Monthly Archives: August 2014

Korg W/01 PSU Mod for New Backlight LCD

Upgrading LCD was described elsewhere on the web, particularly well on those great websites:

http://tellun.com/wavestation/wavestation.html
http://01wfix.blogspot.com/2009_11_01_archive.html

Information found there served me as a reference for my venture into replacement of LCD in Korg 01/WFD. Here is the new LCD already converted, ready to install into 01/WFD.

New modified LCD for Korg 01/Wfd

New modified LCD for Korg 01/Wfd

Important part of the upgrade process is to provide 5V supply for backlight on the new LCD. The backlight on old LCD was of EL type and required 100V AC supplied from the inverter. Here is an easy 3-step process to modify PSU to provide 5V supply on the backlight connector for the new LCD.

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PSU board before modification.

1. Desolder and remove transformer T1

2. Desolder and remove transistor Q1

3. Solder in 100 ohm resistor as shown on the image below.

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PSU board after modification.

That’s it.

There is also a secondary benefit of this upgrade. By removing inverter transformer T1 – you also remove source of high-pitch, annoying noise. So it improves quality of the sound as well. =)

This mod should work fine on any Korg model that uses PSU P/No KLM-1530, like 01/W, 01/Wfd, 01/Wpro, 01/WproX.

Please note, I did test the output after mod to make sure that it really is 5V, and I strongly recommend you to do the same. Just in case. To rephrase – I totally take no any reponsibility whatsoever if you fry your box, or kill yourself in process. Have a fun.

 

Fixing Roland VS-1880 [Part 2 – Faders]

In the previous part we have disassembled VS-1880 to get access to faders located on the Panel Board. Looking at the faders close-up below can see that most faders are not in the best shape (spill damage ?).

VS-1880 faders on the Panel Board close-up.

VS-1880 faders on the Panel Board close-up.

Decided to replace all faders, but finding replacements turned out to be a bit of a challenge,  Here is original fader pot removed from Panel Board:

Original fader sliding pot removed from VS-1880 Panel Board.

Original fader sliding pot removed from VS-1880 Panel Board.

Approximate measurements gave the following specification:

Slide Potentiometer 50k linear
lever height ~ 10mm
length 75mm
width 8mm
height 7mm
travel 60mm
side A pin distance 64.5 mm
side B pin distance 67.5 mm

It took a while to find replacement parts without paying exorbitant price, but the deal was – minimum quantity 50 pcs. Fine. Now I have enough spare faders for more than 100 years of moderate use. Lucky me.

New faders look real good, have also dust protection layer, and are the exact size of the old one.

Repacement sliding pot for VS-1880

Repacement sliding pot for VS-1880

Having new fader pots on hand, I have replaced all thirteen. Also from reading the schematic of VS-1680 (could not get a hold of VS-1880 service manual) that there are only two ICs 0- IC7 and IC8 responsible for reading the state of all faders. You can see them on Panel Board faders close-up in lower left corner. Both are 74HC4051AP, mux/demux chips. Since access to components on the Panel Board is not easy – I decided to replace them as well. So far so good.

I have assembled back VS-1880, Run diagnostic mode, test faders and… Nothing works. At all. Moving lever on any fader does not cause even slightest change of the output values. Hmm…

After some head scratching, when I was going to give up – a question popped out – did you compare pin mapping on old and new pot ? Nope. I didn’t, Apparently I have assume that it is some sort of a standard. Well, assume nothing – it wasn’t, Quick compare test gave the following table:

Mapping sliding pots table.

Mapping old/new sliding pots pins table.

Once mapped, solution became quite obvious. All that was needed was to ‘jump’ pin nr 5 to pin nr 2 on every fader, as in the following picture:

Shown jumper between pin nr 5 and pin nr 2.

Shown close-up of jumpers between pin nr 5 and pin nr 2 on faders 1-3.

This time after assembly all fader tests passed perfect.

VS-1880 diagnostic screen - faders test.

VS-1880 diagnostic screen – faders test.

Conclusion: if faders on VS-1880 (and most likely on VS-1680) start acting up and fail diagnostic test – almost 100% chance is that fader sliding pot need to be replaced. I do not think that there was any problem with 74HC4051AP.

 

Fixing Roland VS-1880 [Part 1 – Disassembly]

Some time ago I got Roland VS-1880. Great stuff, but had a problem with the faders in the mixer section. Some faders did not work at all, some other worked in a strange and misterious ways. Namely, fader 3 did not work at all, 5 worked sometimes, 7/8 at 127 rise level of channel 3 to 16, 9/10 rise level of channel 3 to 105, 15/16 at 127 rise level of Master channel to 20, 17/18 at 127 rise level of channel 3 to 100, and Master fader did not work at all. I had no time to look into it until lately. Here is the brief account on how I tackled the issue.

Best way to test faders on VS-1880 is to enter the diagnostic mode. To do so, press down Status + Track buttons on channel 5 while powering the unit. To select fader test use page down button (F2) to move down in menu to Faders. Then move faders, full range up and down, one by one. Every fader that passed will have number displayed in inverse.

Once confirmed that have indeed problem with sliders, and it is not because of messed up settings, I had to dissassemble the whole thing.

Word of caution here – disassembly of VS-1880 to replace faders is a major PITA, so unless you are totally desperate (as I was), or you really know what you are doing – better give it to Roland service to deal with it.

To get to faders you need to literally tear down everything. Here is little, sparsely illustrated step by step:

1. Remove all knobs and encoder dial, except transport buttons.

2. Peel off gently left top panel (I removed both because was not sure if there are any extra mounting screws under). When removed stick some soft plastic bag on the sticky side of the panel to aviod contamination, then store it safely aside. As Chris Sherwin pointed out peeling off the top panel is unnecessary. I stand corrected.

VS-1880 panels removed

You can see left and right top panel removed, while it is only necessary to remove left top panel. Notice screws.

3. Unscrew eight flat-head screws as marked on the image above. Yes, Marco got that right, without point nr 2, number 3 does not make sense anymore.

4. Flip the unit up side down, and remove all screws from the bottom

5. Remove three marked screws from the back of the unit.

VS-1880 disassembly back

Do not remove any screws except those marked up.

6. Disconnect four blue ribbon connectors from Main PCB . Do not disconnect the  wide one (to IDE drive).

Markings show quite exact location of screws that need to be removed

Markings show quite exact location of screws that need to be removed

7. Remove all fourteen screws as indicated on the image above. Also remove Air Guide (metal profile between PSU and main PCB). Thanks to that you will be able to remove all necessary elements at once as shown on the image below.

Rear panel + main PCB + drive + PSU assembly together

Rear panel + main PCB + drive + PSU assembly together

8. Now, once we have exposed sub-chassis, we can remove all screws holding it.

Sub chassis of VS-1880

Sub chassis of VS-1880

9. Next remove sub-chassis, to get access to the Panel Board.

 

VS-1880 Panel Board exposed.

VS-1880 Panel Board exposed.

10. Once the Panel Board is exposed – we can remove it. In my case there was only two screws holding the Panel Board.

 

VS-1880 Panel Board

VS-1880 Panel Board

11. Panel Board at last. Finally we can take a look at faders.

End of Part 1