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I bought my Yamanha DX7 with this problem.

The INTERNAL MEMORY presets had scrambled named and wouldn't play any sound.

INTERNAL VOICE 7 INTERNAL VOICE 9

Reading the different threads on the web, I figured this was due to the battery although the BATTERY CHECK showed 4.3V.

BATTERY CHECK

Before I attempted to change the battery, I first reloaded the INTERNAL MEMORY with sounds.

Loading sounds to Yamaha DX7

Hereafter the steps found on http://bobbyblues.recup.ch

Set your DX7

  1. Button FUNCTION then button 8 then set MIDI CH=1 i.e. Use the data entry slider or button YES/NO
  2. Button 8 again then set SYS INFO AVAIL with button YES
  3. Button INTERNAL MEMORY PROTECT then set to OFF with button NO

Soundbank transfer to your DX7

Used a Macbook Pro + SysEx Librarian with a Cahaya Midi USB Interface 5 Pin Din Plug Cable for PC/Mac

  1. Run your SysEx transfers program on your computer and load or open (depending on the program you are using) the SysEx file you want to transfer
  2. Choose "SysEx send" (or the appropriate option) on your SysEx transfers program
  3. You must then see MIDI RECEIVED on your DX7/TX7 display (transfer is OK)

This operation restored my internal memory, but the next day the presets were gone again and the label were scrambled.

The battery still showing 4.3V

So I decided to attempt the battery change.

Battery change

DX7 Opened

I ordered a 3V - CR2032 solder pin for Yamaha DX7 found on eBay.

Battery eBay

I followed the instruction found on the NEGATRON BLOG

On my first attempt, I soldered the battery to 2 wires instead of directly soldering to the board, in order to allow the operation to be easier the next time if needed.

wired battery

I closed DX7 but I didn't do the BATTERY CHECK, so I don't know if showed correct.

I loaded the new presets (using MIDI/USB interface) and all looked fined. I turned ON/OFF the DX7 + un/plugged it and checked the INTERNAL MEMORY and the presets were there.

I thought I had resolved it but an hour later the presets were scrambled again. i.e. No sound.

The battery change didn't help. BATTERY CHECK showed 4.3V ??? instead of 3V.

I read further and the first comment of the blog page, Kevin described my issue. BATTERY CHECK showing 4.5V instead of 3V.

That's when I decided to give my soldering another go. Interestingly Kevin says:

the trace coming off of the positive terminal of the battery that was supposed to connect to the next component had a gap in it in this kind of shape: —||—

I had also noticed that and I had bridged the battery pin to the diode...

On my second attempt, I removed the mainboard again and this time, I added more solder to look like on the picture on the blog

Closed the DX7, powered it and BATTERY CHECK showed 3V!!! YEAH!

...BUT the next day, I switched on my DX7 to my disappointment, the internal memory is corrupt again and to my surprise BATTERY CHECK showed 4.3V ???

Why would the BATTERY CHECK show 3V after replacement and 4.3V the next day?

Any pointers of what may be happening?

UPDATE

A minute ago the BATTERY CHECK was showing 3V again. I touched my wires and it fluctuated!

Looks like it might be my soldering or bad wires.

I removed the battery completely BATTERY CHECK showed 4.3V! Wired it again and it's now showing 3V. Let's see if that keeps the memory overnight.

3V

  • I highly suggest you edit out the whole story leading up to your question and just ask your question. We don't need to know the process for loading sounds. – Todd Wilcox Jan 8 '18 at 21:14
  • I will reorganize the question, the history behind the question is important though – zabumba Jan 8 '18 at 21:22
  • I skipped it and I still understand your question. To me it's just noise. You changed the battery but for some reason it's still not storing the presets correctly. That's pretty straightforward. – Todd Wilcox Jan 8 '18 at 21:26
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    There may be a capacitor that helps the battery - they tend not to last as long as the DX7 has been around. – Tim Jan 9 '18 at 9:58
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    You just need more souls. Everyone knows the DX7 runs on human souls. – jjmusicnotes Jan 9 '18 at 15:00
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When the battery is not connected, DX7 BATTERY CHECK shows 4.3V

Check that you have wired/soldered properly the new battery, it should show 3V.

Also this comment in the blog helped a great deal

the trace coming off of the positive terminal of the battery that was supposed to connect to the next component had a gap in it in this kind of shape: —||—

Another lead is to check/replace the capacitor "that helps the battery" as suggested by @Tim in the comment section

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