Spectrum analyser

michel soldevila

Hi group,
Is there a place to discuss Tek spectrum analyser topics ? I own a venerable 491.
Michel (F1GOC)

Sick SG504


Is there a known failure mode when the high side of an SG504 goes dead? Reference and low are working as expected high is out to lunch. I have cleaned the switch and that does not seem to help.

Re: Tektronix 7b92a shuts down crt & graticule illumination on 7904 mainframe


If you haven't run across it yet in numerous threads here, the aging Tek scopes are notorious for shorted tantalum capacitors. So, I would look at your 7904 manual first to see which power supplies are associated with the outages you are seeing, and then look for power supply filter/bypass capacitors in the 7B92A that are on that power supply. Probably a 5V supply.


Re: 5441 trials & tribulations


I'm with you Tim. That delay line connection is a beast, both ends. My 5440 developed a break at the joint even with the strain relief configuration.
The intermittent connection caused my vertical position to drift and flicker. I found it by pushing on the vertical board with a chopstick while watching the trace.

It would be interesting to see how Tek handled the connection on the 7000 series.


Re: 5440 scope vertical creep/jitter (intermittent)


Unfortunately when I added the words [resolved] the the thread's subject, it caused my solution to show up outside this thread. The cause was a cold solder joint at the delay line junction on the vertical board. Everything is working great on the 5440 now.

Now, back to the series of repairs for the whole set of plugins to get the 5S14N up to snuff.
- My 5B44 time base's channels have ghost traces all the place. I believe this will turn out to be dirty connections on the main time switches.
- My 284 Pulse Gen 1ns output is doo doo. Haven't looked at it yet.
- My PG506 smoked C464 10uf 25v tantalum last night that I just put in 3 weeks ago. It's hard to understand why this new cap's failure would be anything other than a bad or mismarked 25v cap because it has a very stable -16v on one side and ground on the other. My experience has been that an electrolytic cap will let you know immediately if you put it in backwards. It has been run for many hours over the last 3 weeks without a problem. I'll confirm it today if installed it backwards and I'll bump it to 35v volts.
- My TG501 Time Mark has problems in the nanosecond range. Haven't looked at this yet. It's this problem that led me to buy the 5S14N in the first place.

And so goes my Tek saga...


Re: 576 serials


I have a 576 but the serial number is partially worn off. It is B32??7P. The second ? might be a 0 or 8.
Is there anywhere else on the unit that has the serial number. i also have a 176 plug in, does that have
a serial number? I could not find one.

Re: 576 serials

Michael W. Lynch

To anyone who might have missed the conversation. There was some interest in compiling a Serial Number List for the Type 576 Curve tracers in the possession of members of the forum. I volunteered to compile the data for anyone who cares to share it. The data and spreadshhet will be anonymized and will not be posted, shared or used for any commercial purpose.

If you have a 576 and would like to share you serial number for inclusion on the list. please reply to me off list at: >< or ><

Michael Lynch
Dardanelle, AR

Re: 576 serials

Michael W. Lynch

On Sun, Feb 7, 2021 at 08:00 AM, David C. Partridge wrote:

Replying here because don't know M. Lynch's email

I have added you to the list.

Anyone else can respond with their Type 576 S/N to >mlynch002atgmaildotcom<.


Michael Lynch
Dardanelle, AR

576 serials



Replying here because don't know M. Lynch's email


Re: Selenium rectifiers in Tek equipment

Colin Herbert

I agree with this. I have been taking Selenium tablets for several years now in order to strengthen a fingernail that had developed an incipient split along its length. While this hasn't solved the problem completely, selenium does indeed have other good points. It contributes to the normal function of the immune system (that should get the fake Covid-cure folks emptying the shelves!) and the maintenance of hair and nails. The tablets I take occasionally are 200 micrograms and contain L-Selenomethionine and Sodium Selenite. As they are an over-the-counter product in the UK, where we have pretty strict health regulation, I would think that one of these tablets per day isn't going to do you any harm and will probably do you a bit of good (but maybe not keeping Covid away). Just don't lick any Selenium rectifiers!

-----Original Message-----
From: [] On Behalf Of stevenhorii
Sent: 06 February 2021 03:49
Subject: Re: [TekScopes] Selenium rectifiers in Tek equipment

Selenium is one of those micro nutrients that you do need. However, it is
also toxic if you get too much. Overheated selenium rectifiers can produce
selenium dioxide which can be toxic if too much is inhaled. If you are
going to power up a piece of equipment with a questionable selenium
rectifier - do it in a place with good ventilation (preferably venting
outside - not to the rest of your workshop or house). This discussion from
the Antique Radio Forums:

This suggests being cautious, but not obsessive-compulsive cautious. We
probably get exposed to more lead fumes from soldering than selenium from
bad rectifiers.

On Fri, Feb 5, 2021 at 20:44 Jim Ford <> wrote:

How could they tell; aren't sheep one of the dumbest animals anyway?!

But seriously, I read somewhere that trace amounts of Se are good for
you. Like most things, even water, too much is bad.

Jim Ford

------ Original Message ------
From: "Harvey White" <>
Sent: 2/5/2021 5:20:43 PM
Subject: Re: [TekScopes] Selenium rectifiers in Tek equipment

I remember an old story about sheep eating a certain plant, loco weed,
and having severe congnitive problems.

Turns out that loco weed is high in selenium.


On 2/5/2021 7:52 PM, Gary Robert Bosworth wrote:
Good to know.

On Fri, Feb 5, 2021, 16:42 Ken Eckert <> wrote:

Burning selenium is very toxic, really bad for your health

On Friday, February 5, 2021, Joe Laffey <> wrote:

If you’ve ever smelled a burned selenium rectifier (stinking up your
office or house for days) you would replace all of them before even
them on.

Joe Laffey

On Feb 5, 2021, at 5:24 PM, Dave Wise <> wrote:

? Even if the Selenium stacks haven't burned up, by this time their
series resistance is out of spec so the power supplies don't have as
mains voltage headroom as they should. I'd replace them without ado
the piece was meant to be a shelf queen.

Dave Wise

From: <> on behalf of Morris
Odell via <>
Sent: Friday, February 05, 2021 2:29 PM
Subject: Re: [TekScopes] Selenium rectifiers in Tek equipment

I have a 127 too and had no compunction in replacing the Se rectifiers
with Si. Nobody can tell you how long it will be before the Se
fail and you will probably always have it in the back of your mind
time you switch on the 127. It's not a diffcult or expensive
to do and gives you peace of mind.
I used cheap packaged 1000 volt 1 amp Si bridge rectifiers and
R601 and R602 with 15 R 3W resistors. I aso inserted a 10R 10W resistor
the negative ground connection of the SR603 replacement.
The Si bridges I used had metal cases so I mounted them on insulating
posts, espaciallyu the SR607 replacement which is elevated a few
volts above the chassis.
Good luck!


Looking for some 2465, 2475 etc blue Bourns front panel pots.

Jared Cabot

I'm looking for a set of 4 of the blue Bourns pots used in the front panel of 2445, 2465 and 2475 scopes.
Which ones they are isn't really important as long as they are the single-gang ones as I just want some internal parts to rebuild my dual gang pots (the wipers are worn).

If you have some of these laying around, I'm happy to help you convert them to currency. :)

Re: Looking to Re-Cap my 2554...

Jared Cabot

As long as you match capacitance, match or slightly increase voltage (not too much), and the pitch (distance) between the legs of each capacitor matches the originals, it'll be fine.

Just be sure to use reputable brands and decent specs (Low ESR on the PSU output for example). Nothing too critical here.

Re: Tektronix 7b92a shuts down crt & graticule illumination on 7904 mainframe


Inspection for burned or leaking Tant caps is a first step...


Re: 2465B CRT board values


Bonjour Hirofumi-san,

very fine to have a new group member in Japan.

All the items you observe are OK, if the scope display is satisfactory.

The Tektronix service manual is online for free and has complet CRT/HV adjustment proceedure.

Chuck is a super experienced Tek veteran and gives the best advice.

I can only add two old American sayings...
"If it ain't broke don't fix it"

"leave well enough alone"

Kind Regards


Re: sighting: Beaverton-built 5110 Mod 709V for Bently Nevada


On Sun, Feb 7, 2021 at 08:47 AM, Paul McClay wrote:

Anyone here know anything more?
From the mod 709V manual:

This manual describes MOD 709V as it applies to the
TEKTRONIX 5110 Single Beam Oscilloscope. MOD 709V
adds a new circuit board for X-Y operation using Right
Vertical versus Left Vertical. Using a TEKTRONIX 5B10N
MOD 709V Time Base plug-in unit, the SECONDS/DIV or
VOLTS/DIV switch is turned to the L versus R position
actuating a switching relay mounted in the mainframe. This
bypasses the normal sweep function of the 5B10N, allowing
for a Left Vertical versus Right Vertical X-Y display. The
display unit portion of the 5110 is supplied with an
illuminated graticule with a special implosion shield, and an
AC coupled EXT INTENSITY INPUT via a yellow binding post
at the front panel.
Bandwidth: Maximum horizontal deflection bandwidth
(using a 5A15N or 5A18N amplifier) is reduced by
approximately 300 kHz by the added wiring. Bandwidth (-3 dB)
for X-axis deflection from either the center or right compartment
is 1.7 MHz minimum. The Y-axis specification is unchanged.

Check the interconnecting wiring to the added X-Y circuit board,
then calibrate MOD 709V according to the procedure in the 5110
Instruction Manual.


sighting: Beaverton-built 5110 Mod 709V for Bently Nevada

Paul McClay

This caught my eye on Bay today:
"Tektronix Oscilloscope MOD 709V W/ 5A19N Amp, 5A19N Diff. Amp, 5B10N Time/Base"

All I could get out of Google was one more add for another instance of the same thing:
"Tektronix 5110 MOD 709V Oscilloscope"

What both of those headlines miss is the "Bently Nevada" branding. A little more poking around suggests that was a legit thing for an application that continues today, but that particular scope has disappeared except for the two listings.

I dumped what I found on TekWiki:

Anyone here know anything more?

Re: 5441 trials & tribulations

Paul McClay

Just looking back through the last few months...

So how did it go? Happy to see another 5441 getting back in the game.

Re: 5440 scope vertical creep/jitter (intermittent)


I would be interested if anyone knows what causes this too, as I have a 2213 where the channel 1 signal wanders vertically.

-- Jeff Dutky

Re: 5440 scope vertical creep/jitter (intermittent)

Paul McClay

It doesn't matter than I can't help with your vertical because you've already solved that.

I just popped in to say: congrats on your 5S14N acquisition! I hope your revival effort works out.

Re: 2465B CRT board values

Chuck Harris <cfharris@...>

Resistors very often aren't the same value at high voltages
as they are at low voltages. Particularly high megaohm types.

And, it is rather hard to measure such high value resistors in
circuit. Your measurements get affected by the leakage of the
dirt on the resistors, the board, and capacitors.

I haven't found a 2465B that has its best focus at 12:00 with
the exception of the 2467B type, which has a trimmer pot to set
the best focus to the center of the range of the focus pot.

Most everything else is trimmed using the computer and stored

-Chuck Harris

Hirofumi Momose wrote:

Hello Chuck,

Tektronix did not consider the CRT voltage to be worth
more than using 5% resistors as their control.
In my experience servicing iwatsu scopes,
cathode voltage is specified as approx 1%.
My 2465B focus knob is far off the center at 3 o'clock.
I think this is because of cathode voltage.
But Yes, this still under adjustable range.

Do you see these "changed" values from the markings on
the parts, or are you measuring them?
Measured (in-circuit)
I think value error is little as long as caps
in the HV-module are good.

Thank you.
Hirofumi JJ2PNX

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