Exchange tips and tricks for the Akai MPC4000
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By Telefunky Mon Apr 04, 2022 6:45 pm
Hi there, 1st post, 1st question... :mrgreen:

I‘m looking for some support (or just a hint to steer me into the right direction) with a recently acquired 4k, full memory, all extensions.
As mentioned the digital io is deaf, signal is recognized as present/not present, but nothing on the meters nor to hear and nothing transmitted via Adat.
Otherwise the machine plays fine.

Since the digital output of the CD is a different path than Adat I suspect the DIO main board, not the Adat extension.
After flashing the OS, there was a small change as it hadn‘t confirmed signal present before.
Of course I‘ve googled the case as good as it gets, but without results.
I’ve started to study the service manual, but it‘s deep... and possibly someone here knows a similar case.
But it’s not the end of the world if it‘s completely unknown.
There‘s a lot to discover with the analog section of the machine... which I already like a lot :smoker:

cheers, Tom
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By Telefunky Tue Apr 19, 2022 9:30 pm
Some progress, strange results, but may help to locate the source of the problem.
The IB-4D doesn‘t output clock on s/pdif (nothing arrives on the reference input of my Mutec clock)
The IB4-ADT is accepted as clock source if connected to the IB-4D, still nothing transmitted nor received.
But without the green cable there‘s a „no Adat signal“ error on the recording screen.
So the card does not run standalone, opposed to what was reported in another thread.

It should run standalone, though... never seen it mentioned that the IB-4D is required to run Adat io.

I didn‘t disassemble the boards on the right side of the 4K yet and will have to print out the circuit diagrams (too small on the iPad, too much scrolling).

reaching for another cup of coffee, Tom
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By Telefunky Wed May 18, 2022 2:42 am
I knew disaster would strike because of the video cable, but couldn‘t resist and disassembled the machine.
Not suspects found, reassembled and of course that cable... failed. Even worse, by fiddling around with it the contrast control died. Maybe I blew the LM358 OpAmp on the display circuit or the crystals are damaged. :Sigh:
(the display itself faintly works, as can be spotted from an angle)

Annoying pause, but someone mentioned he could load programs and at least partly operate the MPC by ak.sys, so I tried that and it worked as expected.

The bizzarre part: S/PDIF and Adat had a sudden recovery, when outputs were activated via ak.sys. Wtf is going on in that box ? :hmmm:
(ok, I‘m happy that the boards are physically ok)
I‘ve flashed the firmware 2 times, no errors reported. Clueless atm...
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By Telefunky Thu May 19, 2022 4:01 pm
The MPC‘s display is up again... it was in fact the LM358. No SMD version at the local store, but there‘s enough height and bending the pins to SMD footprint worked.

While fiddling with the display cable, the IP1 electronic fuse triggered several times, one event must have been too much. Seems it also killed the inverter, but I wanted LED illumination anyway.
(the IP-1 doesn‘t melt but switches off current and recovers after a couple of minutes)

For the time being display light comes from a small LED decoration chain (folded a couple of times so 5 or 6 LEDs fit in the housing of the CCFT) and the thin wire is lead out at the right display mount. Battery pack and the rest of the chain stored behind the display.
(not the most brilliant engineering, but does the job until I find a proper regulator driven by the inverter‘s 5V line) :mrgreen:

Btw in the display descriptions here there‘s an error regarding the contrast pot/voltage.
It‘s not 0 to 5V but rather a -10 to -18V range.

The display cable (mine was in terrible condition) can be reworked:
fix it to some plate with double adhesive tape and remove the plastic with pure acetone (on a q-tip or similiar), if required use a sharp blade to scratch away the worn isolation.
Stop if a metal grey surface appears and measure the contacts to be certain all isolation is gone.
Cut off the bad part in a nice right angle and add very thin tape to the backside to strengthen the construction. I used 2 layers of a fairly stiff heat resistent tape.
Again... not a perfect solution, but better than nothing if nothing is available.
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By Telefunky Fri May 20, 2022 6:11 pm
Thanks for your attention... :-D
I forgot 1 point: the backup battery was completely empty, but there was no message.
The socket is for the slim 2024, but a (more common) 2032 fits, too.
It‘s always some risk to buy 20 year old gear, but it attracts me time and again.
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By Lampdog Fri May 20, 2022 10:17 pm
I’ve had those batteries go out on me before and I didn’t catch on right away, then when you realize it, you kinda wanna kick yourself for missing something so small.
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By Telefunky Tue May 24, 2022 11:35 am
Looks like it was just a strange combinations of config/battery that made the MPC block it‘s digital ports. It now performs great since it woke up again.

I decided to make the improvised LED illumination permanent, until a proper screen replacement (which will be another topic).
It‘s perfectly ok the way it as, as long as one stands or sits directly in front of the machine.
But looking from a side position fails due to the typical performance of this display
.
As mentioned in some screen replacement topics (and ads) it‘s really not worth the costs to add a proper light to the original display.

In my case the illumination came free as part of some x-mas flowers, a $5 Koopmann AX9-720700. The battery holder includes a small controller (7 light fx, 1 steady) operated by a button.
It works on 5V (the label figure is the target output) and handles 6 LEDs equally well as the whole bunch.

The LEDs are tiny drops on a fairly stiff cable with just lacquer isolation and that’s what makes it usable at all in this case.
It can be bent to a straight line with closer LED spacing and that line can be glued to the housing of the original CCFT.
I used small drops of hot glue melted on the tip a small screwdriver (candle) and then pressed the drops to their location. 3 for the line, 1 over the exit hole.

The controller fits into the inverter holder and I snipped off the red cable and it’s neighbor line (5V and ground) right at the inverter connector (no inverter intended to ever be used again) and soldered them to the controller‘s battery + - pads.
The LED output has no polarity, 1 line sends positive pulses, the other negative, orientation doesn‘t matter. A small cable (2 wires) is needed to bridge the distance to the illumination holder.

This would be it... if there wasn‘t that fx gimmick, so the mini-switch has to be removed from the controller and placed outside behind the display. I used 4 lines from a flat ribbon cable, through the opening at the bottom left of the display.

I didn‘t document the process, as it‘s rather crude and not a proper solution anyway.
But those familiar with a soldering iron will likely get the idea for an elcheapo intermediate... :Sigh: :mrgreen:

ps: after powering on the MPC, one has to do 8 button presses to get a steady light... or enjoy a pseudo-psychedelic light show.
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By Telefunky Tue May 24, 2022 3:39 pm
I get the joke :lol: but suspect something in the description wasn‘t precise enough.
The controller is activated manually by a button press, then the screen lights up and plays a mixture of it‘s shows. Next 7 presses fix the current pattern, 8th press gives a constant light (that‘s what I was after), 9th press switches the thing off. The next press will switch it on and starts another go...
It would have been cooler if the 1st press would result in „constant on“ mode, but you can‘t have all.

Btw there‘s nothing to adjust, it’s a single SMD chip, a small crystal and a button.
But the thing immediately grabbed my attention (long before I had the MPC) for it‘s tiny wire construction, applicable to almost any LCD with dead illumination.
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By NearTao Tue May 24, 2022 5:34 pm
Oh I wasn't joking. What you've done is already very clever, and I applaud your ingenuity! I was imagining with some work you could mod the wiring for the SMD so that it just is on/off all the time, or create a circuit that would send the 7 pulses to get it full brightness.
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By Telefunky Tue May 24, 2022 9:01 pm
I‘m sure there are many cheap LED power regulators that turn 5V input into a proper 3,2V 20mA output to drive LEDs, but this thing was laying around and the 8-press switch-on isn‘t too bad.

I‘d really prefer a display with a wider viewing angle, but without hardware addons (to alter signal and timing) I‘m afraid it‘s restricted to LCD technology anyway. :hmmm:
Hard to tell if a replacement screen advertized with „better display panel“ is a true improvement or only a little bit „nicer“... without having seen it personally.
The current display is at least in good condition, no erroneous lines or contrast variance.
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By Telefunky Thu Jun 02, 2022 7:14 pm
After some use I‘m quite happy with the new illumination :smoker:
Not as eye piercing as the original, with a faint blue touch that reminds on those bw TV screens from the past.
The circuit doesn’t like the cable extension for the remote switch, but that only causes a couple of extra presses. It‘s 100% reliable to reach it‘s destination setting.

I reinstalled the 8 analog extension... a little afraid it might mess Adat again, but both boards worked flawlessly.
As velocity was a bit low, the pad sensors and rubbers got some cleaning and I tried to place them as carefull as possible, which gave some 25% improvement.
Solid bangs now exceed the 100 mark again, imho good enough for regular use. Otherwise there‘s still full level to the rescue.