Is it possible to operate the RX in general? Of course without sound, but is it possible for example to select patterns or to select a sound for a voice?
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On 15.02.23 15:50, googdyamaha wrote: Thank you
Cannot be triggered via midi, cannot send midi via daw, and no sound.
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Thank you
Cannot be triggered via midi, cannot send midi via daw, and no sound.
?
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Hello Valeri,
Can you play it by sending MIDI-notes to it?
Florian
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On 15.02.23 14:53, googdyamaha wrote: rx11 no sound. I cleaned the keys, replaced the battery, still no sound. I've tried factory settings and self-test mode, still no sound. Can you provide a little clue?
（Sorry for my bad English）
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Rx11 no sound. I cleaned the keys, replaced the battery, still no sound. I've tried factory settings and self-test mode, still no sound. Can you provide a little clue?
It's a miracle that I don't have any repair experience.
It turns out that broken transformer windings can cause a machine to have no sound. My transformer had been hurt by the previous owner and had 3 broken wires, which I carefully connected with tin solder, and the unthinkable happened - I heard sound.
Thank you all for your enthusiasm.
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Re: TX802 troubleshooting
Thank you for sharing that! I have a broken DX7II lying around I could salvage those ASICs from if I have to.
In my case, I am pretty sure the OPS2 cannot be broken. It takes the following inputs:
- operator frequency - operator amplitude - key on - algorithm
And it produces digital audio samples as output.
Basically, the EGM tells the OPS2 "produce a sample with your current algorithm at pitch X and amplitude Y". Functional testing (listening to the outputs) proves that my OPS2 can do this job. It is functioning as expected.
I can't tell yet if the EGM is functioning as expected. To decide that I need to see if its receiving correct inputs or not. This is what I have ordered a logic analyzer for. If the EGM inputs look correct then it must be broken itself and I will replace it. But because it is such a rare IC, I am reluctant to replace it speculatively. Desoldering is not risk free.
Jacob
I had the same issue with DX7II-FD (which has the same FM engine like TX802). It turned out to be a faulty OPSII chip: YM2604. After replacing the chip the noise issue has been fixed. Finding a brand new or even used YM2604 is impossible these days. My story was related to 10 years ago and I had access to an old Japanese Yamaha service center that had only one set of brand new EGM/OPSII. These chips are very sensitive to short circuit on pins, be careful to not touching them with your tools while TX-802 is turned on otherwise you will damage those in less than a second and make your synth useless forever.
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Re: TX802 troubleshooting
I had the same issue with DX7II-FD (which has the same FM engine like TX802). It turned out to be a faulty OPSII chip: YM2604. After replacing the chip the noise issue has been fixed. Finding a brand new or even used YM2604 is impossible these days. My story was related to 10 years ago and I had access to an old Japanese Yamaha service center that had only one set of brand new EGM/OPSII. These chips are very sensitive to short circuit on pins, be careful to not touching them with your tools while TX-802 is turned on otherwise you will damage those in less than a second and make your synth useless forever. 
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Re: TX802 troubleshooting
yes, the easiest is swapping board(s) from a working unit and
compare.
You?ll find out what works in your broken synth and is good for
spares in future.
Once you got a working machine, you?ll use that anyway
Quick status update.
- PSU recap: no effect
- Upgrade all EPROMs: no effect
- Replace secondary CPU SRAM: no effect
I feel like I'm at the point where I should do what PeWe said and buy
a TX802 that is not broken. However, I'm still curious, so I ordered a
cheap logic analyzer on Ebay. I want to see what data goes into the
EGM.
To be continued.
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Re: TX802 troubleshooting
Quick status update.
- PSU recap: no effect
- Upgrade all EPROMs: no effect
- Replace secondary CPU SRAM: no effect
I feel like I'm at the point where I should do what PeWe said and buy
a TX802 that is not broken. However, I'm still curious, so I ordered a
cheap logic analyzer on Ebay. I want to see what data goes into the
EGM.
To be continued.
Op zo 5 feb. 2023 om 13:16 schreef Jacob Vosmaer <contact@...>:
toggle quoted message
Show quoted text
Thanks Daniel! The TX802 roms are there.
Op zo 5 feb. 2023 om 03:34 schreef Daniel Forro <danforcz@...>:
You can find Eprom data also here:
If it doesn’t work, I can send you it as well.
BTW, one of Eprom keeps preset patches data, somebody did different selection. I have this version, too.
Good luck.
Daniel Forró
On Feb 5, 2023, at 4:04, contact@... wrote:
Hi Grant,
Op za 4 feb. 2023 om 14:54 schreef grantpbt <grantbt@...>:
Two things to avoid: dismissing input from Daniel Forro and making
assumptions. This is first and foremost electronic troubleshooting.
I am not dismissing Daniel's input, I am reacting to his suggestions.
I really appreciate that Daniel refers to actual problems that others
have had with the TX802, such as the output muting transistors.
Check all the Power Supply voltages. I have seen an increasing number of
Yamaha PSU failures which are happening because a LOT of the Yamaha
designs use a Switch Mode PS. I have been able to repair some of the
PSUs, but not all. There are many threads online discussing this or that
synth or effects unit needing PSU repairs and various successes and
failures.
Logical analysis clearly shows that the problem is in the digital
domain. Everything from the EGM chip on down functions correctly. So
the only power line that matters here is the 5V digital supply. I have
checked that, with an oscilloscope, and it looks fine.
Take a look at the block diagram of the TX802 on page 4/5 of the
service manual. Everything from the EGM on down is working correctly.
That also implies that the "master oscillator" works correctly: if it
didn't, you would never get clean sine waves (at the correct pitch!)
out of the outputs.
If you look on the left of the block diagram you see that the "master
MPU" runs on its own clock crystal. It is responsible for receiving
MIDI. If that clock was not running, or not running at the right rate,
incoming MIDI data would be garbled. MIDI works fine so I know that
clock crystal is fine.
I am not pro-cap replacement, but as far as the PSU is concerned this is
a common problem with them.
I agree. But this just doesn't look like a PSU problem. Remember that
the main CPU works fine. The synth responds to MIDI, I can use all the
buttons in the interface, the display works, there is no garbled text
in it. It does not crash.
The BIN files are everywhere.
I wish that were true. I have spent a lot of time looking already. The
only source I can find for the BIN files is
, where you have
to pay $10 a pop.
Do you know where to find them? The ROMs are called XB223, XB224 and XB536.
I agree that a byte for byte comparison is the right thing to do but I
only have those checksums. And unfortunately, that page does not have
the checksums for TX802 v1.2, which is what I have.
Reseating the EPROM was a good move. Sockets get dirty. Bad connections
cause a myriad of problems. Look at the schematics and Service Manual.
Thanks, I have spent a lot of time looking at the service manual
before I even posted here. That is how I know about the EGM and OPS2
chips.
Most of the Yamaha FM products have a huge similarity and some of the
Service Manuals are very helpful, others less so.
Thanks, I agree.
The DX7II is a close relative of the TX802. I have spent a lot of time
reading its service manual too. In spite of them having the same sound
generator ICs, the architectures of the two are different. In the
DX7II the primary CPU drives the EGM/OPS2 and the secondary CPU
handles keyboard inputs etc. In the TX802, the secondary CPU drives
the EGM/OPS. This makes the flow of data quite different. You can
clearly see this if you compare the block diagrams in the respective
service manuals.
The DX7/DX9 service manual has some high level information about the
EGS and OPS sound generator IC's. The IC's in the TX802/DX7II are
different however. For example, the old EGS has an 8 bit input address
bus. The new EGM has only a 5 bit address bus. We have to guess what
the inputs to the EGM exactly are.
The weird thing is that the EGM is getting input data that is mostly
correct (amplitude envelope rates are correct, amplitude L4 is
correct, pitch EG works correctly) and only incorrect in some places:
the output level and L1/L2/L3 of the operator amplitude envelopes.
I see no evidence on my scope that they are broken, but I think I will
try replacing the RAM chip of the secondary CPU and the 74HC138
address decoder that enables the EGM and OPS2 IC's. If I can get hold
of the bin files I will also replace the ROMs because it's easy to do.
Jacob
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Re: TX802 troubleshooting
Wow, your answer is very professional, this is a question that has been bothering me for a long time, and I finally found the answer today.??
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Re: TX802 troubleshooting
Some say it sounds better because of better DAC. And it can be improved more thanks to few new parameters.
Some patches which used MkI imperfections (intermodulation distortion, envelope delay time…) will not sound the same.
Daniel Forró
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On Feb 7, 2023, at 14:09, valerizimlichxxc21@... wrote:
Does importing the original patch from dx7I into 802 sound exactly the same as dx7I?
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Re: TX802 troubleshooting
Does importing the original patch from dx7I into 802 sound exactly the same as dx7I?
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Re: TX802 troubleshooting
Exactly this. Exactly right. ? L. ?
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From: [email protected] [mailto:[email protected]] On Behalf Of José Juan
Sent: Sunday, February 05, 2023 5:34 AM
To: [email protected]; m.tarenskeen@...
Subject: Re: [YamahaDX] TX802 troubleshooting? If you have to replace a bad cap on a PCB...., what makes you think that the other ones, with same age and build quality, are in perfect working condition? In my experience, replacing all capacitors, beyond the psu ones, makes a night and day difference not only to my ears, you get a trustable working machine with glorious sound for years to come. It's about the sound, in the end, and reliability. This is my way, and not necessarily the way for everybody. As example, JP-8000 may put some light. ? On Feb 4, 2023, at 5:31, José Juan wrote:
"Electrolytic capacitors are dead on most 80s Yamaha Roland Korg gear."
From reactions from some of the more experienced experts here I think I can conclude that statement highly exxagerated?
MT
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Re: TX802 troubleshooting
I?d have to double check cause it?s long time ago we had it on the
bench.
But can be it did ...
Am 05.02.2023 um 16:13 schrieb José
Juan:
@pewe?
Does your S-1100 give aes/ebu output?
|
Re: TX802 troubleshooting
No not true,- but there?s a difference between RESTORATION and
REPAIR !
You yourself named it below ...?
It?s great you own good gear in (hopefully) now excellent
condition,- but take care how much time you spend for restoration
and how much time is left to use the gear for music.
And leaves the question if you make enough money w/ that music,-
the/ your creations justifying the effort of restorations and
investments in gear.
P.
Am 05.02.2023 um 15:29 schrieb José
Juan:
I see... my way of doing restorations is not
very commonly accepted.
Not a problem for me to be alone with this, as
all my gear sound spectacular following my own way of doing
electronic restorations, so my personal needs of great
sounding musical instruments are fulfilled.
Good luck!
José Juan?
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Re: TX802 troubleshooting
@pewe?
Does your S-1100 give aes/ebu output?
El dom, 5 feb 2023, 16:08, PeWe < ha-pewe@...> escribió:
>>>
Funny enough this is why I also think
batteries should be soldered. :)
I already elaborated on this in my former/ last post in reply to
Daniel.
It?s doable to make it good an reliable.
I know that my chances of success are much lower on a
digital synth like the TX802 because of the proprietary IC's
and because I don't have a logic analyzer.
^^^^
THIS !
You?d need the right tools to move on,- but often and for a private
uswer, the right tools are way too expensive.
My humble repair shop is limited in this department too,- so I
wouldn?t be much help even you were livin? i the neighborhood.
With an analog synth I can chase the
control voltages using a single oscilloscope probe but in a
digital synth the "control voltages" are byte streams and
for that you need a logic analyzer.
I ran into the same issue w/ 1 of my AKAI S-1100.
It loads samples and programs, you can operate it, see cursor moving
in display, change parameters by pressing buttons and using the
rotatry pot, RAM works, converters work,- but no sound except a very
low level click in headphones when it receives a MIDI note.
the clock seems to be o.k. too ...
We also work w/ an oscilloscope,- but no chance to analyze the
control signals.
We might come back to it again,- but some time again, we gave up,
last but not least because we got the impression the issue must have
to do w/ these big 1xx contact/legs proprietary chips we weren?t
able to solder out and in anyway.
I own a heat gun for soldering too, but it?s not the best as also
not for professional repair shops working all day,- and you need a
lot of accessories for when you want to solder such parts and all
the SMD types too.
I?m a musician and it?s simply uneconomic to buy all of these toys.
... because I enjoy the fault finding.
I think big in that department too,- I always did.
OTOH, I?ll retire soon,- old eyes make problems reading blurry
schematics and service manuals,- same w/ music notation and even
wearing glasses.
ditto
PeWe
|
Re: TX802 troubleshooting
>>>
Funny enough this is why I also think
batteries should be soldered. :)
I already elaborated on this in my former/ last post in reply to
Daniel.
It?s doable to make it good an reliable.
I know that my chances of success are much lower on a
digital synth like the TX802 because of the proprietary IC's
and because I don't have a logic analyzer.
^^^^
THIS !
You?d need the right tools to move on,- but often and for a private
uswer, the right tools are way too expensive.
My humble repair shop is limited in this department too,- so I
wouldn?t be much help even you were livin? i the neighborhood.
With an analog synth I can chase the
control voltages using a single oscilloscope probe but in a
digital synth the "control voltages" are byte streams and
for that you need a logic analyzer.
I ran into the same issue w/ 1 of my AKAI S-1100.
It loads samples and programs, you can operate it, see cursor moving
in display, change parameters by pressing buttons and using the
rotatry pot, RAM works, converters work,- but no sound except a very
low level click in headphones when it receives a MIDI note.
the clock seems to be o.k. too ...
We also work w/ an oscilloscope,- but no chance to analyze the
control signals.
We might come back to it again,- but some time again, we gave up,
last but not least because we got the impression the issue must have
to do w/ these big 1xx contact/legs proprietary chips we weren?t
able to solder out and in anyway.
I own a heat gun for soldering too, but it?s not the best as also
not for professional repair shops working all day,- and you need a
lot of accessories for when you want to solder such parts and all
the SMD types too.
I?m a musician and it?s simply uneconomic to buy all of these toys.
... because I enjoy the fault finding.
I think big in that department too,- I always did.
OTOH, I?ll retire soon,- old eyes make problems reading blurry
schematics and service manuals,- same w/ music notation and even
wearing glasses.
ditto
PeWe
|
Re: TX802 troubleshooting
I see... my way of doing restorations is not very commonly accepted.
Not a problem for me to be alone with this, as all my gear sound spectacular following my own way of doing electronic restorations, so my personal needs of great sounding musical instruments are fulfilled.
Good luck! José Juan?
Agree 100%.
My 2kc worth:
Not all caps do the same function, have the same tolerances, or in some cases are even the right parts for the design. Example: previous generation Apple Time Capsules of which I've repaired many... the PSU dies because the 2 output caps they used were not up to spec for the temps they experience, which means they die within 2-3 years.
Most of the caps I've had to replace were in PSUs. But not always. In old analogue gear (such as my 30 year old monitor for my Atari ST) I decided to totally recap it, because a) a lot of the timings rely on caps being within spec which affect the stability and picture quality and b) if a cap goes in the flyback circuit, your flyback transformer usually explodes, which means an expensive part if you can find one or the monitor goes in the trash if not.
I've also had to replace all the surface mount caps on an Amiga 600, they were only about 20 years old at the time (which is quite young in cap terms that have had an easy life), and they were leaking acid which started eating away at the tracks on the PCB. I caught it just in time. Those caps have nothing to do with the PSU, but are in the video and audio circuits.
Anyway tl;dr, if you wanna replace all the caps and are happy paying the money and time cost, go ahead, but if you want to be a bit more efficient - a good visual inspection combined with some experience, and maybe also a capacitance/ESR meter for when you're not sure.
Jan.
On Sunday, 5 February 2023, 12:02:48 GMT, PeWe < ha-pewe@...> wrote:
I don?t like the sound of a JP-8000 at all,- with or without bad caps. To each his own. When it is your hobby collecting gear and doin? repairs,- perfect. When you made a livin? w/ music,- which requires almost perfect working gear all day,- you and your techs think different. You do what?s necessary, not more,- just because it saves time and money. And,- the most of malfunctioning gear on the used market comes from amateurs treating their gear like s##t. And a cap isn?t a cap, isn?t ... there are different ones and some have never to be replaced because they never dry out. The Oberheim Xpander is a good example for ! There were long discussions about when Yahoo Xpantastic existed and Oberheim expert Karl Schmeer (R.I.P) explained and helped. "reliability" ... A piece of gear is reliable as long as it works and BECOMES unreliable when it doesn?t work. When a repair job bring it back to life, that?s good. You might replace ALL the caps and then other parts fail ... Is that more reliable ? A recap doesn?t prevent from parts failure 100% ,- only a few. Am 05.02.2023 um 12:33 schrieb José Juan:
If you have to replace a bad cap on a PCB...., what makes you think that the other ones, with same age and build quality, are in perfect working condition?
In my experience, replacing all capacitors, beyond the psu ones, makes a night and day difference not only to my ears, you get a trustable working machine with glorious sound for years to come.
It's about the sound, in the end, and reliability.
This is my way, and not necessarily the way for everybody.
As example, JP-8000 may put some light.
Peace José Juan?
On Feb 4, 2023, at 5:31, José Juan wrote:
"Electrolytic capacitors are dead on most 80s Yamaha Roland Korg gear."
From reactions from some of the more experienced experts here I think I can conclude that statement highly exxagerated?
MT
Verzonden vanaf mijn Huawei mobiele telefoon -------- Oorspronkelijk bericht -------- Onderwerp: Re: [YamahaDX] TX802 troubleshooting Van: PeWe Aan: [email protected], danforcz@... Cc: Hi Daniel ! I agree 100%! Since my friend (tech) and me started to do inhouse repairs and service for all my gear many years ago, we never ever had to replace ALL capacitors in any machine, regardless of brand and type. Especially the old Yamaha gear was and still is very reliable. I?m 1st owner,- and my TX816 is still intact, my DX7mkII never failed and younger devices like TG77 and TG500 work flawlessly. Needles to say the same rules for the KX-76, KX-5, D-1500 and REV-7. Necessary service was usually battery change and soldering in battery holders, replacing a by roadies physically damaged display, tact switch replacements and PSU overhaul for REV-7. The TX816 might need a single new LED on one of the TF-1 modules and I think about replacing the original PSU w/ this one (if at all) ... WHEN we had to replace aged capacitors in other gear,- these belonged to the PSU always. AKAI S-1000 PSU capacitors leaked in both machines, S-1100 PSUs are different and didn?t. Ribbon cables and sockets are often culprits ... When cables and sockets aren?t available anymore, removing socket and solder the ribbon directly to the board was the simple solution. That happened w/ a Oberheim DPX-1 not playing a tone, not loading disks and showing cryptic stuff in display. So, PSU and ALL connections (soldering joints, sockets, plugs, ribbon cables) have to work 100% perfect before replacing anything else. Well, this thread is about TX802 which I don?t use, but I?d say, repair and service on electronic gear of that era isn?t soooo special and urgently depending on brand/model. Finding the cause of failure is the most difficult and time consuming,- and I won?t replace anything before being sure what it really is. The common buyer and user of used vintage gear is often not able to identify cause of failure because of lack of tech skills and missing tools for diagnostics (and repair). To save time it?s sometimes better buying a 2nd used machine and swap boards, then use the better one for work and the other for parts in future. :-) P. Am 04.02.2023 um 03:37 schrieb Daniel Forró via :
It is not recommended to replace all caps, only the bad ones. Service experts say: If it works, leave it so.
Daniel Forró
Electrolytic capacitors are dead on most 80s Yamaha Roland Korg gear.
|
Re: TX802 troubleshooting
Agree 100%.
My 2kc worth:
Not all caps do the same function, have the same tolerances, or in some cases are even the right parts for the design. Example: previous generation Apple Time Capsules of which I've repaired many... the PSU dies because the 2 output caps they used were not up to spec for the temps they experience, which means they die within 2-3 years.
Most of the caps I've had to replace were in PSUs. But not always. In old analogue gear (such as my 30 year old monitor for my Atari ST) I decided to totally recap it, because a) a lot of the timings rely on caps being within spec which affect the stability and picture quality and b) if a cap goes in the flyback circuit, your flyback transformer usually explodes, which means an expensive part if you can find one or the monitor goes in the trash if not.
I've also had to replace all the surface mount caps on an Amiga 600, they were only about 20 years old at the time (which is quite young in cap terms that have had an easy life), and they were leaking acid which started eating away at the tracks on the PCB. I caught it just in time. Those caps have nothing to do with the PSU, but are in the video and audio circuits.
Anyway tl;dr, if you wanna replace all the caps and are happy paying the money and time cost, go ahead, but if you want to be a bit more efficient - a good visual inspection combined with some experience, and maybe also a capacitance/ESR meter for when you're not sure.
Jan.
On Sunday, 5 February 2023, 12:02:48 GMT, PeWe <ha-pewe@...> wrote:
I don?t like the sound of a JP-8000 at all,- with or without bad caps. To each his own. When it is your hobby collecting gear and doin? repairs,- perfect. When you made a livin? w/ music,- which requires almost perfect working gear all day,- you and your techs think different. You do what?s necessary, not more,- just because it saves time and money. And,- the most of malfunctioning gear on the used market comes from amateurs treating their gear like s##t. And a cap isn?t a cap, isn?t ... there are different ones and some have never to be replaced because they never dry out. The Oberheim Xpander is a good example for ! There were long discussions about when Yahoo Xpantastic existed and Oberheim expert Karl Schmeer (R.I.P) explained and helped. "reliability" ... A piece of gear is reliable as long as it works and BECOMES unreliable when it doesn?t work. When a repair job bring it back to life, that?s good. You might replace ALL the caps and then other parts fail ... Is that more reliable ? A recap doesn?t prevent from parts failure 100% ,- only a few. Am 05.02.2023 um 12:33 schrieb José Juan:
If you have to replace a bad cap on a PCB...., what makes you think that the other ones, with same age and build quality, are in perfect working condition?
In my experience, replacing all capacitors, beyond the psu ones, makes a night and day difference not only to my ears, you get a trustable working machine with glorious sound for years to come.
It's about the sound, in the end, and reliability.
This is my way, and not necessarily the way for everybody.
As example, JP-8000 may put some light.
Peace José Juan?
On Feb 4, 2023, at 5:31, José Juan wrote:
"Electrolytic capacitors are dead on most 80s Yamaha Roland Korg gear."
From reactions from some of the more experienced experts here I think I can conclude that statement highly exxagerated?
MT
Verzonden vanaf mijn Huawei mobiele telefoon -------- Oorspronkelijk bericht -------- Onderwerp: Re: [YamahaDX] TX802 troubleshooting Van: PeWe Aan: [email protected], danforcz@... Cc: Hi Daniel ! I agree 100%! Since my friend (tech) and me started to do inhouse repairs and service for all my gear many years ago, we never ever had to replace ALL capacitors in any machine, regardless of brand and type. Especially the old Yamaha gear was and still is very reliable. I?m 1st owner,- and my TX816 is still intact, my DX7mkII never failed and younger devices like TG77 and TG500 work flawlessly. Needles to say the same rules for the KX-76, KX-5, D-1500 and REV-7. Necessary service was usually battery change and soldering in battery holders, replacing a by roadies physically damaged display, tact switch replacements and PSU overhaul for REV-7. The TX816 might need a single new LED on one of the TF-1 modules and I think about replacing the original PSU w/ this one (if at all) ... WHEN we had to replace aged capacitors in other gear,- these belonged to the PSU always. AKAI S-1000 PSU capacitors leaked in both machines, S-1100 PSUs are different and didn?t. Ribbon cables and sockets are often culprits ... When cables and sockets aren?t available anymore, removing socket and solder the ribbon directly to the board was the simple solution. That happened w/ a Oberheim DPX-1 not playing a tone, not loading disks and showing cryptic stuff in display. So, PSU and ALL connections (soldering joints, sockets, plugs, ribbon cables) have to work 100% perfect before replacing anything else. Well, this thread is about TX802 which I don?t use, but I?d say, repair and service on electronic gear of that era isn?t soooo special and urgently depending on brand/model. Finding the cause of failure is the most difficult and time consuming,- and I won?t replace anything before being sure what it really is. The common buyer and user of used vintage gear is often not able to identify cause of failure because of lack of tech skills and missing tools for diagnostics (and repair). To save time it?s sometimes better buying a 2nd used machine and swap boards, then use the better one for work and the other for parts in future. :-) P. Am 04.02.2023 um 03:37 schrieb Daniel Forró via :
It is not recommended to replace all caps, only the bad ones. Service experts say: If it works, leave it so.
Daniel Forró
Electrolytic capacitors are dead on most 80s Yamaha Roland Korg gear.
|
Re: TX802 troubleshooting
Thanks Daniel! The TX802 roms are there.
Op zo 5 feb. 2023 om 03:34 schreef Daniel Forro <danforcz@...>:
toggle quoted message
Show quoted text
You can find Eprom data also here:
If it doesn’t work, I can send you it as well.
BTW, one of Eprom keeps preset patches data, somebody did different selection. I have this version, too.
Good luck.
Daniel Forró
On Feb 5, 2023, at 4:04, contact@... wrote:
Hi Grant,
Op za 4 feb. 2023 om 14:54 schreef grantpbt <grantbt@...>:
Two things to avoid: dismissing input from Daniel Forro and making
assumptions. This is first and foremost electronic troubleshooting.
I am not dismissing Daniel's input, I am reacting to his suggestions.
I really appreciate that Daniel refers to actual problems that others
have had with the TX802, such as the output muting transistors.
Check all the Power Supply voltages. I have seen an increasing number of
Yamaha PSU failures which are happening because a LOT of the Yamaha
designs use a Switch Mode PS. I have been able to repair some of the
PSUs, but not all. There are many threads online discussing this or that
synth or effects unit needing PSU repairs and various successes and
failures.
Logical analysis clearly shows that the problem is in the digital
domain. Everything from the EGM chip on down functions correctly. So
the only power line that matters here is the 5V digital supply. I have
checked that, with an oscilloscope, and it looks fine.
Take a look at the block diagram of the TX802 on page 4/5 of the
service manual. Everything from the EGM on down is working correctly.
That also implies that the "master oscillator" works correctly: if it
didn't, you would never get clean sine waves (at the correct pitch!)
out of the outputs.
If you look on the left of the block diagram you see that the "master
MPU" runs on its own clock crystal. It is responsible for receiving
MIDI. If that clock was not running, or not running at the right rate,
incoming MIDI data would be garbled. MIDI works fine so I know that
clock crystal is fine.
I am not pro-cap replacement, but as far as the PSU is concerned this is
a common problem with them.
I agree. But this just doesn't look like a PSU problem. Remember that
the main CPU works fine. The synth responds to MIDI, I can use all the
buttons in the interface, the display works, there is no garbled text
in it. It does not crash.
The BIN files are everywhere.
I wish that were true. I have spent a lot of time looking already. The
only source I can find for the BIN files is
, where you have
to pay $10 a pop.
Do you know where to find them? The ROMs are called XB223, XB224 and XB536.
I agree that a byte for byte comparison is the right thing to do but I
only have those checksums. And unfortunately, that page does not have
the checksums for TX802 v1.2, which is what I have.
Reseating the EPROM was a good move. Sockets get dirty. Bad connections
cause a myriad of problems. Look at the schematics and Service Manual.
Thanks, I have spent a lot of time looking at the service manual
before I even posted here. That is how I know about the EGM and OPS2
chips.
Most of the Yamaha FM products have a huge similarity and some of the
Service Manuals are very helpful, others less so.
Thanks, I agree.
The DX7II is a close relative of the TX802. I have spent a lot of time
reading its service manual too. In spite of them having the same sound
generator ICs, the architectures of the two are different. In the
DX7II the primary CPU drives the EGM/OPS2 and the secondary CPU
handles keyboard inputs etc. In the TX802, the secondary CPU drives
the EGM/OPS. This makes the flow of data quite different. You can
clearly see this if you compare the block diagrams in the respective
service manuals.
The DX7/DX9 service manual has some high level information about the
EGS and OPS sound generator IC's. The IC's in the TX802/DX7II are
different however. For example, the old EGS has an 8 bit input address
bus. The new EGM has only a 5 bit address bus. We have to guess what
the inputs to the EGM exactly are.
The weird thing is that the EGM is getting input data that is mostly
correct (amplitude envelope rates are correct, amplitude L4 is
correct, pitch EG works correctly) and only incorrect in some places:
the output level and L1/L2/L3 of the operator amplitude envelopes.
I see no evidence on my scope that they are broken, but I think I will
try replacing the RAM chip of the secondary CPU and the 74HC138
address decoder that enables the EGM and OPS2 IC's. If I can get hold
of the bin files I will also replace the ROMs because it's easy to do.
Jacob
|
Re: TX802 troubleshooting
I don?t like the sound of a JP-8000 at all,- with or without bad
caps.
To each his own.
When it is your hobby collecting gear and doin? repairs,- perfect.
When you made a livin? w/ music,- which requires almost perfect
working gear all day,- you and your techs think different.
You do what?s necessary, not more,- just because it saves time and
money.
And,- the most of malfunctioning gear on the used market comes from
amateurs treating their gear like s##t.
And a cap isn?t a cap, isn?t ...
there are different ones and some have never to be replaced because
they never dry out.
The Oberheim Xpander is a good example for !
There were long discussions about when Yahoo Xpantastic existed and
Oberheim expert Karl Schmeer (R.I.P) explained and helped.
"reliability" ...
A piece of gear is reliable as long as it works and BECOMES
unreliable when it doesn?t work.
When a repair job bring it back to life, that?s good.
You might replace ALL the caps and then other parts fail ...
Is that more reliable ?
A recap doesn?t prevent from parts failure 100% ,- only a few.
Am 05.02.2023 um 12:33 schrieb José
Juan:
toggle quoted message
Show quoted text
If you have to replace a bad cap on a PCB....,
what makes you think that the other ones, with same age and
build quality, are in perfect working condition?
In my experience, replacing all capacitors,
beyond the psu ones, makes a night and day difference not only
to my ears, you get a trustable working machine with glorious
sound for years to come.
It's about the sound, in the end, and
reliability.
This is my way, and not necessarily the way for
everybody.
As example, JP-8000 may put some light.
Peace
José Juan?
On Feb 4,
2023, at 5:31, José Juan wrote:
"Electrolytic capacitors are dead on most 80s Yamaha Roland
Korg gear."
From reactions from some of the more experienced experts
here I think I can conclude that statement highly
exxagerated?
MT
Verzonden vanaf mijn Huawei mobiele telefoon
-------- Oorspronkelijk bericht --------
Onderwerp: Re: [YamahaDX] TX802 troubleshooting
Van: PeWe
Aan: [email protected], danforcz@...
Cc:
Hi Daniel !
I agree 100%!
Since my friend (tech) and me started to do inhouse
repairs and service for all my gear many years ago, we
never ever had to replace ALL capacitors in any
machine, regardless of brand and type.
Especially the old Yamaha gear was and still is very
reliable.
I?m 1st owner,- and my TX816 is still intact, my
DX7mkII never failed and younger devices like TG77 and
TG500 work flawlessly.
Needles to say the same rules for the KX-76, KX-5,
D-1500 and REV-7.
Necessary service was usually battery change and
soldering in battery holders, replacing a by roadies
physically damaged display, tact switch replacements
and PSU overhaul for REV-7.
The TX816 might need a single new LED on one of the
TF-1 modules and I think about replacing the original
PSU w/ this one (if at all) ...
WHEN we had to replace aged capacitors in other gear,-
these belonged to the PSU always.
AKAI S-1000 PSU capacitors leaked in both machines,
S-1100 PSUs are different and didn?t.
Ribbon cables and sockets are often culprits ...
When cables and sockets aren?t available anymore,
removing socket and solder the ribbon directly to the
board was the simple solution.
That happened w/ a Oberheim DPX-1 not playing a tone,
not loading disks and showing cryptic stuff in
display.
So, PSU and ALL connections (soldering joints,
sockets, plugs, ribbon cables) have to work 100%
perfect before replacing anything else.
Well, this thread is about TX802 which I don?t use,
but I?d say, repair and service on electronic gear of
that era isn?t soooo special and urgently depending on
brand/model.
Finding the cause of failure is the most difficult and
time consuming,- and I won?t replace anything before
being sure what it really is.
The common buyer and user of used vintage gear is
often not able to identify cause of failure because of
lack of tech skills and missing tools for diagnostics
(and repair).
To save time it?s sometimes better buying a 2nd used
machine and swap boards, then use the better one for
work and the other for parts in future.
:-)
P.
Am 04.02.2023 um 03:37 schrieb Daniel Forró via :
It is not recommended to replace all caps, only
the bad ones. Service experts say: If it works,
leave it so.
Daniel Forró
Electrolytic capacitors are
dead on most 80s Yamaha Roland Korg gear.
|
José Juan