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Re: 1000PX - not booting
Did you remove (gently) and re-install the all socketed IC chips?? ? Pin oxidation can cause poor connections preventing boot.
Also visually inspect soldered IC and other parts for cracks in solder - reheat and reflow any suspicious ones. Check for any PCB trace cracks that would give intermittent operation - if you 'nicked' a copper PCB trace with a tool that could break the connection - would need to add wire to fix. I repaired a non-booting Alesis QS7 mainboard just by removing, cleaning with isopropyl alcohol and re-inserting the ROM chip into the socket. A non-booting Yamaha CS1X board had one bad (nicked) PCB trace on a data bus line - adding a wire jumper brought it back to life.? |
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Re: 1000PX - not booting
Give the output relay a tap to loosen it up a bit, then try.
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Sent from my HAL 9000 in transit to Jupiter -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Joey Mastrili via groups.io Sent: Sunday, February 07, 2021 9:14 PM To: [email protected] Subject: Re: [K1000-K1200] 1000PX - not booting Let's take a few steps back: 1. The K1000 powers up but does not boot. I see blocks on the lcd upon power up and that was it. 2. I checked voltages and they were ok. I also resoldered the connectors since the power supply was already out. 3. The synth still didn't boot despite having correct voltages so I assumed there was a problem with the OS. 4. With new OS chips installed, the synth still did not boot but at least went into diagnostics mode. 5. During diagnostics, all tests pass except for the timer and UART. Every time these tests are run, the synth freezes, that is, I hear the relay immediately click and then the lcd goes blank. 6. I replaced the electrolytic capacitors in the power supply. All voltages read as they were before the new capacitors were installed. 7. Now the synth is back to square one-- just solid boxes in the lcd, and it wont even go into diagnostics mode anymore. If the new OS chips are dead, it's possible that whatever killed the original OS chips also killed the new ones. If the OS chips are not dead, something else is preventing the synth from completing the boot process. My guess is it's something common to the timer and UART circuits. Everyone is welcome to chime in. ? Joey <> On Monday, February 8, 2021, 6:43 AM, Vladimir <shtirlitzz11@...> wrote: [Edited Message Follows] Looks like OS chips. I had one with eprom chips problem. When I tested U32V2.1L checksum was failed, it's write at the label of the chip. |
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Re: 1000PX - not booting
Let's take a few steps back: 1.?The K1000 powers up but does not boot. ?I see blocks on the lcd upon power up and that was it. ? 2.?I checked voltages?and they?were?ok. I also resoldered?the connectors since the power supply was already out. 3.?The synth still didn't boot despite having correct voltages?so I assumed there was a problem with the OS.? 4.?With new OS chips installed, the synth?still?did not?boot?but?at least went into diagnostics mode. ? 5.?During diagnostics, all tests?pass except for the timer and UART. Every time these tests are run, the synth freezes, that is,?I hear the relay immediately?click and then?the lcd goes blank.? 6. I?replaced?the electrolytic capacitors in the?power supply. ?All voltages read as they were before the new capacitors were installed.? 7.?Now the synth is back to square one-- just?solid boxes in the lcd, and it wont even go into diagnostics mode anymore.? If the new OS chips are dead, it's possible that?whatever?killed the original OS chips also killed the new ones.? If the OS chips are not dead, ?something else is preventing the synth from completing the boot process. ?My guess is it's something common to the timer and UART circuits.? Everyone is welcome to chime in. ? Joey? On Monday, February 8, 2021, 6:43 AM, Vladimir <shtirlitzz11@...> wrote:
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Re: 1000PX - not booting
I replaced all the electrolytic capacitors in the power supply and 5 more caps in the main board. ?All the voltages are good but?the K1000 went from bad to worse-- now I am back to seeing?the solid blocks and it wont even?run the?diagnostics again.? This is really frustrating. ? On Saturday, January 30, 2021, 6:31 AM, Frank D via groups.io <rhythm4_4@...> wrote:
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Re: 1000PX - not booting
¿ªÔÆÌåÓýFrank,There are some very usable sub-$100 100MHz scopes on the Bay now that would be more than adequate for troubleshooting 1000_X modules.? It may not be worth the investment for just one project, but it's also surprising how many uses can suddenly be found after buying a new toy :) Rgds, Brian
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Re: 1000PX - not booting
¿ªÔÆÌåÓý¡°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... ;-)¡± ? Hi Frank, you may have something going on at a higher freq so the point is even with an RMS meter you¡¯re still looking at an integral answer and a scope would show what¡¯s actually happening. Anyway I think you¡¯re well advised to replace electrolytic caps first (pretty much a base rule with problems be it old syths or vintage Atari consoles & computers ¨C caps are dead or dead enough to risk running other parts to stress). Keep sharing!! : ) Bill |
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Re: 1000PX - not booting
Tantalum and ceramic caps in that form factor kinda look the same:
In any case, I'm not touching them... ;-) Will rework the power supply. P1 connector has already been done. In my case, both the motherboard and a dummy load pulled down the internal 5V supply. The motherboard also pulled down a substitute 5V supply, but the dummy load did not. I'm replacing all electrolytics first. -- peace, Frank Dickinson 90 East Productions |
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Re: 1000PX - not booting
¿ªÔÆÌåÓýA few notes:1. There should be only 3 tantalum caps in the 1000PX: C023, C043 and C060.? If there are more, someone's been messing around in there.? The ones next to pretty much every IC are 0.1uF ceramic bypass caps, as someone else remarked earlier in the thread, and those very rarely fail. 2. If the electrolytics on the power supply are the originals, they're either bad or on borrowed time.? Don't trust a meter to measure them, because the internal current leakage that develops in old caps causes them to read higher than the marked value. 3. If the P1 connector hasn't already been reworked, do it now.? That's the root cause for the majority of problems in these, including the symptoms you're seeing. Regards, Brian On 1/29/21 1:55 PM, Frank D via
groups.io wrote:
There is a tantalum cap next to pretty much every IC in the 1000PX. I ordered a full set of electrolytics last night and will take that route first, especially since I've already determined that the power supply is sagging under load. |
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Re: 1000PX - not booting
If the power supply is sagging it's most likely the power supply that's at fault.? The supply board has a good 5V regulator.? But, there's not much margin on the input to the regulator.? A bit of extra ripple on the big filter capacitor can cause the regulator to lose regulation on the dips.? This is most easily checked with an oscilloscope but if you don't have one put your multimeter on AC and see what your 5V supply reads.? If it's more than a few tens of mV that could indicate losing regulation and causing a power-on reset 120 time per second.
Either high resistance on the transformer connector or decreased filter capacitor value can cause this.? I've had both happen.? Another possibility is an bad rectifier but I've never seen this on these units.? But then again my sample size is only the two that I've kept running over the years.? |
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Re: 1000PX - not booting
There is a tantalum cap next to pretty much every IC in the 1000PX. I ordered a full set of electrolytics last night and will take that route first, especially since I've already determined that the power supply is sagging under load.
FYI, I found everything at good prices here: -- peace, Frank Dickinson 90 East Productions |
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Re: 1000PX - not booting
¿ªÔÆÌåÓýHa! ?You¡¯re asking me? Notta clue. Maybe they decouple, maybe not.? Maybe there¡¯s 50, maybe there¡¯s 5.? No idea. I just threw that out there because the DX7 came out around 1984 and the PX about 4 years later, maybe 3. So the DX guys are going strong on ¡°change the tants¡± because, unlike electrolytics, no one had their eye on tantalums failing, but over this much time, they do with some regularity in the digital timing circuits. Even my local tech was completely baffled by DX7 tantalums and he gave me the long ¡°wellllll¡ that DX7 power supply is a funny thing¡.¡±.? He¡¯s only been doing this stuff for 40 years and had to throw in the towel on my DX because he only considered the power supply. I fixed it myself changing the tantalum caps on a couple boards.? ? I haven¡¯t peeked in my PX in months, maybe years. ? L. ? From: [email protected] [mailto:[email protected]] On Behalf Of Frank D via groups.io
Sent: Thursday, January 28, 2021 7:28 PM To: [email protected] Subject: Re: [K1000-K1200] 1000PX - not booting ? Hi Larry, |
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Re: 1000PX - not booting
On Fri, Jan 29, 2021 at 10:08 AM, Joey Mastrili wrote:
Did you connect the Midi cable loop (input to output) before running the test? https://www.sweetwater.com/sweetcare/articles/perform-self-diagnostics-kurzweil-k1000/ ? -- peace, Frank Dickinson 90 East Productions |
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Re: 1000PX - not booting
Hi All,
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I ran the diagnostics on my non-booting K1000 and all tests pass, except for the Timer and UART. ? Every time the K1000 starts?the Timer and UART test, I?immediately hear the relay click and then the screen goes blank (it doesnt even show?the blocks). I then have to turn off the unit and when I power up again, I hear a clicking sound that repeats indefinitely.? Any clues as to what's the problem here? ? I measured?5v, +12.1v?and -12.1v?at?the power supply and?4.9, +12, -12 at the IC pins.? Thanks. Joey On Friday, January 29, 2021, 9:27 AM, Frank D via groups.io <rhythm4_4@...> wrote:
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Re: 1000PX - not booting
Hi Larry,
Just opened up the 1000PX again... Are you referring to the decoupling caps? I'm pretty sure that's their function. There is one at each IC, most are K5M 104, which (if I am correct) = 0.1uf. There has to be around 50 in here and only around a dozen electrolytics. At this point, I think I will spend a few bucks on new electrolytics all around. They are cheap enough. Changing them out will also refresh the solder connections to the PCB. I am currently making a list and will place an order tonight. If that doesn't do the trick, at least they will be eliminated. -- peace, Frank Dickinson 90 East Productions |
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Re: 1000PX - not booting
I know it's OT, but I just installed a Meanwell LRS-35-5, 5 volt switching power supply in my dead Akai S1000.
Connected 4 leads, drilled one hole to accommodate mounting screws, and it fired right up! Floppy drive still works. External SCSI CD-rom still works. The only thing not functioning is the external 44MB SCSI SyQuest drive (remember those?) and LCD backlight is dim (of course...). Very happy! Gonna take care of a few loose ends and list it for sale. I also have two matching drum trigger units for it. Both working as well!? -- peace, Frank Dickinson 90 East Productions |
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