NBTV Television Analyst

Centralised area for notes about construction projects. Each project has its own sub-forum. In the sub-forums will be topics relevant to parts of that project (e.g., there might be a topic on CRT problems). If you start a construction diary, just post in the forum with your project name as the topic, and a moderator will create a sub-forum for your project.

Moderators: Steve Anderson, Dave Moll, Andrew Davie

Re: NBTV Television Analyst

Postby Steve Anderson » Sat Apr 25, 2020 8:49 pm

Harry Dalek wrote:So next i forgot to look is if this meter is showing the correct pin outs to the other meters as i was trusting it .

Always download the datasheet(s) from reputable sources, e.g. google "ZTX558 datasheet" or "ZTX558 pinout" if that's all you need. I just did it and ended up with over 20 results on the first page, there were a lot more pages to go...

Make a folder to store them all so you don't have to keep wasting time by searching the 'net each time. Sub-folders, NPN, PNP. JFET, MOSFET and so on...same for chips, 4000 series, 74HC series, 74HCT series, then perhaps OPTO, sub-folders, LED, Phototransistor, Phodiode and so on..get organised...

Test the meter with a good known device and use the pin-out from the datasheet.

Steve A.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 4252
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: NBTV Television Analyst

Postby Harry Dalek » Sun Apr 26, 2020 9:16 am

Steve Anderson wrote:Always download the datasheet(s) from reputable sources, e.g. google "ZTX558 datasheet" or "ZTX558 pinout" if that's all you need. I just did it and ended up with over 20 results on the first page, there were a lot more pages to go...


That's what i originally for this did Steve on checking pin connections to the data sheet every thing was in place right way around in the first place ,i tended to use the meter on used parts reason i looked once pulling the ztx558 out to check it then finding out this meter is showing incorrect pin connections on emitter and collector that confused me ! you mentioning the gain was proof checking again with other transistor multi meters ....one the transistor was fine and it was in the correct pinout positions in the first place ...that's ok its a mistake i will not make again learn something every day as they say .

Make a folder to store them all so you don't have to keep wasting time by searching the 'net each time. Sub-folders, NPN, PNP. JFET, MOSFET and so on...same for chips, 4000 series, 74HC series, 74HCT series, then perhaps OPTO, sub-folders, LED, Phototransistor, Phodiode and so on..get organised...


That's a good idea i tended to put a data sheets in one of the project pages still have to go looking when you need it again your for sure better organised ...Remember those old large thick blue data books before the internet ? i still have a some of them i had mainly them for the 74 series .
Yep that's true the search each time is a time waster .

Test the meter with a good known device and use the pin-out from the datasheet.

[/quote]

Way to go for sure ,
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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4427
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: NBTV Television Analyst

Postby Harry Dalek » Sun Apr 26, 2020 10:35 am

Now there's not to much left to check 1n4148 between the zeners is 0.62v when opto led is off and 0.60 when fully on crt full brightness as i recall the original 3bp1 Andereson it was 0.70 v .
The focus is not to bad the brightness control works but the 5.1 v zener still varies with varying the opto led .
It pretty much works apart that very confusing ..
A video below ...here's the result i have spread the raster lines for size so you can see more clearly ,this camera is very sensitive to light very hard to take video and shots
Attachments
DSCN6467_x264.mp4
(18.8 MiB) Downloaded 147 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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4427
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: NBTV Television Analyst

Postby Steve Anderson » Sun Apr 26, 2020 11:29 am

Harry Dalek wrote:...Remember those old large thick blue data books before the internet ? i still have a some of them i had mainly them for the 74 series.

Yes, I still have a few myself, along with those from Motorola, Signetics, Philips and a few others. I don't know why I keep them - they're just collecting dust. I can't remember the last time I referred to them - decades ago. Maybe I keep them for sentimental reasons, they remind me of where I was living (Devon/Cornwall UK) and the job I had at the time. Also quite a few early transistor/diode books and valve/tube data books. Again gathering dust and rarely, if ever, referred to. Everything is available 'out there' on the 'net these days - so they say, and generally it's true.

Steve A.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 4252
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: NBTV Television Analyst

Postby Steve Anderson » Sun Apr 26, 2020 11:49 am

If you are absolutely certain all is correct in the circuit build, try a different 3BP1 CRT, it is possible that one is going 'soft', i.e. a little bit of air has seeped in. Though I'm still stumped why the zener voltage is varying so much, 0.1 or 0.2V - OK, but not the amount you're observing.

A neat little experiment you can do with transistors is plug one into your meter and measure the hFE, say it's 120. Then hold the transistor between two fingers (index finger and thumb) and watch the hFE (current gain) rise - and that's just the difference between room temperature and your fingers, maybe 15 degrees. So you can imagine the gain change between -20 and +100 which most semiconductors are rated for (at least). That's why hFE is usually specified at 25 degrees in datasheets...most other parameters too.

Steve A.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 4252
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: NBTV Television Analyst

Postby Harry Dalek » Sun Apr 26, 2020 3:39 pm

Steve Anderson wrote:If you are absolutely certain all is correct in the circuit build, try a different 3BP1 CRT, it is possible that one is going 'soft', i.e. a little bit of air has seeped in. Though I'm still stumped why the zener voltage is varying so much, 0.1 or 0.2V - OK, but not the amount you're observing.


Yes apart from 2 resistors that are 10k off the 220k and 470k 2w they are both 10k off the 220k is 230k and 470k is 460k

addtext_com_MDEzNTU3MjA3NTc.jpg
addtext_com_MDEzNTU3MjA3NTc.jpg (61.84 KiB) Viewed 1616 times



i have been over the wiring so many times the crt being off did cross my mind ,and i changed all the main parts zeners the diode the transistor even swapped the opto to another not of this batch ,but its working i can show you the reading on the 5v zener adjusting the opto in the a video below



Would you think just disconnecting the crt perhaps show a different result i have been thinking of that ...i do have a another spare 3bp1 or 2 i had a few i was being fussy as to if it the glass had a scratch or the phosphor coating looked better than another but yes i can replace and see but does not look like airs got into it but its a idea to look into .

A neat little experiment you can do with transistors is plug one into your meter and measure the hFE, say it's 120. Then hold the transistor between two fingers (index finger and thumb) and watch the hFE (current gain) rise - and that's just the difference between room temperature and your fingers, maybe 15 degrees. So you can imagine the gain change between -20 and +100 which most semiconductors are rated for (at least). That's why hFE is usually specified at 25 degrees in datasheets...most other parameters too.


OH i will give that a go my meter must have a long socket as new transistor does not poke out much for testing this idea but that's on my mind now to try .

Well that's the test on the zener shown same result both directions i am glad your stumped ! as it has me ..i like to know how things work or the reason but at least here it works but not as expected is the problem
Is it hard to do a sofware simulation on a voltage test the opto adjustment on that Zener with those voltages ?
Its working the crt as wanted and does not seem to be harming any thing that's a good thing may be we are both to worried about it .
Attachments
DSCN6469_x264.mp4
(17.57 MiB) Downloaded 124 times
DSCN6471-crop.JPG
DSCN6471-crop.JPG (237.31 KiB) Viewed 1617 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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4427
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: NBTV Television Analyst

Postby Steve Anderson » Sun Apr 26, 2020 4:05 pm

This really is a puzzle...have you got D101 (1N914/1N4148) the correct way around? A few percent variation in the resistor values is nothing to worry about, even 20% should be OK.

Steve A.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 4252
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: NBTV Television Analyst

Postby Harry Dalek » Sun Apr 26, 2020 4:40 pm

Steve Anderson wrote:This really is a puzzle...have you got D101 (1N914/1N4148) the correct way around? A few percent variation in the resistor values is nothing to worry about, even 20% should be OK.

Steve A.


Yep Steve i was thinking the resistors were more for the focus side than hurting this ,Yes the 1n4148 is the right way around and working .
mmm the circuit is all wired correct seems happy to work as is ....least giving the same result ..
nothing is overheating or showing a sign of a problem .
I think i will just move onto the second crt and see what happens there .
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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4427
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: NBTV Television Analyst

Postby Steve Anderson » Sun Apr 26, 2020 9:00 pm

Harry, one thing I've noticed in the photo of the board(s) is you've got the 1W/2W resistors sat right on the board. I usually space them off the board by about 1cm so they get plenty of air around them. Not worth altering them now, but keep it in mind for the future. That heat has to go somewhere, preferably into the air, not adjacent components or the board itself. An alternative is to mount them vertically - space allowing.

As for this odd zener problem, I'll breadboard just that part of the circuit and see if I can reproduce it.

Steve A.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 4252
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: NBTV Television Analyst

Postby Steve Anderson » Sun Apr 26, 2020 9:32 pm

Harry, I've found the original of the circuit from 2016 (when my Autocad was playing up). There's considerable difference between the this and your previous posting with a drawing and voltages. More to come when I find the later versions...

Note there's about 390V across the 220K resistor, whereas you're getting far less than this.

Check the 68k across the focus pot, with the 68k in place the focus pot should read about 68k, not 1M...dry joint, dead 68k? Check and re-do all joints, something somewhere is starving that resistor chain of current.

While you're about it, check the 470k from focus pot to GND/0V. And I mean to GND/0V, not just the resistor itself.

Steve A.
Attachments
3BP1 NBTV Initial 1-Model.gif
3BP1 NBTV Initial 1-Model.gif (15.31 KiB) Viewed 1613 times
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 4252
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: NBTV Television Analyst

Postby Steve Anderson » Mon Apr 27, 2020 11:51 am

I found a different version, from around the same time, that closely resembles the circuit you're working from. Your voltages will be slightly higher as you're using 1500V not 1400, but otherwise it should work fine.

Note the voltage across R901 (220k) of 385V, that means there's 1.75mA of current, whereas in your build the current is far less than that. I'm sure the problem is a lack of current.

Steve A.
Attachments
3BP1 NBTV Initial 7.gif
3BP1 NBTV Initial 7.gif (15.03 KiB) Viewed 1601 times
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 4252
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: NBTV Television Analyst

Postby Harry Dalek » Mon Apr 27, 2020 6:24 pm

Steve Anderson wrote:Harry, one thing I've noticed in the photo of the board(s) is you've got the 1W/2W resistors sat right on the board. I usually space them off the board by about 1cm so they get plenty of air around them. Not worth altering them now, but keep it in mind for the future. That heat has to go somewhere, preferably into the air, not adjacent components or the board itself. An alternative is to mount them vertically - space allowing.

As for this odd zener problem, I'll breadboard just that part of the circuit and see if I can reproduce it.

Steve A.


Yes i have been keeping an eye on Temperature i don't want things getting hot ! things getting hot do worry me so i keep an eye on that ...i noticed on these's voltages they get warm but i can hold my finger on them so they are not over heating.
i do check with long runs how every thing is going
I again agree that i will change the mounting of these from now on , your way is wise .
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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4427
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: NBTV Television Analyst

Postby Harry Dalek » Mon Apr 27, 2020 6:31 pm

Steve Anderson wrote:Harry, I've found the original of the circuit from 2016 (when my Autocad was playing up). There's considerable difference between the this and your previous posting with a drawing and voltages. More to come when I find the later versions...

Note there's about 390V across the 220K resistor, whereas you're getting far less than this.

Check the 68k across the focus pot, with the 68k in place the focus pot should read about 68k, not 1M...dry joint, dead 68k? Check and re-do all joints, something somewhere is starving that resistor chain of current.

While you're about it, check the 470k from focus pot to GND/0V. And I mean to GND/0V, not just the resistor itself.

Steve A.


The 68 k looks fine but so did one in the deflection amplifier i will check this ...i had to work to day so sorry for the late reply

Ground oh yes ..i have been making sure ground is ground ,thats some thing i can check now the above suggestion ,...get back to you
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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4427
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: NBTV Television Analyst

Postby Harry Dalek » Mon Apr 27, 2020 7:35 pm

Steve Anderson wrote:
Check the 68k across the focus pot, with the 68k in place the focus pot should read about 68k, not 1M...dry joint, dead 68k? Check and re-do all joints, something somewhere is starving that resistor chain of current.


Its showing 63k in circuit across the 1m trimmer

While you're about it, check the 470k from focus pot to GND/0V. And I mean to GND/0V, not just the resistor itself.


R903 showing 472k in circuit with the focus adjustment at any adjustment of the focus trimmer so its not effecting its resistance in the circuit i recall it was 460k last time i tested i must of made a mistake unless these things can change resistance in use i know it gets warm but not hot .

So that's some thing to keep an eye on...mmm
Attachments
addtext_com_MDQzMTExMjI3Mw.jpg
addtext_com_MDQzMTExMjI3Mw.jpg (71.67 KiB) Viewed 1594 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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4427
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: NBTV Television Analyst

Postby Steve Anderson » Mon Apr 27, 2020 7:50 pm

Hang on! Something ain't quite right here. Your measurements added to the drawing are 'odd'. The posting of 26th April shows one end of the 220k resistor as -1400V, the other as -1430V, 30V of difference, a current of only 136uA. Whereas the focus pot end of the same resistor shows +388V (I assume relative to the cathode)...so that's about correct at 1.76mA.

Get the tube at a reasonable brightness with the best focus you can and check again. Don't move/bump the controls as you do so.

68k parallel with 1M is about 63k, so no problems there.

Steve A.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 4252
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

PreviousNext

Return to Construction Diaries - Electronic Televisions

Who is online

Users browsing this forum: No registered users and 0 guests