The 3BP1 Anderson monitor

[Harry Dalek]

There does appear to be some greys, but that might just be the camera/frame rate problem.

The biggest issue I think I can see is lack of timebase lock. Until that occurs you're not going to see much at all. Go back to the stair-step waveform and get that nice and stable to start with. It is a known stable source, anything else at this stage I would view with suspicion.

I did mention some time back that I thought the opto-coupler was perhaps not suitable for this, i.e. not linear enough, but let's first get a nice stable picture, even if lacking grey-scale detail.

Steve A.

Steve no problems on the opto circuit is what it is at the moment good learning exercise which ever way it plays out ,i think it will work perhaps R304 might need adjusting later on ?

I am using the reversing bar wave i just needed something shape wise to make out the bar video is hard to make out on the display at the moment .

[Steve Anderson]

You could try dropping R304 to 4k7 and see if that results in a brighter display. What I'm more concerned about at the moment is timebase lock, especially frame lock.

Steve A.

[Harry Dalek]

You could try dropping R304 to 4k7 and see if that results in a brighter display. What I'm more concerned about at the moment is timebase lock, especially frame lock.

Steve A.

i will see if the coarse and fine frame controls will get it to lock .

It does need a touch brightening up the controls are on the limits ,,,have some time again tomorrow so i will post up results .

[Harry Dalek]

Well about 5 months work i can now see The Anderson monitor is delivered ...

With the time i had left today to work on it i thought the first thing to really show on this monitor is its inventor ,the program i used to make the wav or the levels i used in the picture one of the 2 caused a problem displaying in normal mode but it played in invert , it was my intention for it to display Steve first on this once i got it working enough to see something .
i rushed my test card and after all that got the 3bp1 wrong whoops so forgive that !~i will correct that tomorrow
Steve i ended up trying my resistor wheel on that 8.2k for the opto led and dropped it to 7k and i could then adjust my contrast and brightness controls i think i have it on 6k at the moment still looking whats the best setting here .
Now there is a raster when there is no video so that was the problem or really why the result was no raster before ...
I think i could of done better if i didn't run out of time ,i have uploaded both videos as they play better less loss of frames and such as in the gifs .
The reversing bar video is the 0126 jpg and it locked on to the video fine no frame problems at all i wondered what that would look like ,i think there should be reversed bars on the other side so not sure whats up there ,still i am very happy with results/
It is a little fussy at what it plays but i suppose a lot of the videos are really not standard format so it is what it is .
And last video is me the one who soldered it together .

[Steve Anderson]

Probably the best thing to do now is compile a list of items you feel could be 'tweaked' to improve it.

Then there's that dreaded tidy-up to do!!

Steve A.

Added later....the Reversing Bars should display as below on the screen...(without the black border around the white though)...

[Harry Dalek]

Probably the best thing to do now is compile a list of items you feel could be 'tweaked' to improve it.

Then there's that dreaded tidy-up to do!!

Steve A.

Added later....the Reversing Bars should display as below on the screen...(without the black border around the white though)...

HI Steve

Yes tweaking well better Tweak a bit before its all put away neat as i can ,i will have a look at what still needs doing or might be a problem .

I have just been out to my shed looking at the reversing bar wav video and some other videos ...

What i have found is Normal displayed things are harder to see than when the video invert is switched to that input so the front end of the circuit is causing this.

On the reversing video i can just get one side or the other to display the shades only when i adjust the dark level control for one or the other as below ..
I am very happy with it never got this far with NBTV on A CRT may be it can do better than at the moment its pretty much working so that is the most important thing.

[Steve Anderson]

I agree, there's something amiss in the sync area. It seems to be clamping in the wrong part of the signal.

If you can,'scope in dual trace mode at 6D and 6B with the video normal, then another shot with the video inverted. It all could be down to something simple like the actual video level which needs to be correct for this type of circuit to work as it should.

Using the signal at 6B with the Reversing Bars signal set the video to be 1.5V from sync-tips to the white bar. Then do not change it. Go to all the other controls and try and get the best picture you can.

The detected sync pulse should line up with the sync pulse in the video signal as below...the signal should always be with the sync pulses the as shown.

Yes, no point in doing a tidy-up until all is as you want it.

Steve A.

[Harry Dalek]

I agree, there's something amiss in the sync area. It seems to be clamping in the wrong part of the signal.

If you can,'scope in dual trace mode at 6D and 6B with the video normal, then another shot with the video inverted. It all could be down to something simple like the actual video level which needs to be correct for this type of circuit to work as it should.

Using the signal at 6B with the Reversing Bars signal set the video to be 1.5V from sync-tips to the white bar. Then do not change it. Go to all the other controls and try and get the best picture you can.

The detected sync pulse should line up with the sync pulse in the video signal as below...the signal should always be with the sync pulses the as shown.

Yes, no point in doing a tidy-up until all is as you want it.

Steve A.

Hi Steve
Yes got some results here for you .
The first two are my first go's at your test i wasn't sure i that i adjust something between invert and normal display so i did it again with the next 2 6B and D tests i know they are as same apart from invert and normal video settings .
I left the first lot on as an example as the camping pulse looks lots more like that to the eye at times with a second pulse appearing .
Scope set 1 volt for the video reversing bars and 5 volts for the clamping which is low as i can drop it on this scope ,all on 0.5mS
Switching from invert to normal its near on fine for the reversing video ,i find on other things say a row of test cards in a video wav to view some are fine others video looks all jumpy and again it seems to play it inverted much better try as i might setting the input video level .

[Steve Anderson]

I see what you mean about the double pulse. It doesn't surprise me at all on the inverted versions, so we can forget that, but why in the normal setting?

Perhaps you could repeat the exercise using points 6A and 6B. I'm trying to pin it down to one section, don't bother doing the inverted version this time.

My thinking is that's our good old friend supply bypassing/decoupling, long supply leads (maybe) or one of the monostable inputs has been accidentally left floating. e.g. IC604 pin 5, or IC605 pin 5...and so on.

If we can't crack this by 'remote control' I'll breadboard it and have a look-see myself.

Steve A.

[Harry Dalek]

I see what you mean about the double pulse. It doesn't surprise me at all on the inverted versions, so we can forget that, but why in the normal setting?

Perhaps you could repeat the exercise using points 6A and 6B. I'm trying to pin it down to one section, don't bother doing the inverted version this time.

My thinking is that's our good old friend supply bypassing/decoupling, long supply leads (maybe) or one of the monostable inputs has been accidentally left floating. e.g. IC604 pin 5, or IC605 pin 5...and so on.

If we can't crack this by 'remote control' I'll breadboard it and have a look-see myself.

Steve A.

Yes Steve theres a odd pulse that can appear at times .
Forgot to say yesterday the result on the screen of the test was the greybars swapped sides depending on the video switch .
OK i will do the points 6A and B no problems and will just use normal on video.
Ic604 and 5 those pins are connected to positive 12 v and 11 on both ics
i should have done the test by late afternoon evening .
OH well see how it go's today.

[Steve Anderson]

With the video being inverted it will try to clamp on the white bar which because this is reversing bars are in two different places in the two different line types.

Even so, with those runt pulses running around anything should/could be expected. We have to get rid of them.

Steve A.

[Steve Anderson]

OK, it's hands-up time - I made a mistake!!

In redrawing Klaas's sync detector circuit I got R611 a factor of 10 wrong. Now whether this is causes these 'runt pulses' I don't know, we'll see.

A corrected version of the circuit is below, it requires one resistor change.

Steve A. - with apologies.

[Harry Dalek]

With the video being inverted it will try to clamp on the white bar which because this is reversing bars are in two different places in the two different line types.

Even so, with those runt pulses running around anything should/could be expected. We have to get rid of them.

Steve A.

OK i have done the scope test just left it on normal and dual traced 6A and 6B and A has a little shake to it ,i noticed trying the sync slice control it has a very narrow range all to the end of the trimmer when you adjust it more i just get a vertical line on the monitor any case it must be doing the job or i would have no sync .
scope settings were same as yesterdays settings 1 volt for the video 5 volts for the 6Aand 0.5mS

The volume control has to be just right to get say in this case the reversing bar to show up with out it being distorted ,i would say if i had 2 different pictures to view i set the monitor for one the levels...... in the 2nd picture if shade levels were different would cause a picture distortion on screen ,seems to act like that at the moment .

I am keen to improve if we can would out the problem and i am also wondering why and would like to know.

Edit i just noticed your post i will correct that tomorrow and do the scope tests for you again see it that helps a problem like that is good an easier fix !

[Harry Dalek]

OK, it's hands-up time - I made a mistake!!

In redrawing Klaas's sync detector circuit I got R611 a factor of 10 wrong. Now whether this is causes these 'runt pulses' I don't know, we'll see.

A corrected version of the circuit is below, it requires one resistor change.

Steve A. - with apologies.

HI Steve

I tried my resistor wheel on R611 the looks cleaner but you loose all video modulation the runt pulse seems to speed up and is still there but not at the same frequency as the pulse lined up with the sync pulse tip ...
as you drop its resistance the video fades out to just a raster.
Now the voltage on pins 2 and 3 you had 4 volts i am getting 8.65 on pins 2 and 9.25 on pin 3. so something is up there.

[Steve Anderson]

Now the voltage on pins 2 and 3 you had 4 volts i am getting 8.65 on pins 2 and 9.25 on pin 3. so something is up there.

Yes, definitely wrong. Check the values of R607, R608 and VR601 - measure them. If IC602 and IC603 are in sockets, pull them out and see if you get the correct 4-odd volts at pin 3. Pin 2 should be slightly higher due to the video waveform.

I can't see how changing the value of R611 could affect the video signal - there's an error/solder-splash/whatever around that area.

Steve A.