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Re: Korg DW8000 not working, please help.

Posted: Tue Aug 29, 2017 11:33 pm
by Riinehart
Powered mine back on tonight and now I'm getting no LEDs at all, except the speed light. :/

No change when moving joystick, pressing any button, or moving any fader.

Anyone have any ideas what I might try to test?

Thanks again.

Re: Korg DW8000 not working, please help.

Posted: Wed Aug 30, 2017 12:40 pm
by Mooger5
Did all those DWs have the stock battery replaced? If so, you could try a little experiment: with the unit powered off, remove the battery from its socket and then touch pins 12 and 24 of IC36 with a small value resistor, just a couple hundred Ohms or so, for a few seconds. The idea is to fully discharge the RAM chip, thus erasing whatever residual or corrupt data is still present. Ater that, put the battery back in the socket, power up the unit and attempt a reset.

Edit - Do the same thing to IC37. Just in case (while IC36 is the patch memory chip, IC is the system RAM).

Good luck.

Re: Korg DW8000 not working, please help.

Posted: Wed Aug 30, 2017 4:30 pm
by JHatzia
Thank you for the continued advice Mooger5. I will try this later tonight and report back. In the mean time, here is a video showing the issue.

https://www.dropbox.com/s/fs7dhfx5u79kf ... e.MOV?dl=0

Re: Korg DW8000 not working, please help.

Posted: Thu Aug 31, 2017 12:37 am
by Riinehart
Mooger5, thanks so much for the suggestion.

Unfortunately I just gave it a shot, and no luck.

FWIW, mine is in the same state as in JHatzia's video, except not getting the flickering etc with joystick movement. Occasionally when I try to power up with buttons 5 and 8 held, I'll get some different LED patterns, but even when that happens, nothing I press has any effect, the lights are static.

Re: Korg DW8000 not working, please help.

Posted: Thu Aug 31, 2017 3:03 am
by Riinehart
This is probably a really dumb question, but I have to ask:

When my battery is connected, my meter shows continuity between the positive and negative terminals. When the battery is taken out of the holder, there is no continuity.

Is this normal?

Re: Korg DW8000 not working, please help.

Posted: Thu Aug 31, 2017 5:14 am
by JHatzia
I tried to erase IC36 & 37 with a 220 Ohm resistor and still no luck.

Re: Korg DW8000 not working, please help.

Posted: Thu Aug 31, 2017 10:08 pm
by Mooger5
JHatzia wrote:Thank you for the continued advice Mooger5. I will try this later tonight and report back. In the mean time, here is a video showing the issue.

https://www.dropbox.com/s/fs7dhfx5u79kf ... e.MOV?dl=0
There´s some useful info here: http://www.pallium.com/bryan/dwbattery.php

There it says this:

" [After replacing the battery] Don't be immediately alarmed if when you switch the DW-8000 on nothing happens (i.e. no lights, no digit LEDs, nothing). Mine took maybe 1-2 minutes before all the lights came on and it was acting itself again, and there was a lot of weird random flashing of LEDs during that time. This is probalby due to the fact that the keyboard's memory is full of garbage.

After the patch/parameter lights come back on, reset parameters 84-87 to reasonable values. When you dial in those parameters, you may see weird patterns on the green value LEDs - this is because the parameter's stored value is out of range. Just use the data slider to put in a new value. The data slider will only give you valid values.

Your DW-8000 still doesn't have any patches in memory. It might make sound when you play the keyboard, but it's not likely to be anything pretty. But at this point you can be reasonably sure all is well. "

Re: Korg DW8000 not working, please help.

Posted: Thu Aug 31, 2017 10:37 pm
by Mooger5
Riinehart wrote:This is probably a really dumb question, but I have to ask:

When my battery is connected, my meter shows continuity between the positive and negative terminals. When the battery is taken out of the holder, there is no continuity.

Is this normal?
It´s weird, huh? But it´s normal, though I´ve never understood why :)
My auto-scale DMM shows continuity only when the red probe is on the negative side of the battery (out of the holder) and the black probe on the positive side. My analog multimeter shows continuity on both sides, with the needle going to opposite directions depending on the polarity.
On the PCB, with the battery out, there should not be continuity. That would cause a short across the battery´s terminals.

Re: Korg DW8000 not working, please help.

Posted: Thu Aug 31, 2017 10:39 pm
by JHatzia
I have followed this advice before and left on my unit over night with no change. My issue is that I can't even get the panel board to react. There's no way for me to get to say parameters 84-87. I know it sounds like a battery related issue, and it still might be, but I have had no luck after replacing the battery, reseting it, triple checking all connections, discharging IC36 & 37, swapping out the firmware to a new v12 one and even switched all the tactile switches to see if maybe the 5 + 8 buttons were dead. Still no change. I really appreciate you to taking the time to assist. I'm hoping more DW-8000 owners with this issue can add to the thread.

Re: Korg DW8000 not working, please help.

Posted: Fri Sep 01, 2017 1:31 am
by Riinehart
Yes, huge thanks Mooger5! Unfortunately I'm in the same boat. No amount of time seems to make any difference for me, either.

Though it's interesting that the piece you quoted is similar in some ways to what we're experiencing. JHatzia, did this issue also start for you directly after a battery replacement?

If it helps, a little more detail about mine: I got it for super cheap, as it seemed it just needed a new battery (I had actually been through some basic repairs once before on another DW8000 on which I had replaced the battery, all the tact switches, etc., so I was feeling confident). And indeed I brought it home, put a battery holder in, new battery, re-loaded all the sounds, and everything was perfect.

But immediately it started blacking out, and if I'd turn it off then back on again it would be fine. But this happened more and more frequently (all over the course of just a few hours maybe) until I was just getting jibberish in the LEDs, and eventually nothing but the arp speed light remaining on, which is where I'm currently at. So it DID work for a short time after the battery swap.

I wish I knew more about how to troubleshoot these things, like which points to check for appropriate voltage, etc. I have the tools, but I don't have the skills to translate the schematic in the service manual to what I'm actually seeing. If anyone has anything they can suggest, I'll be extremely grateful.

(Also, I doubt it matters, because I've seen a few instances of the same problem on a few different message boards, but just in case ... mine has the Angel City turbo expansion.)

Re: Korg DW8000 not working, please help.

Posted: Fri Sep 01, 2017 6:34 pm
by Mooger5
Yeah really wish the more knowledgeable people participated like before.
My DW8K was working fine last time I turned it on, a few months ago... still interested to see how things develop in case it happens to mine.
There´s an old thread here on VSE which I can´t find anymore... user got his fixed by replacing the voltage regulators.
Admittedly not the same issue, but I recall members Rhino and Hideaway reporting quality control problems in the voltage regulators of the DW8000.
Who knows?

The Angel City mod subs the original EPROM and adds more memory chips. Also adds a new battery for the extra patch banks. There are reported problems caused by aftermarket add-ons such as the E! expansion for the DX7, Europa for the Jupiter 6 and probably some other mod which I can´t recall. So it´s definitely worth a look!

Re: Korg DW8000 not working, please help.

Posted: Fri Sep 01, 2017 8:40 pm
by Riinehart
Well, today I removed all connections from the main board so I could take it out and inspect everything closely. I cleaned everything up, brushed and vacuumed out any dust (there were some little fuzz balls hiding around some of the IC legs that I thought could've been causing trouble).

There was one tiny spot just under the old battery where there was a little touch of green corrosion and an exposed trace. But when I followed where both ends were going, I checked for continuity and it was perfect, so that doesn't seem to be an issue. (JHatzia, do you have any corrosion from the old battery?)

After all that, I plugged everything back in, and ... it's still not working. Except now it's doing something slightly different: Upon powering up, only the arp speed lights up, as before, but now after about 10 seconds I get some other LEDs and a strange display. Looks like this: https://goo.gl/photos/hmpSQ9uJXyzVrsHeA

No idea what to try next ...

Re: Korg DW8000 not working, please help.

Posted: Fri Sep 01, 2017 9:17 pm
by Riinehart
Got it!

I finally found a legible manual for the Angel City mod, and it's got a big warning about cracking solder joints by pushing the mini board in the wrong way, so I figured I'd just take it out and check the connections. They were all fine, and I reinstalled the board (it plugs right into the IC38 socket), turned it on, and everything worked!

But as soon as I closed up the case, it went out again. So something is going wrong there ... either a cracked joint that loses connection with a little bit of pressure, or maybe I just need to secure the mini board better. But least I know where the problem is and roughly what to work on.

Thank you guys so much for the help. And now that I can get it working, JHatzia, if there are any measurements I can take for you, etc., while I still have it open, just let me know. Not exactly sure how this might apply to your situation, since you don't have this mod, but hopefully something can come of it. Maybe take out and reseat those ICs (36 through 38)?

Re: Korg DW8000 not working, please help.

Posted: Fri Sep 01, 2017 11:10 pm
by Mooger5
Cheers for that. I already hinted at some wire harness I had unintentionally left unconnected after closing the synth, that caused similar symptoms. The harness is so short, it gets disconnected by itself when the case is unfolded by 90º. Ater you service te synth, such as installing a new battery, there´s a chance you reconnect the other wires without noticing the shorter one floating.
In your case, checking/refreshing the joints under all the connectors might be worth it.

Re: Korg DW8000 not working, please help.

Posted: Sat Sep 02, 2017 9:21 pm
by JHatzia
Hey all,

Glad to hear some progress has been made! Fairly certain my unit does not have the Angel City mod, but I have fixed several E! equipped Yamaha DX7s in similar states with no problem. I bought this unit in this state. It had a battery replacement with a holder, I decided to redo it with an additional diode installed in-between the + terminal of the holder and on the board. There is slight corrosion which I scraped off and plan to cover with solder mask. Continuity was checking fine between those traces last I checked. It's very minimal. I will pop out the CPU board and look for any cracked solder joints.