Archive

Posts Tagged ‘LCD replacement’

Korg SDD-3300 Triple Delay – Display Upgrade

August 12, 2011 4 comments

I love my Korg Triple Delay.  I love it so much I actually have three of them.  You might not need three, but you really should own at least one.  I’ve had one since the early 90’s, I bought a busted one on eBay for parts that turned out to have a trivial issue, and the third on eBay because it was just too good of a deal to let someone else get it.  The last one was crazy impulsive but there you go.  There are only three things about the 3300 I don’t like.  Everything else about it is magic. 

If you are unfamiliar with the unit, it is a three input, three output, three delay unit monster.  Each delay unit’s time can be up to 500ms.  You can route any of the inputs 1,2,3 into any of the three delay A,B,C units in any amount you want.  Additionally, you can route the ouput from any delay to any of the three outputs or back to any of the three delay units.  It also sports two LFOs which can be set to a locked phase relationship which makes for great chorus effects.  If you like your feedback like me, this unit is like nothing else.  It is an early digital delay with a ton of character and a great sound to back up the impressive feature set.  Unfortunately, like I said there are three things I don’t like about it.  First, the output is rather low.  Perhaps some reader who is smarter than me will look over the Service Manual and tell me how to boost the output.  Secondly, the units do have a good bit of transformer hum/whine.  Lastly, the displays aren’t great and pretty much every unit I’ve seen the backlights are completely dead.  I only have a solution to the last of these three complaints – the display.

First off, there are tons of drop in replacements for old LCDs with EL backlights on the market.  I’ve been slowly upgrading my displays as I work on gear.  This is not without pitfalls as the pile of VFD and LED displays on my desk left over from this project will attest.  There are two main problems; first, just because a display says it is compatible with the chipset on your old display, doesn’t mean that it is.  In the case of the 3300, I had several LED backlit displays from two different manufacturers that did not work.  I would get the top line of text but not the bottom.  It turns out that the newer chips had tighter and faster timing requirements than the display in the 3300 and thus the problem.  I also had a couple of VFD displays (my favorites) that simply would not power up or display anything at all.  I suspect there was not enough available current in the 5v line on the SDD to drive them properly.  Again, it also could have been a chipset compatibility problem.  I did finally find a display that works.  It has two things going for it (besides the fact that it works).  First, it is an LED backlit model so it should have an extremely long life and secondly it was really cheap.  VFD displays can run up to $60 for the nice Noritake ones and having 3 units to repair I wasn’t looking forward to the bill, especially if they didn’t work.  The displays I’m using are from 411 Technology Systems part number SSC2F20DLNB-D.  They are a steal at $11.49 each.  There are a couple of problems though.  Being LED backlit, they are thicker than the original display and the front panel of the SDD won’t attach with them mounted the way the old display did.  They also have separate 0v and 5v power inputs for the LED backlight which are not jumpered to the 0v and 5v inputs on pin 1&2 of the standard display.  Neither of these is a deal breakers but it means you should expect a frustrating hour cursing at how your fingers are too large (that part only lasts about 10 minutes but it will piss you off).  I recommend you pour yourself a beer.

Replacement LCD with jumpers and current limiting resistor

The first step is easy.  Open the case of the SDD and remove the existing display.  Carefully remove the wire bundle for the display from the main board but gently but firmly pulling on thewire housing (not the wires themselves) until it comes out.  Pin 1 is the one farthest from the front the SDD and in all three of my units it was a brown wire.  The connector is keyed so you can’t put it in backwards but you need to keep track of pin1 so you can wire your new display.  There is also a pair of larger wires that provide voltage to the EL inverter.  These end in a connector on the mainboard.  Unplug this with the display as you won’t need it anymore.  You can cut the wire bundle off the old display and then restrip and tin the wires or unsolder the existing ones from the display.  It’s up to you.  If you flip the display over, you will see pin 1 and 2 labeled on the back.  Resolder the wires from the old display to the new making sure you keep the pins the same.  The odd numbered pins are closest to the display as you look at it from the front and the even pins are on the outside.  It really would be best to install a pin header here and crimp terminals onto the wires and put them in a standard housing.  It really would be.  You can see from my pics though that I didn’t do it.  That’s because these displays arrived yesterday and I was so surprised that they actually worked, I could not wait until next week to place an order and wait on UPS to get them finished with so I just plowed ahead and soldered them.  Once you have resoldered all the wires (or populated a crimp housing which would be better) you will see that there are more pin positions on the new display (16) than the old display (14).  This is because the new display has two more pins for a 0v and 5v supply for the LED backlight.  The easiest thing to do is just jumper the pins by connecting pin 15 to pin 0 and pin 16 to pin 2.  This will provide the voltage you need to drive the backlight.  If you do this you will likely significantly shorten the life of the backlight.  You should install a current limiting resistor between pin 15 and 0 to lower the overall brightness of the display.  Use a resistor between 10 ohm or 20 ohm.  I found the 20 ohm was a good pick and the display was still really bright.  You could go even higher if you want your display darker.  Without a resistor, the display is extremely bright.  You can see how I attached the resistor in the photo.  I always cover resistors and components midwire like this with heat shrink so it doesn’t short out to anything.

Now is where the cursing comes in.  The new display has the same hole configuration as the old display.  However, if you mount it in the same way the old display was, you won’t be able to put the front back on the unit.  You need to mount the display *behind* the brackets and use nuts to hold it in place.  To make matters worse, you can’t actually get the current display behind the brackets without a modification of some sort.  I opted to bend the bottom left post inward (see picture) which gave me enough room to slide the display behind the remaining three brackets.  Alternately, you could completely disassemble the unit and then you could have the room to mount the display to all four brackets and also bypass the cursing that is about to happen.  However, three brackets hold the display fine and probably save you an hour plus of disassembly and reassembly.  I opted for the three bracket route.  There are also 3 capacitors behind the display that might give you problems with having the display sit flat behind the brackets.  I was able to gentle press them flat to the PCB with no problems on the three units I upgraded.  If it is not possible to get them flat enough, you will need to unsolder them and remount them on the other side of the board.  Just make sure you get the polarity right if you do this.  Also, If you have to go this far, you probably best ought just go ahead and disassemble the unit.

Things in the way of your new display

Now, to mount the display is frustrating.  The screws that came with the unit are long enough but you will need to get three nuts to hold the display against the brackets.  Take one of the screws with you to your local hardware store.  Not Home Depot as they are evil and will make you purchase a box of these and you only need three.  Go to your good old local hardware store that has a decent selection of hardware in bins and buy four of the correct size nuts.  Unfortunately, I’m old and can’t remember the exact size I bought so you are on your own.  I said to buy four because you are likely to lose one during this process and you really don’t want to go back to the hardware store a second time.  You only need three if you are foolish, brave, or talented.  I am none of these things – I lost two to the darkest, most distant space under my workbench.  Getting these nuts on tight on the back of the display in a tight space that you can’t reach well is what causes the cursing.  You need these to not only attach, but to attach tightly in order to hold the display in place.  The problem is the brackets themselves are threaded and that makes it difficult to get the nut taken up tightly unless you start it as soon as the screw pokes through the back and don’t let it turn while tightening.  I first screwed the screws all the way down from the front so that the display was lined up with the screws through the mounting holes.  Next I took a small allen wrench and applied a small piece of double sided carpet tape to the smaller bent part.  This holds the nut in place and gives you something to lift up on to make sure the display is tight against the brackets.  Back one screw out enough that you can use it to get the nut in position.  While applying light pressure on the nut to keep it on the screw shaft, back off the screw so that the nut is all the way tight against the bracket.  Now, while applying enough pressure to the nut so that it doesn’t turn, tighten the screw all the way down again pulling the nut tight to the bracket.  Repeat this two other times.  I also tried putting a piece of the carpet tape on my finger to hold the nut and that worked somewhat but a couple of the brackets are just a little too out of the way.  I needed my allen wrench tool on one or two for each unit I did.

Too Much Awesomeness: SDD-3300 x 3!

Now all that you have to do is get the whole thing put back together and back in the rack.  You might want to check the screws you took out of the unit to make sure none of them are stripped or wrong before you go to the hardware store so you can get replacements if you need to.  One of my units was owned by a guitarist and he apparently had lost the screws that went to the rack ears and decided that big #8 woodscrews were close enough to the metric machine screws that are supposed to be used.  I’m not sure how he got this to work but it certainly took a lot of effort to force the woodscrews into the case.  I had to get out my tap and die set to rethread the hole and then replaced them with the correct screws.  What is it with guitarists?  My buddy Brooks and I have long said that we need to release a high-end effect rack that comes in a limited guitarist’s edition that has the rack ears hack sawn off and comes with an empty paint can to put the unit on.  If you are a guitarist and think I’m out of line as you know all your appropriate fasteners and their correct uses, I would suggest that you are playing the wrong instrument.  As to the end result, as you can see they look absolutely great!