Share your knowledge on these two classic MPCs
By F901 Sat Mar 15, 2008 11:26 pm
Dear all,

Since there are so many here sharing incredibly valuable information I intended another first appearance as a new member. But unfortunately it came different. ...

My current problem might be seen in connection with some things Rohan explained about SCSI and the SCSI fuse but as far as I can see in my case it’s worse.

To put it short: Some things with my 3000 sort of worked with a blown SCSI fuse F901, but now nothing works with the repaired SCSI fuse.

I recently bought this 3000, 3.11, 32Mb with professionally (believe me) built in internal ZIP drive.

After receiving the 3000 I tried and tested. I saved on the internal ZIP Params, Sequ. and Programs. Saving seemed to be fine (unless the drive sometimes appears noisy, crunchy).
Problems came when I tried to load the stuff.

It never loads all I saved. Sometimes the program is not correct (it doesn’t have the sounds on the pads)and always there is at least one sound that can’t be read. Error message: the file or the entire disc maybe be damaged. Error code: [FF10:306/29/00].

This frequently happened when I tried to load one special sound. This is a sound I just sampled mono from the input, named it "SN_AMAZI.SND" (or for test purposes "SN_AMAZ.SND") and saved it on ZIP as part of a Program-file. Then turn the 3000 off. When I turn on the 3000 again and try to load that sound it does not work, I get the mentioned error message. I sampled it again, saved it as a test on different freshly formatted disks, different partitions, ... but always the same problem. The (then new) file again with file name starting "SN_ ..." can not be read. Strange. Next try: I deleted stuff before and after soft start/end. Tried to load. Same error. Is the name the problem? Seems not: another sound for test purposes renamed as "SN_TEST" was readable. Does it make sense that a special snare sound produces file data that are unreadable later on? Seems impossible to me. But what can it be?

Anyway I could never be sure which parts of my work I could save and which not.

First I thought it might just be a damaged internal ZIP drive. But I received the tip check if the SCSI fuse F901 is blown.
I got somebody (40 years experience in repairing tech. things) to check it: yes, the Fuse was blown. He fixed it. I was happy and thought problem resolved.

But now it became obvious: something bad happened to the 3000 before.
Whatever has happened to her, it did not only blow the Fuse F901 but also other things.

After I turned on the 3000 with the repaired Fuse F901 quite a lot was messed up:

a) without having pushed the buttons they have red light (the following buttons: Overdub, play, auto punch, wait for key, simul seq., after, 16Levels, pad bank A and C.
b) pushing one button lightens another one: push wait for key lightens / unlightens transpose; pushing after (whick already lights) lightens 16 levels).
c) pushing play button: while playing main screen shows current position shorter, ticks are missing (shows just e.g. “001.02.--“)
d) neither internal nor external ZIP drive is not found (make active doesn’t work, error code: FF48; with blown fuse it was as always, SCSI port 1 internal and 6 external)

Can those things happen if someone tries to install a card reader not properly?

So some things sort of worked with the blown SCSI fuse (changing Params, doing programs and sequ., some saving at least was possible)., but nothing works with the repaired SCSI fuse.

Does anybody have any idea what it could be? What can be damagd? Can it be repaired? Cost? Send her back to the seller? Since it’s a beautiful one I really would like to keep and repair her ...

Any tip were greatly appreciated! Thanks!
By mpc3000le Sun Mar 16, 2008 4:40 am
F901 wrote:After I turned on the 3000 with the repaired Fuse F901 quite a lot was messed up:


Which implies:

a) possible incorrect fuse.

b) now conducting fuse initiating failure in "other marginal components" on the MPC3000 SCSI board. ( not too likely but possible )

c) more likely, incorrectly re-seated SCSI board, incorrectly re-seated panel interface cables and incorrectly re-seated/routed internal SCSI lines.

F901 wrote:a) without having pushed the buttons they have red light (the following buttons: Overdub, play, auto punch, wait for key, simul seq., after, 16Levels, pad bank A and C.


Indicating that the front panel to main board harness is possibly incorrectly seated.

F901 wrote:b) pushing one button lightens another one: push wait for key lightens / unlightens transpose; pushing after (whick already lights) lightens 16 levels).


Further indication of front panel to main board harness communication errors.

F901 wrote:c) pushing play button: while playing main screen shows current position shorter, ticks are missing (shows just e.g. “001.02.--“)


Not so much of a problem at this stage.
The MPC3000 is showing ticks while playing in such a way that continual screen updating will not eat into other processing time.

IE: Don't worry too much about this point right now.

F901 wrote:d) neither internal nor external ZIP drive is not found (make active doesn’t work, error code: FF48; with blown fuse it was as always, SCSI port 1 internal and 6 external)


Which implies bad SCSI continuity/termination inside your machine.

Or ...

A failed SCSI board in the MPC3000. ( hint --- TERMINATION POWER SUPPLY REGULATION CIRCUIT which is "protected" by the SCSI fuse )

F901 wrote:Does anybody have any idea what it could be?


Answers in this reply should give you some general pointers.

F901 wrote:What can be damagd?


Initial thoughts already shared.

F901 wrote:Can it be repaired?


Sure can.

F901 wrote:Cost?


Probably an hour of labor ( $ - $$$ ) and a few $ worse case in parts ?

F901 wrote:Send her back to the seller?


As you have already had some repairs done to the machine this is probably not a possible scenario.

F901 wrote:Since it’s a beautiful one I really would like to keep and repair her ...


Then ...... Keep and repair her :-)

F901 wrote:Any tip were greatly appreciated! Thanks!


All I can think of right now.

Rohan.
By F901 Sun Mar 16, 2008 10:33 pm
Rohan,

Thank you very much for your thoughts and your quick reply! That helps a lot - as your posts always do!

And besides the technical things thank you for spreading positive vibes

IE: Don't worry too much about this point right now.
[...]
F901 wrote:Since it’s a beautiful one I really would like to keep and repair her ...


Then ...... Keep and repair her :-)


:) Thanks :)

Concerning the technical things:

Which implies:

a) possible incorrect fuse.

b) now conducting fuse initiating failure in "other marginal components" on the MPC3000 SCSI board. ( not too likely but possible )

c) more likely, incorrectly re-seated SCSI board, incorrectly re-seated panel interface cables and incorrectly re-seated/routed internal SCSI lines.


I'm afraid it's b).
(Are my following thoughts plausible?)

a) The fuse F901 I think just like a connection A to B. So I think that even if it were a wrong one this were just relevant fo the fuses "decision" blow or don't blow.

c) All connections that were loosened and replugged fit only in one way, no chance to re-seat them wrong (e.g. 180 degr. turned, etc.).
Plus the work on the fuse was done by a experienced certified pro (his knowledge just ends when it comes to 3000 specifics, he doesn`t have a circuit diagram,etc.).

Does anybody have a circuit diagram for the 3000? (I'll also post that question individually).

So if it were b) and only b)

b) now conducting fuse initiating failure in "other marginal components" on the MPC3000 SCSI board. ( not too likely but possible )
[...]
A failed SCSI board in the MPC3000. ( hint --- TERMINATION POWER SUPPLY REGULATION CIRCUIT which is "protected" by the SCSI fuse )


Is it possible that all described effects appear because of failure(s) on only the SCSI board?
Or will there be additional failures in other parts (ICs/processors/...)?
Which other parts should be checked before repairing the SCSI - board?

Are elements of the SCSI-board or the whole board available anywhere?

Thanks a lot again!!!!

By mpc3000le Wed Mar 19, 2008 11:02 am
Without re-quoting stuff above.

Internal connectors "can" be "incorrectly seated".

Even thought they are "keyed" and can only be inserted one way.

They "may" not be inserted all the way in.

A removal and re-seat of the cable fixes the problems. ( unless other circuits have been damaged )

Experienced technician that you have or not; there is no harm in re checking these points.

As for parts on the SCSI board.

All off the shelf.

One of the parts, a PLD contains custom code; but is an off the shelf part all the same.

Tip.

Remove the SCSI board completely.

Boot the machine.

Does it work now ?

If so... Revise the repair and connections of all internal harnesses.

Rohan

By F901 Wed Mar 26, 2008 12:14 am
Hooray!!! She’s working!

Rohan, thanks a lot again for your thoughts and your work on the reply!

mpc3000le wrote:If so... Revise the repair and connections of all internal harnesses.


The problem were the internal connectors and – maybe – another cable (isolation was damaged from being to close to power supply getting quite hot; the cables’ metal had contact with metal at the power supply).

After this was repaired some other things were fixed (e.g new ZIP-drive, some new tactile switches, some new buttons, new display light, etc.). Now she’s working excellent!

[Next thing I’m going to change will be OS 3.11 to Vailixi but I’ll first get working with her some time. (And read everything about Vailixi before)]

Thank you, Rohan!

By mpc3000le Wed Mar 26, 2008 5:18 am
F901 wrote:Hooray!!! She’s working!
Rohan, thanks a lot again for your thoughts and your work on the reply!


F901 ... No problem.

Now to make beats.

Rohan.