Post your questions, opinions and reviews of the MPC1000. This forum is for discussion of the OFFICIAL Akai OS (2.1). If you wish to discuss the JJ OS, please use the dedicated JJ OS forum
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By horisonten Tue Jun 23, 2020 11:44 am
I'm now even more confident that the PWRGDB should be connected to the /RST on the LCD.
I found this in the RAIO-chip manual on the BuyDisplay site.

RST I (Reset Signal)
RST = Low = RA6963 will be reset.
RST = High = Normal mode. RA6963 built-in a Pull-Hi resistor.

And this about usual Power Good implementation:

"The Power Good signal (sometimes called Power_OK or PWR_OK) is a +5 V (nominal) active high signal (with a variation from +2.4 V through +6.0 V generally being considered acceptable) that is supplied to the motherboard when the power supply has passed its internal self-tests and the output voltages have stabilized."

So this should mean that the LCD is in reset state upon Power on of the MPC.
And as soon as the MPC1000 is done with its self-tests the Power Good sends out a High signal to the LCD and it thus enters its normal operation mode.
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By horisonten Wed Jun 24, 2020 7:19 am
Nice! So hopefully we have managed to solve it now. I did get an email from BuyDisplay after sending the images of the circuit board (see below). They also thought that it was the right connection, but they were not sure and did tell me to check first before turning on the LCD. I'll perhaps try the PWRGDB with a multimeter, or I will just hold my fingers crossed. But I will at least try it with the following pinout:

Image

My display should arrive in a couple of weeks. I have also ordered 20 pin idc connectors (note you'll probably need to solder on a "IDC 20 pin transition male connector" on to the LCD, since it looks like there is not a lot of space between the LCD and the front panel housing. I'll first try to fit a regular connector to see if it works. I will try to solve it as clean as possible without soldering the cable directly on the LCD.

Here are the embedded versions of the images I posted on a previous page that made me believe that the PWRGDB should indeed be connected to the /RST on the LCD.

Image

Image
By Sense-A Wed Jun 24, 2020 2:11 pm
Looks good

Here is the pinout diagram you tried to embed:
Image

Let us know how your testing works out.

I'd connect pin 19 to pin 1 as just an extra ground. Doesn't hurt. More grounding is good. Not necessary, though.

I'm working on an aftermarket LED display for the MPC 4000. Problem is finding displays with PCB controller boards that will fit in the housing.
By vanwerk Fri Jul 03, 2020 6:19 am
Sense-A wrote:Mad props to vanwerk for finishing what others started. I hope you didn't have to get a new ADDA board.

I still wonder if a resistor shouldn't be in between pin 3 and 21. I guess not since they are both 5volts.

Did you figure out a way to save the contrast settings, or do you need to re-adjust contrast every time you power it back up?

Updated Pinout diagram to make this work:
Image

I am hoping that vanwerk can respond and clarify what he did with pins 10. I assume he connected them.

It also appears that vanwerk soldered pins 1 and 2 (GND ground) together on the new LCD screen.


Sorry for the slow response, for some reason I didn't get any notifications on new replies! I definitely want to help anyone else trying to figure this out so we can put any uncertainty to rest.

Didn't need to replace an ADDA board thankfully.

I emailed BuyDisplay a few months back about whether I should add a current limiting resistor between Pin 3 (Vcc) and Pin 21 (LEDA, +5V LED anode). Here is what the customer service said: "Thank you for the email. My engineer says that you don't care the current for LED backlight as there is the current limiting resistor in the design, pls supply 5V for LED backlight directly" So, you can directly connect Pins 3 and 21 as they already have a current limiting resistor in the circuit.

Re: contrast settings: I think I might have had to fiddle with contrast the first few times I powered it on, and I also tried jumping between OS2XL and the free OS. Can't remember exactly what I did, but nowadays the contrast setting has saved and I no longer need to tweak it.

Regarding Pin 10: Yeah, I connected it to Pin 10 on the MPC1000 PCB connector. The only changes I made in my ribbon cable were swapping Pins 9 and 20. Every other pin is connected in a 1:1 manner. At least with the BuyDisplay board linked earlier, there's no need to solder Pins 1&2 together -- they are electrically connected in the PCB.

Hope this clarifies things! Appreciate everyone else's work also.
By vanwerk Fri Jul 03, 2020 6:23 am
horisonten wrote:Nice! So hopefully we have managed to solve it now. I did get an email from BuyDisplay after sending the images of the circuit board (see below). They also thought that it was the right connection, but they were not sure and did tell me to check first before turning on the LCD. I'll perhaps try the PWRGDB with a multimeter, or I will just hold my fingers crossed. But I will at least try it with the following pinout:

Image

My display should arrive in a couple of weeks. I have also ordered 20 pin idc connectors (note you'll probably need to solder on a "IDC 20 pin transition male connector" on to the LCD, since it looks like there is not a lot of space between the LCD and the front panel housing. I'll first try to fit a regular connector to see if it works. I will try to solve it as clean as possible without soldering the cable directly on the LCD.

Here are the embedded versions of the images I posted on a previous page that made me believe that the PWRGDB should indeed be connected to the /RST on the LCD.

Image

Image


Just a heads up, I also wanted to avoid soldering the IDC cable directly to the PCB, but beware. I first tried soldering on header pins to use with a female IDC cable connector, but the combined height was too tall to put the MPC back together. Please learn from my mistake, and just use the "IDC 20 pin transition male connector"! Desoldering 20 header pins was a complete pain in the ass.
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By horisonten Fri Jul 03, 2020 12:19 pm
Thanks for updating Vanwerk :worthy:

I have bad news regarding my testing. I used the last pinout available in this thread. 1:1 except the two pins. But I have not been able to get the LCD working. It lights on but then the MPC does not start. So I think I'm doing something wrong.
Fortunately my old LCD still works, so I will keep using it until more people have made the swap successfully.
Glad I did not fry anything while trying :P
By vanwerk Sat Jul 04, 2020 8:01 pm
horisonten wrote:Thanks for updating Vanwerk :worthy:

I have bad news regarding my testing. I used the last pinout available in this thread. 1:1 except the two pins. But I have not been able to get the LCD working. It lights on but then the MPC does not start. So I think I'm doing something wrong.
Fortunately my old LCD still works, so I will keep using it until more people have made the swap successfully.
Glad I did not fry anything while trying :P


Did you also solder connections between 5V and LED_A (LED anode), and between ground and LED_K (LED cathode)? I’m guessing you did given that you see it light up initially.

The other thing is, the contrast might be set in such a way that you can’t see anything on the display — have you tried tweaking the contrast? I seem to remember having this problem too at one point, but I’m struggling to remember exactly what the underlying issue was :?

edit: I do remember double/triple/quadruple checking the pin outs between the new LCD and the ribbon cable using the continuity test of my multimeter. Always good to double check :)
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By horisonten Wed Jul 08, 2020 11:02 am
Thanks for helping me with your knowledge. I'm pretty sure the pinout is correct, and I did connect the pins together like you did.

I also tried to adjust the contrast. But it seems like my MPC did not boot into it's normal operstional mode since no leds on the MPC lit up, qnd I was not able to get the sequencer running when pressing play. So it seemed like it did not boot correctly with the new display.

The only thing I can think of atm is that some of the leads on the ribbon cable does not make a proper connection to the pins in the connector. The thing is I had to push them all down one by one because the connections needed to be mirrored when soldering it on the connector to the LCDs PCB from the backside. So pin 1 became pin 2 and so forth...
By Jacid1968 Tue Jul 21, 2020 10:05 am
Thank you for all the info provided. Put a new screen in my MPC 1000 yesterday, works perfectly, looks great. You don't have to make any changes to the cable, just solder a wire on the board from pin 9 to pin 20. There is no connection on pin 9 on the board so this is completely safe to do, how I did it. Traced from that pin and it has no tracks going anywhere. Thanks again to you all.