Date   

Tek 7104 CRT problem

gsl@...
 

Hello everyone,
My Tek 7104 has a problem in the CRT circuit: on the TP1775, instead of 1200V, there are 625V! I checked everything: resistors, capacitors, U1714, Q 1708, Q1724, HT transformer (all right). The waveform at point "1" is perfect. Can anyone give me a suggestion?
Thanks.


Re: 2465B - Weak Readout Intensity

satbeginner
 

The 2465x uses what I call a "fly by wire" control system.

The settings from the front panel are just digital values counting up or down depending on the setting the user wants, and this is done per setting.

These digital values are available on the outputs of a register.
From there a DA converter converts the value (one at the time) into an analog value.
This analog value is redirected to the proper part of the scope using an analogue one to many switch.

All this happens in a continuous cycle, if I recall correctly there are 8 values in a round robin style.

To make a particular setting "constant" a sample and hold circuit is used.
Each individual setting has its own sample and hold circuit.
Depending on the function within the scope there is some level shifting done as well.

The sample and hold circuits are build using a simple opamp circuit.
The output of the analog switch charges a capacitor, and the high input impedance of the opamp keeps it at the presented level.
The opamp shifts the level depending on what the functionality needs.

I have seen these sample capacitors go bad as well as the opamps. (TLO72???)

I recommend checking these as well.

I'm not at home now, so I can not give you the partnumbers in the schematic right now.


Re: BEWARE of TEK MADE RELAYS

 

Hi David,
Great suggestion. I wish I thought of that. It would have saved me wiring up the push button on my little test fixture.
Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David C. Partridge
Sent: Thursday, January 23, 2020 4:40 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] BEWARE of TEK MADE RELAYS

Just operating the relay with a function generator at about 5Hz for a few seconds will often sort these relays out. Putting some AC across the contacts at a few mA at the same time won't harm either.

David


-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Glenn Little
Sent: 23 January 2020 11:47
To: TekScopes@groups.io
Subject: Re: [TekScopes] BEWARE of TEK MADE RELAYS

What is the failure mode of these relays?
If it is contact resistance, they can possibly be recovered by operating the relay with AC on the contacts.
This is a common problem in some Harris radios.
Glenn

On 1/23/2020 12:22 AM, Dennis Tillman W7PF wrote:
I wanted to make everyone aware of the very poor reliability of certain Tek made relays. Almost every Tek made component was higher quality than industry made components. This is an exception. I think the person Tek hired to oversee the design and manufacture of these relays was a few crayons short of a full box.
These relays are easy to recognize by their light sandy-gray color. They have from 5 to 8 pins made of thin, but stiff, wire on the bottom in two rows of 4 pins. The pins are on 0.1" centers. The PCB will have small single pin sockets in it of the appropriate quantity (8, 7, 6, or 5) and pattern that the relay will be inserted into.
I saved all of these relays from some 7000 parts mules I had. Occasionally I would need one to fix another plugin. I was often puzzled when I substituted one that I saved as future replacement for the bad one because the replacement relay didn't fix the problem or, worse, it created another problem elsewhere. Eventually I discovered the replacement was also bad. After encountering this a few times I made a little test fixture with LEDs on the NO and NC contacts and a push button to energize the coil. This allowed me to quickly test each relay I took from the parts mules and see which relays worked and which were bad. I had close to 100 of these relays and my test fixture found almost 50% were not usable. This confirmed what a few other Ex-Tek folks told me about these relays.

The relays are 0.632" (16mm) long x 0.327" (8.4mm) wide x 0.590"
(15mm) high They were used in a wide variety of things that Tek made in the late 1960s through the mid-1970s.
The 576, 7A11, 7A12, 7A13 Mechanical and Digital, 7A14, and other instruments use them.
Typical part numbers are 148-0034-xx, -0035-, -0044-, -0054-, -0063-, and -0088-.
These are the part numbers versions I have. There are other part numbers as well.

The round CRT Tek bug is on one side of the relay.
The circuit diagram is on the other side of the relay. Below the circuit diagram is the 148-xxxx-xx part number.
Above the circuit diagram is the coil voltage, mine are all 15V.
The coil impedance is also above the circuit diagram. My coils are 600 ohm or 1000 ohm.
The large 3 digit number stamped in ink on the top of the relay is a date code and not significant.
Some relays also have a red dot on the top which doesn't seem to be important either.
The relays are 0.632" (16mm) long x 0.327" (8.4mm) wide x 0.590" (15mm) high.

Fortunately these are not as prevalent as tantalum capacitors.
Dennis Tillman W7PF


--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class of the Amateur that holds the license"









--
Dennis Tillman W7PF
TekScopes Moderator


Re: BEWARE of TEK MADE RELAYS

 

Hi Glenn,
I didn't keep track of what the failure mechanism was. My only interest was weeding out the bad ones as quickly as possible. The test fixture I made did exactly that. And it sped things up by a huge amount. At that point it would have been counterproductive to stop and jot down the results for each failing relay.

My impression is Tek stopped using them in new designs around 1975 so I know I will never need these again except to fix older plugins, etc. Therefore expediency meant the good ones went into my spare parts drawer for safe keeping and the bad ones went into the trash and I moved on to something else that I was itching to play with.

My curiosity is so great I want to take everything I have apart to see what's inside. Unfortunately I do not have enough time to do this and do the really interesting things that always seem to pile up.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Glenn Little
Sent: Thursday, January 23, 2020 3:47 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] BEWARE of TEK MADE RELAYS

What is the failure mode of these relays?
If it is contact resistance, they can possibly be recovered by operating the relay with AC on the contacts.
This is a common problem in some Harris radios.
Glenn

On 1/23/2020 12:22 AM, Dennis Tillman W7PF wrote:
I wanted to make everyone aware of the very poor reliability of certain Tek made relays. Almost every Tek made component was higher quality than industry made components. This is an exception. I think the person Tek hired to oversee the design and manufacture of these relays was a few crayons short of a full box.
These relays are easy to recognize by their light sandy-gray color. They have from 5 to 8 pins made of thin, but stiff, wire on the bottom in two rows of 4 pins. The pins are on 0.1" centers. The PCB will have small single pin sockets in it of the appropriate quantity (8, 7, 6, or 5) and pattern that the relay will be inserted into.
I saved all of these relays from some 7000 parts mules I had. Occasionally I would need one to fix another plugin. I was often puzzled when I substituted one that I saved as future replacement for the bad one because the replacement relay didn't fix the problem or, worse, it created another problem elsewhere. Eventually I discovered the replacement was also bad. After encountering this a few times I made a little test fixture with LEDs on the NO and NC contacts and a push button to energize the coil. This allowed me to quickly test each relay I took from the parts mules and see which relays worked and which were bad. I had close to 100 of these relays and my test fixture found almost 50% were not usable. This confirmed what a few other Ex-Tek folks told me about these relays.

The relays are 0.632" (16mm) long x 0.327" (8.4mm) wide x 0.590"
(15mm) high They were used in a wide variety of things that Tek made in the late 1960s through the mid-1970s.
The 576, 7A11, 7A12, 7A13 Mechanical and Digital, 7A14, and other instruments use them.
Typical part numbers are 148-0034-xx, -0035-, -0044-, -0054-, -0063-, and -0088-.
These are the part numbers versions I have. There are other part numbers as well.

The round CRT Tek bug is on one side of the relay.
The circuit diagram is on the other side of the relay. Below the circuit diagram is the 148-xxxx-xx part number.
Above the circuit diagram is the coil voltage, mine are all 15V.
The coil impedance is also above the circuit diagram. My coils are 600 ohm or 1000 ohm.
The large 3 digit number stamped in ink on the top of the relay is a date code and not significant.
Some relays also have a red dot on the top which doesn't seem to be important either.
The relays are 0.632" (16mm) long x 0.327" (8.4mm) wide x 0.590" (15mm) high.

Fortunately these are not as prevalent as tantalum capacitors.
Dennis Tillman W7PF


--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class of the Amateur that holds the license"






--
Dennis Tillman W7PF
TekScopes Moderator


Re: What Tektronix means to me -toaster ovens

Tam Hanna
 

Hello Folks,

to be honest: my wife would not moan about this. I generally think that, if you have this problem, something is wrong in your end of the zero sum game.


But, here, we would moan together for two reasons:

a) solder contains shit poisonous stuff. And it does not get out of the oven once in, and it also does not get out of your corpse once in there. Friend of my former lab gypsy, like 185cm tall woman, in her 40s from Eastern Europe. Her face is blue though, a bit like the percussionist from the Blue Man Group.

The reason for this is some heavy metal which deposited itself in her body in an accident. My wife would know the exact story, given that she is the medical professional. But trust me that this metal cannot be dislodged, and that a blue face is not helpful if you do not want to become a percussionist or rapper.


b) getting timing for bagels and pies right is insanely difficult. I sometimes keep odd hours alone in the lab and then want to eat a bavarian bagel. Given that I loathe to throw food away (long story why), I spent a lot of time eating barely edible bagels when we got the new oven. What keeps me up at night is the thought of this happening again.

I have perfect timing, adjusted exactly to the location of the bagel in the deep freezer, its temperature and the location of the bagel in the oven. And now think of an entire pie which failed, and must be eaten by someone (aka /me)...


In short: get your own oven, man. I have a Huaqi Zhengbang oven from China, was like 400 bux delivered to Europe, and never looked back. Super accurate temperature control, RS-232 port if I feel like it, and and and. Once you have the solder paste dialed in and the right temperature characteristic, soldering PCBs is as easy as breathing.

--
With best regards
Tam HANNA

Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at https://www.instagram.com/tam.hanna/


Re: What Tektronix means to me

Tam Hanna
 

Hello Chuck,

case in point: an SDK is available for the thing!


Tam

--
With best regards
Tam HANNA

Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at https://www.instagram.com/tam.hanna/


Re: 2465B - Weak Readout Intensity

Lawrance A. Schneider
 

Thank you, larry


Re: 2465B - Weak Readout Intensity

flanneltuba@...
 

Regarding the adjustment of the Grid Bias, the answer is, yes. I can get a marginal increase in overall intensity from both the sweep trace and the readout characters by maxing out the Grid Bias. Alas the increase is only just enough to make the scope usable in low lighting settings. In a bright room, the readout is not discernible, and the sweep is just a bit too washed out to be useful.

There was another responder who asked if I could post a picture or two. I'm afraid I am not certain how to do that here, short of posting URL's to pictures hosted elsewhere. Is there a way to upload pics directly to the forum here?

Thanks,

- Scott


Re: Tel 576 relay

David DiGiacomo
 

On Thu, Jan 23, 2020 at 5:32 PM peter bunge <bunge.pjp@...> wrote:

My relay has an open coil. It is only a spare which I may never need.
For $40 I will repair it if I ever need it. I was hoping to find someone
else that needs one and bring the cost down to $10.
Well, $10 is not going to happen. Minimum package postage US to
Canada is about $8.


Re: Tel 576 relay

peter bunge
 

My relay has an open coil. It is only a spare which I may never need.
For $40 I will repair it if I ever need it. I was hoping to find someone
else that needs one and bring the cost down to $10.
I cut it open and It looks perfect inside. The contacts are fine.
Peter

On Thu, Jan 23, 2020 at 8:53 AM Chuck Harris <cfharris@...> wrote:

It is a really bad idea to seal a relay in an
atmosphere of air. The minute arcing that occurs
when the contacts switch will turn the atmosphere
in the relay case to a soup of nitrogen oxides,
which given a little moisture form nitrous and
nitric acid.

"Real" manufacturers of hermetically sealed
relays fill them with an inert gas such as argon,
or dry nitrogen.

Some relays with sealed cases have a small tit
on the case that can be punched out after the
relay is soldered into the board, and has had
the flux washed away.

A small hole in the relay's molded case would
have saved Tektronix a lot of trouble.

-Chuck Harris

Dennis Tillman W7PF wrote:
Hi Ed,
The eBay ID he provided in his post takes you to one of Pam Kidd's
(daughter of Deane Kidd) listings for a brand new relay for $5.00 and $7.35
USPS Small Flat Rate Box. That is a bargain. The problem is that Peter is
in Canada. The same $7.35 box going to Canada costs $26.00 which makes it a
totally different situation financially.

I offered to help by suggesting he contact Pam to buy 5 or 6 of the
relays and have Pam send all of them to me in the same $7.35 Flat Rate Box.
We are friends and I know she will do this and probably give him a quantity
discount on the relays. Those relays were notorious for their failure rate.
Unlike almost every other Tek made component which was higher quality than
industry made components the so called expert they hired to design their
relays was far from an expert. I removed all of these type of Tek relays
from some 7000 parts mules I had and occasionally would use one to fix
another plugin.

I was often puzzled because the replacement relay didn't fix the problem
or created another problem elsewhere. Eventually I discovered the
replacement was bad. After encountering this a few times I made a little
test fixture with LEDs on the NO and NC contacts and a push button to
energize the coil. I could tell in an instant which relays worked and which
were bad. The failure rate was almost 50%. It confirmed what other Ex-Tek
folks told me about the relays.




Re: 465 Capacitor

 

Use a radial lead 1200 uF/25 volt, 105 °C cap. Be sure to jumper the ground pads if required. Active track is on both sides of the board. Buy the cap from a reliable supplier such as Mouser.

On 1/23/2020 3:27 PM, Rob Naulty wrote:


I recently bought a 465 to fix up and noticed that an aluminum can axial lead capacitor is leaking dried crap from one side. The capacitor is located on the bottom board. C1220 is the location on the schematic printout.
Its listed as 1000uf 20% 10v. Any ideas where to find a replacement? Thanks, Rob




Re: 465 Capacitor

toby@...
 

On 2020-01-23 3:27 PM, Rob Naulty wrote:



I recently bought a 465 to fix up and noticed that an aluminum can axial lead capacitor is leaking dried crap from one side. The capacitor is located on the bottom board. C1220 is the location on the schematic printout.
Its listed as 1000uf 20% 10v. Any ideas where to find a replacement? Thanks, Rob
Usual component supplier should do? It's an electrolytic.

What about Digikey 4008PHTB-ND, 4008PHCT-ND ?

--Toby







Re: Tel 576 relay

peter bunge
 

Thanks; they plug in so I don't want to modify.
I only need one as a spare which I may never use.
I was hoping to find someone that needed one, buy a couple, and mail me one
for real cost.
If I have to pay nearly $40 I will re-wind the coil or find the break and
repair it - when the time comes.
Peter

On Wed, Jan 22, 2020 at 7:33 PM Ed Breya via Groups.Io <edbreya=
yahoo.com@groups.io> wrote:

I see that's one of those little Tek-made ones. I noticed some on my spare
576 boards recently - I didn't recall/realize they had used some of these.
Since the 576 is a very low frequency application, you should be able to
swap in regular type small relays, except for needing to adapt to the
footprint and pinout. I believe this same part may be used in the 7A13
and/or 7A22, so I'd keep these kind for use in them, where it's more
critical for frequency response.

Ed




Re: PIN Diodes used in Tek products

Brian Cockburn
 

Hi,

What are the differences between:

Tunnel diodes, Back diodes, Pin diodes, and Gunn diodes
Have a peek here: https://www.youtube.com/user/w2aew/videos for some useful tutorials about some of those diode types.

Brian.


465 Capacitor

Rob Naulty
 

I recently bought a 465 to fix up and noticed that an aluminum can axial lead capacitor is leaking dried crap from one side. The capacitor is located on the bottom board. C1220 is the location on the schematic printout.
Its listed as 1000uf 20% 10v. Any ideas where to find a replacement? Thanks, Rob


Re: What Tektronix means to me - Modern Times

Eric
 

Leo,

I have to agree with you on that one. I have some of the 7K analog frames on the bench but I have not seen anything I even wanted to acquire after the TAS series. I do have some of the TM 500, 5000 stuff. I do love the SG 502 and the SG 505. I also like the scope calibration plugins. In terms of “new” Tek gear I have been really impressed with Keithley DMM6500 but I am not sure how to Tek is in the 6500.Is there any gear worth looking a post TAS series?

Eric

On 1/23/2020 6:08 AM, Leo Bodnar wrote:
I have great respect for what Tek did before fully digital scopes.
How can't you when every other worthy appnote has images of JW's famous 556 with damaged screen?!

However, to me, Tektronix has died since the time they started making plastic shoeboxes with a carrying handle on top. Nothing Tek produced since 1990's makes me excited or even curious. I had 2465A scope and loved it to bits but nothing I see from current range makes my heart beat faster.

It turns out I have only one Tek instrument - CSA803 (I have three of them because I don't want to be caught out when one dies.)
The rest, about 98% are HP, Marconi, R&S, LeCroys, Anritsu etc. Most of the instruments were bought 50% due to need and 50% because I really wanted one. Ironically, the only Tek I have (CSA803) was given to me by my friend who had to get rid of it due to moving into a smaller flat in Paris.

Neither PSPL or Keithley are part of Tek family - to me...

So here we go... Am I sick? Am I alone in this or is this sad truth that is not usually talked about?
Please tell me that there are still people who are irrationally in love with modern Tektronix!

Cheers
Leo


Re: What Tektronix means to me - Modern Times

Magic_Smoke
 

Are these issues specific to Tektronix equipment, or the modern age in general? I think everything is becoming harder to fix as it becomes more complex, miniaturized, and cheap to produce. I am not in a position to judge for myself, but is there much of a quality gap between manufacturers?


Re: BEWARE of TEK MADE RELAYS

fiftythreebuick
 

Dennis, thank goodness there was never a tantalum cap/relay combo device! That would be pretty much a guaranteed failure! <laughing>


On Wed, Jan 22, 2020 at 09:22 PM, Dennis Tillman W7PF wrote:


I wanted to make everyone aware of the very poor reliability of certain Tek
made relays. Almost every Tek made component was higher quality than industry
made components. This is an exception. I think the person Tek hired to oversee
the design and manufacture of these relays was a few crayons short of a full
box.
These relays are easy to recognize by their light sandy-gray color. They have
from 5 to 8 pins made of thin, but stiff, wire on the bottom in two rows of 4
pins. The pins are on 0.1" centers. The PCB will have small single pin sockets
in it of the appropriate quantity (8, 7, 6, or 5) and pattern that the relay
<text removed>
Dennis Tillman W7PF
TekScopes Moderator


Re: BEWARE of TEK MADE RELAYS

Abc Xyz
 

Does it Work? ... The 650A Desulfating Generator.

On Thu, Jan 23, 2020, 8:25 AM mosaicmerc via Groups.Io <mosaicmerc=
yahoo.com@groups.io> wrote:

Well, these days I use JD1914 12V SPDT heavy duty relays in one of my
products. Beware of a lot of fakes out there. The fakes lack a copper
braid conductor augmentation and this results in a resistance of 80
milliohms instead of 4 milliohms across the NC SPDT contacts. So my 650
Amp pulse generator for desulfating lead acid batteries uses two of
these relays in parallel to deliver the pulses for a net 1.25V drop
transmission loss.





Re: PIN Diodes used in Tek products

Greg Muir
 

I did notice that listing. I sent him a note mentioning that the 1N5767 is not obsolete.

Greg