AVR-Chat

20V of ripple is pretty high, getting it down to something like a  
volt or two would result in a cleaner image. The problems you're  
complaining of aren't related to ripple, however.

If your CRT is of the flat-screen variety then focus voltage will  
need to be adjusted depending on where you are onscreen. If the face  
is fairly spherical then this isn't necessary. I'd tend to suspect  
the regulation on your focus power supply having some interaction  
with the deflection cicuits if you're seeing focus go off when you're  
deflecting the beam off center.

I don't know of any current production CRT controllers for  
electrostatic deflection CRTs. There may be some out there, but I  
haven't worked with any since the early 80's, and I suspect there  
isn't much demand these days.

On the noise, be overgenerous on your grounding of the CRT shield.  
Also, make sure the regulation circuits on your other power supplies  
have a good response time and are relatively immune to noise themselves.

Your signals can look good on a scope but bad on screen because your  
scope probes do a lot of filtering for you. Also, if you're using  
dividers to access the high voltage outputs they'll clean up the  
signal for you, too.

In the past, I have typically done deflection on an entirely  
different board than the board that carries anode, gate and focus  
voltages. The horizontal and vertical amps seem to be happier outside  
the EMF of the other outputs.

Good luck!

-Mark G.

Mark Graybill wrote:
> 20V of ripple is pretty high, getting it down to something like a  
> volt or two would result in a cleaner image. The problems you're  
> complaining of aren't related to ripple, however.
> 
> If your CRT is of the flat-screen variety then focus voltage will  
> need to be adjusted depending on where you are onscreen. If the face  
> is fairly spherical then this isn't necessary. I'd tend to suspect  
> the regulation on your focus power supply having some interaction  
> with the deflection cicuits if you're seeing focus go off when you're  
> deflecting the beam off center.
> 
> I don't know of any current production CRT controllers for  
> electrostatic deflection CRTs. There may be some out there, but I  
> haven't worked with any since the early 80's, and I suspect there  
> isn't much demand these days.
> 
> On the noise, be overgenerous on your grounding of the CRT shield.  
> Also, make sure the regulation circuits on your other power supplies  
> have a good response time and are relatively immune to noise themselves.
> 
> Your signals can look good on a scope but bad on screen because your  
> scope probes do a lot of filtering for you. Also, if you're using  
> dividers to access the high voltage outputs they'll clean up the  
> signal for you, too.
> 
> In the past, I have typically done deflection on an entirely  
> different board than the board that carries anode, gate and focus  
> voltages. The horizontal and vertical amps seem to be happier outside  
> the EMF of the other outputs.
> 
> Good luck!
> 
> -Mark G.


I'd like to know what he wants to do with this thing?

erikc