NBTV Television Analyst

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Re: NBTV Television Analyst

Postby Steve Anderson » Thu Apr 23, 2020 2:15 pm

OK, seems you're one step ahead of me! The only advantage you get from lower voltages on the CRT is increased sensitivity of the deflection, i.e. less drive is needed to the deflection plates, but the existing deflection amps should be able to provide that. The advantages are a brighter trace and better focus, both needed for NBTV.

The maximum from cathode to anode 2/grid 2 is 2200v for a 3BP1. Pin 2 (-ve) and pin 9 (+ve).

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Re: NBTV Television Analyst

Postby Harry Dalek » Thu Apr 23, 2020 2:52 pm

Steve Anderson wrote:OK, seems you're one step ahead of me! The only advantage you get from lower voltages on the CRT is increased sensitivity of the deflection, i.e. less drive is needed to the deflection plates, but the existing deflection amps should be able to provide that. The advantages are a brighter trace and better focus, both needed for NBTV.

The maximum from cathode to anode 2/grid 2 is 2200v for a 3BP1. Pin 2 (-ve) and pin 9 (+ve).

Steve A.


Well i had to make the supply work on maximum voltage more than the crt needed due to what i had ,you and Klaas i have learnt to handle these voltages with the parts i have or i would not of gone far ! then it was just a matter of using what i know from the past to tame the voltage to what i want .

I was running the CRT lower for a few reasons mainly making sure nothing over heated the crt was safe at these voltages i don't want a capacitor going bang ! Also sparking always worries me ,i must of run it to hard at one test with killing the first 75 volt zener so increasing hv negative i might find there's a limit well something else to learn and i did buy a few extra just in case 5 left :wink: .

I might be lucky on the positive side the HV positive has a bit to catch up to low 400's just have to keep an eye on the resistor temperatures mainly on the positive side i don't want any thing going hot ...so far i have increased the voltage to -1300 all ok .
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Re: NBTV Television Analyst

Postby Harry Dalek » Thu Apr 23, 2020 5:29 pm

Steve I have increased the HV negative to 1500 volts focus is a bit better ,i could see the size of the raster decrease and focus increase with increase in voltage here ..
Still problems but adjusting the temporary brightness control it still go's out of focus looks worse on the video as you can't see the lines and they blur with the brightness control brightness decrease catch 22 ~!
I will do a full voltage test with the new voltages on the CRT tomorrow
Those big load resistors temporary wired up at the front are to adjust the secondary of the saturable reactor i got what i was aiming for 1500v the HV positive went up to 390v not to bad ,no over heating which is good .
As i said before i think this projects CRT is going to make me work for it !~
DSCN6392.JPG
DSCN6392.JPG (291.18 KiB) Viewed 1423 times

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DSCN6393_x264.mp4
(1.88 MiB) Downloaded 127 times
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Re: NBTV Television Analyst

Postby Steve Anderson » Thu Apr 23, 2020 8:29 pm

It seems there's some non-linearity in the horizontal (as you have the tube orientated in the video), I would sort that out first before you burn the screen - it seems awfully bright to me. Whatever is causing that may sort out the other matters...

Have a look at the deflection waveforms on the pins of the CRT (AC coupled), they should be nice straight ramps. If not there's probably a problem in the power supply...having checked the input to the amps is correct first.

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Re: NBTV Television Analyst

Postby Harry Dalek » Thu Apr 23, 2020 9:52 pm

Steve Anderson wrote:It seems there's some non-linearity in the horizontal (as you have the tube orientated in the video), I would sort that out first before you burn the screen - it seems awfully bright to me. Whatever is causing that may sort out the other matters...


Yes trying for NBTV scanning for now

Looks very bright via the camera but don't worry its not that bright to the eye or well focused very unlike how it stated with the dead 75 volt zener funny i would of expected the result the other way around but is what it is ..non linearity to the framing wave form i think from a look it was no where as good as the line pulse out of the deflection amplifiers ...I will show up results tomorrow in and out of them .

Have a look at the deflection waveforms on the pins of the CRT (AC coupled), they should be nice straight ramps. If not there's probably a problem in the power supply...having checked the input to the amps is correct first.


OK will do Steve i noticed the waveform does change in the deflection amplifiers on the position controls from memory but again i will take the reading and waveform shots and show you what you think . The deflection amplifiers would be out of balance i have not got around to evening either side out yet need to review the procedure again before trying
The heater has a switch i need not have the CRT on ....
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: NBTV Television Analyst

Postby Steve Anderson » Fri Apr 24, 2020 12:24 am

Whenever I come across anything like this the first thing I suspect (or at least check) is the power supplies are clean (no ripple or very little of it) and at the expected voltages. If they're OK and the input signal is correct then it has to be something within that stage. Garbage in - garbage out.

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Re: NBTV Television Analyst

Postby Steve Anderson » Fri Apr 24, 2020 12:37 am

Ah! I think I may have it...are you using the ramp generators as shown in my posting of April 17? If so we'll need to make some minor changes. Also what deflection amps are you using? If you can post the drawing of the deflection amps you're using, that would help.

If you can check the outputs of the ramp generators are truly nice ramps, that would also help - disconnect them from the deflection amps first and keep the CRT heater off. Set VR201 & VR211 to half-way, the ramp outputs at TP2 & TP4 should be about 5V p-p centred around 0V, i.e +2.5V to -2.5V.

I'll attack this more in the morning - it's getting late here.

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Re: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 24, 2020 9:00 am

Steve Anderson wrote:Whenever I come across anything like this the first thing I suspect (or at least check) is the power supplies are clean (no ripple or very little of it) and at the expected voltages. If they're OK and the input signal is correct then it has to be something within that stage. Garbage in - garbage out.

Steve A.


Hi Steve i am not doing much today so i will work on this i have my little scope here so checking the HV positive negative and low dc is easy to do once i set it up.
i just noticed a problem on one of the sides of the line deflection amplifier as in R403 ....in my case i am using 4 ....47k half watt resistors in series and here for all the deflection amplifiers well one of the resistors seems to be open circuit ..never come across that before unless it was over heated here it is not look new as it was , must of just been faulty from the start ...so only one half of the line amplifier was working here by the looks of it ...
i will correct that today .

Taking in your needs to review what i have done and i will try and post it all up .

Positive Voltage in to this is now 390v
Attachments
3BP1 NBTV Initial 1-Model.gif
Last edited by Harry Dalek on Fri Apr 24, 2020 11:45 am, edited 1 time in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 24, 2020 9:18 am

Steve Anderson wrote:Ah! I think I may have it...are you using the ramp generators as shown in my posting of April 17? If so we'll need to make some minor changes. Also what deflection amps are you using? If you can post the drawing of the deflection amps you're using, that would help.


Yes Steve using that ...for line frame ramp generation

The deflection amplifier circuits are the ones used before last post.

If you can check the outputs of the ramp generators are truly nice ramps, that would also help - disconnect them from the deflection amps first and keep the CRT heater off. Set VR201 & VR211 to half-way, the ramp outputs at TP2 & TP4 should be about 5V p-p centred around 0V, i.e +2.5V to -2.5V.

I'll attack this more in the morning - it's getting late here.

Steve A.

[/quote]


Ok thats a job for today i will do...............just replace that dead resistor in the deflection amplifier before i get suck into that .
Last edited by Harry Dalek on Fri Apr 24, 2020 12:45 pm, edited 1 time in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 24, 2020 11:05 am

I have left for a start the connections to and from deflection amplifiers to show them as is now ..i will after this post adjust and disconnect the ramp inputs to the amplifiers to show wave forms as mentioned in the last post but get these out of the way first
Steve I will first up just changed the one dead 47k resistor in the line defection amplifier ,very strange looks just to be a dud nothing wrong with it from looking at it but its open circuit somewhere inside it .

But this now shows the line deflection amplifier is back .
DSCN6398.JPG
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Out of the line ramp generator to deflection amp input
DSCN6410.JPG



Next i looked at whats coming out of both deflection plates on the line side
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DSCN6402.JPG
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Next the frame ramp out of ramp generators input to deflection amplifier

DSCN6409.JPG
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Now the the frame output of the defection amplifiers to crt plates not really good at all.. i will check for a wiring mistake seems too poor .
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DSCN6406.JPG
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makes sense looking at the ramp out to how poorly the size and position control work on this amplifier
Last edited by Harry Dalek on Fri Apr 24, 2020 12:19 pm, edited 1 time in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 24, 2020 11:18 am

Tested the HV positive and negative and low voltage dc power supplies they all come up clean on the scope Steve no ripple
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 24, 2020 11:44 am

Steve Anderson wrote:If you can check the outputs of the ramp generators are truly nice ramps, that would also help - disconnect them from the deflection amps first and keep the CRT heater off. Set VR201 & VR211 to half-way, the ramp outputs at TP2 & TP4 should be about 5V p-p centred around 0V, i.e +2.5V to -2.5V.



Ok the ramp generators are disconnected from the deflection amplifiers CRT heater is off adjusted vr201 vr211 as above .

below the line ramp from the ramp generator
DSCN6416.JPG
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The frame ramp
DSCN6417.JPG
DSCN6417.JPG (189.33 KiB) Viewed 1403 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: NBTV Television Analyst

Postby Steve Anderson » Fri Apr 24, 2020 1:15 pm

The first thing I notice is that 'spike' at (mostly) the beginning of the line waveform. Then in later photos I notice that you're not using a 'proper' scope probe and that particular scope has no BNC input connector which means you cannot set the probe compensation correctly - not even at all!

I know you have better scopes kicking around, have you got ''proper' probes for it/them? Using this arrangement will likely lead to all sorts of confusion not only here, but on later projects. I suggest putting this scope back on the shelf and getting the 'big guns' out - it really isn't up to the job.

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Re: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 24, 2020 1:21 pm

Ok i have worked out i made a wiring mistake Tr502 base and the centre wipper VR502 ..wired it to R506 dumb dumb mistake it was tight wiring around that area ! :roll:

Apart from evening the deflection amplifiers out they are working now fine

Heres the frame ramp out of the deflection amplifier now much better !

DSCN6419.JPG
DSCN6419.JPG (175.06 KiB) Viewed 1400 times


Here's a quick video of the position and size controls trying to film and adjust so almost here .

Problem is still around the temp brightness control ...i will check again for mistakes around that area ..its adjusting the brightness alright but go's out of focus some thing is up for sure more than likely me ...so double triple checking next .

Ramp out of the line and frame amplifiers at the end ...sorry its video is poor i can't get the brightness lower yet
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DSCN6420_x264.mp4
(12.97 MiB) Downloaded 95 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 24, 2020 1:42 pm

Steve Anderson wrote:The first thing I notice is that 'spike' at (mostly) the beginning of the line waveform. Then in later photos I notice that you're not using a 'proper' scope probe and that particular scope has no BNC input connector which means you cannot set the probe compensation correctly - not even at all!

I know you have better scopes kicking around, have you got ''proper' probes for it/them? Using this arrangement will likely lead to all sorts of confusion not only here, but on later projects. I suggest putting this scope back on the shelf and getting the 'big guns' out - it really isn't up to the job.

Steve A.


Yes i have better scopes i am just at my little work table in my study at the moment with it ,i can tell your disgust at my 1980 something Dick smith job ! :shock:
I am just using it just because of where i am with it at the moment ,i can tinker and look after the kids at the same time multi tasking !
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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