Checking hv
 

Checking hv on color sets is done with brightness down but for b&w sets does the same rule apply with brightness down as well for b&w sets.

Not so, as it says in every SAMS for color sets I have seen, check HV with brightness set at “normal level”, which to me seems logical that it would apply to BW sets for the same reason as color, as there has to be sufficient HV to keep a stable pic at a normal viewing level W/O dropping off when turned up from no brightness.

I’m working on this pilot tv with the d5-100 crt it works nice to see a fresh b&w picture but I’m trying to figure out how to get the screen to open up alittle more top and bottom the pot is maxed to open the screen already maybe a cap or resistor in the right place may do it but I’m open to suggestion.

Well, you are putting a CRT in a TV that it was not exactly made for, so there will be some changes to be made, I'm not sure if I am looking at the right schematic, pilot_tv37_sams_62-16, but if it's right, you say that “the pot is maxed to open” (R4) vertical size, if this is the case, then all you need do perhaps is raise the value of R58 to 1.1 or 1.2 meg or so, just see how it goes, or, if by chance, you have the pot at the other extreme, then lower it to 900-800k.

If you have more brightness then you need you may also be able to get more deflection by slightly lowering HV.

Yes it is 62-16 sams I’ll look into that

It has plenty of brightness but lowering don’t really increase deflection

It’s a small crt so not much I need to fill top and bottom

Well it turns out that vert size is at little over half because I stop turning it when it stopped opening the screen so I don’t know if this complicates this or just try the resistors.

If it was my set, I'd try the slightly different resistor value mentioned, if it does not work, or causes a drastic undesirable effect, you can always put the original value back and try something else.

Ok well I tried all different resistors and with little success not enough to leave a different resistor in seems odd a 3 inch has full screen because original but the small crt I would have thought it wouldn’t be this difficult to get it to fill in being it’s smaller

The picture has the letter box appearance like most cable boxes put out including mine but I ruled out that this is the best I can get with this cable box. It’s so close it’s frustrating

Well then, it's a step in the right direction.

What this will most likely take is someone who has intimate knowledge of this given set and vertical circuitry and how it may be better modified to the CRT you are trying to use.
Cause as it seems as for the vertical section, it's not quite working as well as the CRT that the chassis was designed to use.

This may be a result of load values, resistive and or capacitive, and is being seen more pronounced in vertical due to the lower frequency than the horizontal.
This is almost on the engineering level, and won't be easy, but I'm sure someone out there knows these things well and can offer some guidance.

Well it would have to be heavily modified to work this crt which I would rather not do even though it’s a b&w tube and can no longer get the 3kp4 and I doubt anyone ever tried using this d5-100 crt so I thought this tube would have been a good b&w replacement.

It seems that there are substantial differences between the two that would need to be addressed before it would work well it looks like.

https://tubedata.wernull.com/sheets/168/3/3KP1.pdf
http://www.r-type.org/pdfs/d5-100gh.pdf

Namely in the deflecting plates capacitive loads.
3KP1 seem to be around 8-11 pf, and d5-100 is much lower, .09-3pf? Hard to tell, not in English.
Also the deflecting plates voltages a a bit different, this is no doubt the source of the problem.

Does this the small crt needs more deflection voltage

Hard to tell, one is listed in volts per inch, the other is per cm, not sure how that crosses over.
But more likely than not, it's the difference in pf that is the issue.

And the pf cannot be made up with the proper cap ?

That will have to be looked into by someone who knows the circuit a bit more, but I'm sure it can be adjusted.

Is The pf difference with the circuit or the deflection plates themselves

I did manage to get the screen full but the people on the screen part was missing to big stretched

Yes, since the distance from the center of deflection to the screen is so small in this tiny tube, deflection sensitivity is poor.

jr

The original set and circuit must have been made with the 3KP4 in mind, and the capacitive load it would put on the circuit, so it makes sense that a different tube would have unexpected results, so as mentioned, someone with a good understanding of this set may be able to help adapt it.
May only need a few changes.

I wonder if the hv deflection caps would make any difference

Maybe a different vertical size pot instead of 5 meg

Unfortunately, it won't be as easy as a single part, It will take someone with knowledge of tube circuits who can look over the documentation for the set and theory of operation and make suggestions on how to adapt it better to that CRT, it may just be needing a few changes of caps and resistors in the vertical drive / output area to make it a better match.

Perhaps it would be useful if the B+/B- voltages applied to the vertical circuit were increased :scratch2:....what do they measure now?

jr

So I have to figure out the b+ voltage to the vertical amp or multi.I’m not certain where the voltage comes from for vertical possibly a tap from focus voltage

B+ is from the 25Z6, and B- is from the 35W4...Don’t you have a schematic?
What do they measure now?

jr

Yes I know where to get the b+ but I thought you meant the b+ to the vertical circuit I’ll check the voltage at the rec tubes I do know it’s close to what it should be. And yes I have a schematic. How would I be able to up the b+ ?

If you could post the schematic(s) of the power supply and deflection circuits, the collective wisdom available here should probably be able to walk you thru it. :bigok:

I have been working with the schematic from early television. I don’t remember what the b+ should be 125v or 150v

Is this it?
http://www.earlytelevision.org/pdf/p...sams_62-16.pdf

jr

Yes that’s the one

The riders shows 150v but when I recapped this set the b+ was low 90v so I added a diode to the positive rec tube and I think it came up to 125v so to bring the b+ up would I add a second diode in series with the one I put in already.

On the Riders schematic, it is easier to follow the B+/B- paths from the rectifier tubes to the vertical and horizontal circuits.

http://www.earlytelevision.org/pdf/p..._rider_tv2.pdf

jr

But what would be the best path to take in raising the b+ or would resistors have to be changed from b+ to the vertical

In addition to trying to get more sweep voltage to the plates, it may also be a factor of adjusting the coupling caps / resistors .005uf /47m to better match the new tube to make what you give it most effective, but have no idea what it may or may not have to be changed to!

Well I’m thinking of adding another diode in series to see if this makes any difference

as far as I know putting in another diode will lower the voltage.