DX7 has no sound

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Angel0pdx
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Re: DX7 has no sound

Unread post by Angel0pdx » Thu Mar 26, 2020 10:44 pm

Oh yeah, my friend who gave it to me says it worked when it was put in storage, in a flight case.
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Kropjesla
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Re: DX7 has no sound

Unread post by Kropjesla » Thu Mar 26, 2020 11:14 pm

Angel0pdx wrote:
Thu Mar 26, 2020 10:43 pm
My recently acquired DX7 has no sound. Upon startup the screen finishes out with

internal voice
Int 1 Hammond B

But there is no sound through the output and to my PA, and with headphones in the headphones Jack I only get a crackle when I move the volume slider.

I know nothing about this synth, but I’m guessing there is a specific combination of buttons that tell it to play from the internal data and send sound out when the keys are pressed. What is that combination?
I'm not sure what you mean, but you can get an initialized sound (sine-wave) by pressing Function (brown) and 10
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Miks
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Re: DX7 has no sound

Unread post by Miks » Thu Mar 26, 2020 11:42 pm

Kropjesla wrote:
Thu Mar 26, 2020 8:11 pm
Is the synth already loaded with (some) sounds? Is it possible to choose between them? Are the voice's (=sounds) names appear to be shown correctly on the synth's display? Are you able to send sounds from a computer (whatever model) via Midi to the DX?
yes I reloaded the factory presets via a memory-cartridge, all the buttons work, I can change sounds, edit, rename etc. I should be able to send sounds from my mac but I have to look into it...
That's fine! That leaves me confident that the DX 'should' work...
its a labnation connected to a mac
https://www.lab-nation.com/
http://wiki.lab-nation.com/index.php/Ma ... ser_Manual
I do not have the logic analyzer cable
Uh - that's a piece of gear I don't know...! Do you have the probes for it?
My (key related) gear (in alphabetical order):
Ferrofish: B4000+
Kawai: K1 II
Korg: M1 (up'd to EX, w/ 'Cool Blue'), M1REX (w/ 'Cool Blue'), Poly-800
Roland: D-50, D-110, D-550, PG-1000
Yamaha: AW1600, DX7IID (w/ 'Cool Blue'), EX5R, RM50, RX5, SY99 (w/ 'Cool Blue'), TG500,
TX-802, YMM2
Sector101: SYEMB05 (5x), SYEMB06 (3x), EXFLM2 (1kit), MCD Sweet16 (1x), DataBlade32 (1x),
WaveBlade 8MB Card (1x) & 1x Programmer Unit for WaveBlade
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Miks
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Re: DX7 has no sound

Unread post by Miks » Fri Mar 27, 2020 12:16 am

@Kropjesla & @Angel0pdx:

Please make sure that your DX7's are set to 'Local ON' - NOT to 'Local OFF'

Check this by switching the synth ON, then press [Function] button and then the [8] button - if Local is OFF please set it to ON and see if the synth does make sound now...
My (key related) gear (in alphabetical order):
Ferrofish: B4000+
Kawai: K1 II
Korg: M1 (up'd to EX, w/ 'Cool Blue'), M1REX (w/ 'Cool Blue'), Poly-800
Roland: D-50, D-110, D-550, PG-1000
Yamaha: AW1600, DX7IID (w/ 'Cool Blue'), EX5R, RM50, RX5, SY99 (w/ 'Cool Blue'), TG500,
TX-802, YMM2
Sector101: SYEMB05 (5x), SYEMB06 (3x), EXFLM2 (1kit), MCD Sweet16 (1x), DataBlade32 (1x),
WaveBlade 8MB Card (1x) & 1x Programmer Unit for WaveBlade
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Kropjesla
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Re: DX7 has no sound

Unread post by Kropjesla » Fri Mar 27, 2020 9:36 am

Please make sure that your DX7's are set to 'Local ON' - NOT to 'Local OFF'

Check this by switching the synth ON, then press [Function] button and then the [8] button - if Local is OFF please set it to ON and see if the synth does make sound now...
The DX7 mk1 does not have a local on function unless you have a rom update I believe...

Probes, yeah those got!

where do I start? i was thinking the DAC, but I don't know where it is on the board...
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Kropjesla
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Re: DX7 has no sound

Unread post by Kropjesla » Fri Mar 27, 2020 10:19 am

is it IC42?
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Miks
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Re: DX7 has no sound

Unread post by Miks » Fri Mar 27, 2020 12:16 pm

Kropjesla wrote:
Fri Mar 27, 2020 10:19 am
The DX7 mk1 does not have a local on function unless you have a rom update I believe...
Sure? What happens if you press the [Function] button and then several times the [8] button - does the display show some different menues/functions to choose from? I could not say for sure due not having a DX7 Mk.I with me...
Is it IC42?
Yes, that's the DAC. I would suggest to initialize one of the sounds (and then store it!) to get a plain sine wave and then start withs the measurings.

Clip one of the ground wires to one of the probes, set the probe's switch to x1 and connect the probe to one of the SmartScope's input channels - I suggest to use channel A. Look for a ground potential near the DAC on the mainboard - you could also use Pin13 of the DAC - and connect the probe's ground wire there. Take care not to schort-cut any other contacts/pins! This may result in further damage(s) and could leave the mainboard unrepairable! Be aware that all you're doing you do at your own risk! Now take a piece of cardboard, fold it several times to 'thicken' it, insert it carefully into the gap between the C3 and D3 keys on the keyboard (you may use the gap between B2 and C3 as well) and press down the C3 key so it will stay pressed down 'on its own' - if you see what I mean. Doing this way you'll have a sort of third hand... :wink:

Set the SmartScope's software to Analog Mode. Now you can put the tip of the probe to either Pin18 or 19 of the DAC (IC42) (again take care not to shortcut any pins!) and see if the scope shows any kind of sine signal on your Mac's screen... For correct voltage and/or timebase scalings please refer to the scope's user manual. Come back with the result(s).
My (key related) gear (in alphabetical order):
Ferrofish: B4000+
Kawai: K1 II
Korg: M1 (up'd to EX, w/ 'Cool Blue'), M1REX (w/ 'Cool Blue'), Poly-800
Roland: D-50, D-110, D-550, PG-1000
Yamaha: AW1600, DX7IID (w/ 'Cool Blue'), EX5R, RM50, RX5, SY99 (w/ 'Cool Blue'), TG500,
TX-802, YMM2
Sector101: SYEMB05 (5x), SYEMB06 (3x), EXFLM2 (1kit), MCD Sweet16 (1x), DataBlade32 (1x),
WaveBlade 8MB Card (1x) & 1x Programmer Unit for WaveBlade
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Kropjesla
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Re: DX7 has no sound

Unread post by Kropjesla » Fri Mar 27, 2020 2:17 pm

Ok before I started I had to find out which pins of the IC were which

so this is the voltages I found after I measured the using the multimeter.
keeping the black lead on earth-connection

pin 20 -5,1V
pin 17 15,26V
pin 16 13,88V
pin 15 0V
pin 13 0V

all other pins had some kind of low voltage so I asume these are pins 1 - 12

the scope results of pin 1-12 were all similar
Doesn't look like any sine to me...
Attachments
Pin 19.png
Pin 19
pin 18.png
Pin 18
Pin 12.png
Pin 12 (similar to 1-11)
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Kropjesla
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Re: DX7 has no sound

Unread post by Kropjesla » Fri Mar 27, 2020 2:19 pm

just tested it again on pin 18 and 19
not playing any note or playing a different notes makes no difference in output
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Miks
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Re: DX7 has no sound

Unread post by Miks » Fri Mar 27, 2020 2:30 pm

Question: do you still have that expansion card installed in your DX7? If so - does it show any message when you power up the synth - and if, what's the message? Is that card only plugged in or is/are there any additional wire(s) soldered between the card pcb and the DX's mainboard?
My (key related) gear (in alphabetical order):
Ferrofish: B4000+
Kawai: K1 II
Korg: M1 (up'd to EX, w/ 'Cool Blue'), M1REX (w/ 'Cool Blue'), Poly-800
Roland: D-50, D-110, D-550, PG-1000
Yamaha: AW1600, DX7IID (w/ 'Cool Blue'), EX5R, RM50, RX5, SY99 (w/ 'Cool Blue'), TG500,
TX-802, YMM2
Sector101: SYEMB05 (5x), SYEMB06 (3x), EXFLM2 (1kit), MCD Sweet16 (1x), DataBlade32 (1x),
WaveBlade 8MB Card (1x) & 1x Programmer Unit for WaveBlade
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Kropjesla
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Re: DX7 has no sound

Unread post by Kropjesla » Fri Mar 27, 2020 4:59 pm

Miks wrote:
Fri Mar 27, 2020 2:30 pm
Question: do you still have that expansion card installed in your DX7? If so - does it show any message when you power up the synth - and if, what's the message? Is that card only plugged in or is/are there any additional wire(s) soldered between the card pcb and the DX's mainboard?
No additional wires,
I can just take it out if I want (I think I also have the original ic's)

The welcoming message says

Eigenhuijsen
XJMemory 128

Eigenhuijsen is a music shop nearby that probably provided this chipset. (Nijmegen)
I myself live in Gennep (Netherlands)
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IMG_3971.JPG
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Miks
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Re: DX7 has no sound

Unread post by Miks » Fri Mar 27, 2020 5:32 pm

Kropjesla wrote:
Fri Mar 27, 2020 4:59 pm
Miks wrote:
Fri Mar 27, 2020 2:30 pm
Question: do you still have that expansion card installed in your DX7? If so - does it show any message when you power up the synth - and if, what's the message? Is that card only plugged in or is/are there any additional wire(s) soldered between the card pcb and the DX's mainboard?
No additional wires,
I can just take it out if I want (I think I also have the original ic's)
That would have been my next question - if you have the original DX7 firmware at hand...
The welcoming message says

Eigenhuijsen
XJMemory 128
Ah ok...

My suggestion would be: to carefully take out the expansion and put the original DX7 firmware IC back - just to have a 'genuine' DX7 to work with. Thereafter switch ON the synth and see wether its working correctly or not.

You don't know the firmware version of the genuine DX7's chip, do you? If you (or someone you know) are/is able to program (= 'burn') an appropriate Eprom (27C128) I can send you the latest firmware version (which is v.1.8) for your synth. Let me know if you want it...
My (key related) gear (in alphabetical order):
Ferrofish: B4000+
Kawai: K1 II
Korg: M1 (up'd to EX, w/ 'Cool Blue'), M1REX (w/ 'Cool Blue'), Poly-800
Roland: D-50, D-110, D-550, PG-1000
Yamaha: AW1600, DX7IID (w/ 'Cool Blue'), EX5R, RM50, RX5, SY99 (w/ 'Cool Blue'), TG500,
TX-802, YMM2
Sector101: SYEMB05 (5x), SYEMB06 (3x), EXFLM2 (1kit), MCD Sweet16 (1x), DataBlade32 (1x),
WaveBlade 8MB Card (1x) & 1x Programmer Unit for WaveBlade
User avatar Netherlands
Kropjesla
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Re: DX7 has no sound

Unread post by Kropjesla » Fri Mar 27, 2020 9:08 pm

I switched to the original IC-set, but the results are the same.

I'm not sure why I would want a newer eprom, except for the added local on function maybe...
anyway
after switching the IC's reloading the sounds
initializing the current sound and playing (or not playing) a middle C3 still the same results in the scope.
therefore I think the problem is not the memory-extention-set.

Maybe the test-result is just a noise-floor (it is quite faint in comparison with pins 1-12)

so what does that mean?
either there are no notes registered, but I doubt that, the output still produces a very faint sound like I described before:
The more notes I play the higher the tone gets I thus conclude that the mididata does reach the board.
It makes no difference if I play them on the keyboard or use the midi-in.

So what's next?
shall I put the other IC's in or keep the originals for now?
what parts should I measure next?

Thank you for your help so far!
Attachments
here you can here the "note getting higher with every note I play
test-output DX7 27-3-2020.mp3
(318.69 KiB) Downloaded 6 times
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Miks
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Re: DX7 has no sound

Unread post by Miks » Fri Mar 27, 2020 10:10 pm

Kropjesla wrote:I switched to the original IC-set, but the results are the same.
I'm not sure why I would want a newer eprom, except for the added local on function maybe...
You don't need a newer Eprom if you don't want one - I just wanted to make sure that the extension card is not the cause for the malfunction.
So what's next? Shall I put the other IC's in or keep the originals for now?
I would leave the originals in for now.
what parts should I measure next?
Hard to say - I'm no real expert when it comes to electronics - and little by little I'm running out of ideas... 8O Thing is I have no DX7 Mk.I at hand to do some testings/measurings myself that eventually could be helpful...
My (key related) gear (in alphabetical order):
Ferrofish: B4000+
Kawai: K1 II
Korg: M1 (up'd to EX, w/ 'Cool Blue'), M1REX (w/ 'Cool Blue'), Poly-800
Roland: D-50, D-110, D-550, PG-1000
Yamaha: AW1600, DX7IID (w/ 'Cool Blue'), EX5R, RM50, RX5, SY99 (w/ 'Cool Blue'), TG500,
TX-802, YMM2
Sector101: SYEMB05 (5x), SYEMB06 (3x), EXFLM2 (1kit), MCD Sweet16 (1x), DataBlade32 (1x),
WaveBlade 8MB Card (1x) & 1x Programmer Unit for WaveBlade
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Angel0pdx
Posts: 4
Joined: Thu Mar 26, 2020 10:30 pm

Re: DX7 has no sound

Unread post by Angel0pdx » Sun Mar 29, 2020 1:00 am

Miks wrote:
Fri Mar 27, 2020 12:16 am


Please make sure that your DX7's are set to 'Local ON' - NOT to 'Local OFF'

Check this by switching the synth ON, then press [Function] button and then the [8] button - if Local is OFF please set it to ON and see if the synth does make sound now...
It’s set for midi ch=1. How do I set it to local /on?
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