HP IC, Unobtanium ?

I can't believe this.

the terminsals for the deflection plates are dual. The deflection plates ru n on voltage, not current. The 165 ohm resistors are simply pulling the out put up to the +53 volt supply. The fact that HP decided to put the 165 ohm resistors on the other connections to the deflection plates is irrelevant a s far as I can see, the only reasons are quite esoteric and beyond the scop e of this discussion obviously.

If you are trying to claim thet this CRT uses some form of electromagnetic deflection rsather than electrosstatic, state your case. I can't say it is not true for sure. I said I do not know why they used the two connections p er deflection plate, because as a rule they do operate electrostatically. I f this CRT works on a different principle, say so.

I believe this arraingement with the plates its mainly to reduce and/or rej ect EMI. Either that or to eliminate or use standing waves in the plates th emselves, which I find unlikely because they are too small.

I could be wrong, but I understand how this shit works, until I don't. Clai m it works other than electrostatically or don't. If I am wrong, fine, but until themn it is a voltage amplifier only. It only has to overcome the cap acitance of the load, which is the deflection plates. The low resistance 16

If I am wrong, explain. tell me the differnce between tis and most other el etrostaically dflected CRTs.

We are now on the same page.

It is what it is.

I don't have a case, I'm just looking at the schematic. I don't think it is electromagnetic, I don't think that would be fast enough. Hmm, can you do an inductance test? A resistance test will be near zero ohms whether it is a plate or a coil. It is still all confusing because of the mod that we know, it uses high current devices. But that seems wrong when you see the 165 ohms in series with the deflection (plate).

I can't say it is not true for sure. I said I do not know why they used the two connections per

I'm as confused as you. The label says Plate, the drawing is a coil. And, why is the voltage labeled +53.3VF?

I don't know.

A question for you, assume for a moment it is electrostatic, I would think only one plate is energized at a time. There is no negative drive for the other plate, to drive the beam the plates would need to have opposite polarity OR only one plate is driven at a time. (I think only one plate is driven at a time) If it was electromagnetic, then the leads could reversed on one coil to develop the opposite drive. Do you have another dual trace scope to look at the drive to the defective IC? Pin 7 and Pin 5. I don't know, you might need to open the circuit to the defective IC. Also have you checked that R26 (31.6 ohm) resistor? I see at least one person had that problem. Mikek PS. see if you can find waveforms on a schematic, might save you from checking it with your scope.

Here's the page with the defective resistor, page down to find it.

Mikek

One way to determine whether the 'scope uses magnetic or electrostatic deflection is to look at the specs. They'll probably indicate the deflection type.

If not, look at the bandwidth. It's unlikely a magnetically deflected 'scope would have a bandwidth much greater than 100kHz.

You mean like those plans in the back of the magazine to convert a tv set to an oscilliscope?

Yes, that's definitely going to put a limit on bandwidth.

The concept did work if you wanted some large screens to display lisajous patterns or something more deliberate in the way of visual organs, but fairly useless as test equipment.

Or, there was that project in Ham Radio circa 1973 or so, where someone turned a tv set into an oscilliscope, and then used it to show various ham bands visually. In essence a pandaptor that displayed five bands at the same time.

Michael

No. I remember commercial magnetically deflected oscilloscopes. I think HP made one. But don't hold me to that. I think their purpose was (as you suggest) to get a large display not possible with electrostatic deflection (which would have required extremely high deflection voltages).