Technician in Need


Hi, looking for a technician to help me repair my dad's TS.
Please PM if you know one.

Re: Tektronix 465 No Trace, No Dot



First post here.
Instead of making a new post, I opted for reviving this one, since I practically have the same issue.
This Tek 465 I got recently turns on, but absolutely no trace. Beam finder not working either.
I followed the troubleshooting instructions in the manual, and I’m looking at the CRT schematic.

Here’s what I have found:

R1404 read fine
Q1404 C 2.97V, E 2.97V, B 3.53V
Q1408 E 2.97V, B 3.57V, C 3.6V

TP1536 is exactly -55V
TP1548 is 15.04V
TP1558 however, is 4.74V (too low)
TP1568 is also very low at -6.3V
TP1518 is around 111.3V

I cannot check HV -2450V, I don’t have a HV probe. My DVM will fry.

How did your issue end up?

Cleaning TM500 module pushbutton switches


Hi all,

Hopefully not way off topic:

I have some TM500 modules with sticky/intermittently responsive
pushbutton switches (the small square kind). What is the recommended
cleaning procedure - Deoxit from Caig, or something else?

Cheers, Phil

New member with a currently-dead 2465

Vincent Mallet

Hi group,

I just joined TekScopes after hunting for info on how to go about
resurrecting a dead 2465 I acquired recently. I picked up electronics as a
hobby a little over a year ago and it has been a learning experience for
sure, and my new challenge is to see if I can do something about this
'scope :)

The 2465 powers on and a lot of lights light up and stay lit on the front
panel; the display stays absolutely blank (no hint of a beam anywhere no
matter the position of the intensity settings). No blinking TRIG'D light,
pressing A/B does nothing (actually, pressing any button doesn't change

I started getting familiar with the service manual and going through the
basic troubleshooting steps. The power supply measurements appear to be
within specs as per table 5-1; ripples _seem_ to be within spec but I'm not
sure I'm measuring them right with my DSO.

I moved on the troubleshooting steps until I reached the clock signal
coming to U2092-37 (TP505) where I get a flatline rather than a 5MHz
signal. I looked at the oscillator circuit on A5 and the test points at the
output of U2556B and U2468A are both flat lines too (instead of a 10MHz
square and 5MHz square). I do get a -5V on one side of R2553 and +5V on

Question: how likely is it that the oscillator circuit has failed? Or could
there be an external factor preventing it from oscillating that I don't see?

My next step would be to pull the few components from the oscillating
circuit out so I can test them but I figured maybe I'd ask around if this
rang a bell first.



Restoring 545b


Hi all, I am from London uk and I am restoring a 545b which I obtained from ebay for £30. It was in a bad state when I recieved it and had 7 vacuum tubes missing. I now have got it to the point where I get a dot on the screen from both A and B channels and it seems the vertical output is not working at all. I think a lot of the problems is with dirty contacts on the rotary switches ...
I was wondering what is the best way to clean these as I have tried to clean them with alcohol and cotton buds. Do you guys have a good way to clean them and get all the oxide off ?

My first scope, a Tektronix 11401 with option 2D extended memory and two 11A34 plugins and an 11A33 plugin.


The 11k series, and the elusive 11401. Almost all google searches result in low double digit number of results. The ones that do return a large number of results are mostly user manual sales. The 11401 and other 11000 series sadly has missing extended service technical documentation and I've only seen prototype pcb pictured. There are some cool 1980's 11000 series marketing materials from vintageTEK on youtube and single self test videos on youtube and that's about all I could find. No one seems to care about them largely and It seems to be almost forgotten. Outside of a handful of sites, and a tiny number of posts and pages from the likes of tekwiki, evvblog,, and plus the wayback machine, the internet archive, and ArtekManuals. There is nothing. Compare that to a 453, or the 7854 you get millions and millions. I mostly resorted to scouring the old 1986, 1987, 1988 Tektronix product catalogs for my cross reference knowledge on the machines general capabilities, recommended probes for each plugin, plugin compatibility. Yeah yeah, read the manuals. easier said than done as I had to find them first. People talk about dreading working on their 11400 scopes. But a quoted service center tech said, "The 11400's are boring to fix; they're no fun to troubleshoot because the diagnostics finds the problems so quickly and easily." I'm sure it's mostly marketing but the 11400s were engineered from the ground up with self diagnostics in mind. They offer a very wide range of features and really is the pioneer of DSOs. (probably why they later code named it 'pioneer', if not ... wow that foresight)

Why should anyone care about the 11k and largely the 11400? Do I have buyers remorse?
The Tektronix 11400s brought high expectations and new standards for what a digital scope is and what it could be. The 11k line brought to market advanced triggering, storage, full hardware and firmware program-ability, Live operation, high accuracy, high resolution, multiple channels, plugin modular-ity, 7k plugin compatibility, self calibration, self diagnostics and a freaking touch screen interface + many other features that all good DSOs have today. Going by today's standards almost all of those features are vital. If it were not for the 11k series and largely the 11400 line, i believe the Modern Digital Storage Oscilloscopes probably wouldn't be what they are today. I feel there is enough room for argument to say that the bench-top DSO would probably be nothing more than a pico pci-e card or a phone with a usb dongle if it were not for the 11400s. Why? Well first, everyone was watching Tektronix after the 7854, how could you not? With eyes on them, they had to do something bold, and I believe they did just that. The 11000 series was released in 1986, only 5 years before pico technology. The DSA600s released in 90. Talk about breathing room. If Tektronix didn't go where no scope designer went before, and released just another analogue scope with 500 buttons instead of 250, or a mediocre DSO with 250 buttons, the DSO wouldn't have progressed like it had so vigorously with the 11000s into what they are today. They wouldn't have had time to engineer the 11k line if they made a 500 button analogue or a 250 button DSO first, pico tech would have came out, and with the accessibility of the microprocessor ruling the world. I don't see how DSOs would have been relevant. The 11400 wasn't designed for today in 1982-1986, it was designed for today in 2020. All modern oscilloscopes should look to the 11ks and largely the 11400 for their grandscope. Sure 11ks only have 20 mega samples per second, but it's cousins the DSA600s with plugins like the 11A72 can get you to 500Mhz @ 2ghz sample rate. Truly mental for the 1990s. Anyway, just an afterthought I had floating in my brain, but maybe you can see how if it were not for machines like the 11400s which came out in a crucial time right before mass pc computers and pico technology the mighty DSO might just have become just another piece of software on a laptop or another apple dongle. I think we can almost all agree that this was for the better. The 11k series to me, is likened to zx spectrum, the bbc micro, or commadore 64 of oscilloscopes. The one that started it all. And if you ask why hasn't pico become more popular ? that i think is because established companies were already making DSOs before we were blessed with the pico. so much was already invested into what modern DSOs were to become. so there was no room for pico.

What are my plans with this machine? No... I don't have buyers remorse what makes you say that?
I got this largely for the 11k plugins it has in it, notably the differential comparator, also 2-4 channel amplifiers lol, the mostly working mainframe with Option 2D - Extended Memory is a bonus. My plan is to use this as my first scope, and fix it until I feel like i need breathing room and as i can easily upgrade into a DSA602a while still using the plugins, once i collect enough excess 11k plugins and probes, i plan to get a 11302a and have a very decent set of retro-ish scopes. Currently awaiting arrival. I will update this topic, post pictures, and I will be posting videos on youtube about this scope as this is almost nothing about it online. Im currently in research and developing a robot with multiple dual core 64 bit risc-v chips and fancy mechanical 3d printed parts.

Onto the now hopefully rose tinted machine itself.
I just picked up this Tektronix 11401 with Option 2D - Extended Memory, it came with two 11A34s and an 11A33 from ebay for 199, and 50 usd shipping. It came from a university who's upgrading. Overall seems decently kept for a machine built in 1986. I also swooped up a few P6134c, P6134 and P6135's probes. I also went over to ArtekManuals and bought the 4 volume manual set they offer. I believe that they have the 2 missing extended service manuals i cant find on the open internet. The machine passed almost all of its self tests with a single fault on the TimeBase Test with fault code G2121. There is also a penciled X by channel 2 on the far right 11A34, possible dead channel?. My initial thought without reading the manuals because they haven't arrived yet, is that the timebase G2121 fault is from that pencil'd x channel that could be dead as its marked with a x. lol.... honestly no clue, it's what i can tell from the photo and knowing nothing about the machine or really electronics engineering, im a software guy who just recently fell in love with the programming language of solder! The machine hasn't even shipped yet! Im typing this as I eagerly await my boat anchor. You and I will find out more when it arrives. in the mean time, i await the service manuals and i get to read the user manual :D !!! Wait who reads these anyway?

Time base for 7854: 7B85/80 or 7B92a

Martin Hodge

I have a newly acquired 7854 with one 7b85 time base. Is there any advantage to using a 7b85/7b80 pair over a single 7b92a in the right vertical slot?

Also I am looking for the reference card pocket thing (with cards) that goes on the top if anyone has a spare stored away. Contact me at mhodge[at]innocent(dot)com.

TM500 module pushbutton switch cleaning procedure


Hi all,

Hopefully not too off-topic:

I have multiple TM500 modules that have developed sticky / intermittent pushbutton switches (the square small ones). Is there a recommended cleaning procedure? I was going to do the standard use of Caig's DeOxit in a sparing manner, but perhaps there is a better way.


Tek 465 Turns on, No Dot, No Trace



I have this Tektronix 465 that I got a few days ago. I knew it had that issue, and I thought I could fix it. It turns out to be more difficult than I anticipated. Here’s the issue:

The scope turns on, the fan spins, the graticule illumination is working, when I inject a signal from my function generator, I can see the trigger light go on and off whenever I turn the knob. Everything seems to be working, except there is no trace or dot on the display, and the beam finder is also silent.
As per the troubleshooting steps in the manual, I’m checking the CRT circuit to the best of my ability.

I’ve checked Q1404 and R1404, and they are fine. I even replaced Q1404 just to be safe.
Voltages are not what I would expect: Base: 3.53V, Emiter: 2.95V, Collector: 2.97V

Voltages have been checked as well, and 2 of them are very low:
TP1536: dead on -55V
TP1548: 15.05V
TP1558: 4.74V (too low)
TP1568: -6.3V (way too low!)
TP1518: 111.2V

I can’t check the HV (-2450V) because I don’t have a High Voltage probe. My DVM will fry.

I could use some help...




I’ve just joined, and this is my first post here. I subscribed because I love older Tektronix Analog Equipments, which I believe are unfortunately very much looked down on by many people just because they use, what they call “an obsolete technology”. To me they are far superior in more ways than one might think. Although probably less convenient to use. You have to think more. Anyways, I like to find nice pieces, restore and calibrate them to the best of my abilities. And I do have some Tek calibration tools for that, like a leveled sine wave generator, a time mark generator, etc... I’m in no way an electronics expert Who can pinpoint problems and fix them, let alone calibrate. But I do my best to learn and to get better at it.

However, 3 of the 9 scopes (One inside a TM506) I have, have issues that I’m having a hard time to fix ATM.
That will be the topic of my next post “465 TURNS ON, NO TRACE, NO DOT“. I saw a thread From 2016 on the exact same subject. And although there were some very good advice there, it didn’t help me much so far, cause there was no follow up...
Anyways, I’m glad I found the forum.

I don’t see my posts



I’ve written 3 or 4 posts, some of which are kind of important and to me because I’m asking for advice and help, but I still don’t see any of them. What is going on?


Sent from my 9.7-inch iPad Pro
Stephen S. Nabet

Re: Tektronix 2465b Boo Boo


The guy (his name is Dimos) at Q-Service Electronics is very nice. I’ve talked to him a few time on the phone, and I ordered s few parts from him. Parts arrived within a week at most. But I am in Europe too.
Highly recommended!! He’s been doing that for over 40 years. He knows his stuff.

Frequencies and voltages required to calibrate a 2400-series scope?


Hey y'all,

A topic that frequently comes up here is how to transfer the NVRAM
contents, or how to "fix" a 2400-series scope that's lost its calibration.

My 2467 was in need of calibration after I restored it to function, both
because it was time, but also because I tweaked all the pots and twiddled
all the settings during repair.
In my ignorance at the time, I believed I needed the equipment specified by
the service manual, and so I now have TG501/SG503/SG504/PG506 gathering
dust in a TM504, as well as e.g. a home-made tunnel diode pulser.

In hindsight, this really wasn't necessary, merely convenient to follow
along with the service manual instructions throughout the calibration

What really was needed was a set of signals with some particular specs. I
believe the specs are fairly easy to meet with misc equipment.
I'm sure I have synthesized RF generators that meet the timing spec with
their dominant hand tied behind their back. The voltages are probably near
enough from my HP 3314A, and probably good enough from any digitized pulse
gen or AWG.

Now, the horizontal timing calibration is all done by using the human eye
for a comparator (half the time with the aid of a second scope). While
TG501 outputs easy to use pulses for the purpose, all you really need is
some kind of synthesized frequency generator. Ideally you want a fast-rise
edge to look at, but at a pinch a sine wave and a hard squint will do.

I think in many cases the question of "how do I copy the NVRAM" would be
best answered with "here's what you need to calibrate your scope".
I volunteer to start that Wiki page, but as I've only done this once, I'd
like ask for help in validating and verifying the page for sanity and

So, as a strawman, the periods involved (that I find from a quick scan of
the 2465 service manual) are:
2ns - this is a sine from TG501.

The vertical and trigger calibration is more automated and it wants a
fairly accurate square wave from ground to:

Other mandatory equipment includes a DMM and a second bench scope -
anything else?

There are other inputs required for performance validation and transient
response calibration, but IMHO just doing the DAC/CRT, horizontal &
vertical calibration is vastly preferable to copying the calibration

WDYT? Questions, concerns?


Re: Tektronix 2465b Boo Boo


On Thu, Jul 9, 2020 at 4:29 PM James Theonas via <jamestheonas=> wrote:

Hi Guys, I own the 2465b and I purchased a fm16w08-sg on a conversion
board to fit in the ds1225y place. As a test, I flashed the chip using the
calibration file available in the files section of our group. everything
seems to have gone well and verification is good after some tests. Now my
question. If I want my true calibration data (2465b working fine) I need to
remove the ds1225y copy it and program the new chip with said calibration
data. Am I correct in my assumption? Only other way is full recalibration?
(I don't know where I can do that here in Greece).
To preserve the existing calibration of the scope, you need to transfer the
calibration constants over. There are many tales of woe, where the
calibration data was lost in the process somehow, whether due to heat
stress wiping the NVRAM on desoldering or fumble-fingering the readback
You can get the scope to display its calibration constants through an
exerciser routine (2?), and apparently some people have then successfully
written this back to an NVRAM image with a hex editor or the like (
It's IMHO not crazy to record the constants from the exerciser as a backup,
if you don't have the wherewithal to calibrate the scope, and you intend to
replace the NVRAM. It's also not crazy to recalibrate the scope with
whatever you can rig up. You don't NEED the precise list of equipment
specified by Tek, and after calibrating the scope you can trust what it's
telling you.

Re: Tektronix 2465b Boo Boo

Chuck Harris

If the scope has one of the NVRAMS, with recycled calibration data,
the scope will be way off (5 to 10%) on some of its ranges.

-Chuck Harris

James Theonas via wrote:

Agreed but they also sell the ds1225y pre programmed with calibration data. How would I know if the scope was precalibrated or if they just popped in a pre flashed chip?

On Friday, July 10, 2020, 12:27:47 AM GMT+3, Ken Eckert <eckertkp@...> wrote:

Re: Tek 7904 help!

Chuck Harris

Resistance measurements were originally taken with no plugins,
and using an old fashioned Tripolett or Simpson VOM... the type
is specified in the manual somewhere near the readings.

Anything else, and the already only slightly valid readings become
less so.

If your scope has aluminum can type electrolytic capacitors, they
were replaced by someone earlier in the scope's existence.

The two capacitors on the +/-15V supplies are on the schematic,
but the tantalum on the 50V supply is not... and yet it is there.

You can often figure out which voltage is putting the power supply
in tick mode by measuring the supplies while the ticking is going on.
You will see most of the supply voltages tick up into a goodly fraction
of their nominal voltage, but the supply with the shorted load will

-Chuck Harris

Bill Riches via wrote:

Hi Chck and gang,
I have a later? horizontal board - no tant - 2 small can type caps.  My manual shows the tant caps.  Did check the caps and they were ok.  
Some more measurements.
1. PS disconnected completely2. Resistance measurements taken at Z axis board with Fluke DVM

    +130                    6.6K                9.5K                9.5K
    +50                        2K                 4.6K                4.2K
    +15                        90                  92                    27
     +5                         65                  49                    19
     -15                       110                216                   31
     -50                       2K                   55K                 55K
     +LAMP 5              INF                  INF                 55k
(red underlines from spell check)
3. Highlighted readings look strange.  Could I have 4 plugins with loading.  Inserting each module reduced resistance by a similar amount from 216 ohms to 31 for -15 volt source.  
4. Checked power supply voltages out of mainframe with 120 VAC.  Power about 10 watts or so.130 = 136+5 =   4.8-50= 12+50 = 25-15 = 2+15 = 10
I measured the crt anode voltage out of the PS using and old Pomona tv hv meter and the meter would kick a bit - maybe a few hundred volts..

I guess that low voltages would be low due to burst mode not allowing output filters to charge to normal value.
I am thinking PS is ok or it is shutting itself down.  Just curious why the different resistance readings when plug-ins are installed.  We had quite an electrical storm on Tuesday Evening. Wednesday morning the scope was not working.  As you can see from my page I have a bunch of toys and they are all working - so far.
So - 2 questions - why do plug-ins resistance read low and are my voltages close when the ps is not installed?
Just remembered I do have some old plug ins and will plug them in and see if I get the same resistance drop.
I really appreciate the help.
Bill, WA2DVUCape May

On Thursday, July 9, 2020, 12:04:05 AM EDT, Chuck Harris <cfharris@...> wrote:

There are two tantalum capacitors that every 7904 I have had
has blown.  One is on the +50V supply, and doesn't show up in
my schematics, and the other is on the -15V supply, if I recall
correctly.  They both are rated at too low of a voltage.
They are on the Horizontal board, which is on the left side of
chassis, as I recall.  One has a choke feeding it, and the other
a 10 ohm 1/4w resistor.

You should be suspicious of any tantalum capacitor that is rated
less than 2x the applied voltage.  6.3V caps on 5V, and 16V caps
on 15V are especially bad.  Anything on a 50V supply is a problem
because the maximum voltage a dry slug tantalum can be is 60V.

Be warned, there is a blue harmonica connector on that board
that turns to dust when you touch it.

The power supply itself is usually pretty solid.  Look
at the rest of the scope for a blown tantalum.

-Chuck Harris

Bill Riches via wrote:
  Thank you Raymond and Harvey.  Will try your suggestions and see what happens. Checked all tants in the ps for shorts - no discolored resistors or smell!  Will check them in the nether regions!
    On Wednesday, July 8, 2020, 08:53:08 PM EDT, Harvey White <madyn@...> wrote:

  When I used a variac, I looked at the current draw.  If it turned out to
be excessive, I looked for a problem with the primary supply.

I don't remember that I spent too much time at lower voltages, and ran
it up to the 80 to 90 volt range if the current draw was excessive.  I
used the variac to check if the main bulk supply was shorted.  When it
wasn't, I ran it up higher.

It seemed to work without stressing the supply too much.  Some supplies
draw excessive current because the switch doesn't come on (and off)
until a minimum voltage, that's the reason for being sneaky in this
case.  You try to avoid that overcurrent draw due to the switching
circuit not working.

More of a turn it up and see what it draws, turn it right back down,
then figure out why.

think that'll work?


On 7/8/2020 8:39 PM, Raymond Domp Frank wrote:
On Thu, Jul  9, 2020 at 02:10 AM, Harvey White wrote:

Since you have a variac, you might want to run the voltage up from zero
- The 7904 has a primary switching power supply (PSU), so *no variac* allowed: You may overload (and damage) circuits while varying the input voltage.
- If the PSU is in "tick mode" (it makes a ticking sound several times per second) chances are you won't blow up anything important while testing under power.
- The PSU needs a minimum load to operate, not too small, preferably on several outputs. Sense lines are connected to loads and you at least have to connect those for regulation to occur.

Some things to do if the PSU is in tick mode:
- Check dipped tantalums on the backplane for shorts. Several (at the sides) are easy to reach and the 'scope will be OK while you test without them. Just temporarily lift one leg.
- Check individual parts of the backplane by temporarily disconnecting part of the supply from it. Look in the Service Manual to find their connecting sockets, on the PSU or on the backplane.
- Don't forget: The PSU contains (dipped) tantalum caps as well.
- Be aware that in tick mode, the HV supply may still reach appreciable/noticeable/risky voltages, unless it's not working at all. I've seen it deliver several hundred volts in a ticking 'scope.


Re: Tektronix 2465b Boo Boo

James Theonas

re-calibrated not pre-calibrated

On Friday, July 10, 2020, 12:27:47 AM GMT+3, Ken Eckert <eckertkp@...> wrote:

Re: Tektronix 2465b Boo Boo

James Theonas

Agreed but they also sell the ds1225y pre programmed with calibration data. How would I know if the scope was precalibrated or if they just popped in a pre flashed chip?

On Friday, July 10, 2020, 12:27:47 AM GMT+3, Ken Eckert <eckertkp@...> wrote:

Re: Tektronix 2465b Boo Boo

Ken Eckert

Re: Tektronix 2465b Boo Boo

Chuck Harris

The calibration data is purely digital, so, it can
be copied from one NVRAM to another without consequence.

The actual calibration data only amounts to about 170 bytes
of data in the entire NVRAM. The rest of the space is the
CPU's stack and data area, and is cleared every time you
turn the scope on.

Greece is the source of a lot of the replacement parts
for the 2465 family. Clearly there are folks in Greece
that know about this unit. I would suggest you get into
contact with the Greek guy on ebay, that sells parts,
and ask him. Q-Service, I think.

-Chuck Harris

James Theonas via wrote:

Hi Guys, I own the 2465b and I purchased a fm16w08-sg on a conversion board to fit in the ds1225y place. As a test, I flashed the chip using the calibration file available in the files section of our group. everything seems to have gone well and verification is good after some tests. Now my question. If I want my true calibration data (2465b working fine) I need to remove the ds1225y copy it and program the new chip with said calibration data. Am I correct in my assumption? Only other way is full recalibration? (I don't know where I can do that here in Greece).

Thanks for any answer in advanceDimitris Theonas
On Wednesday, July 8, 2020, 8:44:57 PM GMT+3, Chuck Harris <cfharris@...> wrote:

I am of the general opinion that the only reason to buy
a "pre-calibrated" DS1225, is because you are selling your
scope, and you want to fool the potential buyers into
thinking the scope is calibrated.

Kind of the tektronix version of turning back the odometer
on a used car.

I hope he wasn't thinking a pre-calibrated NVRAM is a
legitimate solution to any real problem.

-Chuck Harris

satbeginner wrote:
Putting in a pre-loaded Dallas or Fram will remove the 'not calibrated' indication (?????? or ............), but this will mean the scope from now on is

"Not Calibrated",

only it will not be visible to a user.
The error could be anything from 1% to 15 or more %, depending on the parameter used.
Timebase, Amplitude, Delay, etc.

Putting in a pre-loaded replacement is the ostrich way....

The only real way to go is calibration.

Just my 2cts...