Author Topic: Fixed HP1741A in a big shape but... I bet in a focus problem, and you? (Read 68755 times)

SAUL BRITTO · « **Reply #225 on:** February 19, 2016, 02:31:35 am »

rf+tech look at this: https://youtu.be/sE2myNBwYzw

rf+tech · « **Reply #226 on:** February 19, 2016, 02:52:06 am »

Yes, the beam is off the top. The pale glow is electron scatter from internal reflections.

So we must go back some pages in this thread to check again vertical amplifier balance.
Set Chan A on (blue button A under Display), 20 Volts/Div, input Gnd.
Set Chan B off (blue button B under Display)
Set Chan A POSN pointing up.

Measure voltage across input or output of delay line (not delay line to ground.)

Set Chan A POSN full left (trace toward bottom)

Measure voltage across input or output of delay line.

Set Chan A POSN full right (trace toward top)

Measure voltage across input or output of delay line.

What are the three measurements?

SAUL BRITTO · « **Reply #227 on:** February 19, 2016, 02:58:04 am »

I did remember trig view end did push the key and appear a nice trace.it's all working,focus,intensity etc.
It still has a vertical problem.

SAUL BRITTO · « **Reply #228 on:** February 19, 2016, 03:20:00 am »

So we must go back some pages in this thread to check again vertical amplifier balance.
Set Chan A on (blue button A under Display), 20 Volts/Div, input Gnd.
Set Chan B off (blue button B under Display)
Set Chan A POSN pointing up.

0k. The V is 0.335V

SAUL BRITTO · « **Reply #229 on:** February 19, 2016, 03:27:00 am »

Set Chan A POSN full left (trace toward bottom)

Measure voltage across input or output of delay line.

V= 0.532V

SAUL BRITTO · « **Reply #230 on:** February 19, 2016, 03:34:49 am »

Full right= 0.350.If iverted the probes all the voltages are inverted = minus

rf+tech · « **Reply #231 on:** February 19, 2016, 03:52:48 am »

Tell me if I understand:

Up = 0.335 V
Left = 0.532 V
Right = 0.350 V

I *think" it should be:

Up = 0V
Left = -0.35V
Right = +0.35 V

Voltage should become minus left, plus right, equal amount. This is hard to describe:

Left -0.35 ... -0.3 ... -0.25 ... -0.2 ... -0.15 ... -1.0 ... -0.05 ... 0 ... +0.05 ... +0.1 ... +0.15 ... +0.2 ... +0.25 ... +0.3 ... +0.35 Right

Probes must be same at each measurement.

SAUL BRITTO · « **Reply #232 on:** February 19, 2016, 03:55:26 am »

Ok I will do it again;Wait.

SAUL BRITTO · « **Reply #233 on:** February 19, 2016, 04:02:24 am »

UP= .-342
Full left= .-335
Full Right= .-334

SAUL BRITTO · « **Reply #234 on:** February 19, 2016, 04:07:39 am »

Please forget it trig view was on! I will be back with news wait.

SAUL BRITTO · « **Reply #235 on:** February 19, 2016, 04:14:24 am »

UP= 0.-288
Full left= 0.-531
Full right= 0.350

And I can zero it a bit to right,around 15 or 20%.

rf+tech · « **Reply #236 on:** February 19, 2016, 04:26:47 am »

Set Chan A POSN UP

Adjust R58 for 0.0 V, measured same way.

Full left -V should now be very close to full right +V

rf+tech · « **Reply #237 on:** February 19, 2016, 04:32:55 am »

Set Chan A off, Chan B on
Set 20 Volts/Div, input Gnd.

Measure at delay line, same as for Chan A

Set Chan B POSN UP
Adjust R50 for 0.0 V, measured same way.
Chan B POSN full left -V should now be very close to full right +V

SAUL BRITTO · « **Reply #238 on:** February 19, 2016, 05:14:43 am »

Ok I began by channel two.I still don't found the adust of channel 1-A sorry my eyes are day after day worse!
Channel 2 I can adjust to 0.000 well on the mid course of position knob.,but on the end of the trimpot of adjust.

SAUL BRITTO · « **Reply #239 on:** February 19, 2016, 05:24:21 am »

Ok column D line 3,correct?

SAUL BRITTO · « **Reply #240 on:** February 19, 2016, 05:31:40 am »

rf+tech I can't zero the channel A like the B.On the trimpot of adjuste the more I can is -120mV, it just be zero with
the "position" a bit to right,maybe 3% but...

rf+tech · « **Reply #241 on:** February 19, 2016, 05:34:54 am »

Our eyes are fine, it's the manual poor quality.

R58 really is R38??

Red boxes I think are correct adjustments.

Check resistors, may be +15.6% like on HV board?

SAUL BRITTO · « **Reply #242 on:** February 19, 2016, 05:42:07 am »

If 58 is 38 then, I adjusted on the wrong trimpot?

rf+tech · « **Reply #243 on:** February 19, 2016, 06:02:09 am »

Quote

If 58 is 38 then, I adjusted on the wrong trimpot?

Really cannot read pot numbers in drawing, all look the same.

Check resistance markings. 2000 = Gain, 200 = POSN.

SAUL BRITTO · « **Reply #244 on:** February 19, 2016, 06:03:46 am »

Ok my friend I think you are tired like me! When we are rested,will think better and do better actions.

Thank you for all ! Hasta la vista. Até a próxima batalha!

as says the Terminator: I will be back!

SAUL BRITTO · « **Reply #245 on:** February 19, 2016, 06:11:40 am »

Just a small question: Why do not the trace appear,is for this vertical problem? When I push trig view and beam finder I see a good trace.

rf+tech · « **Reply #246 on:** February 19, 2016, 02:52:46 pm »

Yes, there is a problem with the vertical amplifier. First image below tells how beam finder works.

For now, set Chan B on, Chan A off
Set 20 Volts/Div, input Gnd
Set POSN UP

Second image shows where to measure across path through vertical amplifier, from delay line to deflection plates. All points should be close to zero Volts. Somewhere there will be a big difference. This pushes beam off top of screen. Beam Find reduces the difference (gain).

SAUL BRITTO · « **Reply #247 on:** February 19, 2016, 04:03:35 pm »

rf+tech these measures has to be accomplished ground refferenced?

rf+tech · « **Reply #248 on:** February 19, 2016, 04:10:15 pm »

Quote

these measures has to be accomplished ground refferenced?

Not ground reference, only side to side same as last night.

SAUL BRITTO · « **Reply #249 on:** February 19, 2016, 05:38:58 pm »


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Author Topic: Fixed HP1741A in a big shape but... I bet in a focus problem, and you? (Read 68755 times)

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