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Korg DW-8000 No Sound - Please Help
Old 4 days ago
  #31
Here for the gear
 

Thanks

Thank you Lector very much. I just had that problem. Clearing ram fixed the issue.
Old 4 days ago
  #32
Gear Maniac
 

Mac OS X Korg DW-8000 Programmer

just thought I'd throw this in this thread... this program for controlling the DW series is great, easy and pretty amazing.
Old 4 days ago
  #33
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Quote:
Originally Posted by mrgkeys View Post
Mac OS X Korg DW-8000 Programmer

just thought I'd throw this in this thread... this program for controlling the DW series is great, easy and pretty amazing.
NICE! Thank you for the share
Old 4 days ago
  #34
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adhmzaiusz's Avatar
Quote:
Originally Posted by Lector View Post
It doesn't store patches in ROM, they have to be loaded from an external source, either tape or sysex.

After the battery is changed, the RAM gets filled with garbage. If you try to program a sound from the start you have to select most parameters and move the slider up and down so it 'aknowledges' the minimum and maximum values per parameter as defined by the OS. Otherwise you'll often run into weird characters that resemble Klingon alphabet. To avoid all this, pressing 5 and 8 while powering up will clear the RAM and the unit is ready to be programmed from scratch, or by sysex, or via tape, glitch-free.
Anyone know would there be a similar power up button command or does this also work on the DW6000? I've got one right now that doesn't seem to want to make a playable sound after a battery change. I've tried adjusting the parameters but everything is at the same pitch and it refuses to take a tape dump. It'll take a midi dump but nothing sounds right.
Old 4 days ago
  #35
Gear Maniac
 
Lector's Avatar
 

Had a look at the service manual and didn't find any mention of such commands.
There is a curious procedure though: when interfacing with a computer the MIDI OUT of the DW must also be connected (pages 8 and 9 of the service manual - point 4)

Was it working before?
Old 4 days ago
  #36
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adhmzaiusz's Avatar
Quote:
Originally Posted by Lector View Post
Had a look at the service manual and didn't find any mention of such commands.
There is a curious procedure though: when interfacing with a computer the MIDI OUT of the DW must also be connected (pages 8 and 9 of the service manual - point 4)

Was it working before?
Unfortunately I’ve never actually heard what this thing should sound like but it seems to be one pitch and as you play one key multiple times the sound becomes more messed up as it cycles through the voices. I took it on as a project to see if I could learn a bit about digital but I don’t quite understand yet where to start past the power rails... need to understand a bit better where the voice pitch comes from beyond the keyscanner.. circuit looks pretty complex with a lot of data lines. Maybe the ram needs purging but I couldn’t see anything in the service manual either. Maybe remove and poke the pins through tinfoil to see if that clears it...
sorry to hijack this dw8000 thread too.
Old 4 days ago
  #37
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Lector's Avatar
 

Why does the memory get corrupted in the first place...? Is it the sudden voltage rise from the battery's 3v to the psu's 5v upon power up? There's a bypassing cap to smooth things out...
If the new battery is on a holder, try removing it and then turn on the power. Maybe the bigger change of potential from zero to +5 will knock those residual voltages out...
With time and motivation, you could also study the dw8000's schematics and learn what it does to clear its memory, because it has to be at component level. Then, try to replicate it on the 6000...

It's very difficult to fix things remotely, and draining.
I'm here trying to help fixing a dw8000 because I also got one.
Had a 6000 for many years and have very fond memories, created lots of good songs with it and just a 909 and two tape recorders.
But I've sold it more than 20 years ago...
Old 4 days ago
  #38
Here for the gear
@ Lector are you getting a reading on your DW when you connect TP-AG to TP-CV and does it match when you connect TP-AG to TP-Ref1?

If you are, I think I'm going to try and trace the signal back from TP-CV and see where its getting cut off on mine.
Old 4 days ago
  #39
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Lector's Avatar
 

Vref1 and tp-ag read 3.45V, vref1 and tp-cv match.
Old 3 days ago
  #40
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Quote:
Originally Posted by Lector View Post
Vref1 and tp-ag read 3.45V, vref1 and tp-cv match.
Thank you Lector, hopefully I can find the faulty component. Any tips you can give me when looking for a needle in a haystack?
Old 3 days ago
  #41
Gear Maniac
 
Lector's Avatar
 

Make sure the klm661 is attached to the chassis. Some of the screws are the link to chassis ground. Pin1 of ic19 must be kept low to enable the chip's outputs.
You need the scope. Testing for continuity to detect broken traces is pretty much all you can do with just a multimeter imho.
Old 3 days ago
  #42
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Hi there, I’ve been trying to debug a dead DW8K myself the past couple of months and it’s been a bit of a nightmare after trying most the usual fixes.
On my one the ram chips used by the DWGS system appear quite hot so possible short? Or just processor stuck in a loop?

Also I’m wondering if anyone can confirm the vss voltage on ic36 (the SRAM) should be 5v on power up? Mine seems to only get to about 4.4V while the other SRAM chip is on 5v. So not sure if it’s the npn transistor further down the line sinking the power via the reset line.
Under the scope the clock seems good, I chucked in a new crystal. Address buss lines seem to be all spinning out data, although the data buss signal d0-d7 appears to be quite noisy compared to this, more so towards the chips driving the leds and panel buttons.

Someone had previously done a battery job on it before I got it but wired it in reverse, so possible a bit off damage there, although I would have thought the diode will have prevented anything serious.

Any help or confirmation on voltages and heat issues would be super!

Adam
Old 3 days ago
  #43
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Lector's Avatar
 

Hi. I can check those for you, no problem. Maybe tomorrow morning

Btw re vss there's a diode in series. Voltage drop 0.6 cheers
Old 3 days ago
  #44
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Ahh that would explain the voltage drop!
Thanks I may have to see if I can find a tape recorder to try the preset load from tape instead of straight wav playback, apparently people have had more success that way.
Curious as to what would be different though, maybe different impedance on tape outs. Main difficulty is there’s no panel, so not even sure the buttons are registering!
Old 3 days ago
  #45
Gear Maniac
 
Lector's Avatar
 

Noise in those lines sounds like decoupling problems, but ceramics rarely fail, right? Maybe increasing the capacitance to 100n per chip will fix it.

ICs 48 to 57 do get quite warm. My synth is working fine, so it must be normal behaviour.

Using TP-DG to probe IC35 ports D0 to D7 now

I could only read pin 51 and there was a ringing and jittery crests. So the noise is probably normal. My probing around must have interfered with the system though because I only got DC out of the ports after that.

Clearing the ram now and resetting.
Old 3 days ago
  #46
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I've had the DC only from ports happen a couple of times, I think possibly maybe I hit a couple of pins together and it crashed the CPU.

But its interesting to hear the noise is not just mine, maybe some of it is chip noise further down the line, as it seems to degrade a bit more the further you get from the CPU. Its almost like some extra ramps in between the main pulse, the further you get from the CPU theres a kind of double crested pulse going on.

I might try checking some of the capacitors in case that is an issue, the only other thing I can think of on the noise is if its a chips failed somewhere and introduced it, although bit of a nightmare scenerio trying to find that.

In the meantime Im going to see if I can find someone local with a tape recorder, I don't want to go pulling any more chips or reflowing circuits if I have to!
Old 3 days ago
  #47
Gear Maniac
 
Lector's Avatar
 

Yeah I must have shorted some pins too. Those lines meet a good number of addresses, so it's possible what we're seeing as noise is a combination of interleaved signals.
My dso is not the best for the job probably, or these probes are faulty.
Tried to calibrate afterwards via tpag+tpsig on the voiceboard and could not get a signal. Even took shortcuts. I'm a little worried now
Old 2 days ago
  #48
Gear Maniac
 
Lector's Avatar
 

What am I talking about, it's either on or off, it should be +5 or 0, and nothing in between, so it's definitely noise. But I'd look elsewhere...
Old 1 day ago
  #49
Gear Maniac
 
Lector's Avatar
 

OK, got the calibration procedure right.
There probably was a cassette tape with the Test Data for servicing. OS V1.2 does not load the programs displayed on page 39 when Test Mode 2 is called (by pressing [7]+[8]). They have to be programed manually, but it's easy. And when calibrating, there is no special Hold function, so the C5 key must be pressed all the time. Sticky tape helps.
Good luck.
Old 1 day ago
  #50
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I think I possibly saw the Test data done as a sysex file on the DW8000 Facebook group files section. I would assume if you've gotten to a stage where you can calibrate then midi will be working

I've been experimenting with tape loading today, had one point where the front panel actually lit something up. I really need to video tape everything I'm doing in sequence just in case it was me moving a wire somewhere. Unplugging the lead to the Delay board and Joystick also seemed to kick the synth into some state where all the panel was lit up, nice to see that panel is actually getting power at least, its been blank for most of a months tinkering!

going to leave the synth with the battery out tonight and see if it properly drains the SRAM, possibly with a resistor between ground and vcc as someone suggested, that was one of the factors I introduced before the tape loading session this afternoon which got some led's going.
Old 1 day ago
  #51
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Lector's Avatar
 

That's some progress. The opposite has happened to me twice (LEDs not lighting up): first after installing the battery holder and then after having replaced the panel switches. In both occasions a few wire looms got switched because of some connectors having the same number of pins!
Another situation when the unit didn't even boot up, when the KLM661 was left unbolted to the chassis. I told the OP the bolts were the link to chassis ground but I apologise for spreading misinformation. There is no chassis ground despite the symbol being all over the schematics. The PCB had moved and was short circuiting with the metal standoffs!

The few times the backup memory got corrupted didn't prevent my synth from booting, it just messed with the parameter values.
Still, shorting the VSS of the other RAM, the system memory, to ground should make sense as well.
I'd short the decoupling cap with the screwdriver. If the chips are holding a charge, with a resistor just take longer to discharge, I think.
Old 23 hours ago
  #52
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Well, kinda ground to a halt. The display coming on if it ever does is pretty random, happens seldomly and never seems to be to a point where any buttons or panel items affect it in any way.
So I need to decide if the next step of action is to replace the program SRAM (I bought two new ones when I got the synth as a sort of get it running kit) or try and borrow a tape recorder to try that route without messing with any more chips.

I've gone down the whole trying to throw wavs into it from the computer far too long now tried different levels, matching exactly -10 consumer(which would have been old portable tape decks, +4 pro levels, cleaning up waveforms before sending etc.
Interesting the two buffers going into the main CPU tape pin look like they clip the signal to get a more pure pulse waveform anyway, so even if the wav file on an editor looks like a sawtooth from all the tape filtering, it goes back to a pulse in the cpu input. Whether thats the correct 320-640 timing steps is another matter!
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