Akai S900 (S950?) Bad ram chips, how common?

Hi everyone,

I am currently in the market for a S900 and I saw some posts about people getting bad ram errors which would cause clicks/pops on samples. Sometimes it freezes the interface completely, outputs suddenly stop working...

The cause of these errors are traced back to the ram chips apparently (at least some times). They seem hard to remove on the s900 but i guess it's feasible. Chips can be found but it's hard to find a good price and even find genuine working chips.

I have been talking to a seller who has a s900 in decent condition but did not test the sample recording function nor did a ram test. All I have is a picture of the machine turned on with the "name of sample to be recorded" screen. He said he would test the ram and sampling this weekend tho.

Now the main question is, is that a very common issue?
If the machine is working now, can I expect it to fail at some point in the near future?
Even better, how many machines have you come across that had bad ram?

I'm very curious and it would be quite frustrating to learn the seller has a broken unit... unless I can fix it and he pulls the price down a bit .

Thanks in advance!

My sample set is just one... but I have an S950, and I installed third party memory into it and have had no problems. I can certainly imagine a system with a stuck bit or similar issue could cause problems such as freezing or clicks, but I actually had never heard of this problem or experienced it myself.

Don't forget, that this is old gear. Given how crazy the prices have gotten, it certainly would be nice to know that it will have some longevity and better even functions as it is is supposed to. That said, it is old, so do be prepared to have to maintain it. Eventually the tact switches will likely be a problem, the backlight or entire display will need to be replaced, might have to blow the dust out of it, plus there are some useful upgrades as well.

This stuff adds up... my suggestion to you is to think about how much you're willing to go "all in" as it were, and then look at what prices for repairs are now. Seriously, if you're not willing to put $200-$300 into it a year, I'd really think about avoiding it. That's not to say you'll put that kind of change into it, but this is now a device that is a novelty to own, and very few people have the time, skills, interest, or knowledge to take care of it.

Personally I totally dig the S950 I have, but I picked it up when people were practically paying people to get it out of their studios. I think I spent $150 to buy it years ago. In that time I had to replace the floppy drive a handful of times, and ended up going for the GoTek drive. I've replaced the backlight a couple times, and have a spare display kicking around for "end of times" when the display finally goes. I picked up the IB105 to get a digital input, which is handy... but continue to be on the lookout for an IB109 so I can actually get SCSI as I'm not going down the Atari HDD route. I upgraded the memory to max, which is really great for time stretching and multisampling for key groups... but both of these things take time to manage and are easier on other systems.

Hey thanks for the reply

Oh yes i am totally aware of the expenses associated with getting old gear and maintaining them. My last restoration project was a S3000 classic, which turned out great. I just wanted to see if the bad ram issue was common or not so i wouldn't be super disappointed in case the S900 was actually shot.

What I did not mention is that I found ram ICs and spare sockets for really cheap, so I got them just in case.
I'm planning on replacing the screen and floppy drive as soon as I get one also.

The S900 the guy is selling is relatively clean, looks like it will need some retrobright for some buttons tho. Also I have a lot of spare tactile switches, I had to replace an entire Roland W-30 set once, super underrated 12bit sampler btw.

So yeah, i'll be busy for a while with this, I'll wait for the seller to test the ram to be 110% sure

I have a s950 and two s900. None of them have RAM issues but the floppy drives on both........
peace

NearTao wrote:. but continue to be on the lookout for an IB109 so I can actually get SCSI as I'm not going down the Atari HDD route.

I don't know about you but I don't see much point in paying prime price for the IB109 when using a Gotek would be sufficient enough to max out the 1.5mb of memory on that S-950. Unless you just want it for the sake of having all the upgrades, which I can understand as well.

ArtyGZ wrote:Now the main question is, is that a very common issue?
If the machine is working now, can I expect it to fail at some point in the near future?
Even better, how many machines have you come across that had bad ram?

I can't gauge how common it is but I've always made a point to do the ram test on an S-900 whenever I've purchased on.

The S-950 is far less stress in that regard as newly produced memory upgrade cards are available enough to get on whim.

But like you said, the issue is to find legitimately new memory IC from that time. Especially as 99% of the ones on eBay are repainted with this black resin paint and are e-waste components from China. They also like to paint the legs silver to cover up any past use or corrosion. This is also the exact issue with a few EPROM sellers online using the same source for their ROM chips.

It is also unfortunate that I've noticed that majority of the newly produced S-950 memory upgrade cards are using those same components (I can tell from the picture) I guess the only take away is that I'd imagine they'd have to test them enough (hopefully) before sending out.

richie wrote:

NearTao wrote:. but continue to be on the lookout for an IB109 so I can actually get SCSI as I'm not going down the Atari HDD route.

I don't know about you but I don't see much point in paying prime price for the IB109 when using a Gotek would be sufficient enough to max out the 1.5mb of memory on that S-950. Unless you just want it for the sake of having all the upgrades, which I can understand as well.

The Gotek drive is fine... but it is slow as dirt. Also the s950 maxes out at 2.25mb, still only 2 disks of data, but would get a 8-10’ish minute load process down to seconds. It is mostly a question of how much do I value my time. I definitely would not want to pay over $300 for it, which is likely way under market value for it at this point. So... probably not going to happen for me lol.

Well the seller called me and we did the test: Bad ram bit on IC71 (DK6), no other error code. Although other ram chips might be out too.

That sucks, however, the price is just too good to pass so I got it. Meanwhile the chips and IC sockets I ordered from China shipped so I will try to make a full restoration of that thing as I've done in the past on other hardware. I've heard people say the chips are usable, I hope that's true .

I will keep this post updated with my progress in a few weeks maybe, or even make a new thread if I have enough material to show about that. Most importantly I'll test the chips and tell you guys if they are legit or not.

(FYI: the chips are MN41256-12, from aliexpress)

Worst case scenario i'll put it up for sale again for cheap.

Thanks!

ArtyGZ wrote:Worst case scenario i'll put it up for sale again for cheap.
Thanks!

Since you're going the route of de-soldering existing IC and replacing with sockets for easy install, I don't estimate you'd have many other issues.

I would however suggest thinking about recapping the power supply while you're at it.

Quick update.

I received the s900. Turns out the error code was "Bad Ram Bit DK09" so it's IC62, not DK06...

However, I recorded a sample at full quality (16000) and maximum length. I used a sawtooth from a DX7 so it's easier to spot "pops" or any sound problem as it's a uniform continuous sound. And guess what: nothing

Sound is clean to my ears.

I have the tools ready, I'm still waiting on the chips and sockets to arrive so I can begin the repairs. Also got a brand new screen. I am currently in the process of de-yellowing the buttons, so far so good.

If it all goes well I'll document my repair progress with pictures.

Sounds cool man... good to keep these old things in rotation and working at tip top capacity

Update!

Good and bad news:

Bad news first, the floppy drive was dead, it couldn't write on floppies. It has been replaced with a drive I had around.

But the good news: I was a bit impatient and the sockets for ICs are extremely late. So i went ahead and removed 4 bad ram chips to replace them with the chinese ones. And it works! I finally have the RAM OK message!

Here are the chips I used: https://imgur.com/gallery/Dql3pZr

I find it crazy that these chips are actually functionnal, i filled up the ram with a sawtooth and it plays back without any issue. Sampling works perfectly.

Tools I used:
-Manual desoldering Iron (to remove the bulk of solder)
-Desoldering braid (to remove the last bits of solder)
-Precision wireless soldering iron (to resolder new chips)
-A bunch of MN41256-12 from Aliexpress
-Some 90° alcohol to clean the solder joints

Ideally you would need DIP16 sockets but I couldn't wait to get them .


Now I am wondering why did the machine still work perfectly before?
Maybe the actual memory was working but the access time was too slow?

I'll probably never know


Anyway to conclude: yes, chinese chips (the ones i got at least) are working!
Also bad ram seems to be common, always check before buying or get ready for some time consuming repairs.

Good job fixing it man!

The ram being bung is only really a problem when it is program or operating system data that gets bunged up. If it's in a sample the worst you get is a momentary spike or other weird noise from the machine.

When it is reserved program memory though... imagine you've got a sample named "saw", but due to a bit being stuck the system thinks it should be "stw"... sure you could rename your sample or change the program, but it becomes a massive hassle. Another example would be let's say the bit that is stuck is in the ADSR of the key group... all of a sudden your sample is always set to A of 64 or lower... that's not cool.

Anyways... glad you made headway!

As for the drive... I'd suggest checking out the Gotek drives as a replacement... it'll get you the ability to save the "disks" as USB images that you can then copy/backup/manage on your PC. You'll need special software to access the contents of the image, but at least you can make backups and save your dope programs for later or share them around.

Alright makes sense, since I haven't used programs or ADSR parameters in depth. Maybe these were KO but i couldn't know. Seems good now, that's what matters.

Still waiting on a new screen, a gotek drive (so I can use flashfloppy) and some sunlight so I can retrobright the buttons for good .

Strange that no one documented this repair on S900s since it's somewhat common after all ...

A lot of the forums that would have had that information are dead, lost posts, go to dead links, and such.