I am a total newb when it comes to repairs, so please bear with me. I have an SQ-80 that works brilliantly but it does have one minor issue. The display only works intermittently. Most of the time, I have to press the front panel of the synth down to get it to light up. When I do this, I can see everything so I don’t think the problem is with the display itself, but with some sort of connector. As I said, I’m new at this, so if anyone has any idea as to what I should be checking for I’d appreciate the help. I have no problem taking the panel off and looking inside; I just don’t know what I’m looking at.
It looks like the display is vacuum fluorescent. This type of intermittent failure usually means a component such as a resistor supplying power is faulty from dry solder joint, or over overheating. Many displays of this type used undersized resistors, so they would eventually overheat. Most likely its both.
You should take the unit in for servicing as this failure can overheat the display through internal intermittent arcing causing leaking of the vacuum seal. Typically these displays cannot be replaced as each one is custom built for their intended purpose, and spares are only available when another unit dies.
Never use any force on any part of the synth at anytime, some of them are so cheaply made that the plastic over time gets brittle and the last thing you want to do is break a face plate.it could also cause a short rubbin the coating of fa wire. Just take it apart, takin pictures and noting which screw goes where. You will have to take out the keyboard contact circuit board[s] maybe, the main board for sure to get to the display board. Use bright light and a mag glass and just keep lookin around the area of where the ribbon cable attaches. Look very well ,don;t touch anything, even walk away and come back look hard again ,your problem might be very small and hard to locate, but could be just as simple as the ribbon isn;t seated in its connection block. They only go in one way and it can only be the one cable that fits that block Its fail safe. Pull it out first and look at all the pins and in the holes in the block a piece of dirt caught somewhere could be the culprit. ALways use the K.I.S.S. principle.Since you have the board on a towel and foam blocks or rolled towels on the ends to protect the bender,you have an air gap.To reach the display plug it up and power it on and use a small mirror to see what the display is doin after pluggin the ribbon back in before you add power. Its possible theres a wire ribbon for lcd controls and a small 2 wire block for the LCD power.If he lcd seems to be workin normally now, the ribbon was stretched or pinched by the back cover meanin some one has been inside it before and didn;t put the cables back in the right place. Displays almost always give a " death rattle" warning sign when they are fixin to go out ,but your problem is not a death rattle/symptom.If you still have to push on the diplay to get it to function and you can tell someone’s been it it before you then its a good chance that some pins in the ribbon are bent and not makin contact, you can try to straighten but a new ribbon might be in order. It could also be the female end ,the block on the lcd c.board,which would mean replacing it. The whole LCD. These are generic parts and theres hundreds to chose from l at a elec supply site like digi-key or mouser. They are identified by the amountof lines and the number of characters in each line and also by its viewing window size and overall size. Not an expensive part unless you go for the fancy backlit color change models…Doubtful there would be any soldering work in this display swap. If you have more than one synth that has the same display configuration, you could just buy one then swap out to the new one and see if you have to press on the faceplate to get it to work or not and if its not needed just put it up, you’ll use it one day and I;ve done quite a few for guys that couldn’t see the stock display on a dark stage plus folks are color blind too ,so upgrading a display though its not broken happens. This info is just basic generic guidelines and will vary due to the amount of keys and the display location on the face plate or even more different if its a rack or module type. Just remember to take pictures ,label screws and know that the plugs only go back one way ,there should be no forcing anything back in, the same way there should be no tuggin on a cable to get it out. Have a can of deoxit or CRC Qd contact spray handy and some dielectric grease handyand do a good cleanin and before starting check the battery voltage. The owners manual will tell you how. Put a new one in if its down any more than say 1/2 -to 1 full volt. This might mean soldering in a battery holder,then changing memory battery is easy pop in and out, and the owners manual will tell youhow to reload the stock sound, you will lose anything you created unless you back it up on another device. Alot of synths take the standard cr2032 coin battery, good for 5 years plus. do the work away from other famil y members [especially kids and animals] little hands and paws and fur get in the dangdest places
I don’t disagree with midnights thoughts on this, but it sounds way more like a connection problem than the vacuum holding the fluid in the display. Obviously when its opened up a leak will be easy to spot and maybe these were custom built back in the day, but I believe there are options now. Contact a supplier
I mentioned with the numbers on the back of this display and any other number on its C. board and there may be more than one option. Resistors and caps were often times used that just barely covered the job it was required to do, to save money and its always a good idea to upgrade the caps with a better brand and value. You don’t have to be a electronics geek to figure out the best upgrade and always replace all of the caps, resistors,etc…Not just the problem area,they can be bought cheaper in bulk anyway and are generic ,you will use them… Theres alot of vids on YT that go over this
My beloved SQ-80 had a similar problem. I carefully reflowed the solder on all of the displays pins. It’s been great for the last year.
Hello friends, Hope the new year got you happy and full of energy.
I had a similar problem on a Roland display (brightness control), the solution was a BYPASS WIRE FROM DISPLAY TO POT (posted on YouTube back on early 2000’s)
Use your computer, do a search for service/parts manuals, check amazon and ebay.
I’ve found some parts at Fullcompass.com, Partsexpress.com. They don’t carry all brands, but it’s worth a quick check.
Usually when you have an intermittent short is a broken wire, a lose connection or a failing display, I would suspect a lose connector first.
The only way to find out: GET YOUR UNIT OPEN, PLUG IT IN AND CAREFULLY JIGGLE THE DISPLAY WIRING, (if you have a voltmeter check voltage supplied to your display, usually 24v dc)
DISCHARGE YOUR BODY’S STATIC ELECTRICITY BEFORE YOU TOUCH ANY PC BOARDS, CONNECTORS OR WIRES. (use static removal bracelet)
Please use your fingertips or “NON METAL TOOLS” WHEN TOUCHING OR SEATTING CONNECTORS.
Good luck finding and fixing your keyboard !!