TekTronix Scope  466 tiny  tiny Vertical deflection ! Need Help Please - Page 1
Forum section: electronics / testgear

author: sebalele
author_rank: Contributor
timestamp: January 31, 2015, 12:30:36 am
content: Hi evryone ,Iread this forum for years as a guest and found lot of answer to my elettronic job.Now i need a scopeThis 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 appreciatemany thanksGabriele

author: tautech
author_rank: Super Contributor
timestamp: January 31, 2015, 12:38:52 am
content: 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.

author: PaulAm
author_rank: Frequent Contributor
timestamp: January 31, 2015, 02:26:27 am
content: 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.

author: sebalele
author_rank: Contributor
timestamp: January 31, 2015, 02:30:55 am
content: 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 modelCiao

author: sebalele
author_rank: Contributor
timestamp: January 31, 2015, 02:38:40 am
content: I can't get any schematics , just some owner manual... Don't need !Someone can lead me to right place for downloading ?Thanks,gabriele

author: sdg
author_rank: Regular Contributor
timestamp: January 31, 2015, 09:53:57 am
content: http://elektrotanya.com/tektronix_466.pdf/download.html

author: tautech
author_rank: Super Contributor
timestamp: January 31, 2015, 10:12:49 am
content: http://elektrotanya.com/tektronix_466.pdf/download.htmlhttp://bama.edebris.com/manuals/tek/466dm44/You'll likely need this as well:http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

author: sebalele
author_rank: Contributor
timestamp: January 31, 2015, 03:17:10 pm
content: 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

author: sebalele
author_rank: Contributor
timestamp: January 31, 2015, 03:58:28 pm
content: 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 465here's some photohttps://drive.google.com/folderview?id=0B1RoJfLPtfMHYXBNTU1PQzRlN2s&usp=sharingciao

author: iDevice
author_rank: Regular Contributor
timestamp: January 31, 2015, 10:55:49 pm
content: You just have the "early" 466, the one with the neons.Later models were upgraded to LEDs and...more ic's.So you needthis manual.

author: sebalele
author_rank: Contributor
timestamp: February 01, 2015, 09:36:26 am
content: Thaks Idevice ! this is mine!

author: Rupunzell
author_rank: Frequent Contributor
timestamp: February 01, 2015, 04:52:47 pm
content: Check the power supply voltages and function first and look for shorted tantalum capacitors before moving on to other possible problem areas.Bernice

author: sebalele
author_rank: Contributor
timestamp: February 01, 2015, 08:51:22 pm
content: 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

author: David_AVD
author_rank: Super Contributor
timestamp: February 01, 2015, 08:59:10 pm
content: 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?

author: tautech
author_rank: Super Contributor
timestamp: February 01, 2015, 09:05:13 pm
content: Quote from: David_AVD on February 01, 2015, 08:59:10 pmGood point, the Cal output may be faulty.Never overlook the simple answers.

author: sebalele
author_rank: Contributor
timestamp: February 02, 2015, 08:02:07 pm
content: 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..

author: sebalele
author_rank: Contributor
timestamp: February 02, 2015, 08:04:42 pm
content: 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.

author: tautech
author_rank: Super Contributor
timestamp: February 02, 2015, 08:11:38 pm
content: 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?

author: sebalele
author_rank: Contributor
timestamp: February 02, 2015, 08:43:06 pm
content: 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 rearThanks