Korg DS-8 Main PCB or troubleshooting help?

The place for parts & services: Modifications, Spare Parts and Repair Services, Sample Packs, Accessories.
Forum rules
This forum follows the same rules outlined in Gear For Sale Rules and Guidelines

Moderators have the right to edit your posts to keep them within the framework of these rules.

Korg DS-8 Main PCB or troubleshooting help?

Postby Audity » Thu Nov 28, 2013 4:15 am

THE STORY: Picked up a Korg DS-8 the other day whose user interface is completely unresponsive. Powers on with a blank LCD and all right side LEDs frozen on. Looks like something may have been spilled on it many eons ago =/
I've cleaned and inspected all the PCBs and gone through the whole thing with a scope and meter. All the voicing circuitry and digital clocking seem to be fine, it's just not able to boot up properly. No signs of stress or thermal damage around any of the components. With only a partial service manual, I can only speculate as to the function of some of the larger, more proprietary ICs.
THE PITCH: I'm hoping someone here may either A) have some experience repairing this synth and could help me troubleshoot, or B) knows where I can source a new Main PCB (KLM-1071C).
Thanks in advance!

Image
User avatar
Audity
Newbie
Newbie
 
Posts: 23
Joined: Sun Jan 22, 2012 11:33 pm
Location: Reno, NV
Real name: Chris
Gear: Access Virus A, Waldorf Rocket, Alesis Micron, Yamaha DX7, etc. ...circuit bent and modded pieces
Band: (in progress!)

Advertisement:

Re: Korg DS-8 Main PCB or troubleshooting help?

Postby Hiwatt » Thu Dec 12, 2013 7:17 pm

Your symptoms seem to imply a frozen microprocessor. Here are a few things to try

1) Try to obtain a complete service manual (i know, might be easier said than done but absolutely essential).

2) Verify correct voltages at the power supply board. If voltages are incorrect unplug power connections to other boards and re-test. If voltages are correct now one of the boards is loading the power supply. Connect the boards one by one to identify the culprit.

3) Verify correct voltages on the processor board, best to measure the processor pins directly. If voltages are correct check for proper reset activity and subsequent data activity.

4) Measure the backup battery voltage directly. Nominal voltage should be > 3.0V, replace if not.

Hope that helps.
Hiwatt
Newbie
Newbie
 
Posts: 14
Joined: Fri Oct 08, 2010 1:12 am

Re: Korg DS-8 Main PCB or troubleshooting help?

Postby Thermistor » Sun Mar 30, 2014 9:45 pm

Audity-

Did you ever troubleshoot the issue? I just picked one up that plays but the front panel is also unresponsive. I cleaned all the connectors and that didn't help. One brief time I was able to get some buttons to do something but it is not repeatable.

Thanks,
Thermistor
Thermistor
Newbie
Newbie
 
Posts: 2
Joined: Sun Mar 30, 2014 12:30 pm

Re: Korg DS-8 Main PCB or troubleshooting help?

Postby gent de Synth » Mon Mar 31, 2014 2:32 am

Did you try replacing the battery? you'll need a soldering iron and a battery . This place sells parts for the DS-8 . http://www.syntaur.com/korg_ds.html
gent de Synth
Newbie
Newbie
 
Posts: 1
Joined: Mon Mar 31, 2014 2:07 am

Re: Korg DS-8 Main PCB or troubleshooting help?

Postby Thermistor » Mon Mar 31, 2014 9:32 pm

Ah, Syntaur, they slipped my mind. I will be surprised if the battery fixes it but I will try it!

Thanks!
Thermistor
Newbie
Newbie
 
Posts: 2
Joined: Sun Mar 30, 2014 12:30 pm

Re: Korg DS-8 Main PCB or troubleshooting help?

Postby Audity » Tue Apr 01, 2014 2:39 am

Thanks for the tips :) ...PSU is healthy (loaded and unloaded) and the backup battery is a solid 3V. I'm getting good voltage and signal readings on the PCB test points, although it is hard to determine whether or not they are all correct without the full service manual :|
The backup battery and everything around it appears to have been changed at some point, so that area was of particular concern for me, but all the resistors and caps around there seem to be doing their jobs.
I DID notice a small bit of white corrosion around several pins on one of the SRAM ICs, possibly from whatever got spilled in it, especially if it was something corrosive like soda. Could a fried SRAM chip be giving me these types of symptoms?
User avatar
Audity
Newbie
Newbie
 
Posts: 23
Joined: Sun Jan 22, 2012 11:33 pm
Location: Reno, NV
Real name: Chris
Gear: Access Virus A, Waldorf Rocket, Alesis Micron, Yamaha DX7, etc. ...circuit bent and modded pieces
Band: (in progress!)


Return to Gear Services & Other Goods

Who is online

Users browsing this forum: No registered users and 3 guests