MATRIXSYNTH: Sequential Circuits MultiTrak Battery Leak Fix

Monday, January 29, 2007

Sequential Circuits MultiTrak Battery Leak Fix

Update: The original site appears to be gone. The following is from the Internet Archives WayBackMachine. Unfortunately the additional images referred to further below are gone, however you can make out the mod (albeit blurry) to the left. Update: pics added below.

"SCI MultiTrak (Model 615) battery drain fix

So you found this page. Maybe intentionally, as you don't like the lifetime of your backup battery of your MultiTrak, or just by browsing. Anyway - if you have problems with your backup battery only keeping up power for several months, you may want to modify your synth a bit. I found this fix today, when i searched the last problem of my MultiTrak after the monster repair i initially did on this synth. After the repair, i had a temporary battery in it, a button cell 3V lithium battery. It took about 3 months to drain the power from this battery. Even after the second one, after 3 months, end of lifetime. So i purchased the large cell this synth usually needs, but as i didn't feel very comfortable with this very short lifetime, i didn't put it into the synth. Until today, where i wanted to track down this problem and find a solution, if there is any. And i did.

For i impatient and the ones not interested in the technical description of this problem, just the following show modification is needed to fix the problem.
Modifying the MultiTrak

In fact, my MultiTrak had a design bug, which lead to the short lifetime of the battery. If you want to fix this, disassemble your MultiTrak (i don't describe the procedure here, you can find out yourself or somewhere else i think), remove the keyboard cable and put the electronics assembly in front of you, with the connectors away from you. Remove the voice board (the upper board of the stack of 2 large boards) to reveal the CPU board. Near the keyboard connector, you see a large 40 pin chip, which is the keyboard processor, and right of the keyboard connector, you find a CD4022 (maybe it has other letters, but it must have the number 4022 on it). Left of this chip, there are 2 resistors of 10KOhms. The left one (more away from the 4022) is the one we neeed to touch. Desolder the pin of the left resistor which is nearer to you (goes to a thick trace, which connects it with its neighbour resistor), you can also cut it, but we need to connect it elsewhere, so be careful when cutting it. Next, isolate the board and maybe the neighbour resistor, that your modification can't touch something it shouldn't. Now connect the resistors open end to pin 16 of the 4022. That's it. Maybe you want to fix everything with some hot melt glue or another piece of isolation tape. Of just use a piece of wire stiff enough to keep everything in place.

Have a look at the photo (sorry, it is very blurred, i seem not to be capable to do those near-shots in a better quality :) to see how it has to look.

If you are not interested on what you did in detail, you are done now and may reassemble your MultiTrak. Otherwise, read on.
What happens in this modification?

If you want to know, you may want to first measure the current flowing through the battery. On my synth, it was around 200µA. After the modification, it is around 1µA:

So why that? Let's have a look at the schematics:

(Strange. This near shot worked...) You see the 4022 here. As you can see, it gets power from Vnv, the non-volatile power. Besides this, what you can't see here, the RST pin is pulled high by the same signal turning off the RAM access when the main power goes away. Read the datasheet. Pulling RST of the 4022 high sets CARRY and Q0 high. For Q0 this doesn't matter if you don't hit any keys on the keyboard. And even if you would, it should make no trouble, as the CARRY signal also doesn't leak to the keaboard scanner (partially left in the photo). But there is a completely different problem. The 10KOhms resistor used as pullup for the CARRY signal is connected to +5Vd, which is the main power for all other electronics. So you have a high signal on CARRY. A signal of maybe 2,5V. This goes over the resistor, at the other end (the +5Vd) around 0,5V are left from this power. Use your calculator - 2,5V - 0,5V = 2,0V. Using Ohm's law, R = U / I, you get I = U / R, 2,0V / 10KOhm = 0,2mA = 200µA. Quite a lot. If your battery has 1000mAh, you need 5000 hours to drain the battery. 24 Hours per day (assuming you don't turn it on all the time) = 208,3 days and your battery is gone. After the modification, the NV circuits draw 1µA from the battery according to my multimeter. That's 1 million hours then, which again is 41,7 years. No, don't think "i never have to replace this battery again" - lithium batteries have a lifetime of about 10 years, so it's not the synth drawing the power, it's the battery itself, which leads to you replacing the battery after some years again. Maybe 5, maybe 10 - but not one year, as it might be the case until now."

Update: pics via the comments, via Deep Signal Studios:


  1. He only needed a diode or two.

  2. It would be nice to ask the owner of the photos before just putting them on other pages without any credits, don't you think?

  3. Not Matrix' style.
    He thinks himself as a modern day Robin Hood.
    Has no shame in what he does; No respect for those he does it to.

  4. Hm. Okay. I don't really have a problem with this, but maybe i would like to see a better photo here, as this photo is real bullshit, too blurred. It was kind of... temporary. Until i unscrew my MultiTrak the next time.

    Never mind, it's for a good thing, so it's okay :)

  5. I promote others' sites. Read the post and all my posts. The credit is there and the sole purpose is threefold.

    One it's my personal site to keep track of stuff I come across so I can find it later.

    Two I put it up so others that might not have run across it themselves can check it out.

    Three, to promote other people's sites. If you don't want people seeing what you put up, why put it up?

    I think someone was a little upset because I took everything of theirs down. I don't promote bozos.

  6. His name is Michael, not Kevin.

    But this is just a lame excuse=

    One it's my personal site to keep track of stuff I come across so I can find it later.

  7. Michael, please realise that Matrix doesn't ask and never apologises.
    Do you see an apology here?
    He just justifies his thefts.

  8. Tha't not lame to me... coz I do that too. It's like how people do old newspaper cutting and filing them up as a hobby. And I don't think anyone can shoot someone down for having a hobby... He could easily and has no obligation to share... he can just set his postings to private. But he shares and that's been delightful for a geek like me. Please give Matrix a break...

  9. Hey, I'm a big Al Capone fan.
    Can I have a hobby like his??
    It won't be lame because I'll do it too!
    It's all good!

    Lameness can't defend lameness.
    It just provides you lamers as company.

  10. The title link goes to the source site for more info. I'm promoting the site, not ripping it off. There is not mention of Michael on that site? Who's Michael? Are you saying the other site I linked to is ripping someone else off? If that's the case let me know and send me the source so I can update the post. As for "One" being bullshit, I don't think so. Take a look at my old crap site: link. What was that site? A link list to everything synth I used to check out back then. I started that in October 97. Matrixsynth is just the same site on steroids. I never claimed it to be more than that.

  11. "There is not mention of Michael on that site?"

    Reason: I don't write my name on every page. If you rip the page out of its context, don't wonder where the name is. That's what the little "back" link at the bottom of the page is for. Besides this - just check the metatags.

    "Who's Michael? Are you saying the other site I linked to is ripping someone else off?"

    Looks like you are extremely interested where you rip your information out (especially if i look at the 2 posts i placed which have the link to the same site behind the name - just to the top level). And no - my site is not ripped somewhere else.

    As said - it's okay for me, i learned my lesson that i will never again publish any "beta" infos to see them somewhere else in the web. And as i said, it's okay, there is no reason for justification or somewhat. This is like "i stole your car, but it's because i had to drive to get a box of beer". Would be better to just say nothing, for me, the story was closed yesterday, but as you don't even know the name "Michael", maybe you don't really read the comments here. At least not completely.

    @sonicbrat: "It's like how people do old newspaper cutting and filing them up as a hobby."

    Bad example. I have lots of mirrors and copies of websites here at home. _THAT_ matches your example. Not the republishing of those sites, which i definitely avoid due to copyright reasons, in which some people don't seem to be interested very much.

  12. I'm a big supporter of Matrix, I love this blog, but I have a couple of minor objections here:

    1. Quoting the entire instructions was unnecessary. A link to the orignal is all that should have been done, along with a short description of why it is important. That big quote goes beyond promoting another site.

    2. No mention of the post by Michael/Mik on AH/Nabble. I think that should have been attributed.

    3. Although I agree with the spirit of the "personal" site argument, that argument is weakened by the fact there is advertisement (Google, eBay, Amazon, etc) on the page. If it was *purely* a site for personal reference I doubt it would have ads.

  13. Oh man. I thought "michael" was a heckler!!! I sincerely apologize. Please accept my apology. I've updated the post to just include the image and a link to your site for more info.

    If you or anyone wants me to explain myself, ask a question and I'll answer it.

    I feel like quite the "bozo" at this point.

  14. Ah, now i understand why you sounded a bit pissed after my friendly hint about asking/crediting :) No, you're right, i'm the author of the text and the one who shot this blurred photo (was of temporary nature, but as someone on AH needed the info to fix hix 615, i decided to post the stuff earlier - in this temporary version).

    Your first comment after my comments nearly pushed me towards taking down, as i really don't like to provide free information to the world and run into discussions of this kind like here afterwards, so good that this is cleared now, as i in fact like putting online information which might be of use for others.

    Apologize accepted, and as said - it's okay to use the photo here, even if i personally don't like it and will replace it somewhen on my site. Or better said, a real site will be created for all this in (hopefully) near future.

    Hope we finally can close this discussion now.

  15. Thanks for accepting my apology michael and apologies for not seeing the light sooner. Today was one of those days were I was away from the blog for most of the day and rushing to catch up this evening, hence me missing things and not replying until later in the day. Again, I apologize for any inconvenience.

  16. Oh man. I thought "michael" was a heckler!!!

    I think this named "paranoia."

    Matrix, it is pathetic that you apologised only after making this fellow prove himself.
    Had you asked first, there would be no problem, yes?

    You said "If you don't want people seeing what you put up, why put it up?"

    Fine. With this logic, why do you say that is not ok to copy YOUR blog?

    This question very much irks me.

    Why is ok for you to take without asking, but no one else has the right to take from you?

    Can you answer this question?

  17. Shut up already you whiny brats! Get off the internet if you can't handle it.

  18. People can take from my site any time and they do. Do a search for Matrixsynth on SoNiCbRaT,, Music Thing, Create Digital Music and so on. You will find posts there with a courtesy link back to Matrixsynth. I do the same and we mutually appreciate the support and exposure. People find out about other sites from sites. There is a difference between saying, "hey look at this thing I found on this site" vs. no link back, no mention of the other site, etc.

    BTW, Search engines also work by assessing the number of links to a site. The more links you have to your site, in general, the better your ranking. So the more people post what I post and link to me as a source the better. Many sites and blogs out there refuse to put links to other sites because it promotes their so called competitors. I don't see it that way. I put up a link for every single post when I can. I even do it for the via links when people have an address in their signature. They don't even have to ask. If I was really out to do evil, I'd grab the content, talk about it and not link back. I can do this by claiming fair use. But again, I'm not evil and I want to promote others so I link back. When I link to michael's site the search engines will see a link to it for words like "Sequential Circuits MultiTrack Batter Leak Fix" and anything else that was previously in the body of the post. Now when someone that has the same problem but isn't on any of the lists michael posted a link to, searches for these terms, michaels site will come up higher in the list of results and the person searching for the fix will more likely find the site. Think about that. That helps the person looking for the info and it helps michael get that information out. And if my site came up instead? Anyone looking for the fix would click through for more info as I stated "Title link takes you to more."

    As for the copyright, I had one problem with one site that was aggregating feeds from multiple sites, mine included. That site wasn't putting up their own posts manually and referring back to the others' sites, but instead it was completely copying each post word for word, links and all. It was an exact mirror copy of my site and others, and that is wrong. That's what my copyright is about, not the images or references to this site. I spoke to the person who ran this other site and the owner apologized as well as adding a link for every post. However the owner did not have an easy way to not scrape each post. So what did I do? I didn't tell him to screw off and take my site off the list. I instead set my feeds to partial, so if someone who reads his site sees something interesting they can click through to my site for the full story. Why did I do this? Because he was sincere and it was an honest mistake, and two because it promotes my site. Both of us were happy with this resolution. So... We worked it out.

    As for this original post, I admit I put too much up, but if you had clicked through you would have seen more as I stated in the bottom of the post and most of my posts, "Title link takes you there." Also the key audience for the information is someone looking for the fix. That person would click through for more info. When I realized michael wasn't a heckler I apologized and took the extra content down.

    Hope this helps anon.

  19. "©2006 Matrixsynth - You do not have permission to copy posts from this blog."

    "People can take from my site any time"

    Confusing, isn't it?

  20. Not really. Copy means just that, copy. That's not the same as putting up your own post on the subject and linking back.

  21. I'll be doing this mod next week and I'll take some sharp pictures which you may use freely.

  22. Pictures are available here:


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