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| Inside the new Korad KA3305P linear PSU |
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| torch:
The replacement board arrived in the mail today (but postmarked October 6). The new one is on the right, beside the original. They look identical, right down to the funny twist to the crystals. The M4 bug is fixed, but I found another, minor bug. I'm not sure if it was always there and I just missed it, or if it was introduced with this latest firmware. It happens in Serial mode only. When Serial is selected, the current limit is displayed as 0.000 (both channels). When setting the current limit (ie: press CH2 twice, so a digit flashes) the current limit is displayed temporarily. When setting either OVP or OCP (ie: press and hold OCP for 2 seconds) the OCP set point is displayed. When the output is turned on, the actual current is displayed. The current setpoint is properly displayed when the output is off in both Parallel mode and Independent mode. |
| torch:
--- Quote from: torch on September 09, 2015, 06:05:07 am ---I still haven't figured out the serial port connection but either it's dead or maybe requires a null modem cable (manual shows straight pass-through). --- End quote --- Ok, I was wrong and the serial port works with a pass-through cable as described in the manual. However, I still can't get a terminal program like hyperterm or MTTTY to work, as they don't send the command until "Enter" is pushed and pushing "Enter" adds a CR character. The Korad ignores any command with an appended CR. The only way I can make this work is through the Send tab of Realterm, which sends the command without a CR or LF when you hit the Send ASCII button. The reason I could not get the serial port to respond before was a classic PEBKAC: I set the port speed to 9600 in the port tab in Realterm, but did not realize it doesn't take effect until you hit "Change" -- despite the big green checkmark on the Change button. Doh! I did finally successfully communicate through the USB cable to the virtual Serial-USB adapter installed in the PSU itself. It's too bad the supplied software is so buggy. I can see where the programming and logging features could be real handy. What I need now is a Mechatrommer: someone with the skills to create a decent software interface! |
| Messtechniker:
--- Quote from: torch on September 09, 2015, 06:05:07 am ---It's too bad the supplied software is so buggy. I can see where the programming and logging features could be real handy. What I need now is a Mechatrommer: someone with the skills to create a decent software interface! --- End quote --- Why not roll your own with this: http://www.abacom-online.de/uk/html/profilab-expert.html. For an example I programmed, see here: https://www.eevblog.com/forum/projects/building-your-own-voltage-reference-the-jvr/?action=dlattach;attach=177041;image |
| Gall:
Ok, regarding the bugs, it is possible to replace the MCUs with something else with our own program? I bet these funny chips with "Korad" marking are nothing else as ATmega or MCS-51, so it shouldn't be hard to find a pin-compatible replacement. |
| torch:
--- Quote from: Messtechniker on October 20, 2015, 05:34:42 am ---Why not roll your own with this: http://www.abacom-online.de/uk/html/profilab-expert.html. --- End quote --- That looks pretty nice. Unfortunately Korad is not one of the supported devices listed on their website. Reading between the lines, the software uses some sort of driver for each device. Does it include the capability of writing a custom driver for an unknown device? Can it send data alone to the serial port without a CR or LF? Also unfortunately: that software costs about as much as the Korad. Mind you, it appears to have Spice-like capabilities as well? --- Quote from: Gall on October 20, 2015, 01:15:21 pm ---Ok, regarding the bugs, it is possible to replace the MCUs with something else with our own program? I bet these funny chips with "Korad" marking are nothing else as ATmega or MCS-51, so it shouldn't be hard to find a pin-compatible replacement. --- End quote --- Two are marked Korad1 and one is marked Korad4. Possibly identical HW with different firmwares. They seem to be associated with the individual channels by location and there are also a j-tag looking header near each. Beyond that, I couldn't say what the heck they might be. I think Korad is trying to protect itself from competitors reverse-engineering and copying the product. Quite possibly they programmed in something to make ID more difficult too. The one remaining bug in the firmware (showing current limit of 0 in Serial mode) is livable. The remaining bugs are in the PC software for running a script, not in the PSU itself. So for me personally, it's not worth the effort of trying to ID and reprogram the chips. |
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