If not obvious: Cut the legs of the ICs to be replaced with a pair of pliars and desolder one leg at a time. Removing an entire IC without destroying it is a pain and only worth the effort if we're talking CEMs, SSMs and similar rarities... -- electronically yours, jesper - -- --- ---- ----- ---- --- -- - www.electronic-obsession.se simmonssds7fan skrev 2013-05-22 16:47: > I can tell you from personal experience that it took the better part of > two afternoons to de-solder the old caps and solder in the new ones (but > as I stated before I replaced all 100 caps that were of the same value > on the board, probably overkill, but since I was there....) I can only > imagine how long it will take to replace the six 4051 chips and the one > other that controlls them (16 pins each chip). Michael mentioned > possible replacement of all the tl84 chips as well, which I believe > there are 20 sum such of them on the board (14 pins each). > > --- In Simmons_Drums@yahoogroups.com > <mailto:Simmons_Drums%40yahoogroups.com>, Jacquot.Patrice@... wrote: > > > > I guess I will confirm you that suspicions quite soon , as my both 9 > are asthmatic at the moment ;) > > funny enough at the same moment actually. > > > > Michael is it a lot of time consuming that Demux stuff to check & > change ? > > > > thx for your precious advice. > > > > > > ----- Mail d'origine ----- > > De: Michael Buchner <buchnerelectronics@...> > > À: Simmons Drums <Simmons_Drums@yahoogroups.com > <mailto:Simmons_Drums%40yahoogroups.com>> > > Envoyé: Wed, 22 May 2013 14:34:32 +0200 (CEST) > > Objet: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault > > > > > > > > > > > > I had nearly 30 SDS9 in my shop for repair, in nearly all cases the > fault was the demux. I repaired some SDS9 by changing the s/h caps, some > by replacing the demux chips. To be honest: The last few times I cut out > all these demux responsible parts (4051, TL 84 and the caps) at once and > renewed everything, I saved a lot of time (testing and thinking) and the > parts were not expensive. > > > > > > The demux is built up like a matrix, meaning that one single demux > chip is responsible for (example) low tom trigger, snare filter > frequency, mid tom pitch a.s.o. I sent you the (brilliant) schematics of > Thierry EPPHERRE, so you can see this there. It is NOT one demux chip > responsible for ONE instrument. > > > > > > If you touch the legs of the demux chips, while the unit is running, > you should hear something changing, stopping or getting better or worse. > You can apply pressure with your thumb and finger like you would want to > pull the chip out. As long as you don't lick, your skin resistance is > big enough that nothing can be damaged. > > > > > > Good luck, and I bet 10 bucks on a faulty demux. > > > > > > Michael > > > > > > The "lick" test is ok, without licking. > > > > ----- Original Message ----- > > > > From: simmonssds7fan > > > > To: Simmons_Drums@yahoogroups.com > <mailto:Simmons_Drums%40yahoogroups.com> > > > > Sent: Wednesday, May 22, 2013 11:57 AM > > > > Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault > > > > > > Sorry, the cap value should have read 100nf-63v, or .1uf-63v, NOT > .1nf it is early here...LOL! > > > > > > --- In Simmons_Drums@yahoogroups.com > <mailto:Simmons_Drums%40yahoogroups.com>, "simmonssds7fan" <ptmetcalf@> > wrote: > > > > > > > > > > I replaced all the polyfilm caps that were rated at .1nf-63v on the > board as I was told that these were "worn out and at the end of their > useful life". I was also told that it was the ones in the mux/demux > circuits that would be faulty specifically, that those are "usually the > problem". It was my decision to replace all of them on the board of this > value since I figured, if the mux/demux ones are worn out and they are > all the same age, then it made sense to replace them all. > > > > > I'm in the USA and the power transformer is wired up to run at 115V. > > > > > The erpom chip I used for the 3.0 OS is of the same type as the > original. It is an Intel 27128a chip. I bought a bought a bunch of NOS > ones a while ago for extra sound proms for my sds7 and tested them all a > while ago, and yes I did use a prom eraser to make sure it was good to > go. Also, I do have a good prommer and know how to use it. I'm sure it's > not in the OS EPROM since the unit does the same thing with the 3.0 as > the 4.0 OS that was installed in it when I first got the machine. > > > > > > > > > > I will try the "lick test" next......we'll see what happens next I > guess... > > > > > > > > > > --- In Simmons_Drums@yahoogroups.com > <mailto:Simmons_Drums%40yahoogroups.com>, "philmurr" <philmurr@> wrote: > > > > > > > > > > > > I'm from the "replace electrolytics caps" school. Especially the > power supply section. I can't remember for sure, but think there are > only half a dozen electrolytics on the board, and none of them doing > anything "critical". > > > > > > > > > > > > It's not unusual for an SDS9 to run hot (underneath) as that's > where the PSU board is connected. Where in the world are you, and what > is your mains voltage, as the transformer is multi-tapped and the unit > will run quite happily on a higher tap, unless you're in the UK in which > case you've got no choice :(. > > > > > > > > > > > > With the box running and doing the random triggering, lick your > finger and touch the top of all chips, see if any dry out quickly, an > indication of them running hot. > > > > > > > > > > > > Are you sure the ROM chip you replaced is fast enough (and is the > RAM original for the same reason?) > > > > > > > > > > > > Can you also check the +5V at various points on the board (esp. > furthest away from where the power connector is). On one of mine I > connected a 100uF or similar near the CPU chip just to help the power > supply out and it stopped it doing odd things. > > > > > > > > > > > > From memory, and I haven't checked the service manual recently, I > recall there is a "full-on" test mode that you can put the unit into, > can anyone else confirm ? > > > > > > > > > > > > Phil. > > > > > > > > > > > > --- In Simmons_Drums@yahoogroups.com > <mailto:Simmons_Drums%40yahoogroups.com>, "simmonssds7fan" <ptmetcalf@> > wrote: > > > > > > > > > > > > > > Alright then.....let me run the issue by you then and see what > you think it is. > > > > > > > > > > > > > > When you power it up, it initializes normally. Then the low tom > circuit trigger led comes on and sound is faintly generated, sounds like > a constant "doom-doom-doom", then it slowly stops. After the low tom > stops any one of the other toms or snare will trigger randomly at full > volume until they are all triggering at the same time, generating a > buzz/white noise. The bass channel never does this, only the snare/rim, > and the toms. The unit gets rather warm when it does this. If you shut > it off and let it sit until it gets back to room temperature, it goes > back to near normal and the cycle repeats. I have changed the OS chip to > the 3.0 version, it did have the 4.0 version, but it only slightly helped. > > > > > > > > > > > > > > Any ideas which mux/demux chip I should start with? I'm > thinking the low tom, but I don't understand if it starts with that one > and it goes off, how it could influence the others to randomly trigger > like that. Wouldn't that mean they all have issues? > > > > > > > > > > > > > > --- In Simmons_Drums@yahoogroups.com > <mailto:Simmons_Drums%40yahoogroups.com>, "gordonjcp" <gordon@> wrote: > > > > > > > > > > > > > > > > > > > > > > > > > If the mux/demux caps are worn out and ALL the caps are the > same age on the board, wouldn't it make sense to change them all? They > are cheap enough. > > > > > > > > > > > > > > > > They don't wear out. They rarely fail. When they do, they > cause very, very distinctive faults. > > > > > > > > > > > > > > > > It's worth noting that just about the only capacitors I have > ever seen fail have been electrolytics used in cheap crappy > switched-mode power supplies (which you don't have here) and disc > ceramics used at high voltage or in RF amps. In synthesizers I've > changed maybe a dozen genuinely faulty capacitors in 20-odd years. > > > > > > > > > > > > > > > > Capacitors don't fail, and they don't wear out. > > > > > > > > > > > > > > > > > As I stated previously, that didn't change the issue I'm > having with it, so now it has to be the mux/demux ICs, as stated earlier > in this thread by Michael himself on the issue with this machine that > this member is having. > > > > > > > > > > > > > > > > Of course it didn't, and now you've got to do what you should > have done to begin with - diagnose the fault! The 405x family > multiplexers do fail, with either an output getting "stuck" usually to > one supply rail or the other, or the inputs just not switching at all. > Get an oscilloscope, track down the fault, and replace just the part > that has failed. > > > > > > > > > > > > > > > > > If I've replaced all the caps with the proper values and it > does the exact same thing it did before, how then could I have created > more problems? Can you please explain that theory? > > > > > > > > > > > > > > > > How good is your soldering? Are you sure you read all those > capacitors correctly? Are you sure you didn't damage the fragile > through-hole plating on the boards? Are you sure you didn't zap > something with static? > > > > > > > > > > > > > > > > I won't touch *anything* that's been "re-capped". I often see > synths that have been "re-capped" by some Expert Synth Doctor that then > never quite works right again, and then they're just too much bother to > put right. > > > > > > > > > > > > > > > > Don't muck about. Track the fault down and fix *just that fault*. > > > > > > > > > > > > > > > > -- > > > > > > > > Gordonjcp MM0YEQ > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > [Non-text portions of this message have been removed] > > > > > > > > > > > > [Non-text portions of this message have been removed] > > > > > > No virus found in this message. > Checked by AVG - www.avg.com <http://www.avg.com> > Version: 2012.0.2242 / Virus Database: 3162/5848 - Release Date: 05/22/13 > -- electronically yours, jesper - -- --- ---- ----- ---- --- -- - www.electronic-obsession.se
Message
Re: Re : Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
2013-05-22 by jesper