By horisonten Thu Jan 23, 2020 1:29 pm
What's the verdict of your testing Sense-A?
Sense-A wrote:The one I installed into my Kurzweil K2000 has a resistor jumping from pin 3 to pin 21. pin 22 is not used.
I looked at the pinout for the linked replacement T6963 and the LCD pinout in the MPC1000 service manual. Most pins appear to match up. However...
The MPC 1000 LCD has 20 pins. The replacement has 22 pins.
Pin 9 from the mpc1000 must go to pin 20 on the T6963. Just how Slump drew it.
Slump left pins 10 disconnected on both sides. I'm not sure if that's okay.
Pin 10 on the T6963 is "Reset Signal" whereas on MPC 1000 it says "PWRGDB"
Also the T6963 has +5V backlight on pin 21 and 0V backlight cathode on pin 22. I'm not sure if these can be left unhooked or not...Although, I found that if I connected the anode pin (LED_A) and logic power pin (VCC) together on the actual display unit, while also connecting the ground (LED_K) to ground, I could get the backlight to light, but it's generally advised against for reasons I'm not sure of. This Is why I ultimately decided to pull a separate 5v for the LED from the power section of the PCB. The problem is the mpc is so much more complex and I don't know if I have the technical know how to find a clean and easily accessible 5v source just to power the backlight's LED. Again, looking at the mpcstuff.com's product photo I can see that the A and K pins on the board have big globs of hot glue on them. Did they just connect the anode (Pin A) to the logic supply voltage (VCC)? Does it actually matter that much to have a clean independent voltage to power the LED?
On the one for my Kurzweil K2000, I think the guy jumped pin 3 (VCC +5V) to pin 21 as you did. But he used a resistor to make the jump, which probably is there for protection and for the same reason you were advised not to use the single source 5V to power both the VCC and backlight without a resistor.
You can probably leave pin 22 not connected (NC).
Too bad Slump hasn't responded. he seemed to be the furthest along and close to getting it working.
aarb wrote:Do you guys think that the same can be performed on a MPC 60 MKII, since both machines use 240x64 displays? I j:hmmm:
The Power Good signal (power-good) is a signal provided by a computer power supply to indicate to the motherboard that all of the voltages are within specification and that the system may proceed to boot and operate.
PWRGD is an open drain output; asserts low if output voltage is low due to thermal shutdown, overcurrent, over/under-voltage or EN shut down.
The usual use for PWRGOOD is to hold other devices in RESET, though you could use it (indirectly) to drive a P-MOSFET series switch. The problem is you then have to implement soft start or it can glitch on the inrush current of any downstream decoupling and turn the MOSFET off again! https://www.microchip.com/forums/m614064.aspx
There are many, many uses for a PG (power good) signal. One of the most common is to control power-sequencing of circuits with many different rails. For instance, you may have a Supply B that is not supposed to turn on until Supply A is on, and stable. By feeding the PG signal from Supply A to Supply B's enable input (either directly, or through some simple logic gates or a CPLD), they will sequence themselves in the proper order.
Another common usage is for reset supervisor ICs. If such a device has an active-low manual-reset input, OR'ing together all the PGs from supplies (assuming each is open-drain), if any of them fail / go out of regulation, the reset supervisor will toggle a reset of the system.
So it's really up to you, but there's two common uses. You should check the datasheet to see when PG is asserted/de-asserted; for some regulators, if they detect you're out of regulation by 7.5% - 10%, the signal will assert. https://electronics.stackexchange.com/q ... l-properly