This may be worthless as I’m not as familiar with my KW insides as I should be. Everyone, but everyone, will tell you to “replace the electrolytics” which is always good advice and you should always do when their lifespan is measured in decades like these KW units are.? Whether that’s the cause of your troubles right now, or not, it WILL be. But in a DX7 there is a similar mantra of “change out the tants!” There are tantalum capacitors, “timing caps” they’re called.? Tiny orange things that straddle some of the memory chips.? They don’t leak.? They don’t explode.? They don’t even discolor.? They just don’t work right and the result (again, on a DX7) is a no-boot condition and bad display. At an internal clock speed of 10 MHz or so, it’s kinda hard to catch a glitch or two during boot. ? Anyway, before you go total shotgun, it might be worth a try. ? L. ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Frank D via groups.io
Sent: Tuesday, January 26, 2021 10:39 PM
To: [email protected]
Subject: Re: [K1000-K1200] 1000PX - not booting? Wow, thanks for the great suggestions from everyone!? I implemented what I could with what I have on hand...
Coincidentally, I am also trying to get an Akai S1000 working again, and ordered a 35w 5v power supply (Meanwell LRS-35-5). The PS came today, so I rigged it into the circuit by pulling the pins from #s 3 and 8 on the Molex and tack-soldering leads. Same issue... the +5vdc is pulled down to 4.4, and blocks appear on the display. I figured this indicated a motherboard issue, but tried the other suggestion anyway and connected a 12ohm power resistor from the disconnected internal +5v supply to ground. This also pulled the voltage down to 4.4!
I suppose I could go into shotgun mode and replace all electrolytic caps (there aren't many). Traces on PS appear OK, I did not look under motherboard.
To Bill: My DMM (EEVblog/Brymen BM235) is true RMS, but does not have a separate RMS chip. I think that's fine for lower frequency measurement. Let me know if you think otherwise. (I'm not an engineer, I only play one on TV... ;-)
So... I toss this info out with great appreciation for y'all's responses!
BTW Nicole, I also have a Matrix 6R which is starting to act a bit wonky. Was planning (after this project and the S1000) to check PS, seat chips, clean ribbon cable connectors and such.
--
peace,
Frank Dickinson
90 East Productions
|
Wow, thanks for the great suggestions from everyone!? I implemented what I could with what I have on hand...
Coincidentally, I am also trying to get an Akai S1000 working again, and ordered a 35w 5v power supply (Meanwell LRS-35-5). The PS came today, so I rigged it into the circuit by pulling the pins from #s 3 and 8 on the Molex and tack-soldering leads. Same issue... the +5vdc is pulled down to 4.4, and blocks appear on the display. I figured this indicated a motherboard issue, but tried the other suggestion anyway and connected a 12ohm power resistor from the disconnected internal +5v supply to ground. This also pulled the voltage down to 4.4!
I suppose I could go into shotgun mode and replace all electrolytic caps (there aren't many). Traces on PS appear OK, I did not look under motherboard.
To Bill: My DMM (EEVblog/Brymen BM235) is true RMS, but does not have a separate RMS chip. I think that's fine for lower frequency measurement. Let me know if you think otherwise. (I'm not an engineer, I only play one on TV... ;-)
So... I toss this info out with great appreciation for y'all's responses!
BTW Nicole, I also have a Matrix 6R which is starting to act a bit wonky. Was planning (after this project and the S1000) to check PS, seat chips, clean ribbon cable connectors and such.
--
peace,
Frank Dickinson
90 East Productions
|
Hi Frank, ? As a EE I’d suggest putting a separate resistive load on those off nominal Vsupplies & ideally look at them with a scope. If the supply collapses with that load you’ve already separated the rest of the system from the PSU which always makes me happy. ? Note a DVM isn’t ideal to diagnose problems once you see something other than the rated output (esp under load). A failed cap for example (likely) could be revealed by higher freq switching/modes that the meter tries to average poorly esp if it’s not a true RMS meter. ? Hope that helps. ? Bill 
Embedded Systems Engineering - Product Development ?
|
That is exactly the function of the relay, and much joy has been had in the past with giving it a tap. I've also found in the past with my machines that powering the unit up and getting the blocks then doing a fast power off and back on often resolved this issue, at least for the moment. (I have to do something similar with my Matrix 6r)
Sent from my HAL 9000 in transit to Jupiter
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Frank D via groups.io Sent: Monday, January 25, 2021 10:47 PM To: [email protected]Subject: Re: [K1000-K1200] 1000PX - not booting OK, I went back in... The 4.3vdc readings at the power supply are present when the PS is connected to the motherboard. If I pull the Molex connector from J4, 5vdc is present at the same pins. Seems that the power supply works correctly when not connected. Looking at the PS schematic from k1000.net, I can not see any reference to pins 9 and 10. The rest of it is a bit hard to read. I also found a small AC voltage present at pin 9. 4.3 v is reaching the CPU at pin 14. Here's what I have at the connector: Pin# - VDC disconnected - VDC connected 1. gnd gnd 2. gnd gnd 3. +5 +4.3 4. +12 +12 5. -12 -12 6. -0.5 0 7. +5 +5 (backup) 8. +5 +4.3 9. +1.9 (2.2vac) +1.2 (1.5vac) 10. +5 +4.3 If anyone can interpret this or give any suggestions, I would truly appreciate it. Many thanks! P.S. I'm also curious about the relay which Nicole mentioned. Seems like its function is to prevent a pop on the outputs during power-up. In any case, I do not hear it click. Is that a clue? ;-) -- peace, Frank Dickinson 90 East Productions Our "lockdown" videos <>
|
All good suggestions. As previously mentioned too much load could be bad caps on mother board or other load not on Power Supply. If you have not done so, I would check the traces and solder joints on the Power Supply.? If corroded, the normal load will pull down the voltage.? Sometimes the solder joints corrosion is really hard to see - re-solder if in doubt.??
The relay is closed by the processor after the boot, so if it does not boot, the relay will probably not close.?
------ Original Message ------
Sent: 1/25/2021 9:47:06 PM
Subject: Re: [K1000-K1200] 1000PX - not booting
OK, I went back in...
The 4.3vdc readings at the power supply are present when the PS is connected to the motherboard. If I pull the Molex connector from J4, 5vdc is present at the same pins. Seems that the power supply works correctly when not connected.
Looking at the PS schematic from k1000.net, I can not see any reference to pins 9 and 10. The rest of it is a bit hard to read. I also found a small AC voltage present at pin 9.? 4.3 v is reaching the CPU at pin 14.
Here's what I have at the connector:
Pin# - VDC disconnected - VDC connected
1.???????? gnd???????????? gnd
2.???????? gnd???????????? gnd
3.???????? +5 ???????????? +4.3
4.???????? +12 ??????????? +12
5.???????? -12 ??????????? -12
6.???????? -0.5 ??????????? 0
7.???????? +5 ???????????? +5? (backup)
8.???????? +5 ???????????? +4.3
9.???????? +1.9 (2.2vac)?? +1.2 (1.5vac)
10.??????? +5 ???????????? +4.3
If anyone can interpret this or give any suggestions, I would truly appreciate it. Many thanks!
P.S. I'm also curious about the relay which Nicole mentioned. Seems like its function is to prevent a pop on the outputs during power-up. In any case, I do not hear it click. Is that a clue?? ;-)
--
peace,
Frank Dickinson
90 East Productions
|
The +5V supplies that you measure at +4.3V when connected is a problem.? K1000 won't likely boot.
Digital logic of this era needs at least +4.75 V to operate properly.
Some component is dropping this voltage under load - either on power supply itself or on main board.
But not enough to blow a fuse from excessive current (short circuit)
This low voltage would prevent boot.? I would closely inspect the power supply capacitors on +5V.
Some ideas:
1)??If you have a bench power supply with +5,?output (sufficient current > 3 amps? ), you could substitute for the K1000 supply +5V.
Must make sure to tie supply grounds together.?
2) Use a triple bench supply (+5, +12 and -12V)? or maybe an old PC power supply with these output voltages?
3) Test the? K1000 power supply with a?resistive load (power resistor 10 ohms -> 500mA current, 2.5 Watts) on the +5V supply to see if voltage drops to 4.3V
If voltage drops, then power supply is problem (capacitors are first to check).
The relay is as you describe- protects from output 'pop' on power up until K1000 is fully booted.
Good luck.
|
OK, I went back in...
The 4.3vdc readings at the power supply are present when the PS is connected to the motherboard. If I pull the Molex connector from J4, 5vdc is present at the same pins. Seems that the power supply works correctly when not connected.
Looking at the PS schematic from k1000.net, I can not see any reference to pins 9 and 10. The rest of it is a bit hard to read. I also found a small AC voltage present at pin 9.? 4.3 v is reaching the CPU at pin 14.
Here's what I have at the connector:
Pin# - VDC disconnected - VDC connected
1.???????? gnd???????????? gnd
2.???????? gnd???????????? gnd
3.???????? +5 ???????????? +4.3
4.???????? +12 ??????????? +12
5.???????? -12 ??????????? -12
6.???????? -0.5 ??????????? 0
7.???????? +5 ???????????? +5? (backup)
8.???????? +5 ???????????? +4.3
9.???????? +1.9 (2.2vac)?? +1.2 (1.5vac)
10.??????? +5 ???????????? +4.3
If anyone can interpret this or give any suggestions, I would truly appreciate it. Many thanks!
P.S. I'm also curious about the relay which Nicole mentioned. Seems like its function is to prevent a pop on the outputs during power-up. In any case, I do not hear it click. Is that a clue?? ;-)
--
peace,
Frank Dickinson
90 East Productions
|
Thanks so much for the tips! Will get back into it tomorrow.
I no longer have a 'scope, but can perform the other tests.
--
peace,
Frank Dickinson
90 East Productions
|
Scanning the schematics, the DC supply voltages are:? +12V,? -12V,? +5V and +5V backup (present with power off)
I don't see a 4.3V supply that you measured - unless this is the +5V backup voltage (low battery ?)
If 4.3V is the +12V supply, then you may focus on that part of the power supply (regulator, capacitors, etc)
Also, see that the RESET signal is low for normal operation.? It will go high briefly at power up.
At the CPU, it is inverted as RESET* - should be active high in normal operation.
POWER_OK* should be low? (0V) in normal operation.
if you have a oscilloscope or logic probe, check clock input,? address and data pins on the CPU - are they active?
If yes, then the CPU is attempting to run code - which is a good sign.
|
Check every electrolytic capacitor with a magnifying glass.? These units are very old and some of the caps go bad and, if so, they usually leak.? The leak corrodes the traces and or contacts under or around the cap.? Repair is sometimes possible. Good luck Dennis
------ Original Message ------
Sent: 1/20/2021 6:16:12 AM
Subject: Re: [K1000-K1200] 1000PX - not booting
I have a K1000 with exactly the same symptoms as your 1000PX. ?
I?did everything that?you mentioned (following the tips in K1000.net)?and still got?solid blocks on the display. ?
I replaced the OS chips and the synth was?able to do?some (but?not all) of?the diagnostics functions,?but it still does not?boot.
Joey On Wednesday, January 20, 2021, 7:01 PM, Nicole Massey <nyyki@...> wrote: Sounds like the relay. Give it a decent (but not excessive pop) on its cover and see what happens. The tap will work for a while, but if this is it and you still have it open it's good to replace it. See K1000.net for suggested part replacement. Sent from my HAL 9000 in transit to Jupiter -----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Frank D via groups.io Sent: Wednesday, January 20, 2021 12:27 AM To: [email protected]Subject: [K1000-K1200] 1000PX - not booting Belated Happy New Year! Finally spent a bit of time on my non-functioning 1000PX. Here's where I am so far... The unit comes on, but does not boot. All I see is black blocks on the upper row of display. Tried hard reset and test mode. Nada... Checked solder joints on bottom of power supply board where transformer connects. All looks good (I remember fixing these a while ago). Backup battery had been replaced at that time also. Showed a solid 3v on meter. Re-flowed the solder, all is tight, no cracks, voltages are present. Power transformer secondaries give me 16-32 and 7-14 volts. Power supply is working. DC voltages to motherboard are + and -12v, 4.3v and 5v. Seems like pretty standard values. Went through and exercised any socketed ICs in their sockets. I don't have a chip puller, so didn't pull them all the way out to clean pins. No change, so I put it back together... Looking for any info or suggestions from the group. Many thanks! -- peace, Frank Dickinson 90 East Productions Our "lockdown" videos <>
|
Thanks, Nicole!
Will give it a try and report back...
--
peace,
Frank Dickinson
90 East Productions
|
I have a K1000 with exactly the same symptoms as your 1000PX. ?
I?did everything that?you mentioned (following the tips in K1000.net)?and still got?solid blocks on the display. ?
I replaced the OS chips and the synth was?able to do?some (but?not all) of?the diagnostics functions,?but it still does not?boot.
Joey
On Wednesday, January 20, 2021, 7:01 PM, Nicole Massey <nyyki@...> wrote: Sounds like the relay. Give it a decent (but not excessive pop) on its cover and see what happens. The tap will work for a while, but if this is it and you still have it open it's good to replace it. See K1000.net for suggested part replacement. Sent from my HAL 9000 in transit to Jupiter -----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Frank D via groups.io Sent: Wednesday, January 20, 2021 12:27 AM To: [email protected]Subject: [K1000-K1200] 1000PX - not booting Belated Happy New Year! Finally spent a bit of time on my non-functioning 1000PX. Here's where I am so far... The unit comes on, but does not boot. All I see is black blocks on the upper row of display. Tried hard reset and test mode. Nada... Checked solder joints on bottom of power supply board where transformer connects. All looks good (I remember fixing these a while ago). Backup battery had been replaced at that time also. Showed a solid 3v on meter. Re-flowed the solder, all is tight, no cracks, voltages are present. Power transformer secondaries give me 16-32 and 7-14 volts. Power supply is working. DC voltages to motherboard are + and -12v, 4.3v and 5v. Seems like pretty standard values. Went through and exercised any socketed ICs in their sockets. I don't have a chip puller, so didn't pull them all the way out to clean pins. No change, so I put it back together... Looking for any info or suggestions from the group. Many thanks! -- peace, Frank Dickinson 90 East Productions Our "lockdown" videos <>
|
Sounds like the relay. Give it a decent (but not excessive pop) on its cover and see what happens. The tap will work for a while, but if this is it and you still have it open it's good to replace it. See K1000.net for suggested part replacement.
Sent from my HAL 9000 in transit to Jupiter
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Frank D via groups.io Sent: Wednesday, January 20, 2021 12:27 AM To: [email protected]Subject: [K1000-K1200] 1000PX - not booting Belated Happy New Year! Finally spent a bit of time on my non-functioning 1000PX. Here's where I am so far... The unit comes on, but does not boot. All I see is black blocks on the upper row of display. Tried hard reset and test mode. Nada... Checked solder joints on bottom of power supply board where transformer connects. All looks good (I remember fixing these a while ago). Backup battery had been replaced at that time also. Showed a solid 3v on meter. Re-flowed the solder, all is tight, no cracks, voltages are present. Power transformer secondaries give me 16-32 and 7-14 volts. Power supply is working. DC voltages to motherboard are + and -12v, 4.3v and 5v. Seems like pretty standard values. Went through and exercised any socketed ICs in their sockets. I don't have a chip puller, so didn't pull them all the way out to clean pins. No change, so I put it back together... Looking for any info or suggestions from the group. Many thanks! -- peace, Frank Dickinson 90 East Productions Our "lockdown" videos <>
|
Belated Happy New Year!
Finally spent a bit of time on my non-functioning 1000PX. Here's where I am so far...
The unit comes on, but does not boot. All I see is black blocks on the upper row of display. Tried hard reset and test mode. Nada...
Checked solder joints on bottom of power supply board where transformer connects. All looks good (I remember fixing these a while ago). Backup battery had been replaced at that time also. Showed a solid 3v on meter. Re-flowed the solder, all is tight, no cracks, voltages are present. Power transformer secondaries give me 16-32 and 7-14 volts.
Power supply is working. DC voltages to motherboard are + and -12v, 4.3v and 5v. Seems like pretty standard values.
Went through and exercised any socketed ICs in their sockets. I don't have a chip puller, so didn't pull them all the way out to clean pins.
No change, so I put it back together... Looking for any info or suggestions from the group. Many thanks!
--
peace,
Frank Dickinson
90 East Productions
|
Re: K1000-PX Plus and K1200 need TLC in 2021.
I still have a K-model. I’ll give you what you paid or your strips, just cuz… Contact me offlist. ? L. ? ? I had a K1000 with a couple keys that seemed to be stuck at full velocity. It turned out to be the little rubber contacts underneath the keys. They got old and wore out after several decades of use. The rubber contacts came in strips of twelve in a row. I ended up with four of the strips. I think I paid something like $15 (US) per strip. I'd be willing to sell them since I no longer have the K1000. I do not know if that is a fair price for them or not, so more information about that would be welcome.
Joe
|
Re: K1000-PX Plus and K1200 need TLC in 2021.
I had a K1000 with a couple keys that seemed to be stuck at full velocity. It turned out to be the little rubber contacts underneath the keys. They got old and wore out after several decades of use. The rubber contacts came in strips of twelve in a row. I ended up with four of the strips. I think I paid something like $15 (US) per strip. I'd be willing to sell them since I no longer have the K1000. I do not know if that is a fair price for them or not, so more information about that would be welcome.
Joe
|
No joy.? Confirmed in a
1000 PX that the Crystalfontz OLEDs are NOT plug-n-play
operational replacements (not to mention the different mounting
footprint).?? The display won't even start up, which leads me to
believe it may the same problem I ran into when using these
before, but worse.? Not a lot of free time to dig into it now, so
I'll take another look after the holidays.
Regards,
Brian
On 12/19/20 5:37 PM, Brian M. via
groups.io wrote:
toggle quoted message
Show quoted text
J.C.,
Thanks for saving the post.? Aliexpress was carrying some of the
displays, but they're not always a dependable marketplace,
either for finding products or actually getting them shipped
after paying. :-(
Crytalfontz in Spokane Valley, WA has some OLED 16x2s for around
$20 ea at
that I've been using on a product at work.? They're
Winstar-based and have a very similar, but not -identical-,
instruction set and timing as the Hitachi-based Seiko displays
that were originally in the Kurzweil modules and keyboards.?
This almost-compatibility caused some odd issues that forced me
to tweak code for our application, so there's a possibility that
they won't work as plug-n-play replacements here, either.?? It's
on my list to test on Monday evening, so I'll report back here
if they're viable replacements.
Regards,
Brian
On 12/19/20 12:19 PM, J.C. Tedder
wrote:
I have saved the
facebook post with pictures about the new LED. (See attached
word doc.) I need to replace mine also. I searched Aliexpress
but didn't find a source there at the time. Haven't searched
lately. Someone had them posted on ebay at over a hundred
dollars each. LOL! about ten times the cost!
I think there have been some newer sources for a
display replacement for the keyboards that were posted
recently on the old Yahoo group or perhaps the Facebook
page but I may not have updated K1000.net site.? Anyone
point me to newer sources or methods I will update the
K1000 page.
Dennis?
------ Original Message ------
Sent: 12/17/2020 8:52:44 PM
Subject: [K1000-K1200] K1000 led light
hope someone reposts the info on upgrading fixing
a fading led light on a K 1000 keyboard. Sooner or later
I have to get this done!
|
> <snip> I stopped at this point in the repair, partly to take pics, and partly because I'm still debating whether or not to delete
> the connector on this one, due to the condition of the foil trace at pin 2.
One idea re: pin 2, might be to use your wire wrap idea with the stripped end of a piece of insulated wire, then solder the other end to wherever that circuit trace is going. Or... use a length of bare wire, wrap it, and solder it along the length of the trace.
--
peace,
Frank Dickinson
90 East Productions
|
J.C.,
Thanks for saving the post.? Aliexpress was carrying some of the
displays, but they're not always a dependable marketplace, either
for finding products or actually getting them shipped after
paying. :-(
Crytalfontz in Spokane Valley, WA has some OLED 16x2s for around
$20 ea at
that
I've been using on a product at work.? They're Winstar-based and
have a very similar, but not -identical-, instruction set and
timing as the Hitachi-based Seiko displays that were originally in
the Kurzweil modules and keyboards.? This almost-compatibility
caused some odd issues that forced me to tweak code for our
application, so there's a possibility that they won't work as
plug-n-play replacements here, either.?? It's on my list to test
on Monday evening, so I'll report back here if they're viable
replacements.
Regards,
Brian
On 12/19/20 12:19 PM, J.C. Tedder
wrote:
toggle quoted message
Show quoted text
I have saved the facebook post with pictures about the new LED.
(See attached word doc.) I need to replace mine also. I searched
Aliexpress but didn't find a source there at the time. Haven't
searched lately. Someone had them posted on ebay at over a
hundred dollars each. LOL! about ten times the cost!
I think there have been some newer sources for a display
replacement for the keyboards that were posted recently on
the old Yahoo group or perhaps the Facebook page but I may
not have updated K1000.net site.? Anyone point me to newer
sources or methods I will update the K1000 page.
Dennis?
------ Original Message ------
Sent: 12/17/2020 8:52:44 PM
Subject: [K1000-K1200] K1000 led light
hope someone reposts the info on upgrading fixing a fading
led light on a K 1000 keyboard. Sooner or later I have to
get this done!
|
Nicole,
I'd never call someone clueless for being genuinely interested and
asking questions.
The wires themselves are of more than adequate size for what
they're carrying, only ~2A max on startup, 1.7-1.8A continuous, so
they aren't the problem. That's why soldering them directly to the
board ensures that it'll never happen again. But the wires, like
the connector pins, are far too small for the holes in the board,
so they really should be bent down against the foil traces before
soldering.
Attached are a couple photos from a unit I just started working
on, after being inspired by the conversation here.? Note how much gap there is
around the middle four P1 pins that haven't been reworked
yet.? These should be a slight
friction fit, binding a bit when inserted, but they're just
swimmin' in them thar holes.? Makes one wonder if Engineering
knew about this at the time, because if they did, they
shouldn't have let it go to production. Related question: Does
anyone know if Kurzweil did board assembly in-house, or did
they farm it out to a subcontractor?
Pin
1 (right side) has the wrap-and-solder fix, and pin 6
(left side) is only wrapped, so far. There's a short "tail" of
wire intentionally left to solder to the foil trace, for added
stability. You can see that pin 2 had gotten so hot that
it burned the board, and on the top side of the board, the plastic
on both parts of the connector was slightly melted and charred.
While desoldering the pin from the board, part of the trace
disappeared, because there's so little of it around the oversized
hole.?
I stopped at this point in the repair,
partly to take pics, and partly because I'm still debating
whether or not to delete the connector on this one, due to the
condition of the foil trace at pin 2.? More of the saga later,
if anyone's interested.
Regards,
Brian
On 12/19/20 11:59 AM, Nicole Massey
wrote:
toggle quoted message
Show quoted text
I have only a cursory experience with electronics hardware, so feel free to tell me I'm clueless. Would it be possible to hardwire the connection using thicker wire to remove any wiggle room from the connections? I seem to remember that would lower resistance, but would that matter?
Sent from my HAL 9000 in transit to Jupiter
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of LarryS
Sent: Saturday, December 19, 2020 7:00 AM
To: [email protected]
Subject: Re: [K1000-K1200] Thank you! P1
I think this is what I’m going to do. Just solder the leads straight on.
My units are from 25-30 years ago. And NOW I’m getting ready to repair a couple.
Of course, the temptation is to “restore” it because “someday I might want that to plug-in”. After all “if it was good enough for the factory”, but, like you said, it was for the exigencies of assembly, not end-user advantages.
But I can’t think of an overriding reason to have a disconnect there. And I can think of several reasons to have hard-soldered leads – a proven technique of reliability for many years.
L.
I've had severe cases where heat from the pins has melted the connector. When that happens, I completely remove P1 and solder the transformer leads directly to the board. This also eliminates the original problem, but requires a bit more work than the fix above. The connector was for ease of assembly in the factory, anyway, so there's nothing lost by removing it.
Hope this helps someone!
Regards,
Brian
|
Dennis Spanogle (Mr. Kurlewin K1000.net)