Tag Archives: battery

Changing battery on the TX-816

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.
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.
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.
Battery is unsoldered.
The space between the battery's legs is 16 mm. Unfortunately I could only find battery holders with 19 mm space.
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).
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.

I recommend this site for more info on the TX-816.

Battery mod and Midi upgrade in Oberheim DMX

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.
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;

  1. I prefer to have all connections at the rear and second
  2. 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 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.
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 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!