Recent content by ccureau

From what I understand, it was broken in the original. I think though that this chip is okay. It's a NXP PC16550DV, and the datasheet doesn't mention anything about it being faulty.

Well, that made a world of difference...leaving the FIFO off seems to have solved the entire issue. Thank you! Now...what would have made enabling the FIFO cause that sort of behavior I wonder?

Yikes, forgot that! Yes, BAUDOUT and RCLK are connected, sorry.

I've already posted this at the 6502.org forums, but I figured I'd also ask the question here since it isn't strictly 65xx specific. I'm breadboarding a design that has (so far) a 65c265, 64k of SRAM, and a 16550 UART which is fed directly from a CP1201 USB to Serial converter. So far...

Well, there's good news and bad news. The kaypro seems to work fine...I can use the A drive perfectly. The B drive seems not to want to move the drive head... I'll have to pull it out and figure out the problem. But as it is, it is doing the job it was built for forty years ago.

I've made this mistake before...embarrassingly quite recently. Forgot that the side with the triangle on it (when did they switch from a plain old minus?) was the negative side, and didn't check. Thankfully I didn't blow anything else up! This! A thousand times, this. I really like working on...

@cj7hawk and @Hugo Holden - I am happy to present a working CRT! :cool: I adjusted the VLIN to center the image, then the VSIZE to stretch it, and then the brightness to remove the lines...et voila!

Don't be sorry...I am grateful for your and Hugo's help. The V-LIN pot has a range of about 9 ohms (completely counterclockwise) to about 1.9K ohms (completely clockwise). C310 presents as an open circuit -- resistance is 0.05 by my meter, roughly the same as when the two probes touch. Just...

I thought that it was too, but looking through the datasheet regarding adjustment methods of flyback time under Method 2 -- "The voltage of pin 9 is a half of the power supply voltage." Apparently it is also possible to connect a resistor between pins 2 and 9 to decrease the middle potential of...

Pin 1 = Square wave with a sloped falling edge. Voltage range between 1V-12V. Appears to be very close to 60Hz. Pin 2 = +12V Pin 3 = Odd shaped wave, sloped rising and falling run. falling edge also seems slightly sloped. Voltage range between 4V-19V. Pin 4 = Sawtooth wave, approx 16 ms. 60Hz...

I've gone through and measured all of the resistors (Toshiba was kind enough to label all of the vertical components as X3nn, where X is component type and all associated components are between 301-399) and found a few discrepancies... List below shows resistor number, what it says on the...

It's interesting that you mention this...I ran across a couple of resistors in the vertical circuit that measured beyond their 5% tolerance levels. I chalked this up to some other resistance in the circuit interfering with the measurement, but it could be the case that they are just bad. R312 is...

@cj7hawk Here's the two images I captured last night from the scope. I finally found an unused flash drive, so I have much clearer images. I took measurements directly from the yoke in these images. Probe 1 (yellow line) measuring the yellow wire on the yoke, and probe 2 (blue) measuring the...

In the meantime, I am working on a KiCad schematic for this board based on the traces that Hugo has done and what I am doing now. Maybe once that is done, that will help us to diagnose further. One thing I've noticed is that diodes are incredibly difficult to identify. For instance, on the tube...

Well spotted indeed, @cj7hawk -- I saw something on the south end of D406 and did some reflow work. Sadly, it didn't have any effect, but it was a good exercise. I did notice that the strange raster lines from yesterday's image were far enough at the bottom of the screen to be almost off of the...