Roland GW-7 display repair

About a month ago I bought a Roland GW-7. A few keys not working but more worrying: the display isn’t working properly.

This is my second GW-7. The first one had a bunch of non functioning keys as well. This looked a lot like the problem I had with some Roland Juno-D’s I bought years ago. Normally when a key doesn’t work you clean the contacts and that’s it. With the Juno-D’s and the first GW-7 (which I think has the exact same keybed as the Juno-D) this didn’t work. I just couldn’t get all the keys to work. This particular GW-7 had 1 key that didn’t work and about 10 that weren’t velocity sensitive anymore. A set of new key contact rubbers cost me around 20 euro’s last time but I will try to clean the contacts first to see if it fixes the problem.

I use q-tips and 96% cleaning alcohol for this. Usually does the job 🙂

After cleaning all 5 octaves I assembled everything to find out that now only 1 key wasn’t velocity sensitive. All the others keys worked fine. I removed the keybed again and cleaned the contact of that one key. Put everything back together and now all 61 keys work. Great! I will keep an eye on this and see if a few weeks from now they still work. If keys start to fail again I will order new contact rubbers.

Next. The display. This is what it looks like:It seems that the issue is confined to the top part of the screen but there are also elements missing from the bottom part. Not really visible here but if you put it in ‘backing’ mode and press a chord with your left hand you see the chord in the lower left section of the screen along with the name of the chord. For example C 7 or G dim etc. some of the words didn’t show.

The backside of the screens looks like this:See the long ribbon cable a the top? That’s the problem. When I run my finger over it I can see the missing lines coming back. This ribbon cable comes from the glass substrate that is on the other side of the green circuitboard. It is somehow heatpressed / soldered to the green circuitboard.

Applying pressure fixes the problem. Because I don’t want to try and fix this with a soldering iron (never attempted a repair like this..) I thought why not make something that puts pressure on the connector… so I fired up TinkerCad and drew this:Switched on my 3D printer and printed the part. 😎 After an hour it was done and I installed the part. Fits perfectly:Perfection 🙂

I turned the keyboard over and switched it on…No change at all.I was now looking at the 14th YouTube video of someone trying to fix this problem (on a Gameboy or something else) with a soldering iron wrapped in aluminium foil.

What to do… leave it like this or attempt to repair with a soldering iron and risk destroying the display (and the keyboard)?

Some people used a simple soldering iron at 300C and dipped it in water before applying heat, wrapping it in aluminium foil and what not. Very sketchy. There where some professionals showing how to do this but this required expensive equipment. Another video showed someone doing this with a temperature of 150C and putting a piece of baking paper (the stuff you put underneath your pizza before you put it in the oven) between the tip of the soldering iron and the flat cable.

I have a temperature regulated soldering iron and baking paper so f*ck it. I’m trying this.

I changed the tip of the soldering iron from a very sharp tip to one with a flat spot so I could apply the heat to a slightly larger area. Then I set my soldering iron to 125C and started.

Gently going over a 1 cm stretch of lines and making sure the paper was in between the iron and the flat cable at all times. I kept the keyboard on so I could turn it around once in a while to check if this was going somewhere. I gradually increased the temperature to 180C and then I started to see results. At this temperature it still seemed impossible to burn a hole through the flatcable so that wasn’t worrying me at that time. I applied heat rubbing the iron over a 1 cm stretch for a few seconds and then pressed on the area with my finger to try and create a bond between the flex cable and the circuitboard. More and more lines came back and after fiddling with this for about 15 minutes:

Yeah baby! 100% result!

I don’t know if 180C is hot enough to create a lasting result so I will check the keyboard the next couple of weeks to see if the display stays good. I still had the 3D printed part I made and I thought: why not install this as backup.. So I did and now I’m hoping this is a permanently lasting result. The GW-7 is back alive! 🙂

I’m so glad I tried this 🙂 it wasn’t very difficult and the result is insanely rewarding 🙂

Edit: here is the Thingyverse link to the 3d printable bracket:

https://www.thingiverse.com/thing:5190549

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