Exchange tips and tricks for the Akai MPC4000
By bensonone Mon Apr 03, 2017 7:14 am
Hallo,

i got some problems on my 4k. it starts up normally, but after an half an hour the display gets blank. but it`s definitly not the screen itself, cause i copped another and it has the same issues. tried to reconnect boards etc. tested the cable. but can`t find any errors. would be nice if anyone had an idea what to do...
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By Lampdog Mon Apr 03, 2017 8:23 pm
Did you see the same problem with the other 3999 screens?





































































jk.

I've never heard of that problem before.
By bensonone Tue Apr 04, 2017 8:13 am
yeah it`s the same with the new display. i don`t think that this is caused by overheating. i guess it`s a connection but on the other hand i looked at all wiring and stuff and tested it.
By tenax Mon Jun 05, 2017 7:47 pm
Hi, I had a very similar issue with my MPC4000. In the last days it was very hot outside and in the home studio too. After a while the display becomes blank but he MPC was still running. I never had this issues before. Because the display came back as I change the angle I thought it is a loose connection at the ribbon on the back side of the display (small ribbon cable).
After I opened my MPC I found out that the display connector on the mainboard was in bad condition (wiggle slightly display became blank).
I disconnected the ribbon cable from the board and with sleight of hand I fixed it and for the moment it works fine.
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By monogee Fri Jun 16, 2017 2:12 pm
Is there a way to secure this ribbon better. My screen cuts on and off. Very annoying.
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By TheUnfuckwithable Fri Jun 16, 2017 3:48 pm
monogee wrote:Is there a way to secure this ribbon better. My screen cuts on and off. Very annoying.


A piece of plastic might do the trick to fill the small gap (similar to the pad sensor ribbon connection).

Just don´t put it on the side where the connection is made. :mrgreen:
By sinik Tue Jan 25, 2022 4:45 pm
hey, i have the same problem with a newly purchased mpc 4k.
i turn it on, everything seems normal, then, after half a minute or so, my screen gets dark, like you would turn the contrast knob down.

could this be a screen issue, or a issue with the HD?
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By bizon Thu Jan 27, 2022 8:05 am
Please check Tr2 micro transistor right near the lcd connector to the main board.

That was my issue with the screen and replacing that transistor solved everything.
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By Kalou Tue Dec 13, 2022 12:50 am
bizon wrote:Please check Tr2 micro transistor right near the lcd connector to the main board.

That was my issue with the screen and replacing that transistor solved everything.


how did you realise this was the the issue? and how difficult was replacing that transistor. i’ve got a similar issue to the op except the screen is blank from boot. if i press the contrast knob in to a very precise point i can see the screen and i’ve tried two screens same issue. so don’t think it’s the screen itself. any help so welcomed! :worthy:
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By Telefunky Tue Dec 13, 2022 4:08 am
It’s quite obvious as TR2 is driving the main LCD voltage of -24V.
(service manual IO,VR Schematic, bottom right)
Transistors TR1 and TR2 (both DTC144ES) are „space savers“ because each has 2 internal resistors, it‘s not a regular transistor.

My TR2 is also broken (black screen), but some smart ass bridged 2 pins of it and it works.
If I remove the bridge wire, the screen is dark.
I wasn‘t amused when I detected the bridge and will replace it one day (there might be side effects under certain conditions). Iirc Mouser has these transistors.

They are SMD parts, but not the most tiny ones. With a small iron and a calm hand it‘s manageable.
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By Kalou Wed Dec 14, 2022 11:19 am
this is so helpful, thank you!

it's such a tiny part, and to get to it would involve a fair amount of work inside. let alone replacing it. i've actually had to do some soldering work on my asr 10 recently, so feel less inhibited or diparaging about my soldering abilities.

because i'm curious what does this tr2 do? and do you have a sense of what broke it? (it was working fine until one day it seemed it didn't!). also wonder what this bridge you're talking about is. sounds like something i can maybe do until i properly replace the tr2 transistor.

also keen to get the screen working even temporarily because the reason i'm messing with it is because i installed one of those new led screens (wanted to have something brighter and without a hum). but i want to check it works and can't atm.

i think this is the right replacement part? 'DTC144EKA'

if curious this is what i get atm
Image

...and if you touch the contrast dial just right you get...

Image