# Yamaha DX7 locked in Change Battery mode **URL:** \ **Category:** Synth Repair\ **Created:** [December 26, 2024, 7:46pm UTC](https://forums.syntaur.com/t/yamaha-dx7-locked-in-change-battery-mode/8245 "2024-12-26T19:46:53Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![LouBourbon](https://forums.syntaur.com/user_avatar/forums.syntaur.com/loubourbon/32/2040_2.png) [@LouBourbon](https://forums.syntaur.com/u/LouBourbon)\ **Post date:** [December 26, 2024, 7:46pm UTC](https://forums.syntaur.com/t/yamaha-dx7-locked-in-change-battery-mode/8245/1 "2024-12-26T19:46:54Z")
Hello community. This is my first post although I always lurk here looking for great info. I have a DX7 MK1 (completely stock) that is locked in the “Change Battery” screen even after replacing the battery. None of the buttons will work to get it out of this mode. (For comparison, I have removed the battery from a recently repaired and working DX7 and it does not lock in this mode when the battery is removed. Pressing “cartridge” or “internal” will release this battery mode and the synth can actually be used.) I have gone down the rabbit hole of replacing the diode, cap, and the two transistors in the battery circuit, to no avail. I’ve also tested all resistor values in this circuit and have also made sure that the @ 3.2 volts from the new battery is getting to the ROMs and continuity on these traces is perfect. Also, all voltages are correct coming off the power supply. I feel that perhaps a processor someplace is bad. The board looks good. No damage anywhere and I’ve been extremely careful with my soldering (I’ve been repairing stuff since the late 80s). I’m not great with digital circuitry though. I was wondering if anyone had any leads, advice, insight, on what my be the issue? ---
**Author:** ![krips](https://forums.syntaur.com/letter_avatar_proxy/v4/letter/k/a587f6/32.png) [@krips](https://forums.syntaur.com/u/krips)\ **Post date:** [July 5, 2026, 3:38am UTC](https://forums.syntaur.com/t/yamaha-dx7-locked-in-change-battery-mode/8245/2 "2026-07-05T03:38:38Z")
Hi! Did you ever figure out what was wrong? I seem to have this exact issue. ---
**Author:** ![Travis](https://forums.syntaur.com/user_avatar/forums.syntaur.com/travis/32/1382_2.png) [@Travis](https://forums.syntaur.com/u/Travis)\ **Post date:** [July 8, 2026, 10:30pm UTC](https://forums.syntaur.com/t/yamaha-dx7-locked-in-change-battery-mode/8245/3 "2026-07-08T22:30:20Z")
Check this schematic. To the left of the RAM chips on the schematic there are some components. If any of these are faulty, you’d likely see the battery voltage drop low even with a new healthy battery. Check the battery voltage with the unit off. It should be about 3 to 3.3 V to the left of D4 and around 2.4 to 2.7 V on the right side of D4. ![image](https://forums.syntaur.com/uploads/default/original/2X/6/6eee0bd4697e0766f58e21199cd4b17b5dfa8048.png) Next check that the ADC is receiving the battery voltage on pin 4 IC11. It will only measure about 1.5 V because of the highlighted 10 M resistor (typical multimeter input impedence is 10 M so it creates a voltage divider between the resistor and multimeter which divides the voltage in half). ![image](https://forums.syntaur.com/uploads/default/original/2X/d/dffe01f0796baa72f6e6075512cc064eb3423687.png) ![image](https://forums.syntaur.com/uploads/default/original/2X/d/d5296047692ac18c2a53de74bb124f1c4268099e.png) I’m fairly sure the DX7 MK1 _should_ let you continue past the “Change Battery” screen but I don’t quite remember for sure. If everything checks out fine and the battery voltage is making it to the ADC then it might be a deeper issue causing it to freeze. I recommend checking out your power supply and making sure it’s all healthy as well, if anything is out of spec weird glitches can happen. ---
**Author:** ![krips](https://forums.syntaur.com/letter_avatar_proxy/v4/letter/k/a587f6/32.png) [@krips](https://forums.syntaur.com/u/krips)\ **Post date:** [July 9, 2026, 10:38pm UTC](https://forums.syntaur.com/t/yamaha-dx7-locked-in-change-battery-mode/8245/4 "2026-07-09T22:38:48Z")
First off, thanks for helping! I just got around to testing it. With the board out of the dx7 and the battery attached. I tested the battery voltage of the to the left and right of the d4. It shows: Left 3.298v Right 3.291v I also tested using the dedicated diode test on the multimeter. It shows around 0.3v - 0.4v Next, as you suggested I tested the IC11 voltage on pin 4 of IC11. It shows around 0.443v. I assume I should go about changing the diode first. What should I replace it with? ---
**Author:** ![Travis](https://forums.syntaur.com/user_avatar/forums.syntaur.com/travis/32/1382_2.png) [@Travis](https://forums.syntaur.com/u/Travis)\ **Post date:** [July 10, 2026, 4:23am UTC](https://forums.syntaur.com/t/yamaha-dx7-locked-in-change-battery-mode/8245/5 "2026-07-10T04:23:41Z")
I have a working DX7 MKI at home. I will measure those same voltages in mine and get back to you. The voltage at the DAC seems low in yours but I cant be sure until I check mine. The diode test on your multimeter only gives a good reading if one leg of the diode is lifted (because the battery is applying power to the circuit) but no need do that yet. I’ll get back to you soon on how mine measures.