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.

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.

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.

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

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

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.

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.

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

Does this the small crt needs more deflection voltage

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

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:

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/pilot_tv37_sams_62-16.pdf

jr

Is this it?
http://www.earlytelevision.org/pdf/pilot_tv37_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/pilot_tv37_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

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.

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

In series it should come up some I think. There’s one in there already if it don’t come up I don’t know what else to do to get the voltage up more to see if it makes any difference

In series it should come up some I think. There’s one in there already if it don’t come up I don’t know what else to do to get the voltage up more to see if it makes any difference

where exactly in series did you put it on this schematic?

ANY diode, no matter the type, solid or tube type, will have a forward voltage loss, solid having the least, and schottky type having the lowest forward loss.

the more in series, the more the loss

where exactly in series did you put it on this schematic?

ANY diode, no matter the type, solid or tube type, will have a forward voltage loss, solid having the least, and schottky type having the lowest forward loss.

the more in series, the more the loss

I had put a 1n4007 at the 25z6 positive tube and the voltage came up from 90v to iirc 125v common for these sets to have low b+

Series’s meaning I would add another to the one in there now

The only thing that makes sense to me to raise positive bias is to remove the 25z6 and replace with one1n4007 , leave the heater connected, and wire in the diode from the 10 ohm resistor on the plates to the 40 UF / spkr field coil, making sure to keep the cathodes p 4/8 unhooked.

This will raise the B+ by a lot, but may also have an effect on the negative bias.

the forward voltage of the 25z6 is 22v and the forward voltage of the 1n4007 is lest than one, you gain almost 21v by changing to so;id state.

The only thing that makes sense to me to raise positive bias is to remove the 25z6 and replace with one1n4007 , leave the heater connected, and wire in the diode from the 10 ohm resistor on the plates to the 40 UF / spkr field coil, making sure to keep the cathodes p 4/8 unhooked.

This will raise the B+ by a lot, but may also have an effect on the negative bias.

Well I would have watch the voltage that it don’t exceed the caps rating in there already and there is a resistor already in there to take the place of the field coil. Why not just pull the tube out and put a resistor in place for the heater

the forward voltage of the 25z6 is 22v and the forward voltage of the 1n4007 is lest than one, you gain almost 21v by changing to so;id state.

Well that would bring it close to 150v as riders says

If it were me, I would leave the tube in for ascetic values, and for the balance of the heater load, and just put in the new diode under it, making sure that the old tube is out of circuit for the new diode.

If it were me, I would leave the tube in for ascetic values, and for the balance of the heater load, and just put in the new diode under it, making sure that the old tube is out of circuit for the new diode.

I already have a diode in there so all I have to do is the disconnecting and then check voltage riders says 150v with the negative tube 35w4 so if it’s higher it should be good for negative

Why not increase the B- supply as well, it is also used by the vertical deflection circuit.:scratch2:

jr

Why not increase the B- supply as well, it is also used by the vertical deflection circuit.:scratch2:

jr

With a diode ?

That may bring voltage to high don’t know yet

With a diode ?

Yes, but remember that you are working with a negative supply, so pay attention to getting the diode polarity correct.

jr

Yes, but remember that you are working with a negative supply, so pay attention to getting the diode polarity correct.

jr

Lol yeah I don’t want fire works

Well that idea is out since warmed up it’s 147v if I do the diodes and cut out the positive tube the voltage will be to high likely for the caps in there even though it drops but initially it would be high.

Did the vertical scan improve when you increased the B- supply?

jr

Did the vertical scan improve when you increased the B- supply?

jr

I didn’t increase the voltage because it was at 147v and if I got the voltage up it may have been to much for the power supply caps.

lAccording to the data sheet for the D5-100, the deflection sensitivity is about 100volts per centimeter when operating at 2000 volts. I believe that the hv in the Pilot is closer to 2500 volts, which would reduce the deflection sensitivity to around 125volts per centimeter.

http://www.r-type.org/pdfs/d5-100gh.pdf

The vertical height of the D5 is about 3 centimeters, so it would require about 375 volts to scan from top to bottom of the screen.

The voltage that you have available from your B+ and B- supplies, which power the vertical circuit is less than 300 volts total, so you can’t achieve a full vertical scan.

jr

The voltage that you have available from your B+ and B- supplies, which power the vertical circuit is less than 300 volts total, so you can’t achieve a full vertical scan.

jr
I missed the connection between the vertical output and the hv supply (from the bottom of the focus pot). Perhaps io would be possible to increase vertical deflection voltage by changing or eliminating the resistor above or below the focus pot.
:scratch2:

jr

I missed the connection between the vertical output and the hv supply (from the bottom of the focus pot). Perhaps io would be possible to increase vertical deflection voltage by changing or eliminating the resistor above or below the focus pot.
:scratch2:

jr

I did try exactly that with the focus voltage and the whole screen filled in still with a picture but the focus was out of focus. Which resistor are you referring too and the hv I already lowered to around 1900v. Are referring to the focus resistor string to the focus pot.

Which resistor did you change? Is the focus voltage too high or too low now? :scratch2:

jr

Which resistor did you change? Is the focus voltage too high or too low now? :scratch2:

jr

I didn’t change a resistor I jumped from the last focus resistor to the focus pot momentarily to get a full screen and the voltage was around 272v good for the 3kp1 but the d5-100 needs 800v for focus

800 volts for focus is the ABSOLUTE MAX focus voltage according to the D5 data sheet....see the typical operating conditions on the next page.

jr

Ok I see it I missed that

So if I do the diodes instead of using the tube and the voltage jumps to 180-190v there is no guarantee the deflection with fill the screen and I still would have to worry about the power supply caps

I would think that the voltage would not go that high...perhaps 150 volts or so, if the current draw is low. :scratch2:

jr

Which resistor did you change? Is the focus voltage too high or too low now? :scratch2:

jr

I would think that the voltage would not go that high...perhaps 150 volts or so, if the current draw is low. :scratch2:

jr

The voltage as it is now is 147v. On the d5-100 would you know what the WE is on pin 3 and AST on pin 12

Pin 3 is the grid, pin 12 is astigmatism.

jr

I wonder if I have the tube wired wrong on those 2 pins.

Finally got full screen wiring differences at the crt socket and focus voltage was to high.

picture = 1000 words! :P

picture = 1000 words! :P

I’ll get the picture up I have last minute things to do. Biggest problem was obviously the crt any changes were made at the crt didn’t have to change anything with the chassis.

This is the best picture I could get using a cell phone it is much clearer and crisp and it’s full screen. Cell phones seem to change a lot in a picture. I had to take the picture up close because the cell phone camera seems to cancel out light.

There are 3 12at7 tubes in this pilot tv is it a problem replacing one with a 12ax7 I know the gain is 100 while the others are 60. Is there much of a critical balance.

This is the best picture I could get using a cell phone it is much clearer and crisp and it’s full screen. Cell phones seem to change a lot in a picture. I had to take the picture up close because the cell phone camera seems to cancel out light.

It looks like you have full deflection but poor focus. That probably isn't hard to fix. There's probably fixed resistors on both sides of the pot...just need to move a resistor from the side the wiper is touching to the side the wiper isn't touching to get more range.

It looks like you have full deflection but poor focus. That probably isn't hard to fix. There's probably fixed resistors on both sides of the pot...just need to move a resistor from the side the wiper is touching to the side the wiper isn't touching to get more range.

Actually the focus is perfect it’s the camera I used I wish I could get a nice picture to post. And I could not move any resistors at the pot because the voltage coming off the last resistor from the network feeds vertical so I had to use resistors at the tube base had to drop focus voltage from around 350v to around 125v I originally tried the resistors at the pot and lost full deflection.

Tried to get the picture better but cell phones not good for clear pics the picture is bright and focus is clear despite what the picture shows. Now a pilot 37 with a b&w picture no more hoping for an unobtainable 3kp4.