Time flies, it’s been one and a half year since I started this project and progress is slow. Though there is progress!
Battery change, service V8.3 upgrade
In March I discovered a battery leak in the PPG Wave 2 and decided to send that board to Virtual Music for repair. I also did the same with corresponding 2.2 board. Since the V8.3 firmware upgrade goes on the same board I sent the chips as well. Besides the battery change, the 2.2 also got a little service.
Today, nine months later, I decided to put the card back in the 2.2 and it started right up! Great success on that and I feel that the hardware is now serviced. Focus will now be on the racking process.
Rack measurement
A year ago I also purchased a rack chassis. I bought a 6U rack with the widest inner width I could find. The inner width is 434 mm and the outer width is 436 mm.
I’ve also done a lot of measurements of the PPG and rack, and right now I’m feeling very hopeful. There were two main obstacles, both having to do with the width.
The first one was the fact that the original LCD and the “button board” simply wouldn’t fit. With the newer LCD, that will not be a problem. The board is around 240 mm and the lcd is 182 mm. That means more than 10 mm margin.
The second one, and this still needs to be solved, is the 2.2 motherboard. The width is 435 mm which is 1 mm wider than the inner width. I see two ways of solving this:
Use washers or some other kind of spacer on each side to move the side panels a few millimeter outwards. According to my measurements I could probably gain 6-8 mm by doing this
Shave off the motherboards right edge – from what I can tell it’s probably possible to shave off around 2-4 mm of the motherboard. In a way, I feel this is kind of risky, but on the other hand the rack case will be properly assembled.
No matter what route I take, there’s one thing that also has to be modified. On the motherboard’s other edge, there are two pin headers that have a 90 degree angle. They need to be desoldered and straightened up, otherwise the connectors will hit the side panel. They can’t be bent when soldered to the board since they’re very thick.
I think the best thing to do next is to simply test fit the board in the case and actually see how many mm that are missing!
2.2 board at the top, 2 board at the bottom.
The I/O Memory board is back in the PPG
The new battery
The two motherboard headers must be desoldered and bent upwards.
Ugly, but at least it’s serviced and fully working!
The 2.2 booted without any problems and the new display is nice!
Sooner or later the battery will go dead on a TF1 module. It has a standard 3V CR2032 Lithium battery that can be found everywhere. When the voltage drops to low, the TF1 will fail to hold it’s memory and all patches and settings will disappear. Unlike the DX7, each TF1 doesn’t have a cartridge reader, but similar to the DX7 there’s no ROM memory. If you lose or edit the patches, the only way to get the factory patches back is to transfer them by sysex from a computer or another DX7. The TF1 lits the error led and displays a 4 if the battery voltage is too low.
The error led is lit and the alpha numeric display shows a 4. This means error number 4 = low battery. At the top and bottom you can see the hex screws that need to be unscrewed.
As with a lot of synths from the early eighties, when patch memory was a novelty, the battery is soldered to the TF1’s circuit board. So it has to be desoldered to be changed. Then the new battery must be soldered back. One alternative is to put a CR2032 battery holder there instead, then next time no soldering will be required. I chose the battery holder path.
First you have to remove the TF1 module and it’s actually very easy to do. Unscrew two Philips screws on the back, and two screws with 2.5mm hex heads (IKEA style, but smaller) at the front. Then push the card from the back so it pops out of the front. Pull it gently towards you without using any force, it should go smooth.
The TF1 module is nearly out.
I desoldered the old battery and used a solder sucker to remove the old solder. I then measured the distance between the two holes to approximately 16 mm.
Battery is unsoldered.The space between the battery’s legs is 16 mm. Unfortunately I could only find battery holders with 19 mm space.
Unfortunately I couldn’t find a holder with 16 mm distance between it’s pins, 19 mm was all I could find (bought here). Fortunately the pins were quite long, so I managed to bend them inwards enough for them to fit and penetrate the holes.I then soldered the battery holder and put the battery back.
Look closely to see the bent pins (19 -> 16 mm conversion).
A quite simple operation. I think it’s worth the extra time and cash ($2) with a battery holder. That time will be spared next time the battery must be changed.
The error led is lit and the alpha numeric display shows a 4. This means error number 4 = low battery. At the top and bottom you can see the hex screws that need to be unscrewed.
The lid does not have to be removed for this operation, however this photo shows how well built and modular the TX-816 is.
The TF1 module is nearly out.
Here’s a good overview of the TF1 board. This is equivalent to one Yamaha DX7! The battery is very easy to reach.
Another view of the battery.
The board from behind, the battery is soldered with two joints (+ and -).
Backlit board from underneath. It’s easy to spot the battery. Better make sure to unsolder the right thing.
Battery is unsoldered.
The space between the battery’s legs is 17 mm. Unfortunately I could only find battery holders with 19 mm space.
The battery holder is soldered in place.
Look closely to see the bent pins (19 -> 17 mm conversion).
New battery in place.
I noticed that two of the capacitors were bulging. They should probably be replaced soon.
I recommend this site for more info on the TX-816.
Today I did two things on my DMX that should have been done long ago.
First task was to solder in a new battery. The old battery was removed a couple of months ago, but I never put in the new one (bought from Electrongate). Since I don’t think it’s a good idea to solder the new battery in the same spot due to possible leaking disasters, I soldered two new wires. The battery was then placed in the bottom right corner and insulated with tape.
A non working Chinese iPhone charger cable was used. The battery is placed down to the right, far away from the board.
The next thing to do was installing the Midi upgrade from Electrongate. My Midi upgrade was actually a special order – normally you place the Midi jacks on one of the walnut side panels. I didn’t want to do it for two reasons;
I prefer to have all connections at the rear and second
And most important – mine are mint. It would be shame to drill in them
So I mailed Paul, the owner of Electrongate, asking if it was possible to get the Midi jacks in a breakout box instead. To avoid drilling holes, Paul made a special cable that goes from the Midi board to the 12-pin Molex that was used for triggering. Then the breakout box was connected to the trigger Molex. A very neat solution – the trigger in functionality was sacrificed – on the other hand I don’t need it when I have Midi.
This breakout box is a special order. Since the walnut panels are mint on my DMX I asked Paul for an alternative. He suggested to use the trigger input port back to get the midi cable through without drilling.This cable is also part of my special order. One side goes to the midi card, the other goes to the cable that is connected to the trigger Molex.
Installing the kit is fairly straight forward, there’s an excellent guide with photos that is very simple to follow (so I didn’t take any photos). My DMX had the memory upgrade board, in the guide the upgrade is performed on a non memory upgraded DMX, so there were some differences, however – they are pointed out in the text. The Midi board replaces the memory upgrade board and a bonus is that the Midi board actually upgrades the memory as well.
The midi upgrade card itself.
The installation procedure is mostly about taking chips from one place (the main board or memory board) and putting them on the Midi board. I recommend having both an IC puller and a small flat screw driver for this. The hardest part of the upgrade is soldering two tiny wires (“E1” and “F1”) to the main board. It was hard because in one case you have to solder the wire directly to a copper lane, in a very tight place. Another challenge is to cut the copper lane next to it, and then avoid soldering the wire over the cut so that the cut isn’t cut anymore.
I’m not a soldering expert, but if you know someone that can do it for you, or if you live close to Paul, pay him to do it for you! It took me a couple of hours, and I wasn’t very comfortable cutting and soldering on such an old expensive piece. On the other hand, doing such stuff is the best way to learn.
I took the DMX back to the studio and connected the Midi – it worked flawlessly! Even though the DMX is very fun and easy to program, it’s just more convenient to have Midi. I really feel that I have to modify my Boss DR-110!
The box, yet to be unboxed.
Receipt…
Nice packaging!
A new NiCd battery.
Thumbscrews for the front of the DMX and standoffs for the Midi upgrade card.
The midi upgrade card itself.
This breakout box is a special order. Since the walnut panels are mint on my DMX I asked Paul for an alternative. He suggested to use the trigger input port back to get the midi cable through without drilling.
This cable is also part of my special order. One side goes to the midi card, the other goes to the cable that is connected to the trigger Molex.
I ordered some extra Molexes for future “tuning experiments”…
The DMX is opened and ready for surgery.
The battery was removed right after I bought the DMX, since I believe it was the original battery.
This is the minus joint that I will solder the battery cable to.
This is the new nickel cadmium battery. These tend to leak when they get old. A lot of old Korg Polys have died because of this.
A non working chinese iPhone charger cable was used. The battery is placed down to the right, far away from the board.
The Midi board is installed. In the standard kit from Paul the connectors “IN” and “OUT” goes to the Midi jack console that is normally mounted on the right walnut panel. In this special order, these instead go to another connector. (see next photo)
The TRIGGER IN cable was removed from the board and instead connected to the special cable from Paul.
This is the custom made breakout Midi box, connected to the the TRIGGER IN Molex that no longer go to the main board inside, but instead to the Midi board.
