Checking hv

[old_coot88]

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.

[timmy]

Originally Posted by old_coot88

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.

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

[jr_tech]

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

jr

[timmy]

Originally Posted by jr_tech

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

jr

Yes that’s the one

[timmy]

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.

[jr_tech]

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

[timmy]

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

[Yamamaya42]

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!

[timmy]

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

[Yamamaya42]

Originally Posted by timmy

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.

[timmy]

Originally Posted by Yamamaya42

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

[Yamamaya42]

Originally Posted by timmy

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

[timmy]

Originally Posted by Yamamaya42

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+

[timmy]

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

[Yamamaya42]

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.