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[Resurrecting a Tek 485] Sweep not from left to right ?


Tom Lee
 

Hi Leon,

Your post takes me back in time! I feel like adjusting an ion trap magnet now.

-- Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 1/15/2021 11:23, Leon Robinson wrote:
In the days of 60 degree deflection all it took was turning the yoke end for end.


Leon Robinson  K5JLR

-------- Original message --------
From: Tom Lee <tomlee@ee.stanford.edu>
Date: 01/15/2021 10:23 AM (GMT-06:00)
To: TekScopes@groups.io
Subject: Re: [TekScopes] [Resurrecting a Tek 485] Sweep not from left to right ?
In the old days of crt TVs, it was fun to swap connections on the
deflection yoke. Upside down, right-to-left TV? Nanoseconds of hilarity
for kids.

Simpler times.

--Tom


Leon Robinson
 

In the days of 60 degree deflection all it took was turning the yoke end for end.


Leon Robinson  K5JLR

-------- Original message --------
From: Tom Lee <tomlee@ee.stanford.edu>
Date: 01/15/2021 10:23 AM (GMT-06:00)
To: TekScopes@groups.io
Subject: Re: [TekScopes] [Resurrecting a Tek 485] Sweep not from left to right ?

In the old days of crt TVs, it was fun to swap connections on the
deflection yoke. Upside down, right-to-left TV? Nanoseconds of hilarity
for kids.

Simpler times.

--Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 1/15/2021 08:18, marcosjl31@gmail.com wrote:
that one was an easy fix.





Tom Lee
 

In the old days of crt TVs, it was fun to swap connections on the deflection yoke. Upside down, right-to-left TV? Nanoseconds of hilarity for kids.

Simpler times.

--Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 1/15/2021 08:18, marcosjl31@gmail.com wrote:
that one was an easy fix.




marcosjl31@...
 

that one was an easy fix.


Roger Evans
 

The most likely explanation is that the two wires from the X amplifier board to the CRT X deflection plates .have been swapped over by mistake. Take care in correcting this, the pins on the CRT do like being bent and then straightened.

Regards,

Roger


marcosjl31@...
 

Hi guys !

The newbie is back !
Some news : PSU of the 485 delivers proper Low Voltage, I had to adjust the calibrator amplitude (the 5V was out of spec +/- 5mV).

I've been checking (visually) several things :
=> "Ready" indicator does not work.
=> on Chanel 1: leds (x1, x10 are not working), 1MOhm/50ohm selector has no light indication.
=> on chanel 2 : 1MOhm/50ohm selector has no light indication.
Don't know if it's complicated/hard to fix ?

Then, I was watching an interesting video on YouTube (https://www.youtube.com/watch?v=7Qg6ory3L8Y) and suddenly I realize that the sweep on the Tek 485 I've purchased seems to be inverted !

Here is what I get on Channel 2 (1MHz cal signal) : https://drive.google.com/drive/folders/1_9cXIKxCFtC60aFQ6zIm4ujq2paW4tSH

Here is the same signal picture taken from video : https://drive.google.com/drive/folders/1_9cXIKxCFtC60aFQ6zIm4ujq2paW4tSH

To check if I was right to suspect the sweep was not from left to right, I selected GND and turn TIME/DIV to 50ms : the sweep spot on the screen travels from right to left on this 485 !!

Don't think this is correct... but I may be wrong. Could this be due to improper reassembly following a repair?

Hope to here from you,
Jose