Getting my little monitor to work

David Rutherford wrote in news:3F53F224.6B669169 @softcom.net:

I am not sure what you inteded purpose is, but there is a fair amount of information you are going to have to verify. I would start with a pinout of the CRT, a verification of the existence of a power supply. and then determine if the unit runs on 12 VDC, 120 VAC or some other voltage. This can be a rather tedious chore. If it is as somple as you say it is, it sounds like there is not power supply. If you don't have a power supply for the beast, then it is only good for parts AFAIC.

r

--
"Any sufficiently advanced technology is indistinguishable from
magic."

Arthur C. Clarke (1917 - ), "Technology and the Future"

Betcha what you have there is a old Motorola style black and white 5 inch video chassis. You need to feed it power, video and separate syncs. I think it needs

12VDC or some such. I even have one lying around, but I can't find it right now. I had a schematic somewhere on how to hook it up... I'll try to find it.

Whether they are standard assignments I cannot say. However, these are not oscilloscope monitors, they are television monitors. They must scan, and you cannot have a constant intensity electron beam pointing at the screen.

Vertical sweep is always on, and is fixed at 60 Hz. Horizontal sweep is generated from an external oscillator, and is used to derive the high voltage.

Because the horizontal sweep is driven, the components in the monitor can be damaged with improper drive.

These were made to be driven directly from a CRT display controller chip, such as the Motorola 6845 or the 6847. Video can be a TTL level video, I think, and the drive signals can also be TTL level.

Since the 6845 and 6847 (for example) do not put out the proper signals without programming, this monitor is designed to be the display for a system that has a microprocessor, one of the two display chips, and enough programming to make it work right.

It will not work with your computer unless you can provide it with the right drive signals, and at the right frequency. Even then, it will work with only the lowest resolution and in black and white.

Harvey

drive

Oh yes another thing. I think you have to have the H drive to get the high voltage for the CRT.

Bill K7NOM

I think putting all of your valuable suggestions to work might be a bit much for my meager electronics abilities. I may have to try some other way of doing what I need to do. Thanks, Harvey, for all your help.

Dave

drive

Getting the monitor to work may be a little to much for me, due to my lack of electronics knowledge. I'll give it a try until I reach the point of diminishing returns (or diminishing patience). Thanks for all the help, Bill.

Dave

drive

Keep in mind that it's not going to do what you want. It's not an oscilliscope, it's a video monitor. Only by adding external video circuitry will you get your dot in the middle of the screen (and since you didn't really say what you wanted the dot for, likely you'll need more circuitry after that).

An oscilliscope is directly driven, so if you apply a signal to the horizontal plates, the dot will move horizontally, the direction defined by the polarity of the input signal. The same with the vertical deflection.

With a monitor, that "dot" is constantly being deflected around the screen, vertically, then down to the next line, and so forth. The deflection is done with coils, and you won't get much if you stop that scanning.

Michael

Well it's possible to wire a choke in place of the yoke on the chassis to get the HV, then you can externally drive the deflection coils, but oscilloscopes use electrostatic deflection, the electromagnetic deflection on a normal CRT is very limited in bandwidth and not very linear. You can get some interesting patterns but nothing that even comes close in usefulness to the old Heathkit, Eico and similar low bandwidth oscilloscopes that show up at fleamarkets and on ebay for $10 or so fairly often. Also if the dot sits in the middle for even a fraction of a second at full brightness it'll burn a hole in the phosphor.

David Rutherford wrote in news:3F54337B.9AFFAA78 @softcom.net:

with a

is

as

how

and

circuit

controls

inch video

it needs

right now.

it.

I am not sure why you would want a single high intesity dot in the center of the screen, but if you would take the yoke off the crt, that would stop any sweep and you would have a single dot in the center.

r

--
"Any sufficiently advanced technology is indistinguishable from
magic."

Arthur C. Clarke (1917 - ), "Technology and the Future"

video

needs

now.

Just be sure it's the same thing... According to my inventory the actual monitor is buried two boxes deep... As others have said, this is a video monitor.

That sounds like it's probably the easiest way to concentrate the beam at the center of the screen. I didn't want to bore anybody with the details, that's why I didn't mention my reasons for wanting to center the beam. I'm actually using it for a physics experiment.

Dave

video

needs

right now.

monitor is

Thanks, A E. I'll check my monitor against your schematic.

Dave

Some people will pay a lot more attention to postings if they include the reasons, not just the immediate needs.

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And some people will pay a lot _less_ attention if they include the reasons :^).

Dave