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WTB 4xx Series Trigger Knob

 

I¡¯d be interested in buying a 4xx Series Trigger Knob, preferably from Europe.
Does anyone have a spare one they¡¯re ready to part with?

Thanks
Re: Tektronix PG 502 250MHz Pulse Generator

 

sold
Re: New Member

 

Welcome Stefan!
Enjoy this forum. ?You will find very knowledgeable and nice people.

Cheers
Re: Tektronix PG 502 250MHz Pulse Generator

 

Still available. See for details: /g/Test-Equipment-For-Sale-Wanted-or-Exchange/message/3170
FS (US) Tektronix 485

 

I have a Tektronix 485 in great condition for sale. I have maintained it for many years, but have several other portable Tek scopes, so selling this one. Comes with cover, CRT EMI screen, and two P6053B probes. CRT is crisp and bright. (See picture)

$375 cash or PayPal.? Local pickup only and will demonstrate. It is located in San Diego, CA.

More details here: /g/Test-Equipment-For-Sale-Wanted-or-Exchange/topic/91655659#3128
FS: (US) Tektronix PS503A Dual Tracking Power Supply Module

 

Reminder, Tektronix PS503A Dual Tracking Power Supply Module for sale

Details at:
/g/Test-Equipment-For-Sale-Wanted-or-Exchange/message/3161?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3Acreated%2C0%2Cps503A%2C20%2C2%2C0%2C91737927
Re: 2465B wobbly display

 

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Any large Transformers or other AC magnetic sources in the local vicinity of the Oscilloscope?

?

You might move the Oscilloscope away from the area and try it to see if the problem goes away.

?

Ross

?

From: [email protected] <[email protected]> On Behalf Of David
Sent: Friday, June 17, 2022 9:13 AM
To: [email protected]
Subject: Re: [TekScopes2] 2465B wobbly display

?

50Hz coupling through the supply somehow if it affects everything.

Re: 2465B wobbly display

 

Dear Chuck fine to hear from you!


Perfect answer re the jitter adjust and 2467 MCP intentionally slightly wobbly....

Bon Soir¨¦e

Jon

PS here in Paris, just received a fine 7L5!
Re: 2465B wobbly display

 

i'll check the vertical jitter adjustment but it won't be until later in the weekend.

Richard
Re: 2465B wobbly display

 

Hi Richard,

I cannot think of any way you could have 50Hz mains injected
into the vertical amplifier (after the channel mux), and not
have it injected into the horizontal amplifier.

Check the vertical jitter adjustment. It affects everything
vertical.

-Chuck Harris

On Fri, 17 Jun 2022 03:49:18 -0700 "Richard" <mole42@...> wrote:
Unfortunately I'm not able to check voltages right now, the
instrument is in my shop and my tools are in my workshop - a few
miles away.....

Tests reveal that the wobble is in the vertical amplifier, horizontal
is stable. It looks like 50Hz noise. Focus & Intensity controls work
as expected, Sweep & Channel voltage selection work, most other
controls seem to work properly.

I will check the power supply over the weekend and report any
findings.

Richard
Re: 2465B wobbly display

 

Hi Jon,

I am well.

The 2467's have the feature of moving the readout to prevent
burning the rather unique MCP (Micro Channel Plate) CRT,
but that feature is disabled when the firmware is used with
a 2465B configured motherboard.

-Chuck Harris


On Thu, 16 Jun 2022 23:01:46 -0700 "Froggie the Gremlin"
<jonpaul@...> wrote:
Chuck, great to see your excellent notes on general
troubleshooting...long time, How are you doing?

Agree on the bus and 15 V PSU caps notes. The bus caps are ample for
50 or 60 Hz mains.

Could the " wobbly" traces be the readout multiplexing, eg as sweep
rate changes, the readouts move slightly to prevent burnin?

Bon courage

Jon

The OP should send some scope photos or post a video to clarify the
problem....
Re: 2465B wobbly display

 

All four channels are affected, grounded or not. The Alphanumerics are similarly affected.
Re: 2465B wobbly display

 

Trace it back to the imput to see where it comes from.
Does it do it if the input is set to ground or 50ohms?
Re: 2465B wobbly display

 

Unfortunately I'm not able to check voltages right now, the instrument is in my shop and my tools are in my workshop - a few miles away.....

Tests reveal that the wobble is in the vertical amplifier, horizontal is stable. It looks like 50Hz noise. Focus & Intensity controls work as expected, Sweep & Channel voltage selection work, most other controls seem to work properly.

I will check the power supply over the weekend and report any findings.

Richard
Re: 2465B wobbly display

 

Chuck, great to see your excellent notes on general troubleshooting...long time, How are you doing?

Agree on the bus and 15 V PSU caps notes. The bus caps are ample for 50 or 60 Hz mains.

Could the " wobbly" traces be the readout multiplexing, eg as sweep rate changes, the readouts move slightly to prevent burnin?

Bon courage

Jon

The OP should send some scope photos or post a video to clarify the problem....
Re: 2465B wobbly display

 

First things first:

When you get a new piece of test equipment, you should
always measure the power supply voltages, and check the
ripple. When doing the ripple measurements, you will
need a scope, and you must jumper the two scope's ground
jacks together.

Second, the vertical and horizontal amplifiers can create
jitter due to the instantaneous heating of the parts in
their respective hybrids. This jitter can be balanced
out using the jitter adjustments as described in the
calibration section of the manual. The adjustment won't
bother the calibration significantly.

If the ripple isn't coming from the power supply, nor the
jitter, you can determine if it is mains related by
placing the trigger in the LINE position. If the ripple
stops drifting, it is MAINS related.

I don't usually find the big electrolytics that filter
the rectified power line to be a problem with the 2465,
but some do. I almost always find the filter for the
+15V supply to be bad. It won't cause ripple, though.

-Chuck Harris

On Thu, 16 Jun 2022 11:57:17 -0700 "Richard" <mole42@...> wrote:
I've recently acquired a 2465B. The instrument powers up okay but the
display has a vertical wobble (about the 50Hz mark..) which affects
both the trace and the alphanumerics. I'd think it's power supply,
but is there anywhere to look first?

Thanks,
Richard
Re: 2465B wobbly display

 

50Hz - I'm in the UK, our mains frequency is 50Hz and can affect things if the power supply smoothing caps are not too good....
Re: 2465B wobbly display

 

no idea what the "50 Hz mark" means.

does wobble change with any setting eg time/ div? vert pos ?

Refer to the service manual J119 A1 board check every power supply V and ripple

bon chance

Jon
2465B wobbly display

 

I've recently acquired a 2465B. The instrument powers up okay but the display has a vertical wobble (about the 50Hz mark..) which affects both the trace and the alphanumerics. I'd think it's power supply, but is there anywhere to look first?

Thanks,
Richard
Re: Tek 2335 arcing and bad trim pot

 

¿ªÔÆÌåÓý

Thanks Dave and Jeff-
Definitely need "Electronic grade" ie no acetic acid....I had been looking at data sheets all the consumer grade stuff- (easy available locally)- does not even spec dielectric breakdown or constant, their folks in the tech support departments have no idea or can even find the data. ( this was GE and Permatex)
I did as Jeff suggested ordered the ASI 388....it is at least specified on the tube! more product than I will ever need for this and and another( waterproofing) application.
the other good ones are as stated below.
this will take a month due to work that has just started for the summer...
CoronaDope ( GC electronics) was what I used at work for flyback xfmrs and? some of the HV corona issues....I did not think it was appropriate for this application since I am literally filling a hole.
Thanks again
¸é±ð²Ô¨¦±ð


On 6/16/22 7:12 AM, Jeff Dutky wrote:

In terms of non-corrosive RTV you want some kind of electronic grade silicone rubber. I use ASI 388 Electronic Grade Silicone. It costs about twice as much as run-of-the-mill silicone sealant by volume. Chip Quik, Gc Electronics, and MG Chemicals also make electronics grade silicone RTV. I buy mine from Amazon.

According to the label ASI 388 has a dielectric constant of 2.7 from 50 Hz to 1 MHz.

-- Jeff Dutky

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