MPC2000XL display works, works not, works (All pixels black)

Hi,

as a first time poster I gotta give a shout out to this very helpful community here... I'm reading for a long time and found help almost always. Unfortunately I could not find anything regarding my current problem.

Regarding my problem. I have a couple of MPC2000s and 2KXLs. I successfully transplanted a 2000 display into an XL a while ago. Now I had an XL where the display is all black when I switch it on (as if all pixels switch to black and all you get is a fat black rectangle). First I thought the display is **** and did a transplant with a fully working 2000 display again - but to no avail, exact same problem as before.

Now I have another XL that does the same thing BUT only sometimes. I switch it on and off and wiggle the display cable a little bit and then it works perfectly fine every 3rd to 10th time.

Does anybody have any experience with this phenomenon? Since I did not exchange the flat flex cable when doing my transplants I'm wondering if it might be a broken cable? I got a new one here but it's quite time-consuming to get all the plastic out between the contacts to get the soldering done. The any other explanation would be an error on the board I guess which seems unlikely to me since the problem is only occuring sometimes and not all of the time.

If any of you has a recommendation it would be much appreciated. I have some 15 MPCs with displays in all kinds of states, so don't hesitate to give me tips that require part switching. I'm willing to swap out each and every part to find the source of this problem.

Thanks in advance and best regards from Berlin
Felix

Short update: It seems to me that the problem does not occur after I disconnected the power cable and waited for a while. On the first boot up afterwards everything works as expected, only to be black again when you switch it off and on another time.

So maybe this is some kind of power supply issue? I disconnected and reconnected all the cables (also on the little display power board) but it did not change anything.

On the other device the problem is still permanent though.

I'll continue my monologue for a little bit since my findings might be helpful to others in the future.

It is almost definitely a power supply problem. The backlight is always working, so the little extra board and transformer for that part seems to be fine (on all my devices).

Things I discovered:
- For whatever reason I had a T2A 250V fuse in one of my MPCs, even though the board is clearly labeled F2AL 250V. All other MPCs seem to have F2A fuses installed though, so even Akai did not care about this too much apparently. I also got to admit that I'm not sure if there is too much of a difference between F2A and F2AL but a T2A seems clearly wrong.

I guess it has to do with the transformer itself or some IC and/or capacitor that delivers the wrong kind or not enough charge - that would explain why the one MPC works fine again after letting it rest for a while.

Anyways, tips or ideas are still greatly appreciated.