EX-8000 problem
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EX-8000 problem
I bought an EX-8000 with known lack of sound. The battery had been replaced with a stand off holder, and nothing else was changed. After much futzing around, I managed to load Bank A into the EX-8000 from computer using a USB MIDI interface. The sound is about five octaves too high and plays strangely. This could be the normal intonation, however, since I have never heard all the samples of an EX-8000 as they should sound. Even the Tuning button does not play an A440 but instead chirps with a very high pitch like a tiny bird. What could be the source of this problem? I am, as you can guess, loathe to start testing every component with a multimeter. I do have a copy of the service manual. Thanks to anyone who can offer advice.
Starting off by creating a simple program from scratch with basic waveforms (saw, sine) and simple VCA/VCF settings, while checking all eight voices by pressing several (musical) keys simultaneously might be a smart first step.
Without having even a rough idea what the 'chirping' sound might be like, it can be the digital waveform generator or a trashed filter/EG section, or even something completely different. There is only one waveform and control voltage generator but 8 VCA/VCF sections with demultiplexer circuits between them, so knowing whether the problem is the same on all voices or just a few of them would be a start. Maybe you want to make a short recording and post it somewhere so that we can listen to it.
If it is feasible at all (should be, if you have the service manual), I'd try to inject some test signal (sine? square?) around the D/A part (outputs of the demultiplexing chips IC17- IC20) and see what happens. It would already be an achievement to know whether the problem comes from the digital or the analogue domain.
Another approach would be to start troubleshooting backwards: injecting some audio into the (line/headphone) output stage, into the filter/EG section, etc. I just don't know whether the analogue or the digital section is easier to 'attack' first.
Without having even a rough idea what the 'chirping' sound might be like, it can be the digital waveform generator or a trashed filter/EG section, or even something completely different. There is only one waveform and control voltage generator but 8 VCA/VCF sections with demultiplexer circuits between them, so knowing whether the problem is the same on all voices or just a few of them would be a start. Maybe you want to make a short recording and post it somewhere so that we can listen to it.
If it is feasible at all (should be, if you have the service manual), I'd try to inject some test signal (sine? square?) around the D/A part (outputs of the demultiplexing chips IC17- IC20) and see what happens. It would already be an achievement to know whether the problem comes from the digital or the analogue domain.
Another approach would be to start troubleshooting backwards: injecting some audio into the (line/headphone) output stage, into the filter/EG section, etc. I just don't know whether the analogue or the digital section is easier to 'attack' first.
Thanks for replying. I guess a signal generator and an oscilloscope would be nice at this point. Don't you wish Rent-a-Center carried stuff like that? I'll see about making a video and posting it, probably on DeviantArt later today.
One thing I am curious about: one of the main traces on the right edge of the top PCB is gouged through. I'll include a picture of mine as well. I thought it was the result of an accident that the seller did not mention, but I recently looked at pictures of EX-8000 PCBs for sale, and that also appears to have a gouge in exactly the same spot. See the third photo down, just to the right of the varistors for the eight voices. Is that trace intentionally cut at the factory?
One thing I am curious about: one of the main traces on the right edge of the top PCB is gouged through. I'll include a picture of mine as well. I thought it was the result of an accident that the seller did not mention, but I recently looked at pictures of EX-8000 PCBs for sale, and that also appears to have a gouge in exactly the same spot. See the third photo down, just to the right of the varistors for the eight voices. Is that trace intentionally cut at the factory?
A video of the EX-8000 in action has been posted on YouTube. Other issues not shown in the video include the same octave timbre repeating up and down the keyboard, and apparently random silent octaves for some sounds. Also, and this may mean nothing since I have not heard the original sounds in toto for comparison, but some sounds play and rise up or down in pitch, almost like the sound you get when a capacitor is going bad and leaking current during use. I would have to hear an EX-8000 with proper sounds to know if that is what is happening in mine. Anyway, if anyone can shed any further light on this, I will be very grateful if not necessarily forthcoming with monetary remuneration. synthjoe, I will try creating a sound by hand and post here news of the result. Thanks for the idea.
Hi gridsleep,
The pictures are too small for me to see what you mean, but if it is what I think have seen on your video then the cutting of the trace might be intentional. I think it might have something to do with inductance as the trace runs around the PCB and having a loop is usually not such a good thing. Maybe that's why it is cut.
The sound I hear on the video doesn't sound that bad to me, all keys and the A440 button works consistently, so I'd definitively try and put together a program manually from scratch with different waveforms, one oscillator at a time and see what happens. Also, it would have been useful to see what the sound is like with other programs...
Some examples you can listen to:
http://www.youtube.com/watch?v=SnG-urPc ... r_embedded
http://www.synthmania.com/dw-8000.htm (this is the DW-8000 but it should sound the same - identical engine) (you can stream the whole demo material from here)
The pictures are too small for me to see what you mean, but if it is what I think have seen on your video then the cutting of the trace might be intentional. I think it might have something to do with inductance as the trace runs around the PCB and having a loop is usually not such a good thing. Maybe that's why it is cut.
The sound I hear on the video doesn't sound that bad to me, all keys and the A440 button works consistently, so I'd definitively try and put together a program manually from scratch with different waveforms, one oscillator at a time and see what happens. Also, it would have been useful to see what the sound is like with other programs...
Some examples you can listen to:
http://www.youtube.com/watch?v=SnG-urPc ... r_embedded
http://www.synthmania.com/dw-8000.htm (this is the DW-8000 but it should sound the same - identical engine) (you can stream the whole demo material from here)
That doesn't sound bad to you? The fact that I am playing the keyboard in the middle register and the EX-8000 is playing in the highest register it can produce? Why did I even bother to do this? Am I delusional and imagining all this? If I were fantastic Mr. Fox at this point I would declare I am going insane because I just can't understand how anyone can hear those teeny tiny noises coming out of the speaker after what was a normal load of bank A... I mean, even the A440 button should be playing a middle register A 440Hz, no matter WHAT bank is loaded...
OK, OK... calm down... never mind... sorry... I just got up, my back and extremeties hurt, I'm waiting for the happy pill to kick in (sorry, result of a car accident a few years ago--I am very grouchy in the morning). OK...
Is it possible that, when Bank A loaded via MIDI, it was somehow "sped up" or "transposed" so that it is the sound that was distorted and not due to any deformity in the synthesizer itself? Because I have nothing to compare it to here. I don't have a DW-8000 that I can also load the bank into to see if it functions differently in a different machine, or if it is my loading method that is flawed.
OK, and with that idea in mind, in the middle of this editing, I decide to scoot over to eBay and see what else is there annnnnnnd..... lo! and behold! (as they used to say in Shakespeare's plays and some books of the Christian Bible) there be whales here! Uh, no, wait, that's Star Trek. There lay a Korg DW-8000 with the Angel City mod. Yes. An original. The place selling it did not even mention that in the description, but the yellow sticker is unmistakeable. And now it's mine. So. I have a DW-8000 Angel City, and an EX-8000. Now, some time next week, I will have something to compare the EX to for further diagnosis.
And I did not know that about the trace. You are right, the big trace goes all the way around the outside of the PCB. I must have been blind. I would not have thought that something with so little current would have presented inductance problems. But, then, everything on the PCB is low current, so it might have an effect at that. Interesting.
OK. I'm going to clear out the memory again, and try to program a sound from scratch according to the manual. We'll see how it goes.
Angel City mod. Sweet...!
OK, OK... calm down... never mind... sorry... I just got up, my back and extremeties hurt, I'm waiting for the happy pill to kick in (sorry, result of a car accident a few years ago--I am very grouchy in the morning). OK...
Is it possible that, when Bank A loaded via MIDI, it was somehow "sped up" or "transposed" so that it is the sound that was distorted and not due to any deformity in the synthesizer itself? Because I have nothing to compare it to here. I don't have a DW-8000 that I can also load the bank into to see if it functions differently in a different machine, or if it is my loading method that is flawed.
OK, and with that idea in mind, in the middle of this editing, I decide to scoot over to eBay and see what else is there annnnnnnd..... lo! and behold! (as they used to say in Shakespeare's plays and some books of the Christian Bible) there be whales here! Uh, no, wait, that's Star Trek. There lay a Korg DW-8000 with the Angel City mod. Yes. An original. The place selling it did not even mention that in the description, but the yellow sticker is unmistakeable. And now it's mine. So. I have a DW-8000 Angel City, and an EX-8000. Now, some time next week, I will have something to compare the EX to for further diagnosis.
And I did not know that about the trace. You are right, the big trace goes all the way around the outside of the PCB. I must have been blind. I would not have thought that something with so little current would have presented inductance problems. But, then, everything on the PCB is low current, so it might have an effect at that. Interesting.
OK. I'm going to clear out the memory again, and try to program a sound from scratch according to the manual. We'll see how it goes.
Angel City mod. Sweet...!
Which turned out not to be true. They posted the wrong photograph. It's a plain, ordinary DW-8000. I am still dickering about it. For a company that prides themselves on the accuracy of their listings, they sure don't appear to practice what they preach.
Anyway, I tried programming the EX-8000. From the first touch of the programming knob, even the high pitched noises disappeared. Trying to create a sound creates nothing. It's almost as if the sixteen basic sound waves have disappeared. I think this is up the creek without a paddle. When I was programming in the 40's, I think 44 first showed "G5" the note rather than a number. 46 showed the same thing. 51, I think, came up "F5". Everything adjusts OK, but saving results in no sound at all. Or rather less sound. Voice 15 did come up with a kind of mild whistling sigh noise, like the synth itself has just plain given up and is sitting in the corner waiting for nothing to happen. I do not think this EX-8000 is going to work.
Anyway, I tried programming the EX-8000. From the first touch of the programming knob, even the high pitched noises disappeared. Trying to create a sound creates nothing. It's almost as if the sixteen basic sound waves have disappeared. I think this is up the creek without a paddle. When I was programming in the 40's, I think 44 first showed "G5" the note rather than a number. 46 showed the same thing. 51, I think, came up "F5". Everything adjusts OK, but saving results in no sound at all. Or rather less sound. Voice 15 did come up with a kind of mild whistling sigh noise, like the synth itself has just plain given up and is sitting in the corner waiting for nothing to happen. I do not think this EX-8000 is going to work.
Sorry mate. Being a techie saying that something like this sounds bad to me or scares me means that I could give up my job right now. I see much worse things on a daily basis (burned out power supplies, expoded components, mechanically destroyed equipment that people need some data back from, etc.).
Sorry, I'm afraid it'll be too difficult to do remote troubleshooting for this. However, you can see some test procedures from page 40 onwards in the service manual, I think it would be worthwhile to set up programs suggested on that page anyways (all parameters for all test programs are shown on that page). I do not encourage you to change any physical setting (VR's, etc.) on the board, but setting up those test programs might give you further clues as to where the problem might be. Beforehand a memory clear (see page 40 at the bottom) would be a good idea, but I assume you've done that already - it should be standard procedure when changing the battery.
Also, from page 32 and in particular from page 36 there's a rather good account of the working principle and circuits of the module, so I'd suggest to read those in depth as it can be some serious help with further troubleshooting ideas.
Hope you'll succeed and enjoy the 'new' DW-8000, too!
Edit: added the memory clear thing but McHale beat me to it...
That would have been my guess. However, the fact that trying to create some programs from scratch yields no good result suggests that there's indeed something wrong with the digital part. The awkward display would hint to me that there might be some problem on the data bus (as the display is directly connected there - via some latches), but the fact that the machine boots and makes some noise, plus it reacts to MIDI suggests otherwise.gridsleep wrote:Is it possible that, when Bank A loaded via MIDI, it was somehow "sped up" or "transposed" so that it is the sound that was distorted and not due to any deformity in the synthesizer itself?
Sorry, I'm afraid it'll be too difficult to do remote troubleshooting for this. However, you can see some test procedures from page 40 onwards in the service manual, I think it would be worthwhile to set up programs suggested on that page anyways (all parameters for all test programs are shown on that page). I do not encourage you to change any physical setting (VR's, etc.) on the board, but setting up those test programs might give you further clues as to where the problem might be. Beforehand a memory clear (see page 40 at the bottom) would be a good idea, but I assume you've done that already - it should be standard procedure when changing the battery.
Also, from page 32 and in particular from page 36 there's a rather good account of the working principle and circuits of the module, so I'd suggest to read those in depth as it can be some serious help with further troubleshooting ideas.
Hope you'll succeed and enjoy the 'new' DW-8000, too!
Edit: added the memory clear thing but McHale beat me to it...
Last edited by synthjoe on Sun Jul 10, 2011 1:11 am, edited 2 times in total.
before you load or program any patches, perform a wipe on it to clear out any goofy parameter settings by holding the 5 and 8 buttons when you power it on. When was the battery replaced? If it wasn't recently, do that, wipe RAM, and try again.
-Mc
-Mc
Current Korg Gear: KRONOS 88 (4GB), M50-73 (PS mod), RADIAS-73, Electribe MX, Triton Pro (MOSS, SCSI, CF, 64MB RAM), SQ-64, DVP-1, MEX-8000, MR-1, KAOSSilator, nanoKey, nanoKontrol, 3x nanoPad 2, 3x DS1H, 7x PS1, FC7 (yes Korg, NOT Yamaha).
It is working.
Apparently the load of bank A from the computer did not work right. Banks A and B on the MEX-8000 are not working right. But, I finally got bank C to load in from the MEX and the EX sounds just right. What a marvelous headache.
I'm going to see if I can get the MEX A and B banks loaded into the MEX properly, and figure what went wrong with the computer load of the factory A bank to the EX. Thanks for your assistance.
Later: The MEX D bank also appears to be scrammed. Vintage gear has to be a labor of love, because nothing but that kind of madness would put up with all this. It's no wonder the young musicians only buy new stuff. They don't have the battle scarred hearts to take this kind of aggrivation.
Later still: Better luck getting the A and B banks to load into the EX. Now I find that the banks available from Bryan Ressler's site and Deaf Eddie's site have a couple of repeated voices in them. For instance, after loading bank A from Eddie's download, 22 and 24 appear to have the same sound (or thereabouts--I'll have to go over them all to get the correct numbers, but there are repeats.) There are differences from the patch examples playable on SynthMania's DW-8000 page.
Also, I got the Angel City DW-8000, after all. Yeah, I'm smiling. Very sweet codge.
Apparently the load of bank A from the computer did not work right. Banks A and B on the MEX-8000 are not working right. But, I finally got bank C to load in from the MEX and the EX sounds just right. What a marvelous headache.
I'm going to see if I can get the MEX A and B banks loaded into the MEX properly, and figure what went wrong with the computer load of the factory A bank to the EX. Thanks for your assistance.
Later: The MEX D bank also appears to be scrammed. Vintage gear has to be a labor of love, because nothing but that kind of madness would put up with all this. It's no wonder the young musicians only buy new stuff. They don't have the battle scarred hearts to take this kind of aggrivation.
Later still: Better luck getting the A and B banks to load into the EX. Now I find that the banks available from Bryan Ressler's site and Deaf Eddie's site have a couple of repeated voices in them. For instance, after loading bank A from Eddie's download, 22 and 24 appear to have the same sound (or thereabouts--I'll have to go over them all to get the correct numbers, but there are repeats.) There are differences from the patch examples playable on SynthMania's DW-8000 page.
Also, I got the Angel City DW-8000, after all. Yeah, I'm smiling. Very sweet codge.
