Share your knowledge on these two classic MPCs
By MPCHunter Mon Feb 22, 2010 5:26 pm
skylab001 wrote:Is there anybody that can get a binary read from each of the Voice EPROMS? I ended up taking my mpc to an old EE who has given me some answers and rebuilt my unit. But he needs to rewrite the voice chips for me before I get it back and wants to be sure the read comes from a clean working machine. Any capable volunteers??

Do you mean a ROM dump or a the checksum for the chips?
By skylab001 Tue Feb 23, 2010 4:30 am
ROM dump.

not entirely sure but isn't the checksum just a bit at the end of each string? All I definitely know is that the guy that has my machine said at least one of the EEPROMS has 'bit rot'? He's not a music tech but a former computer designer, so he has left it up to me to find the binaries.
By MPCHunter Tue Feb 23, 2010 4:07 pm
Not exactly, the checksum is a signature made up of the saved bits that is used to verify the integrity of the stored data. It's a quick test method to see if the saved data has been changed or corrupted.

If you friend is saying that you have bit rot, then it's likely the data on the ROM is bad. I would be surprised if Rohan did not have the binaries already.
By skylab001 Wed Feb 24, 2010 4:46 am
Yeah I thought Rohan might have them, or somebody on the forum could get me the binaries but nothing yet. I tried VST and they don't have them and said they can't get them. They told me the eproms were no longer available??? I told them mouser and digikey had them, they are disappointing. I even conversed with Roger Linn about the issues, and he said he can't be of any help, that he didn't design the mpc hardware, akai did, and if he ever had any issues he'd send his MPC off to VST. That was disappointing as well, but fodder for another thread. Anyway if anybody has or can get them please let me know.
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By Beatdiggerjazzcat Sat Feb 18, 2012 11:41 pm
I noticed the ghost problem on my old 60 when I first got it.

It usually only occurs when you sample a new (shorter) sound on a pad that has an existing (longer) sound already on it.

Sample or load samples from scratch or record silence onto the pad to over ride it first
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By Juppdich Thu Oct 04, 2012 8:12 pm
Sorry if i woke up this dead Thread, but actually i could need your help in an related issue.
I just picked up an faulty MPC 60.
From the former Owner i know that the Problem is located on the Operation PCB.
There is an Eprom on it, too which has a Note on it saying: "MPC 60 OP 1-1"

The Problem is that my MPC boots up fine (Reads Floppy etc...), but it doesnt react at all (No Leds light up, No Buttons react as if OP PCB is dead).

The former Owner tested out another OP PCB and told me the MPC worked with it.

My next step in the Repair is to exchange the Linear Voltage Regulator 78l05 and his caps, but if that doesnt fix it i guess i would need an Rom Image of that OP1-1 Rom.
Just in case this happens: Could anybody help me out with that?

btw.: The Voice Roms Say: "Voice Rom 1.0", could that be a Problem with the OP Roms Version 1-1?
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By Juppdich Fri Oct 05, 2012 6:55 pm
Ok, thanks.
So i exchanged the 78L05 and the Caps around it, but still no signs of life from the Board.

Mpchunter, do you think you could provide me a dump of the Op Rom?

You think the Operation PCB should work without the Drum and the smaller PCB with the Decay Poti connected or is it essential for function that those are also connected?
By MPCHunter Sat Oct 06, 2012 8:08 pm
Have you looked at the D78C11 microcontroller on the Operation board to make sure it is functioning? The crystal for the external clock is at X1. If you can't get a clock signal there, then either the crystal is bad or there is an issue with the microcontroller.

From memory, I believe you do need the Brown Drum PCB connected to the Operation PCB. I do nott think you need the second Operation PCB with the Decay slider attached.

I will have to look through my files to see if I have the image for EPROM for the Operation PCB. If not, I will have to open my MPC up to make a copy.

If you have a EPROM reader you should be able to look the EPROM to see if it is corrupted. I am assuming that you have access to one since you asked for an image.
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By Juppdich Sun Oct 07, 2012 1:48 pm
Thanks for your Help!
I´m gaining access to a reader (bought one off Ebay today... )

I meassured X1 with my Frequency Counter and the Frequency is 11.963 MHZ +/- 0.001 Mhz (Last Digit keeps flipping between 3 and 4). Seems good so far.

Is the D78C11 in theory replacable?
I got the adequate soldering equipment, but it seems to me that its a Version with a custom Rom mask? ... 8C11A.html

This is the Datasheet for the "A" Version but the text on my chip says: d78c11G.
In the Datasheet you can see that every Version with a G in its Descriptor got that custom Rom mask. I´m little unsure about that...

Next things to do for me:
-wait until the Reader arrives and read my OP rom
-get an Oscilloscope to have a better look at the clocking signals

With that Oszi i could meassure the output data lines of the D78C11 to see if there is some reasonable activity.
Thats my plan so far...
By MPCHunter Tue Oct 09, 2012 5:36 pm
I don't think the microcontroller is easily replaceable. There is custom code on the chip programmed by Akai. You may be able to read the code off a good chip in circuit using a programmer. Hopefully the issue lies elsewhere than in the microcontroller.

I managed to make a copy of the Operation PCB ROM off my MPC 60II. The ROM was labeled Version 1.2. I am not sure if a different revision level will matter in your case.
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By Juppdich Thu Nov 01, 2012 5:57 pm
Hey, I´m back again.
That was what i presumed from that MicroController.
Now, finaly my Rom Reader has arrived and i made a copy of that OP Rom...
Here it is:

As I look at the dump it seems reasonable besides that the Chips contains just Value FF from adress $000460 onwards.
Maybe this is normal? What does your OP Rom dump look like?
Think you could also upload it somewhere?

Now i managed to buy an Oszilloskope and i will take a look at the Datalines as soon as i got some Time...

*Edit: Download Link Corrected*

MD5 Checksum is
Last edited by Juppdich on Mon Nov 05, 2012 8:27 pm, edited 1 time in total.