson
 

My hope and intent is to write up a 465 tear down page - perhaps on the Tek Wiki? Somewhere where I can create some hierarchy and include inline pictures.

Been parallel researching methods. EEVBlog: blogs loose pictures or other such barriers and instabilities. Groups.io can't do inline pictures, nor linkable hierarchy (I don't think?). Web sites require annual fees, die, etc. And I hate Wordpress. It's not an all consuming soul eating hate. Just never quite cuts it. Like using a flat blade to take out a philips head.

I prefer wiki's as they're more maintainable and enable hierarchy and inline pictures. They have issues - like web page stability, organizational management, ... I'll be reaching out to the admin on Tek Wiki.

As nice and helpful as EEVBlog and ModemHead have been, they don't really give the first timer clear instructions and insights into the do's and don'ts of the tear down. Don't you hate it when you break something because you didn't know about the little clip behind the thing that releases what you pried open with a 1/2" screwdriver?

I'm hesitant to write incremental tid-bits, but the "trick" for me behind the vertical assembly removal was that the BNCs are NOT bolted to the face - like the trigger BNCs are.
They come out with the entire assembly.

The assembly is held to the face plate with the four 1/4" nuts buried behind C3/C53 of the CH1/CH2 attenuator shields. The rest of the connections and screws are relatively obvious. I'll detail those in my full how-to.

My workbench/toolkit is somewhat limited. I only have a 1/4" socket - no open ended wrench. I don't know if that would help or not. Perhaps there are other tools to get around C3/C53? What I did was remove C3/C53: I wicked the solder from the bundle of R1, C1, C2, and C3. I was able to wick from beneath: a little flux on the wick, with the scope on it's trigger side (vert assembly up), put the solder tip under the component lead bundle with the wick between, and "ssssss" all that solder just sucked nice and neatly into the wick. Then separating the C3/C53 lead from the bundle was simple with some tweezers and the iron.

Then detachment from tiny 1/4 watt R3/R53 is easy. Note that in my scope C3/C53 have a ground post plugged into the A1/A2 attenuator board. Because it's plugged in it swiveled the cap around nicely while unsoldering from the other components. Then it just lifts out. That gave enough room to get the 1/4" socket on the nuts. Pliers _might_ have worked, but I hate tearing things up like that. Makes it look armature.

I discovered all this after unsoldering EVERYthing from the BNCs. The connections to the 10x wire is sketchy and tenuous. R1/R51 to the BNC center wasn't bad, but still. Uhg. Now I have to put all this back together. Completely unnecessary.

I have to say this is one aspect of Tektronix construction I'm not thrilled with. Definitely not mil-spec!

Hope that helps.
Dave


Re: Resistor in series

Chuck Harris
 

Resistors have voltage ratings, and power ratings in addition to
their resistance values. It is probably not the voltage rating that
is at issue here, but possibly the power rating.

More likely, however is sometimes a value is needed that cannot be
bought due to temporary shortages, in those cases, you can sit and
wait for the part, or you can make your own out of two parts.

How do you know tektronix did this? Most of the stuff we have hasn't
been at the factory for 20 or 30 years.

-Chuck Harris

Jeff Dutky wrote:

Colin,

Yes, this thread is a response to my thread "Fix or Part Out a 475A" and specifically is a discussion of the perplexing arrangement of resistors R1354 and R1356 across the collector-emitter of the Q1354 transistor in the beam intensity amplifier circuit. In the actual circuit we have two fat (1/2 W) resistors mounted vertically with their upward pointing leads soldered together.

In the schematic this looks exactly as you would expect a voltage divider to look, except that there isn't anything tapping the voltage between the two resistors, so the question was why Tek put them in rather than using a single resistor of twice the resistance, and why they mounted them in this odd way rather than flat to the PCB.

The two theories on offer (from Roger Evans and Milan Trcka) are 1) that the two parts were used to get better thermal properties in a small space, and 2) that the two resistors were put together to get a total resistance that was not available in a single part.

-- Jeff Dutky






Re: Choosing the right replacement cap

adesilva_1999@...
 

Thanks. No, I have not taken the vertical out yet. I did think about it but since I can get to those contacts without the hassle, I will attempt it as it is. But would you document the steps you did as it is fresh in your mind? I may need it later. If it come to that, I will email you as well. Thanks for thinking of it.
Ananda


Re: Choosing the right replacement cap

Jim Ford
 

Me, too.  I used to order tons of components for work, and the few times they messed up, they made it right immediately.  Could not ask for better customer service!Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: toby@telegraphics.com.au Date: 11/25/20 8:47 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Choosing the right replacement cap On 2020-11-25 11:11 a.m., Tom Phillips wrote:> Dave,> > Regarding your question "How are places like Mouser and Digikey with small time onsie-twosie buyers..."> > I have found that they are amazingly cooperative with small orders. I have been refurbishing many of my personal test equipment units each of which need a variety of replacement electrolytic caps. I end up ordering "kits" of parts after spending a significant amount of time using the search engines on the supplier's web site to find high quality replacements of suitable size and value. I choose only "in stock" parts because the stated manufacturers lead time for non stocked parts is just an estimate and usually requires a substantial minimum order quantity. I also want my "kit" to arrive complete so I can get on with the project. During my last order I found that Mouser didn't quite have all the parts I needed but Newark did and the Newark pricing was better. Digikey is a good supplier too. I just haven't needed to use them recently.+1. I use Digikey constantly, they will ship a single part just asefficiently as 10,000. I've had (free) deliveries of tiny orders within11 hours of ordering.Just a happy customer.--T> > Tom> > > > >


Re: Choosing the right replacement cap

Jim Ford
 

Usually I wait until I have about $100 worth of stuff before I order from Digi-Key or Mouser.  Just so I'm not paying $10 shipping for $20 worth of components.  I don't like Newark because they don't offer package tracking, among other things. Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: n4buq <n4buq@knology.net> Date: 11/25/20 8:33 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Choosing the right replacement cap I might be wrong, but I have to think that, for the most part, their systems are automated and little is done by hand.  If they weren't making money, they wouldn't do it.  I'm a very pleased customer of many, many very small orders.Thanks,Barry - N4BUQ----- Original Message -----> From: "John Ferguson via groups.io" <jferg977=aol.com@groups.io>> To: TekScopes@groups.io> Sent: Wednesday, November 25, 2020 10:24:48 AM> Subject: Re: [TekScopes] Choosing the right replacement cap> > > I find Mouser an excellent source for my onesie-twosie orders.> > I confess to a bit of discomfort with sending them orders for $25 worth> of components which cannot possibly be profitable for them. For example,> ordering 4 or 5 SMD sensors can require that they take them off a reel,> and repackage them with a moisture sensitive card in a sealed packet.> What they charge cannot possibly support the cost of the time spent.> > Additionally, they have a section of the site which allows you to> accumulate parts in groups under the heading projects.  This can be very> useful for re-ordering where I've forgotten  what I needed to complete a> reprise of something I scratch built.> > I try very hard to drive the total price of an order up to $50 assuming> that will help share their costs.> > I did have a telephone conversation with one of their reps years ago on> this subject and asked why they didn't have a minimum order like Digikey> had at that time.  She said something like they hoped one of my projects> would turn into a big deal and I would remember them when it came time> to order reels instead of onesie-twosies.> > Alas, I'm not smart enough to come up with anything like that.> > > > > > > >


Re: Tek 3A1 Module

David Kuhn
 

If not for FleaBay, then where else can one obtain these old scope modules?

On Wed, Nov 25, 2020 at 1:19 PM - <rrrr6789@gmail.com> wrote:

My rule of thumb when looking at electronic equipment on E-bay or
anywhere else is to look *closely* for signs that anyone has been into it.
If it isn't *sealed* and it's not guaranteed to work then expect the
worst. I wouldn't pay more than a *minimal* price for anything that has
been opened and that isn't guaranteed to operate properly. I've seen far
too much equipment for sale by big time used equipment dealers such as
Tucker Electronics being sold in "as-is" condition that I'm sure have
already been stripped of anything useful.

On Wed, Nov 25, 2020 at 10:08 AM David Holland <david.w.holland@gmail.com>
wrote:

Yeah, as Brenda said....

The manuals detail what vacuum tubes are in the plugins. I'd pay close
attention to any photos as I've gotten burnt once or twice by not paying
attention to them. I would presume if there's no photos, and no
statement
one way or the other, that the tubes are missing.

If you start getting into the advanced (sampling) plugins, I would pay
closer attention to the photos for the presence of the transistors, as
most
of them are socketed, long obsolete, and made from 99.95% pure
unobtanium.

A few plugins (ex: 3B3) use tunnel diodes, but as far as I've seen,
they're
generally soldered to the board. Tunnel diodes are also mostly made of
unobtanium, and may be dead, but at least they'll likely still be
there...
:-)

Again, the various plugin manuals all have a relatively complete parts
list
in the back, if you wonder what should be in a given plugin.

David


On Tue, Nov 24, 2020 at 12:05 PM 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: Why you MUST USE the PayPal "FRIENDS and FAMILY" option for Peter's book

Jean-Paul
 

Dear Dennis, we are fortunate to have the chance to buy this book.

I Understand completely the issues in PayPal.

I notice that the email for the PayPal account seems to be an organization. If it received many payments marked "friends and family" the PayPal robots may raise a red flag.

IDEA.... you could offer an alternative payment to PayPal:
eg the buyer posts to you or Peter a check ( only for buying by USA not overseas)
Just a name and address needed, NO PayPal holding, fees or commercial vs friends questions.

I am gladly going to send the $37, but I await your response, as I prefer to post a check.

DENNIS THANKS FOR ALL YOUR KIND WORK OVER THE YEARS!

from A very grateful TEK afficanado ( since 1970!)

Jon


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

 

The prices are more than I'm willing to pay, but there are a bunch of mechanical keyboard whackos out there inflating the prices for this kind of stuff. The market will do what the market does, whether the motives of the participants is in any way rational.

I also suspect that there is a large element of supply & demand at work: for lots of reasons this kind of equipment is becoming rarer and rarer, and that's simply got to drive the price up if there is any kind of demand. The prices would certainly have been a lot lower a decade or two ago, but those days are gone. You might also be able to find some of these things at a hamfest for lower prices, if you can find a hamfest to go to (I haven't seen a hamfest in my area in many years), but even there you are likely to see increasing scarcity of older equipment.

Finally, my impression is that IBM equipment generally didn't make its way into private hands, both because these systems were marketed almost exclusively to corporate and institutional buyers, and because IBM preferred to lease equipment rather than sell it outright. This had the effect of radically restricting the aftermarket on such things, which is reflected in current scarcities. You'll have similar difficulty finding systems from other manufacturers in the same space (e.g. Burroughs, Honeywell, Univac, Sperry, etc.).


Re: 7A26 no signal

Colin Herbert
 

If changing R160 didn't have any effect, then are the +15 VDC and -15 VDC present at its two ends? Did adjusting both R160s not do anything on either channel? I suppose it is possible that something drastic has happened to both baluns (T1301 on both channels), if someone accidentally fed in too much voltage on both channels, but I would have thought that Q150A/Q150B would have died first.

A resistance of 56R between the centre of the BNC input and the non-earthy end of R130 looks to be correct - it is R10.

You might have dirty AC/GND/DC switches - these contacts are a bit prone to getting a bit mucky after years of service, but they should only be cleaned with isopropanol and carefully. It is easy to bend the gold-plated leaves if you are too aggressive and the board substrate can be damaged by other solvents. I have cleaned attenuator cam-switches, but not the AC/GND/DC switches. Others may give you advice on that. You may also have dirt on the attenuator switches, but time will tell.

You may well have faulty Q150s, but since they are dual FETs in the two channels, I would have though the failure of all four devices was a little unlikely.

I don't think that dirty attenuator switches would give the symptoms you describe, but I could be wrong, I often am. Dirt on these switch contacts usually has an effect on the frequency response of the affected attenuator, the dirt being capacitative. It's a pity that both channels are exhibiting the same fault, because otherwise you could swap components like the individual attenuator units and the Q150s between the two.

I have had a problem (still do, to some extent) with one of my 7A26s in that one channel was showing a different gain to the other. I think I got near to sorting that out by replacing the faulty U1350, but my memory is a bit hazy - not that that helps with your problem.

I am assuming that you have the appropriate Service Manual (you are quoting part-numbers) and that you have checked all of the voltage rails. That is often a cause of faults.

Good Luck, they are nice amplifiers,
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jouko Koskinen
Sent: 25 November 2020 14:38
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7A26 no signal

Thanks for the replies,

R160 didn't have any effect on the trace.
I think the problem might be in the attenuator/source follower part
Attenuator in 10mV/div setting. Resistance from BNC to R130 shows 56R. Probe in place and connected to calibrator I can't see any signal in R130.
Input resistance from BNC is only 340k. When I remove Q150 it is 1M as it should be.
Situation is similar in both inputs. Q150 damaged in both inputs???
I suppose the attenuator switches can't make this behaviour?

Regards,

Jouko


Re: Choosing the right replacement cap

adesilva_1999@...
 

BTW, Newark is having a 15% off black Friday sale now. Just got an email.


Re: Choosing the right replacement cap

adesilva_1999@...
 

Yes, that is the one.


Re: 2710 Spectrum Analyser 'Cannot count VCO, IF' error

Jaap Rusticus
 

Hi all,
Nice to meet you.
Just after answering I saw all the other responces. Sorry for not having checked further developments in time.
Jaap


Re: Choosing the right replacement cap

Dave Peterson
 

Hey adesilva_1999, please feel free to email me directly to discuss any 465 questions. We seem to be on the same path. Have you taken out the vertical preamp yet? Message me if not. I learned a few things taking it out that were not at all obvious for a first timer like myself.
Dave


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

Siggi
 

On Wed, Nov 25, 2020 at 12:53 PM Lawrance A. Schneider <
llaassllaaass@gmail.com> wrote:

To pay with PayPal, it need more than MarianT@... . I don't know what
the "..." is. Clearly, I'm lesserly smart than others, but I just don't
know what to use.
It looks like the web interface on groups.io garbles anything that looks
like an email address. I don't have trouble with this in email delivery,
see https://groups.io/g/TekScopes/message/173743.

7721 - 7740 of 181259