New Screen Replacement Option

Yamaha SY77 is a 16 voice multitimbral music workstation first produced by Yamaha Corporation in 1989. The SY77 is a synthesizer whose architecture combines AFM (Advanced Frequency Modulation) synthesis, AWM2 (Advanced Wave Memory 2) for ROM-borne sample-based synthesis, and the combination of these two methods christened Realtime Convolution and Modulation Synthesis (RCM).

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Svanis1337
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Re: New Screen Replacement Option

Unread post by Svanis1337 » Thu Mar 31, 2016 2:44 am

Hello everyone! I successfully completed this mod on my TG77. Picture story here: https://goo.gl/photos/pkCEKPGY3GrjxJPJ9
I used a White/Blue 240x64 Arduino display as linked earlier in this thread. If you read the datasheet, (http://www.buydisplay.com/download/manu ... asheet.pdf) you will find that there are many wild colors available that aren't listed on the website! To order them, you'll have to ask specifically, it states this in the datasheet. There's black and red, inverted color schemes and all sorts of crazy stuff!

It was a very simple install. You can follow the existing guide by Derek Cook at http://www.xfactory-librarians.co.uk/Do ... pgrade.pdf

HOWEVER, there is no need to drop the 5V power supply, since the Arduino display from BuyLCD takes 5V. We also found no need to move the diodes behind the LCD, even though it's 12.6mm vs the "too thick" Newhaven display at 12.3mm. Although we put some electrical tape over the diodes anyway.

I bought the LCD with the option to have the header soldered on. Do not do this! It uses an uncommon 22-pin connection. We took the old 20-pin header from the original Optrex DMF5005n display and soldered it to the connections 1-20 on the Arduino display. Then we could simply use the old cable and connect the new LCD. Pins 21 and 22 on the Arduino are for the +5V Anode and 0V Cathode which we solder onto the LCD card from the TG77's 5V supply, so they're redundant. Buying a 20-pin header and ribbon cable would be much easier. You can't simply unplug the cable from the old Optrex display since it's soldered onto the card.

For the R476 resistor, we crafted a 5.8k resistor to replace it like SYmon recommended.

Some people have had problems removing the outer output knob. There's no point in forcing it out with pliers and ruining the plastic, just push it out from the inside while pulling and it'll pop out! Easy!

We've encountered a few problems though, which we will look into. The left arrow key is kind of stuck, but it still works, and the plastic window with the TG77 logo which goes over the display is bulging slightly outwards, but not too much. I suppose this could possibly be remedied by moving the diodes to the other side as explained in the tutorial. As for the arrow key, it's probably just stuck somehow. EDIT: Tightened some screws related to the display and this fixed the button.

Now the TG77 is a rackmounted unit, and unfortunately all the replacement displays including the Arduino have a viewing angle of 6:00. This means it's viewed best from an angle straight infront of and/or slightly below the screen. I don't really know if there's a way to remedy this. Let me know! You could put some foam under it and stand it at an angle, have it on a shelf slightly above your head or buy a slanted, angled rack case for it, I suppose.
Now the contrast is not perfect. It's only good when at one extreme of the contrast knob. We tried a 5.6k resistor and a 6.6k resistor but it made the screen either too dark or too light. SY77/99 owners talk about replacing TWO resistors, 158/159. Why is this? And what would the equivalent be for the TG77? I've only ever read of people replacing resistor 476 on the TG77.

For SY77/99 users I think this display is a no brainer. It's just much simpler to install than the Newhaven display, and doesn't seem to have as much of an issue with thickness. It's also cheaper. I don't know the difference in quality between the Newhaven and Arduino displays, but I can't imagine there being any substantial differences. In real life the Arduino display is really bright and the color of the backlight is light blue. My Iphone had a hard time focusing because it's so bright, as you see in the photo story, But it looks pretty much like this: (Picture borrowed)
Image
Last edited by Svanis1337 on Fri Apr 01, 2016 9:04 pm, edited 2 times in total.
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Derek
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Re: New Screen Replacement Option

Unread post by Derek » Thu Mar 31, 2016 5:25 pm

Well done! And it's a better option if it takes 5V directly.
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Derek Cook

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radiolite22
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Re: New Screen Replacement Option

Unread post by radiolite22 » Sun Apr 17, 2016 8:24 pm

Pins 21 and 22 on the Arduino are for the +5V Anode and 0V Cathode which we solder onto the LCD card from the TG77's 5V supply, so they're redundant. 
Hi,

Do you mean that we can tap the power directly from cn605 and solder them directly to pin 21 (for positive) and pin 22 (for ground)?

Or do we still make use of power from psu XG966?

Hope to clarify on this before I place my order on the new display for my TG77.

Thanks

Regards,
Keith
Svanis1337
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Re: New Screen Replacement Option

Unread post by Svanis1337 » Sun Apr 17, 2016 11:32 pm

Yes that is correct. Use the 5V supply and send it directly into the LCD, there is no need for the XG966 board. It is useless. It's simply there because the old display couldn't function correctly without it, the newer displays don't need it. It might look different to your synth in the photo story because the previous owner had made a modification where you could short-circuit the inverter to turn the backlight foil off on the old display and get rid of the hum. That's why the wires are cut. When you are done it should look similar to the old display:

Image
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zerocharisma
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Re: New Screen Replacement Option

Unread post by zerocharisma » Fri Jul 08, 2016 2:56 pm

HI all, new member here and a proud new owner of a used TG77 that I am just ecstatic about. However, I'm not too ecstatic about the LCD so I'm really glad I found this thread. I will definitely be giving this DIY screen replacement a try!
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Derek
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Re: New Screen Replacement Option

Unread post by Derek » Fri Jul 08, 2016 4:42 pm

hello and welcome. You won't regret doing the upgrade :)
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Derek Cook

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zerocharisma
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Re: New Screen Replacement Option

Unread post by zerocharisma » Fri Jul 22, 2016 10:08 pm

Can anyone point me to where I can order the right value resistor and 1 x 20 pin header? Thanks in advance!
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Re: New Screen Replacement Option

Unread post by Derek » Sat Jul 23, 2016 8:48 am

Hi,

Assuming by 'Murica you mean America? Then what about Tandy or RadioShack? Or similar electronic component distributors. If you Google "electronic components america" then you get a few hits back.

It looks like RS Components (the company I buy parts from in the UK has American distribution http://www.alliedelec.com/
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Derek Cook

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zerocharisma
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Re: New Screen Replacement Option

Unread post by zerocharisma » Tue Jul 26, 2016 11:55 pm

Thank you, Derek!
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rluijend
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Re: New Screen Replacement Option

Unread post by rluijend » Mon Nov 07, 2016 7:50 pm

Hi,

I finally dared to replace my TG77 screen too.
I used Derek's manual and followed up on all advises given by Svanis1337. Thanks a lot to both of you!

The biggest challenge was de-soldering the connector from the old display. With some patience I succeeded and re-used it for the new display. I ordered the display without header, just like Svanis1337 advised, and it was easy to reconnect the old connector in pins 1-20. Pins 21,22 are not used and the A and K from the new display were powered by the 5V coming from CN605 connector. For R476 I used a 10K potmeter. I've drilled a hole in the back of the synth next to the old brightness control knob. That works great!
There was no need to replace the diodes nor issues with buttons. It all worked and re-assembled as I hoped it would. I'm a happy man now!

Now that my inverter board has no wires connected anymore it finally stopped making the HF noise that frustrated me for a long time. Another good reason to do this display replacement.

Thanks to all who shared their experiences and encouraged me to start my own project too.

Ruud
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r0main
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Re: New Screen Replacement Option

Unread post by r0main » Thu Dec 01, 2016 1:21 pm

Dear Ruud, I also just replaced my screen. Unfortunately still got a contrast problem, even after replacing R476 with a 10k pot. Any tip or schematics to share?
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acemonvw
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Re: New Screen Replacement Option

Unread post by acemonvw » Mon Mar 06, 2017 9:56 pm

Hello everyone, new SY77 user here - looking to upgrade my screen.

A lot of tutorials are out there, and they're very good. I believe I am just not technically literate enough with electronics to understand these tutorials or comments in the threads like these. Can someone tell me whether I'm on the right track?

Parts:
New screen: http://www.buydisplay.com/default/5-2-i ... k-on-white
New Resistor? - 10K variable resistor
New 20-pin IDC pins and cable (or remove old one), like this? https://www.newegg.com/Product/Product. ... lsrc=aw.ds

1) To get power to the new screen, you'd use the red/black leads that I believe are just soldered wires on the old LCD. These should then be soldered to pin 21 (red) and pin 22 (black) - there is no "A" or "K" designations in this screen. Does the other end just plug back in to the same spot it plugged into originally? I would imagine so.

2) You need to replace a resistor on one of the boards (DM1 board?). It's resistor 158 or 159 - people mention both resistors in this thread, though the tutorials do not mention replacing any resistors at all (See here: http://www.xfactory-librarians.co.uk/Do ... pgrade.pdf). I see people mentioning specific values for resistors but also variable resistors (I assume to change the contrast)?

I can do basic soldering, but it's very easy to get lost in the details. :(

Thanks for your help.
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greensweater
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Re: New Screen Replacement Option

Unread post by greensweater » Sun Mar 12, 2017 5:13 am

Another successful SY77 upgrade, thanks to these forums. The PDF linked at the beginning of this thread is great. The only thing it doesn't mention is changing the resistor for the contrast.

Image
Image

So many screws and connectors! The wire connectors snap into the holders with little teeth. With a jeweler's screwdriver, you can pry open the holders slightly to easily remove the connectors.

I got the BuyDisplay white-on-blue, SKU ERM24064SBS-1. Using desoldering braid, I removed the header from the old display for reuse. I also reused the power supply wiring as described in the article, soldering red to K and black to A on the new display, and then attached to CN118 (I measured -5V red-to-black). Luckily my display had extra solder points marked A & K on the opposite end of the board, which made things a bit easier. The traces went back to pins 21 & 22. The spec sheet says pin 21 is A and pin 22 is K. http://www.buydisplay.com/download/manu ... asheet.pdf

I used a 10K trim pot ($1 at Radio Shack) set to 5.6K, and replaced R159. I'm 100% satisfied with the appearance of the contrast.

I also replaced the old battery with a repurposed CR2032 battery holder from an old PC motherboard. I don't have a floppy belt, oh well, next time. Took me about five hours. Saturday afternoon well spent.
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greensweater
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Re: New Screen Replacement Option

Unread post by greensweater » Sun Mar 12, 2017 5:32 am

acemonvw:

Do you have the display already? Mine had A&K pins on the left side, which made it much easier to connect. Otherwise, red goes to pin 22 (K) and black goes to 21 (A). (Normally A would be red but it's reversed, I guess that's just the way they did it...)

The 10K trim pot can be adjusted from 0 to 10K. I measured the leads with a voltmeter to dial it in to 5.6K before I swapped it out with R159. I used a trim pot so that if I needed to tweak it afterwards I could just turn the little screw, rather than having to resolder anything, but 5.6K was perfect in my case. I can still adjust the contrast further using the contrast knob on the rear of the unit, so I have no reason to ever touch the trim pot again.

I used this trim pot, I just broke off the front lead: https://www.radioshack.com/products/rad ... er-trimmer
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greensweater
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Re: New Screen Replacement Option

Unread post by greensweater » Sun Mar 12, 2017 5:37 am

Also, regarding the 20-pin connector ribbons... I think that will work, but you'll need a header as well, something like this, but with 20 pins:
Image
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