DX7 Mk1 - Stuck in Bootscreen

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joneskey98
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DX7 Mk1 - Stuck in Bootscreen

Unread post by joneskey98 » Sun Oct 14, 2018 9:11 pm

Hello everyone!

I have just bought a non working DX7 today. With the intention, to just have to replace the battery, i thought i've made a bargain. But it still measured 3V and looks like it was already replaced at some point.

Long story short... When I power it on, the LED shows 88 and the Display says *Yamaha DX7 Synthesizer* And it is stuck in this state, no matter what i try. But every 5 seconds, for a really short period of time, it says "Memory Protect Cartrige On" or something like that. (it is very hard to read)

I hope, i'm in the right place to find somebody to help me. I'm good at electronics, and have all the testequipment, but don't know where to start searching.

I already checked:
-Power supply
-Voltages at the Chips
-Clock Signals at the chips

I also disconnected all of the connectors in different combinations, still the same.

It also does the same without the RAM chips installed.

Does somebody have a clue, what might be damaged?
And also sorry if my english is not so good... i'm from germany and a little bit rusty

Thanks!
Jonas
Last edited by Miks on Tue Oct 16, 2018 12:12 pm, edited 1 time in total.
Reason: typo
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parametric
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by parametric » Mon Oct 15, 2018 1:41 am

Hi joneskey98 and welcome to the forums . . . .

From memory, hold down [FUNCTION] [16] and [32] at the same time and power on.

I think this does a reset . . . . .

Our member <Miks> is from Germany and is very knowledgeable about the DX7.

I'm sure he will be along shortly with more suggestions . . .

ATB

parametric
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by purcell » Mon Oct 15, 2018 1:45 am

Ask Miks ! Even as PM?

I hope you get in contact with Miks - already today!

Übrigens sind Miks und ich auch Deutsche!
Vereinfacht die Unterhaltung! :lol:

Viel Glück! Miks und Du schaffen das Problem!
Da bin ich mir absolut sicher!

Gute Nacht!

Das waren noch Zeiten! Allein die grünen Plastikschalter/tasten :mrgreen: ...

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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by joneskey98 » Mon Oct 15, 2018 5:12 am

Oke, erstmal vielen Dank! Genau so Jemanden suche ich!
Trotzdem werde ich erstmal hier die Diskussion hier offen lassen, anstatt über PM zu gehen. So können Leute mit ähnlichem Problem auch mitlesen, oder es findet sich jemand der bereits eine Lösung dafür hat. :wink:

Außerdem habe ich gerade erfahren, dass ich von der Arbeit erstmal bis Freitag Unterwegs bin. :roll:
Ich kann also erst am Wochenende dann meine Hausaufgaben erledigen :lol:
Aber ich hab nochmal schnell Bilder und Videos rund um den Synth und sein Verhalten gemacht... Somit kann ich auch die ein oder andere Frage beantworten.

Edit:
@parametric I already tried all of the known button combinations. I think the problem is, that the synth gets reset before it even can load that menu. My guess is, that the RAM or ROM chips are corrupted. But I'm not sure with that.

Grüße,
Jonas
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by Rara » Mon Oct 15, 2018 11:02 am

When I had a DX7 many years ago, it had the same problem as you described. It was caused by a failed clock chip.
somewhere near the CPU from memory.

Rara 0-)
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by Miks » Mon Oct 15, 2018 11:12 am

I've read somewhere on the web that a female electronic technician named Wendy repaired a DX7 which fell off a stand from 4 ft. height causing the crystal being damaged - the display was showing '88' and the LC-Display showed a row of blocks...

Also make sure that the output voltages from the PSU are 'plain' - which means showing very little to no ripples!
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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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by joneskey98 » Mon Oct 15, 2018 5:12 pm

As some of you mentioned a bad clock signal... I don't think that is the case here. Without the clock signal, the display could not be initialized and text could not be displayed.
Rara wrote:
Mon Oct 15, 2018 11:02 am
When I had a DX7 many years ago, it had the same problem as you described. It was caused by a failed clock chip.
somewhere near the CPU from memory.

Rara 0-)
Was that the exact same problem as mine? Because as I mentioned, all of the clock related problems i've seen so far result in black boxes on the screen. Or did you also get the startup message displayed.

@Miks
Thanks for your PM! I havn't quiet figured out, how i can answer to that. But I will read through all of the stuff you sent me. I tested the power supply already. Everything within specs.

In order to save some time later, i will order a new rom chip (there is this special edition one on ebay)
and the capacitors for the mainboard and the power supply. They still look good, but I don't trust them. I also try to find some new ram chips.

I also have the full scematic printed out. I will go through and mark some possible points of failure

In case somebody has a DX7 on the bench right now, it would be very helpfull if you can power it on without the two ram chips installed. Mine does the exact same thing with the static text on the display, with or without the ram!
Maybe my Ram is bad.

Greetings!
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by joneskey98 » Mon Oct 15, 2018 7:46 pm

Sorry for double-posting but the edit function is not working on my phone... I looked over the whole schematic and found another suspect. 8O

There is a white wire coming from the power supply board. It drives the reset function for the whole synth. (marked section)
IMG_20181015_202411.jpg
When i measured it last sunday, it was reading around 1.8V to ground. (If I remember correctly)
Is that normal?

And BTW: Thanks for everyone trying to help me! I'm so glad that there are people like you around!
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by Miks » Tue Oct 16, 2018 12:32 am

joneskey98 wrote:In case somebody has a DX7 on the bench right now, it would be very helpfull if you can power it on without the two ram chips installed.
Sorry, can't be of help on that due not having a DX7 Mk.I - I own a DX7II/D :?
and the capacitors for the mainboard and the power supply. They still look good, but I don't trust them.
Good idea - capacitors often tend to look good but they aren't really! Lost capacity & a high ESR are things you don't see - but that can be measured using the appropriate equipment...
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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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by purcell » Tue Oct 16, 2018 2:16 am

Hello everyone!

I have just bought a non working DX7 today.
----------------------------------------------------
Finde ich ungewöhnlich.
Das erstaunt mich irgendwie...!
Da ich so etwas nie tun würde.

So ähnlich: Ich habe mir ein kaputtes Radio gekauft!
Was ich auch nie getan hätte.

Klar! Verstanden! Wenn nur eine Batterie gewechselt werden müsste...!
Dann wäre es ein guter Kauf.

Viel Glück weiterhin!

IHR SCHAFFT DAS !!!
-----------------------------
Info DX7 Safety Warning

https://yamahamusicians.com/yamaha-dx7- ... y-warning/
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by joneskey98 » Tue Oct 16, 2018 11:38 am

purcell wrote:
Tue Oct 16, 2018 2:16 am
Hello everyone!

I have just bought a non working DX7 today.
----------------------------------------------------
Finde ich ungewöhnlich.
Das erstaunt mich irgendwie...!
Da ich so etwas nie tun würde.

So ähnlich: Ich habe mir ein kaputtes Radio gekauft!
Was ich auch nie getan hätte.

Klar! Verstanden! Wenn nur eine Batterie gewechselt werden müsste...!
Dann wäre es ein guter Kauf.

Viel Glück weiterhin!

IHR SCHAFFT DAS !!!
-----------------------------
Info DX7 Safety Warning

https://yamahamusicians.com/yamaha-dx7- ... y-warning/
Hab ich schon öfters so gemacht. Meine ganzen Gitarren Amps hab ich alle als defekt gekauft. Meistens habe ich tatsächlich auch nur einen Bruchteil davon bezahlt, was das Zeug funktionierend kostet.

@Miks Ich habe mir zwar bereits einen neuen Rom Chip bestellt, aber ich glaube mich zu erinnern irgendwo noch einen Eprom Brenner zu haben. Allerdings ein sehr altes modell... warscheinlich mit parallelport oder so :mrgreen:
Aber nur zum Spaß kann ichs ja mal probieren. Wäre also echt cool wenn du mir die Datei zukommen lässt.

Ansonsten werde ich einfach heute Abend nochmal den gesammten Schaltplan durchgehen und mögliche Fehlerquellen anmerken. Und sonst kann ich wohl erst am Wochenende wieder was machen, da ich dann wieder Zuhause bin. Ich glaube ich fange dann gleich mal mit den Kondensatoren an.

If somebody knows what Voltage the white wire from the power supply should carry, let me know!

Greetings!
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by joneskey98 » Tue Oct 16, 2018 3:12 pm

Erstmal Danke Miks für die Daten!
Aber trotz deiner Anleitung funktioniert das Antworten auf PMs immer nochnicht. Bei mir gibt es keinen "send reply" Button irgendwo... Entweder schaltet man diese Funktion erst ab einer bestimmten Anzahl an Posts frei (um zB. vor Spam zu schützen) oder es liegt daran, dass ich momentan das Forum nur per Handy aufrufen kann.

Vielleicht können wir ja auch per Email weitere Dinge besprechen. Da bin ich ganz offen :mrgreen:

Ansonsten habe ich mich jetzt erstmal mit Kondensator-Sets fürs Netzteil, und der Hauptplatine und einem neuen Romchip eingedeckt. Gleich dazu habe ich mir mal eine neue Ram-Batterie und für den Fall der fälle den Quarz
geholt. Ich hoffe mal, dass ich damit das Probleme lösen kann, denn neue Ram Chips dauern ca 2 Monate bis diese geliefert werden.

Grüße!
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by Miks » Tue Oct 16, 2018 3:19 pm

joneskey98 wrote:
Tue Oct 16, 2018 3:12 pm
Aber trotz deiner Anleitung funktioniert das Antworten auf PMs immer nochnicht. Bei mir gibt es keinen "send reply" Button irgendwo... Entweder schaltet man diese Funktion erst ab einer bestimmten Anzahl an Posts frei (um zB. vor Spam zu schützen) oder es liegt daran, dass ich momentan das Forum nur per Handy aufrufen kann.
Yes, that could be one of the reasons why it still don't work... :?
Ansonsten habe ich mich jetzt erstmal mit Kondensator-Sets fürs Netzteil, und der Hauptplatine und einem neuen Romchip eingedeckt. Gleich dazu habe ich mir mal eine neue Ram-Batterie und für den Fall der fälle den Quarz geholt. Ich hoffe mal, dass ich damit das Probleme lösen kann, denn neue Ram Chips dauern ca 2 Monate bis diese geliefert werden.
OK. I'll keep my fingers crossed that it just needs some new capacitors for the PSU and (eventually) a 'new' firmware chip... 8)
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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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by Rara » Tue Oct 16, 2018 4:20 pm

joneskey98 wrote:
Mon Oct 15, 2018 5:12 pm
As some of you mentioned a bad clock signal... I don't think that is the case here. Without the clock signal, the display could not be initialized and text could not be displayed.
Rara wrote:
Mon Oct 15, 2018 11:02 am
When I had a DX7 many years ago, it had the same problem as you described. It was caused by a failed clock chip.
somewhere near the CPU from memory.

Rara 0-)
Was that the exact same problem as mine? Because as I mentioned, all of the clock related problems i've seen so far result in black boxes on the screen. Or did you also get the startup message displayed.
Sorry i missed your reply, it was both actually, normal text on start up then freeze with black squares.
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Re: DX7 Mk1 - Stuck in Bootscreen

Unread post by joneskey98 » Tue Oct 16, 2018 4:46 pm

Rara wrote:
Tue Oct 16, 2018 4:20 pm
joneskey98 wrote:
Mon Oct 15, 2018 5:12 pm
As some of you mentioned a bad clock signal... I don't think that is the case here. Without the clock signal, the display could not be initialized and text could not be displayed.
Rara wrote:
Mon Oct 15, 2018 11:02 am
When I had a DX7 many years ago, it had the same problem as you described. It was caused by a failed clock chip.
somewhere near the CPU from memory.

Rara 0-)
Was that the exact same problem as mine? Because as I mentioned, all of the clock related problems i've seen so far result in black boxes on the screen. Or did you also get the startup message displayed.
Sorry i missed your reply, it was both actually, normal text on start up then freeze with black squares.
Ok that is kinda interesting. On another forum i found a very recent post from somebody having the exact same problem as me. They also mentioned capacitors could be the problem.
Greetings!
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