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453 Voltage Sanity Check

Bill
 

If possible could someone check a few voltages on the A Sweep Board for me. Points CA, CB, and CC. The pics in these links show the locations. The Q-Tip is pointing to them.

I have lost the Trigger for both A and B channels. The LV voltages have all been ok until I checked these points. Now I need a sanity check because it isn't making any sense.

https://i.imgur.com/w8MbIiz.jpg?2
https://i.imgur.com/hA4C0DT.jpg?2

Thank you,
Bill Smith

Rob Naulty
 

I think that's the B Trigger Generator. On mine, I get CA +.9v CB+6.5v and CC +6.6v. Understand I'm working on mine, so I'm not sure my voltages are correct.

Bill
 

Ok thanks a lot. Looks similar to mine.
Bill

Michael W. Lynch
 

Bill,

I am in the 453 manual Pg. 219 (Not the 453A). Looking at the B sweep generator schematic.

Unless I am looking at the wrong manual, those points do appear to be the "B" Trigger Generator part of the B Sweep board. The "A" sweep is located on the bottom side of the instrument.

CA would be variable voltage level, depending on the position of the "B" Trigger level control. + and - 12V is supplied to either side of that R660 B Trigger Level potentiometer. I would say that it should be near Zero when centered. Check the voltages on either end of the B Level Pot, you should have + 12 on one side and -12 on the other. Does the voltage at CA go up and down as you rotate the B Trigger level control? This level should change or the trigger level will be fixed.

CB should be 7.9V, again according to the manual I am looking at. (this voltage would depend on the controls of the scope being set as listed in the manual)

Therefore, CC would be either whatever voltage is present at CB (which should be about 7.9V) or Grounded, depending on the position of the B slope switch.

Can you use an external trigger signal on either channel and get a horizontal sweep? The scope should free run in the Auto position.

This is me just looking at the schematic and making an educated guesses.

--
Michael Lynch
Dardanelle, Arkansas

Bill
 

Thanks for checking it out for me.  In my 453 manual for serial numbers over 20,000 it's the A Sweep Board.https://imgur.com/fFo2tl7

Been writing all this down as well so I won't forget what I have done to date.
Bill

On Thursday, April 9, 2020, 09:45:57 PM CDT, Michael W. Lynch via groups.io <mlynch003=yahoo.com@groups.io> wrote:

Bill,

I am in the 453 manual Pg. 219 (Not the 453A).  Looking at the B sweep generator schematic.

Unless I am looking at the wrong manual, those points do appear to be the "B" Trigger Generator part of the B Sweep board.  The "A" sweep is located on the bottom side of the instrument.

CA would be variable voltage level, depending on the position of the "B" Trigger level control.  + and - 12V is supplied to either side of that R660 B Trigger Level potentiometer.    I would say that it should be near Zero when centered.  Check the voltages on either end of the B Level Pot, you should have + 12 on  one side and -12 on the other.  Does the voltage at CA go up and down as you rotate the B Trigger level control?  This level should change or the trigger level will be fixed. 

CB should be 7.9V, again according to the manual I am looking at.  (this voltage would depend on the controls of the scope being set as listed in the manual)

Therefore, CC would be either whatever voltage is present at CB (which should be about 7.9V) or Grounded, depending on the position of the B slope switch.

Can you use an external trigger signal on either channel and get a horizontal sweep?  The scope should free run in the Auto position. 

This is me just looking at the schematic and making an educated guesses. 

--
Michael Lynch
Dardanelle, Arkansas