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

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.

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

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.

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

With a diode ?

That may bring voltage to high don’t know yet

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

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

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

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

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

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.

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.