Author Topic: TekTronix Scope 466 tiny tiny Vertical deflection ! Need Help Please (Read 6399 times)

sebalele · « **on:** January 31, 2015, 12:30:36 am »

Hi evryone ,
Iread this forum for years as a guest and found lot of answer to my elettronic job.
Now i need a scope
This scope has been recovered for about 12 y in my garage .
It was used in my old lab and worked fine till was packed .Was testet by Tek in 95 as written on label .
when on, all 2 tracks are readly visible , base time it's ok (from slow ball to shine flat line ; vertical can be moved up and down with no trouble .works fine.

Now , i send a signal to the input appling 1 Vrms 1KHz the signal on the scope are very very low at evry V/div step .
Yes the signal came amplifie don video touching V/div but very very low !
Both channel have same olay .

I read something and many stated(logically) this will be vert amp fault .
This may occour in output vertical deflection I see..

Could someone give me some pro to operate .I wiil appreciate

many thanks
Gabriele

tautech · « **Reply #1 on:** January 31, 2015, 12:38:52 am »

Welcome to the forum.

Are you sure this is not a error by just using 10x probes?

In the Repair board there is a Tek troubleshooting guide in the first post.
Links in the same thread for manuals.

PaulAm · « **Reply #2 on:** January 31, 2015, 02:26:27 am »

Since it's been in storage, the attenuator switches could be dirty.

Both channels behave the same?

Could be V amp, could be a vertical switching fault.

First thing to do with Tek scopes of this vintage when they fault is to check the power supply voltages and ripple. Do not bother looking at anything else until you have verified the low voltage power supplies are operating within spec.

sebalele · « **Reply #3 on:** January 31, 2015, 02:30:55 am »

Thanks ,
Well it's not a probe attenuator (i tried both 10&1 X) .it's common to both channels ,going to look at schematics.... But i like to know others exp within these model
Ciao

sebalele · « **Reply #4 on:** January 31, 2015, 02:38:40 am »

I can't get any schematics , just some owner manual... Don't need !
Someone can lead me to right place for downloading ?
Thanks,
gabriele

sdg · « **Reply #5 on:** January 31, 2015, 09:53:57 am »

http://elektrotanya.com/tektronix_466.pdf/download.html

tautech · « **Reply #6 on:** January 31, 2015, 10:12:49 am »

http://elektrotanya.com/tektronix_466.pdf/download.html
http://bama.edebris.com/manuals/tek/466dm44/

You'll likely need this as well:
http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

sebalele · « **Reply #7 on:** January 31, 2015, 03:17:10 pm »

Many thanx sdg & tautech , these are correct .
I'm going to check all voltage but I'm afraid is a contact - trouble or vertical amp to crt .
Let's on

sebalele · « **Reply #8 on:** January 31, 2015, 03:58:28 pm »

$:-\$
Ops I've got a different early version .My version doesn't has any IC on vertical preamplifier just lots of transistors ,maybe this 466 is an "improved 465 with memory.."
I'm going to look for 465
here's some photo
https://drive.google.com/folderview?id=0B1RoJfLPtfMHYXBNTU1PQzRlN2s&usp=sharing
ciao

iDevice · « **Reply #9 on:** January 31, 2015, 10:55:49 pm »

You just have the "early" 466, the one with the neons.
Later models were upgraded to LEDs and...more ic's.

So you need this manual.

sebalele · « **Reply #10 on:** February 01, 2015, 09:36:26 am »

Thaks Idevice ! this is mine!

Rupunzell · « **Reply #11 on:** February 01, 2015, 04:52:47 pm »

Check the power supply voltages and function first and look for shorted tantalum capacitors before moving on to other possible problem areas.

Bernice

sebalele · « **Reply #12 on:** February 01, 2015, 08:51:22 pm »

Thanks,
Yes , just take apart and knocked around to look for false contact.
Pull out and refit all transistors in vertical preamplifier board . Also for connectors.
Seem strange to me ,all function works ;basetime it's ok , it can trigger the weak signal from output calibration ( I've put also a stronger signal from wave gen.) but on screen it' always compressed .
If i touch the probe with finger , the signal goes over the full screen (my higher body impedance..) if this coulb usefull... And this happen on both channel . I'm going to check the voltage at first but signal on screen goes to became "clipped" . Isn't ?
See soon

David_AVD · « **Reply #13 on:** February 01, 2015, 08:59:10 pm »

Did you measure (with a DMM) the signal you're applying to the 'scope to confirm it's really 1V RMS ?

Does the 'scope have a test terminal (1KHz 1V square wave) for adjusting the probe compensation? If so, did you try that as well?

tautech · « **Reply #14 on:** February 01, 2015, 09:05:13 pm »

Quote from: David_AVD on February 01, 2015, 08:59:10 pm

Did you measure (with a DMM) the signal you're applying to the 'scope to confirm it's really 1V RMS ?

Does the 'scope have a test terminal (1KHz 1V square wave) for adjusting the probe compensation? If so, did you try that as well?

Good point, the Cal output may be faulty.
Never overlook the simple answers.

sebalele · « **Reply #15 on:** February 02, 2015, 08:02:07 pm »

You're right no signal from test output .... Not measure from my dmm just little mv.
So i put 1khz from ipod ...nada . ok , take the signal from ipod and put into 30 w final .
Checked with dmm for different output from 1 to 5 Vrms.
On CRT just appear a weak signal with no more than 1/3 of 1 square on screen.
Let start with voltage check . I 've followed throught the schematics and checked on test point , they are all fine . This on preamp board . Others board will be check next days . Seem that the signal is loaded or goes in a defective transistor ; will be easier with another scope..

sebalele · « **Reply #16 on:** February 02, 2015, 08:04:42 pm »

Cal output seem doesn't work as I writen above ... So could be involved with another part . Check on schematics where is the 1khz gen.

tautech · « **Reply #17 on:** February 02, 2015, 08:11:38 pm »

On some scopes there is a DC test procedure.
It will be described in the service manual.
The scope must be set in a special way and then many DC voltages can taken from test points.
This way a faulty section can be found quickly.

Did you test the Cal output with AC range on your DMM?
Will it measure 1 KHz frequency?

sebalele · « **Reply #18 on:** February 02, 2015, 08:43:06 pm »

From signal test vac about 10-15mv 50hz , just noise .
Measure Test point on schematic with dmm are fine (just on preamp)
There are others signal note on schematics to get throught a scope with a scope setting in a give way.
Take measure on the others board it's not so easy ; they are located on the rear

Thanks


EEVblog® Main Site	EEVblog® on Youtube	EEVblog® on Twitter	EEVblog® on Facebook	EEVblog® on Odysee

Author Topic: TekTronix Scope 466 tiny tiny Vertical deflection ! Need Help Please (Read 6399 times)

Share me