#sanyo crt-36

[commodorez]

Problem solved.

[commodorez]

@tumblokami​ ordered up some PCBs and gathered the parts to make a few of Geoff Graham’s ASCII Video Terminal board kits. 

I enjoy small projects like this that serve a unique compact function, and I certainly can find a use for another serial terminal. It provides VGA or composite video output, PS/2 input, and TTL serial output (which I adapted to RS232 voltage levels).

[commodorez]

New layout, same problems: PC40-III doesn’t take to installations onto IDE drives that aren’t in its list. 

[commodorez]

So, I hooked up my PET 2001-32N to an external composite signal combiner circuit, and piped that video into my Sanyo CRT-36.  The combiner circuit happens to be what I based the H89′s equivalent on last year.  I filled the screen with garbage characters to make sure it looked right from top to bottom.

This test (at @aperture-in-the-multiverse‘s suggestion) confirms that the problem with the PET is located on the video board.

[commodorez]

An authentic H19 keyboard arrived in the mail today. After a bit of cleaning up, I hooked it into my fledgling terminal, along with its new 9V power supply -- one of sufficient wattage.  It took some mild troubleshooting to bring it to functional status, but it works!

The video signal still needs a bit of tweaking, but I would say that looks like a functional and viable terminal.  I love this sense of accomplishment.  Next I’ve got to find a suitable enclosure for the guts, and fashion some more permanent connectors.

[commodorez]

The H19 board works!

After extensive H19 terminal tests, I keep getting a MASSIVE voltage drop from the 9V source whenever I connect it to load, which means I’m overlooking something critical but I’m not sure what it might be.

I replaced a few capacitors, no dice.

I replaced three of the five voltage regulators (two 7805′s and a 7812), no change.

I hooked up my working H89′s Terminal Logic Board to my custom power supplies, same problem.  So maybe it’s not the H19 board’s fault...

Then I tried hooking my H19 board into the H89′s power systems only.  My prototype composite output board provided video output to my Sanyo CRT-36 to confirm my wiring.  Using an Arduino to stream random characters over serial as a test signal, I powered it on.  Nothing.  Oh wait, my TX from the Arduino is plugged into the TX of the H19 board... lemme fix that.  I powered it off, fixed the wire, and powered it back on.

Then the screen started spewing characters everywhere!  The H19 board works!  The 9 volt power supply that feeds it does not.  I have 9 volts standing in for the 8.5 volt rail because reasons.  Soon I will try my independent +/-15 volt supply (standing in for the +/-16 volt supply).

[commodorez]

Ummmm, what?

For some reason, my composite video circuit lets you see the top line of text... but only on my Sanyo CRT-36 monitor.  What the fuck?

Also, check out my first use of KiCad to build my schematic in a digital editor.  It’s crude, and clearly demonstrates that I have NO idea what I’m doing but whatever.

Lastly, the rats-nest that is my breadboard where I’m testing this whole crazy experiment.

[commodorez]