7908...I nearly burnt myself

How hot can the 7908 get before I should start to worry? Everything else seems to work just fine. Just the 7908 can boil water half a second after powering on.

Your input is 9V AC? I’m surprised because this is certainly not the one that gets warmer (100mA x a dropout of 5 or 6V = much less than 1W to dissipate).

Yes it’s AC. :x

sounds like you are shorting the -8V rail to ground somewhere. Check the resistance betwen -8V and gnd

Indeed I am. I suppose I can swap a 1N5819 for a 5817? There’s one inverse (D5).
Feeling like an idiot right now.
Now the next problem - No LEDs light up on midi input. Did I fry something? There’s proper 5V on the Atmel, dunno what else I could measure. But no midi input indicator on the display.

Okay nevermind I did fry the 7908. Hopefully not the voice cards with -8V actually being +10V

So with a new 7908 in place and correct voltages, the voice cards are still not doing anything. I tried all 6 of em and on each the LEDs light up very very dim, other than that, nothing happening.

I checked the ISP connections from the voice card headers to the motherboard ISP header, the SS layer connections to the 74138 and everything seems fine.
Sent note on/off on all channels and the LCD shows it’s recieving them, but the voice cards stay dark.
I wonder why there’s 220 ohm between the motherboards ISP connections and the voice cards?

My only guess now would be a faulty 74138…Or could it be the Atmels aren’t programmed?
Hm, nope, I just programmed a voice card without a problem.
I’ll pick up a 74hct138 tomorrow, but if that doesn’t work I’m out of ideas.

> I wonder why there’s 220 ohm between the motherboards ISP connections and the voice cards?

To isolate the SPI bus from the ISP programmer while a voicecard is being programmed. See AVR910.

If you’ve had a lot of failed power on/off, the voicecards might have locked themselves in firmware update mode. If you don’t have a programmer, try upgrading them from the SD card.

Like I said, I freshly programmed one, same symptoms though. And sine this is happening with all voice cards, although jumpers are in place, I think I can only blame the logic on the motherboard.
What signal would cause the data LED to light up? The SS signal coming from the 74138, no? I’m assuming it’s normal that both LEDs light up so dimly that it’s barely noticeable.

Should something happen if I simply apply 5v to SS?

> I’m assuming it’s normal that both LEDs light up so dimly that it’s barely noticeable.

This is not normal.

The LEDs are controlled by the MCU. The MCU lights up the orange LED when it receives a valid command from the SPI bus, so it’s not just a matter of putting a line to ground or to +5V…

I’m out of ideas then. The LEDs light up brighter if I remove either the 74138 or the jumper.
I suppose the Atmel is working fine, since I could flash it…LEDs aren’t inverse either.

Flashing from SD-Card did the trick
I have no idea why a successful ISP flashing didn’t work but I’m surely happy as hell right now.

I had pretty much copy-pasted the stuff you wrote for flashing from ISP, changing only my programmer accordingly.

I think what happened is that the voicecards locked themselves in firmware update mode due to numerous failed power on/off cycles. I am not sure how you flashed them from ISP, but the flashing procedure might have written just the flash, not the eeprom with the necessary flags to put the voicecard out of update mode.