S900(/s950) crackling samples issue

Hi everybody!
I have an Akai s900 which adds a crackling/popping kind of sound after half of the overall sampling time is used on whatever frequency. This happens if I sample something thats longer then half of the overall sample time or sample something after using half of it.
Does anybody know how to fix this or is there something I can do?
Has this happened to any of you s900/s950 users or is it just mine?
Can post the crackling/popping sound if it would help.

Chris_P

Sounds to me like a RAM problem. I don't know how many RAM ICs are build in the the 900 but if the problem is always after a specific amout (the half) of memory you use I guess there are 2 ICs. One of them seem to be corrupt/damaged or probably just lack on contact to thee board. You can search for the 900 sevice manual. Should be realative easy to find the RAM inside the machine (PULL POWER CABLE BEFORE!). If it's inside a socket you can gently press on the top of it and/or use a few drops of isopropyl alcohol on the pins (LET IT DRY 10 MIN BEFORE YOU PLUG IN AND TURN ON THE MACHINE!). If this won't help it might be a broken solderingpin. A task you shouldn't do if you've never done it before. Ask someone who is experienced with soldering & electronics.

peace

Thanks for the reply Peterpiper! Will definitely check the RAM out tomorrow and let you know how it goes. If it's the RAM that's damaged, is it replaceable?

Off-topic: You also using the MPC 2000(non xl), s900 combo? Might be good to know in the future

Chris_P

I use the 2000 mainly as a sequencer coupled with a few samplers (s950, TX16w and Casio FZ1)


peace

I'm back.
Checked inside the box on the VOICE PCB and CPU PCB and took some pictures of it. I pressed gently on the ICs that were in sockets to see if it would help. Couldn't find the RAM IC. Can someone help me out? Checked the service manual too but I couldn't find it.
Well here's the pictures of the inside:


CPU PCB


VOICE PCB
Right click and save picture if you want to zoom. (Damn photobucket making my pictures lower res ) The red on the ICs in the top-middle is from the light when I took the pictures.

Update: It didn't solve the problem. I checked the data-sheets to the ICs in the sockets and they don't seem to be RAM. If someone knows or have an idea what the RAM IC/ICs name is or where it/they are placed, please reply.

Chris_P

Peterpiper, think you could help me out finding the RAM? Maybe finding it in the service manual or on the pics, or do you know where the internal RAM is on the s950?

If anybody knows where it is on the s950, reply. It might help me.

Chris_P

Ok I've searched thru the service manual and it seem that the RAM ICs are the 28! MN41256-12 on the CPU board.



You can search the net if these are still available for cheap but keep in mind that the RAM COULD be the problem they dont really have to. If there were only two or 4 RAM chips I would say renew the soldering points if you're familiar with it but 28 chips times 16 pins......over 400 soldering points.....you should test which chip is faulty before (if its the RAM)


peace

peterpiper wrote:Ok I've searched thru the service manual and it seem that the RAM ICs are the 28! MN41256-12 on the CPU board.

Dayum Sunn!
Don't think (don't want to think) it's the ram then but I'll test it. Can I test it while it's still on the board, if so then how?
If it's not the RAM then I think I'll take everything out the box, check it, put it back in and see if it works.
Forat thought it could be an address line issue. Not sure what that means.

Chris_P

peterpiper wrote:I use the 2000 mainly as a sequencer coupled with a few samplers

peace

same here
+ some synths

Forat is a good adress. I'm not into this stuff to know what exactly he ment with that address line issue. You should ask him what he ment and what could cause this issue.
I also don't know how to test the RAM...wait.....that reminds me to a internal RAM test youcan do. I don't know if it works on the s900 but on the s950 you can do a RAM test:

1. Turn on the machine
2. Press 0 & + & - togerther (you'll notice that the blinking LED on the panel will stay on or off)
3. Press the LETTER button

Now the machine is doing a RAM test and you'll have to wait. After the test you'll have to hit the ENT button to exit this (test)mode.


peace

Back again.

Did the RAM-test(thanks peterpiper, I owe you one) and guess what...

It immediately said "BAD RAM BIT DK07".
Now I need to know what this means so I'm going to check the service manual again. Has anybody had this kind of problem before with their s900/950? If anyone could help searching through the service manual I would appreciate it!.

Bump

Can anybody help me with this? Do you guys think akai might have support for this machine still? I'm thinking that "DK07" is some name for akais techs to look up if you were sending it in to them back in the days. I'll send a mail to akai to see what they say. If akai don't know about this do you think there is someone who actually might know what this means? Maybe someone who worked at akai back in the 80s.

Chris_P

akai hardly has support for their current line of MPCs... i can assure you they won't be of much help at all with their 80's gear. internet forums are seriously your best bet for info regarding this sort of thing...

Ok. I'll post on some other forums and see what they say. Really hard to do anything on it with half the memory

maybe time to cut and run -- cheaper and easier to buy another one?