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Tek 465 Sweep Start Calibration


david
 

Hi guys, I need your help again, I am trying to do horizontal calibration on my 465 but I cannot set step one of calibration, "Check/Adjust Sweep Start and A Sweep Calibration", With Sweep start adjustment R1115 fully counter clockwise, the Intensified sweep starts at 0.96 on Delay Time position dial, cannot get it to 1.0, Is out of range of R1115. Trimmer R1115 is in the middle of a voltage divider between R1113, R1112 and R 1117. Has anybody had this problem? In service manual, parts list says R1113 is "196 ohm (NOM VALUE) SEL". My 465 has a 145 ohm resistor for R1113, changing R1113 to 196 ohm would probably get enough range to fix Sweep Start. I don't know where else to look for the problem. Also have a newer version of service manual where parts list says R1113 is "196 ohm". Does not say nominal value select. The rest of the horizontal cal went OK.
David


 

On Wed, Aug 19, 2020 at 09:59 PM, david wrote:


With Sweep start adjustment R1115 fully counter clockwise, the Intensified
sweep starts at 0.96 on Delay Time position dial,
What is the DTM mechanical max CCW reading ? It should be 0.20
http://www.hakanh.com/dl/docs/hardtofind/dtmsettings.pdf

/Håkan


david
 

DTM max CCW reads 0.085 ohm


david
 

I checked with DTM unplugged from A7 board with Kelvin clip test leads.


david
 

With DTM plugged in to A7 board reading is 0.10 ohm


 

On Thu, Aug 20, 2020 at 03:56 PM, david wrote:


With DTM plugged in to A7 board reading is 0.10 ohm
What I meant was the reading of the dial when the knob has been turned to it's CCW stop.
For 465 it should not be zero but set to 0.20 as indicated by the link in the previous post.

/Håkan


david
 

Sorry Håkan, I didn't understand what you meant, I adjusted dial,but calibration is still off 0.30 at setting of 1.0.,and R1115 is full CCW, I know that's close enough but I'm retired and have time to fuss with it. :-), If I set dial to +0.50 at full CCW it is correct at 1.0. Is changing the value of R1113 an acceptable way to change the range of adjustment on R1115?
David


 

On Fri, Aug 21, 2020 at 03:55 PM, david wrote:


Is changing the value of R1113 an acceptable way to change the range of adjustment on R1115?
That would be changing it to nominal so I can't see anything wrong with that.
You could also check R1112 and R1111 which in my manual also are selectable.
(R1111 nominal: 562 ohm, R1112 nominal: 49.9 ohm).
I have not been able to find any info on acceptable ranges for these resistors.

/Håkan


david
 

Yeah, I checked and R1112 is 49.9 ohm, R 1111 is 562 ohm, ordered 196 ohm 1% 50ppm resistor, I can replace R1113 without removing A7 board.I will let you know if it works. Thanks for help.
David