CZ-1000 lights and display will not turn off until power is disconnected.

[Jokeyman123]

You go! I never put my keys back together until I power it up..you are so right that anything can go when you reassemble-I actually put keys back together while powered on-to see if I am doing anything to break connections or even worse! I wouldn't recommend this though, unless one is extremely careful, as if something does get mangled in reassembly-powered on components can be foobarred even worse than-always a tough choice. I am saving this troubleshooting thread for future reference..in case I add an older CZ back to my inventory, i cut my programming chops on these when first out. 8-stage envelopes-if only on the new ones!  Can do amazing stuff with 8-stage envelopes! 

[HELVETIA]

22 hours ago, IanB said:

@Jokeyman123 It may well be that but I'm a bit more optimistic for a couple of reasons. This is all logic level stuff so there's less chance of a cascade failure of that type; plus it worked fine on the bench but then immediately after reassembly did not work, which suggests to me that something was disturbed during reassembly. These are old boards after all, with joints that were all soldered over 30 years ago! So my guess is one of the solder joints on an interconnecting cable has failed.

This kind of "fail after fix" is particularly demoralising, but hopefully we're on the last lap now!

Me and my hubby got great  experiences with soldering de-soldering   replacing components  tracing  errors  mostly in organs  and computers stuff . If you not knowing what you are doing don't do it ....you could easily overheating   components  by soldering or ...static electricity  will kill IC's  from older times  unless you  want to experiment  else  you will probably end up with a death instrument !  in case of  the CZ-1000  power stays on failure i would really not be happily  cutting and past away in this  keyboard as it was already marked as unstable  for along time as I read the reports about it  ...just a hint   sometimes it's better to leave  things as they are  l  ......and don't fix it if it is not broken !    (esp. CMOS and MOSFET devices getting  killed by static electricity)

 

 

[IanB]

Well, I don't think things are so bad Helvetia. I strongly think something simple is the cause of the failure after reassembly. Let's see

[HELVETIA]

1 hour ago, IanB said:

Well, I don't think things are so bad Helvetia. I strongly think something simple is the cause of the failure after reassembly. Let's see

Let's hope so  !  interesting anyway

 

[lulu_joe]

OK. Guys and gals. Reseated chip. I socketed it when I replaced. Turned synth back on while pressing p. All better! Didn't put all the case screws back in yet though just in case. TX. Again. JoeF.

[IanB]

I have my fingers crossed but hopefully this time this is it Joe!

And *nudge* feel free to try my Windows CZ Patch Editor

[Jokeyman123]

Nice! I have repaired a few computer/music/electronics where all that was needed was a re-seating an IC or ribbon cable..when I got lucky! And by judging the used prices for the CZs now, and for your own satisfaction, I'm sure this has been worth the time and trouble.

[IanB]

Must admit the single scariest thing I've done with a soldering iron in a long while was desoldering the 933 chips in my CT6500; they're the CZ sound generators and if I broke one, that was it, you can't get replacements! I don't recommend this as  normal procedure, it was part of my reverse engineering project

[IanB]

This is all interesting but shouldn't it have its own thread? I keep getting notifications, think Joe's keyboard has another update and instead we're discussing secondhand Casiotones

[Jokeyman123]

Check with the moderators, Ian-they can do that. I think we already have another user area specifically for classic CASIO's.

[Brad Saucier]

I split the off-topic discussion into it's own thread.  

 

[CYBERYOGI =CO=Windler]

It is important to regard that an IC that once has been overloaded by short circuits, wrong voltages or static electricity can still starve many days or months later even when it seems to have survived without damage. This is caused by small internal short circuits on the silicon die, those can come into being by the "lightning strikes" of static electricity or local overheating from too high currents. These so-called "hot spots" make the chip draw more current and make its silicon locally overheat again. The local overheat softens the different layers of the chip and thus makes them slowly melt together (electro- migration) , which enlarges the heat producing short circuit area.

But do not become too hysteric about static electricity. Particularly the warning never to place a mainboard on carpet is absurd nonsense because it contradicts physics. (To prevent furniture scratches, I even rarely place PCBs on uncarpeted surfaces.) This false urban legend obviously originated from the fact that scuffing shoes on synthetic carpet can produce static electricity, so someone formed the idiot equation "carpet = evil". But damage can only happen where a large conductive object (i.e. your body) insulated from ground (through your shoe soles) gets charged with highvoltage against environment and then rapidly discharges by making a current pulse flow across IC pins to ground. I.e. an ungrounded IC (e.g. PCB disconnected from anything) gets unlikely damaged at all because no current can flow anywhere. When only the PCB rests on carpet, it lacks that large charged conductive object; accidentally rubbing the PCB itself such strongly against carpet that friction produces a potential difference with enough current to cause harm is next to impossible, because metal traces on the PCB are conductive enough to short that voltage before it builds up high enough, and the spiky pins prevent slipping (hence no friction), and particularly there is nothing to store such a charge, which keeps currents too low. (The installed capacitors act like a shortcircuit to such very short HV spikes.) Your body (large conductive object) is the problem; it does not matter whether it got charged by a carpet (shoe friction) or anything else (e.g. synthetic, silk or wool clothing rubbing on a seat with insulating upholstery or plastic). Also the airflow by cleaning with a household vacuum cleaner in real life does not damage ICs by static electricity; only avoid to touch with the metal nozzle or pipe (a charged conductive object) and reduce suction if possible. Shipping a PCB inside a too large generic plastic bags might be a greater risk, because rapid sliding around during transport (e.g. RAM modules have not spiky side to stop this) may damage chips. Therefore antistatic packaging exists; if you have none, you may wrap in aluminium foil, but do not use this for anything containing batteries (e.g. PC mainboard) to avoid shortcircuit. Most sensitive against static discharge are old CMOS ICs (e.g. early button cell operated things); modern ICs are better protected by internal diodes.

I generally never use a grounded wrist strap - not because of awkwardness, but it invites the reaper! And not only while working in mains operated devices, grounding oneself means calling for death. That is to say, the ground line of the mains grid is infested with all kinds of EMF crap; so hooking up your nervous system directly to this pulsed high frequency dirt for hours during work is an absolutely terrible idea. I doubt that the 1M serial resistor can filter much of this, so unless you have a water pipe without connections to mains (e.g. bare wire flow heaters spoil it), an average room has no safe place to attach an ESD strap. Instead quickly grasp something grounded (e.g. radiator, water tap, socket ground prong or grounded metal case) after walking around before you touch ICs. To me, simply wearing no shoes and sitting on floor in cotton-based jeans during work turned out to be fully sufficient to prevent jolts and chip crashes by static shocks (hence no risk of damage). In real life most chip damage during DIY is caused by other unremembered incidents (wrong polarity, wrong current flow by disconnected GND, misplugging) and falsely accusing static discharge. When the rest is done properly (no insulating clothing or shoes), an antistatic wrist strap is almost a placebo to calm the mind of repair companies and insurances, and knowing the health risks it should be better avoided.

[Jokeyman123]

Agreed-might as well hook yourself up to a car battery! 

[CYBERYOGI =CO=Windler]

a car battery is DC - one pole wouldn't hurt. The problem is high frequency dirt on the mains line. (To make it clear, the ground current through an 1 megohm resistor at the strap can not kill you when touching live mains parts.)

[HELVETIA]

1 hour ago, CYBERYOGI =CO=Windler said:

It is important to regard that an IC that once has been overloaded by short circuits, wrong voltages or static electricity can still starve many days or months later even when it seems to have survived without damage. This is caused by small internal short circuits on the silicon die, those can come into being by the "lightning strikes" of static electricity or local overheating from too high currents. These so-called "hot spots" make the chip draw more current and make its silicon locally overheat again. The local overheat softens the different layers of the chip and thus makes them slowly melt together (electro- migration) , which enlarges the heat producing short circuit area.

But do not become too hysteric about static electricity. Particularly the warning never to place a mainboard on carpet is absurd nonsense because it contradicts physics. (To prevent furniture scratches, I even rarely place PCBs on uncarpeted surfaces.) This false urban legend obviously originated from the fact that scuffing shoes on synthetic carpet can produce static electricity, so someone formed the idiot equation "carpet = evil". But damage can only happen where a large conductive object (i.e. your body) insulated from ground (through your shoe soles) gets charged with highvoltage against environment and then rapidly discharges by making a current pulse flow across IC pins to ground. I.e. an ungrounded IC (e.g. PCB disconnected from anything) gets unlikely damaged at all because no current can flow anywhere. When only the PCB rests on carpet, it lacks that large charged conductive object; accidentally rubbing the PCB itself such strongly against carpet that friction produces a potential difference with enough current to cause harm is next to impossible, because metal traces on the PCB are conductive enough to short that voltage before it builds up high enough, and the spiky pins prevent slipping (hence no friction), and particularly there is nothing to store such a charge, which keeps currents too low. (The installed capacitors act like a shortcircuit to such very short HV spikes.) Your body (large conductive object) is the problem; it does not matter whether it got charged by a carpet (shoe friction) or anything else (e.g. synthetic, silk or wool clothing rubbing on a seat with insulating upholstery or plastic). Also the airflow by cleaning with a household vacuum cleaner in real life does not damage ICs by static electricity; only avoid to touch with the metal nozzle or pipe (a charged conductive object) and reduce suction if possible. Shipping a PCB inside a too large generic plastic bags might be a greater risk, because rapid sliding around during transport (e.g. RAM modules have not spiky side to stop this) may damage chips. Therefore antistatic packaging exists; if you have none, you may wrap in aluminium foil, but do not use this for anything containing batteries (e.g. PC mainboard) to avoid shortcircuit. Most sensitive against static discharge are old CMOS ICs (e.g. early button cell operated things); modern ICs are better protected by internal diodes.

I generally never use a grounded wrist strap - not because of awkwardness, but it invites the reaper! And not only while working in mains operated devices, grounding oneself means calling for death. That is to say, the ground line of the mains grid is infested with all kinds of EMF crap; so hooking up your nervous system directly to this pulsed high frequency dirt for hours during work is an absolutely terrible idea. I doubt that the 1M serial resistor can filter much of this, so unless you have a water pipe without connections to mains (e.g. bare wire flow heaters spoil it), an average room has no safe place to attach an ESD strap. Instead quickly grasp something grounded (e.g. radiator, water tap, socket ground prong or grounded metal case) after walking around before you touch ICs. To me, simply wearing no shoes and sitting on floor in cotton-based jeans during work turned out to be fully sufficient to prevent jolts and chip crashes by static shocks (hence no risk of damage). In real life most chip damage during DIY is caused by other unremembered incidents (wrong polarity, wrong current flow by disconnected GND, misplugging) and falsely accusing static discharge. When the rest is done properly (no insulating clothing or shoes), an antistatic wrist strap is almost a placebo to calm the mind of repair companies and insurances, and knowing the health risks it should be better avoided.

   Static shocks are more common when it's cold and dry. This dry, cold air holds less water vapour than warm summer air. ... So, when you touch something like a metal doorknob or car door, those extra electrons will rapidly leave your body and give you the shock and I had a synthetic carpet in the past  and you could see the spark fly over to my finger  .even so way more dangerous      as a cellphone   and filling up you car with gas   is  ...static electricity  can set you car on fire   .electronics esp older parts are not well protected against  this  every self respected  electronics company use anti static mats or floors  and bands   believe me   ! it is not an urban legend be careful with static electricity and electronics simple   esp.the mos type and some other oldies ...newer electronics got more protections build in .

 I have this not from my self but my hubby is electric engineer and 1 of my daughters is   electric teacher  

https://creativeloafing.com/content-197734-the-straight-dope---can-static-electricity-kill

[HELVETIA]

16 hours ago, IanB said:

This is all interesting but shouldn't it have its own thread? I keep getting notifications, think Joe's keyboard has another update and instead we're discussing secondhand Casiotones

Sorry for that lol

 

[IanB]

Yes and no in my opinion regarding the static. I can honestly say I've never myself (so far as I am aware) ever harmed an IC with static, and I use the "touch earthed metal" approach, not a wrist strap, and to be honest have often forgotten to. But I live in dreary England where the weather is our favourite topic of conversation; we don't get much dry air. I have heard anecdotage from people in other places with dry climates that they have a much greater problem and personal experience of damaging electronics just by touching them. Humid air rapidly discharges you. It can depend on the carpet as well. And your shoes.

I've seen no scientific evidence that high frequency "dirt" on mains ground would hurt anyone. Here in the UK at least all exposed conductive parts like water pipes are by regulation bonded to mains earth. That means your radiators, metal sink, gas pipes, electrical conduits, etc etc etc. And we live in a soup of broadcast RF, which is why radios, phones and wifi work. Plus all those Switched Mode Power Supplies broadcasting at perhaps 66kHz as they switch.

So anyway, normally I just touch my (earthed metal) desk lamp before touching anything static sensitive.

[HELVETIA]

4 hours ago, IanB said:

Yes and no in my opinion regarding the static. I can honestly say I've never myself (so far as I am aware) ever harmed an IC with static, and I use the "touch earthed metal" approach, not a wrist strap, and to be honest have often forgotten to. But I live in dreary England where the weather is our favourite topic of conversation; we don't get much dry air. I have heard anecdotage from people in other places with dry climates that they have a much greater problem and personal experience of damaging electronics just by touching them. Humid air rapidly discharges you. It can depend on the carpet as well. And your shoes.

I've seen no scientific evidence that high frequency "dirt" on mains ground would hurt anyone. Here in the UK at least all exposed conductive parts like water pipes are by regulation bonded to mains earth. That means your radiators, metal sink, gas pipes, electrical conduits, etc etc etc. And we live in a soup of broadcast RF, which is why radios, phones and wifi work. Plus all those Switched Mode Power Supplies broadcasting at perhaps 66kHz as they switch.

So anyway, normally I just touch my (earthed metal) desk lamp before touching anything static sensitive.

  yes that will work discharge your self   I killed really some older tone generator and divider chips   and transistors  in organs    and after  grounding i have had never problem anymore  ..better safe as  having to repair again .

[CYBERYOGI =CO=Windler]

I generall try hard to keep room humidity above 50%, because else my hand knuckle skin becomes very sore and keeps bleeding. My Amiga computer workstation is built into a DIY wood and chrome case (had been a Wega loudspeaker box, Amiga 500 PCB, DIY external keyboard with aluminium bottom, constructed around 1990) with quite a cable mess inside. I run this machine daily for my diary etc. despite it has various quirks. So it tends to crash by static electricity when touching the aluminium front panel (diskette drives) in winter, which has somewhat drilled me to touch the radiator first anyway. (This Amiga also crashes e.g. when I power on my cassette deck (Telefunken TC650) at the same power strip, so it would likely not survive a nuke attack.)

Due to there is a mobile radio mast directly in front of my bedroom window, my bed corner got a special shielding (overleaping horizontal aluminized wallpaper stripes interconnected with capacitors and neon lamps) and the rug area under the bed has an earthed metal mesh underneath, connected to the radiator pipe (NOT socket ground).

If you insist wearing an ESD wrist strap (IMO an as bad habit as drinking chlorine bleach solution to sanitize your own guts) it may help to put additionally to the 1M resistor a small inductor (coil) in series into the cable to reduce HF dirt from socket ground. When working inside a device with shielded metal case connected to GND line of its PCB, simply touch the metal case to equalize potential with its PCB to prevent ESD. When the device is powered off and plugged out, you may also connect the wrist strap (crocodile clip) only to that case frame to stay at same potential like the PCB without hooking your nervous system for hours to socket ground.

[HELVETIA]

1 hour ago, CYBERYOGI =CO=Windler said:

I generall try hard to keep room humidity above 50%, because else my hand knuckle skin becomes very sore and keeps bleeding. My Amiga computer workstation is built into a DIY wood and chrome case (had been a Wega loudspeaker box, Amiga 500 PCB, DIY external keyboard with aluminium bottom, constructed around 1990) with quite a cable mess inside. I run this machine daily for my diary etc. despite it has various quirks. So it tends to crash by static electricity when touching the aluminium front panel (diskette drives) in winter, which has somewhat drilled me to touch the radiator first anyway. (This Amiga also crashes e.g. when I power on my cassette deck (Telefunken TC650) at the same power strip, so it would likely not survive a nuke attack.)

Due to there is a mobile radio mast directly in front of my bedroom window, my bed corner got a special shielding (overleaping horizontal aluminized wallpaper stripes interconnected with capacitors and neon lamps) and the rug area under the bed has an earthed metal mesh underneath, connected to the radiator pipe (NOT socket ground).

If you insist wearing an ESD wrist strap (IMO an as bad habit as drinking chlorine bleach solution to sanitize your own guts) it may help to put additionally to the 1M resistor a small inductor (coil) in series into the cable to reduce HF dirt from socket ground. When working inside a device with shielded metal case connected to GND line of its PCB, simply touch the metal case to equalize potential with its PCB to prevent ESD. When the device is powered off and plugged out, you may also connect the wrist strap (crocodile clip) only to that case frame to stay at same potential like the PCB without hooking your nervous system for hours to socket ground.

   last thing i post here  about this  subject   the wrist bands I used to use got resistors with it    similar  to this 1 

    http://www.leggesystems.com/Anti-static-wrist-bands-with-grounding-cord-ESD-control-and-protection    

[CYBERYOGI =CO=Windler]

Regarding old hardware and ESD. I remember that Commodore C64 computers in shopping centers indeed often died by it. There were atrocious synthetic rugs (and escalator handrails) where I got jolts when ever I touched metal in winter. When we kids had loaded a C64 game from cassette (secretly "lended" from a shelf nearby) and plugged a joystick in, often the thing crashed and needed to reload everything (which could take 15 to 30 minutes!). Even worse, sometimes accidentally touching the joystick port pins caused a shock that killed the port IC and so made one joystick direction and some keys stop working. Also the userport at the back was sensitive.

One reason for ESD damage is hotplugging ungrounded CRT TV sets or monitors. When they switch on, the CRT (acting as a glass capacitor) is charged to about 28KV with the chassis GND as its 2nd pole. If the TV is grounded (through mains or antenna plug) the 2nd pole stays at earth level, but if not, the entire chassis GND will instead charge to half of that highvoltage. If now the TV is plugged into anything grounded (e.g. antenna jack of a computer, game console or audio-in of an amplifier) that charge can flow into the connected device, and if something else than a GND pin connects first, it may fry ICs. This was likely the main reason for the warnings never to hotplug SCART cables. Among VHS recorders I did this all days without any damage (beside lousy plugs falling apart). Some think the warning was due to the 12V at some pins that might flow wrongways, but it is certainly an ungrounded CRT TV chassis that can cause mayhem.