sci.electronics.repair@googlegroups.com

Google Groups

Unsure why you received this message? You previously subscribed to digests from this group, but we haven't been sending them for a while. We fixed that, but if you don't want to get these messages, send an email to sci.electronics.repair+unsubscribe@googlegroups.com.

"Arfa Daily" <arfa.daily@ntlworld.com>: Nov 19 02:30AM I avoid keyboards whenever I can. They are heavy, have too many screws in, and take up too much bench space. On this occasion however, I was asked to look at a Korg LP-350 electric piano by a music store that I have only recently started doing work for, so had to be 'accommodating' to ...   The shop owner said it was dead, and that he had tried another power supply already. I figured that this might be something nice and straightforward like a socket busted out of the board. When it arrived, I was delighted to see that the socket and on - off switch were located in a largish 'pod' secured to the bottom of the unit with just 6 screws. So I stood the unit vertically, leaned against the bench, and removed the pod. In fact, the entire electronics seems to be on a single board in this enclosure, with just the keyboard itself and the control switchery being in the main part of the cabinet. The problem turned out to be some miniscule little sm device in series with the DC connector centre pin. It is too small to have any value marked on it, but does have the designation "R" on the board so maybe its a tiny safety resistor (anyone know ?)   So to get it going initially and check for any other problems, I hung a 1 ohm fusible R across the pads. This restored life to the LEDs on the control section, so I hooked it to an amp. And this is where it got odd - for me at least.   Some notes sort of worked, although you had to pound them quite hard. Other notes didn't work at all. Then when you went back to one that worked a few seconds ago, now it didn't. Clearly, it's a keyboard with full velocity sensing, but this seemed very arbitrary as well. My heart was just beginning to sink when I decided to turn it 'right way up' i.e. horizontal, just in case. And Lo! Then it all worked. Every note was fine, and the 'touch' behaved perfectly. Now I don't pretend to understand keyboards, but as far as I can recall, all the ones that I've previously seen have either been based on bus bars and springy contacts, or rubber keymats.   So how is this one done such that it won't work when the unit is standing upright on its end ?   Arfa

jurb6006@gmail.com: Nov 18 06:49PM -0800 I had one like that. I mean I owned it. With the weighted keys. People who play keyboards'll tellya there is a big difference in a piano. Mine was a Previa PX-110. It is a cheaper one actually but plays really nice. And I've gotten on other ones that are also touch sensitive but not weighted, and I can tell you there is a world of difference.   It depends on weight and mass. The mass the key moves is actually partly counterbalanced, which only takes care of gravity. The mass makes it feel like the key is pushing the stirrup or whatever, and hammer in a mechanical piano.   I think they're cool. In fact I like pianos too, and think about how long ago they were invented. Damn them people were smart back then.

John Robertson <spam@flippers.com>: Nov 18 10:00PM -0800 On 11/18/2014, 6:30 PM, Arfa Daily wrote:   > So how is this one done such that it won't work when the unit is > standing upright on its end ?   > Arfa   Mercury switches?   John :-#)#   -- (Please post followups or tech inquiries to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

"Gareth Magennis" <sound.service@btconnect.com>: Nov 19 10:16AM "Arfa Daily" <arfa.daily@ntlworld.com> wrote in message news:nhTaw.1073179$AB3.600108@fx07.am4... > miniscule little sm device in series with the DC connector centre pin. It > is too small to have any value marked on it, but does have the designation > "R" on the board so maybe its a tiny safety resistor (anyone know ?)   Its probably a diode to prevent the wrong polarity PSU breaking stuff. (probably shottky for low Vf).   I have a SP-250 schematic that shows a diode between DC centre pin and regulators, marked S8540, but didn't find anything in Google. Sometimes these things will have a reverse diode shunt to ground instead of a series one. Whatever, there should be reverse polarity protection there somewhere, not a fuse or resistor.     As for the key shennanigans, the key contacts are probably operated by the hammers that the key moves, rather than the key itself. Up-ending the keyboard causes all these hammers to hang loose, probably close or even touching the contact strips, so you will get very unreliable results. The hammers give a realsitic impression of how a real piano feels to play, something a lot of pianists like.   Trouble is it makes the keyboard the weight of a small car.         Gareth.

"Arfa Daily" <arfa.daily@ntlworld.com>: Nov 19 11:09AM "Gareth Magennis" <sound.service@btconnect.com> wrote in message news:xvudncudyIi58_HJnZ2dnUVZ8nednZ2d@bt.com... > Sometimes these things will have a reverse diode shunt to ground instead > of a series one. Whatever, there should be reverse polarity protection > there somewhere, not a fuse or resistor.   There is both. Centre pin goes straight to this tiny device. It is designated R4. Off the back side of it, there is a small ceramic decoupler to deck, and a series choke, L2, the back side of which trundles off to the single pole on / off switch at the front edge of the board, as well as having another little ceramic decoupler to deck. The return from the switch comes all the way back to the rear of the board again, where it fetches up at the arse end of a series protection diode, D3, marked 348A. The cathode of this diode is then the main power distribution point into the 3v3 regulator etc. So the device that has failed is definitely some very low value series element, and I'm still thinking resistor, as it is called "R4". I too tried Googling without finding anything. The unit is needed for Friday, so not finding anything definitive on what the device is, or its value / type, I think I am going to stick with a low value fusible R. The volts drop is very small across the 1 ohm that I hung in there. I might go down to 0.47 ohms, just in case it draws enough to increase that drop under some circumstances. Can't see anything that looks particularly current-thirsty on the board, though. > The hammers give a realsitic impression of how a real piano feels to play, > something a lot of pianists like.   > Trouble is it makes the keyboard the weight of a small car.   Yes, I think you are probably right. The keys do have that mechanically 'weighted' feel of inertia, and it *is* the weight of a small car ... :-)   Arfa

"Gareth Magennis" <sound.service@btconnect.com>: Nov 19 03:15PM "Arfa Daily" <arfa.daily@ntlworld.com> wrote in message news:%T_aw.783840$Kk6.298930@fx22.am4... > there. I might go down to 0.47 ohms, just in case it draws enough to > increase that drop under some circumstances. Can't see anything that looks > particularly current-thirsty on the board, though.       Yes, I guess I can't see how anything called R4 in this circuit can be anything other than a resistor really.   I have 2 other Korg piano schematics, 1 uses a series 1N4002, and the other a series SMD shottky: http://pdf1.alldatasheet.net/datasheet-pdf/view/99827/ROHM/RSX301L-30.html         Gareth.

Klay Anderson <klay@klay.com>: Nov 18 09:18AM -0800 On Tuesday, November 18, 2014 9:12:54 AM UTC-7, Robert Macy wrote:   > REALLY like these units and want to keep. The pushbotton switches have > become unreliable, often yielding two numbers and sometimes not even > registering!   I too have quite a few and like the system. I've purchased broken and surplus phones and simply replace the culprit buttons when they go out. Parts are probably no longer available and I don't see any reason to attempt to clean them when the issue is wear.     Yours truly, Mr. Klay Anderson, D.A.,Q.B.E.

Jeff Liebermann <jeffl@cruzio.com>: Nov 18 10:26AM -0800 On Tue, 18 Nov 2014 09:14:52 -0700, RobertMacy   >Have quite a few landline Panasonic Easa-Phones, Model KX-T2315   <https://www.google.com/search?q=KX-T2315&tbm=isch> I have one of those. It's a good phone well worth fixing. I don't want to take mine apart as long as it's working.   >Could be the type of cleaner, or the method of doing, or there simply is >no more 'contact' left in the switches. But since using over and over >seems to almost repair, suspect should be able to do something.   See exploded view of keyboard section: <http://www.eserviceinfo.com/downloadsm/5538/Panasonic_KX-T2315.html> It uses individual "sealed" switches, which might be replaceable or cleaned. I can't tell from the manual.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

"Gareth Magennis" <gareth.magennis@ntlworld.com>: Nov 18 06:29PM "RobertMacy" wrote in message news:op.xpi3e2d22cx0wh@ajm...   Have quite a few landline Panasonic Easa-Phones, Model KX-T2315   REALLY like these units and want to keep. The pushbotton switches have become unreliable, often yielding two numbers and sometimes not even registering! The worst offenders are the telephones that haven't been used for a while.   Any way to fix? I've tried contact cleaner injected in but that hasn't taken.   Could be the type of cleaner, or the method of doing, or there simply is no more 'contact' left in the switches. But since using over and over seems to almost repair, suspect should be able to do something.   help!         http://www.mcmelectronics.com/product/PANASONIC-PQSH1A33Z-/P-PQSH1A33Z       Gareth.

RobertMacy <robert.a.macy@gmail.com>: Nov 19 06:17AM -0700 > attempt to clean them when the issue is wear.   > Yours truly, > Mr. Klay Anderson, D.A.,Q.B.E.   I believe wear is involved, but what really caught my attention was that the least used phone is the one that does NOT work well. Swapped out so it got daily use, and it came back a bit and the other phone has quit - making me think/hope maybe there is a 'crud/corrosion' build up? And, these phones may be salvageable.

RobertMacy <robert.a.macy@gmail.com>: Nov 19 07:15AM -0700 On Tue, 18 Nov 2014 11:26:39 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:   > <http://www.eserviceinfo.com/downloadsm/5538/Panasonic_KX-T2315.html> > It uses individual "sealed" switches, which might be replaceable or > cleaned. I can't tell from the manual.   Thanks ! The second URL I got a manual. You know I'm on dial-up here and that first URL still had not filled a single image even after 10 minutes so had to give up. Plus, these webpages don't even download in the background, no, they hog the browser, hang it up, freeze the cursor, can't even go off and work on other applications. Just have to sit there and ...wait.   I don't know how you find all these worthwhile websites so fast. But thanks again for the manual.

RobertMacy <robert.a.macy@gmail.com>: Nov 19 07:29AM -0700 On Tue, 18 Nov 2014 11:29:58 -0700, Gareth Magennis   > http://www.mcmelectronics.com/product/PANASONIC-PQSH1A33Z-/P-PQSH1A33Z   > Gareth.   GREAT! Thanks for that URL!   interestingly no picture of the part, their picture is a symbol.   but nt a bad price either. will have to call.

"Arfa Daily" <arfa.daily@ntlworld.com>: Nov 19 01:30AM > Cheers,   > Gareth.   In reply to everyone, the bias did move with the valve - it was one of the first things that I checked, so the board was 'doing its thing' and balancing this valve into the other three. Information that I have since found out today, indicates that one valve was changed on its own a few months back, so I guess that's probably the one that is different, so I think I'm going to add this new knowledge to what the man at Fender said about them having had board problems, and that the new board was a pre-packaged spare, and declare it "good to go" !   Arfa

"Arfa Daily" <arfa.daily@ntlworld.com>: Nov 19 01:55AM "Phil Allison" <pallison49@gmail.com> wrote in message news:62358070-9217-4fe4-ba11-3f88805e8b67@googlegroups.com... > Arfa Daily wrote:   >> So, the nonsense bias board arrived.   > ** The "nonsense" is all coming from you - fuckhead.     The board is a nonsense piece of design. It's not needed, and only adds another layer of complexity into an item that is needed to be robust and reliable. For most purposes in this type of equipment, fixed bias at the simplest or single level-pot and sometimes a balance pot is all that is required. Owners should not be arsing about changing valves in the first place, and particularly should not be mixing types.     >> matched quad - we didn't fit them - but clearly they aren't, quite.   > ** One valve, 1 volt out is about as near to matched as any 4 output > valves I have ever seen or ever need to be.     You miss the point as always by running your stupid mouth before engaging that pathetic walnut of a brain. Fucking dope       > Jesus Christ you are a neurotic fuck.     Bwaaaahhhaaahhhaaaa !!!!! That from YOU ??!!! Neurotic ? Fuckhead ? That would be YOU with bells on ...     >> quite a bit.   > ** The 4 bias currents are IDENTICAL !!   > You stupid twat.   Philip. Mirror ...       >> owner replaces all four tubes now for a properly matched quad.   > ** FFS - there is nothing improper about the set you have.     I didn't say that there WAS. I was just examining the possibility that there MIGHT be. But then you don't actually read and understand anything before you run that dopey gob of yours, do you ?   >> signs of any flashovers or other nasties going on, but I still have that >> niggling doubt that something might have twatted that board,   > ** Fender have already told you the boards fail all on their own.     So they did. But that doesn't mean that they don't also fail as a result of something else as well. There was no serial number identification offered by Fender in regards of this bad batch. Just a statement that they had had a bad batch "around that time" when told its age. Therefore, this one may or may not have come from that batch. I can't say for sure, and YOU most certainly can't ...     >> and that one of >> the outputs clearly doesn't quite match the other three.   > ** Twaddle.     Bollocks. If the board arrives at a solution that sets the bias near as a gnats cock identical on three of the valves, and sets the fourth a volt or so different, then that 'odd one' clearly doesn't QUITE (look the word up if you're not sure) match the other three     >> looks like have already been replaced not long ago ... :-\   > ** If it ain't broke, don't fix it.   > Only crooks do that.   And you would know, of course ... Now go take your meds, and shut the fuck up. Twat.   Arfa

"Arfa Daily" <arfa.daily@ntlworld.com>: Nov 19 02:09AM > but cannot now find it or could you at least repeat the model number. > What was the failure in the board, could you tell whether over-current or > over-voltage, any deliberate track thinnings for tell-tales.   It's a Supersonic 100 head. The board failed to produce any 'controlled' bias to the valves, and all four grids were at -89 volts. It looks as though it works by measuring the voltage across four low value Rs in the cathodes by using A-D inputs on the microcontroller on the board. The bias is then produced by feeding PWM signals from four port pins to driver transistors followed by filter caps. In the case of this board, the supply volts, reset pin etc were all at correct levels, but the micro did not produce any output. You could not even measure any clock at the xtal pins. No evidence of any cause was visible. Board was pristine. Double sided surface mount, and all examined under strong magnification, but no signs of any damaged components.   Arfa

"Tom Miller" <tmiller11147@verizon.net>: Nov 18 09:29PM -0500 "Arfa Daily" <arfa.daily@ntlworld.com> wrote in message news:nZSaw.1124894$Fy6.125771@fx25.am4... > surface mount, and all examined under strong magnification, but no signs > of any damaged components.   > Arfa Any numbers on the cpu?

"Arfa Daily" <arfa.daily@ntlworld.com>: Nov 19 02:45AM "Tom Miller" <tmiller11147@verizon.net> wrote in message news:m4gvbm$ghe$1@dont-email.me... >> but no signs of any damaged components.   >> Arfa > Any numbers on the cpu?   STM32F 101C6   This appears to agree with what it says on the schematic   Arfa

Phil Allison <pallison49@gmail.com>: Nov 18 07:05PM -0800 Arfa Daily wrote:     > >> So, the nonsense bias board arrived.   > > ** The "nonsense" is all coming from you - fuckhead.   > The board is a nonsense piece of design.   ** No it is not.   > > ** One valve, 1 volt out is about as near to matched as any 4 output > > valves I have ever seen or ever need to be.   > You miss the point   ** There was no point get - you lunatic.   Jesus Christ you are a neurotic fuck.     > > ** The 4 bias currents are IDENTICAL !!   > > You stupid twat.   > Philip.   ** You completely missed the point, as usual.     > > ** FFS - there is nothing improper about the set you have.   > I didn't say that there WAS.   ** You did, three or four times.       > > ** Fender have already told you the boards fail all on their own.   > So they did.   ** Believe them.   > But that doesn't mean that they don't also fail as a result of > something else as well.   ** Sheer, paranoid fear of the new.   If the design was that fragile, there would be constant PCB failure.   You will find there is a very high resistance between the output valve grids and the bias PCB circuitry and the cathode resistors are protected from over-current too.   What a dickhead.     ... Phil

"Tom Miller" <tmiller11147@verizon.net>: Nov 18 11:22PM -0500 "Arfa Daily" <arfa.daily@ntlworld.com> wrote in message news:DvTaw.655114$J62.246927@fx03.am4... > 101C6   > This appears to agree with what it says on the schematic   > Arfa   Put this whole number in a search to get the datasheet.   STM32F101C6   It is an ARM Cortex 32 bit CPU with 32k bytes of flash. I don't know how successful you would be copying the firmware over to a new chip..

"Arfa Daily" <arfa.daily@ntlworld.com>: Nov 19 09:27AM "Phil Allison" <pallison49@gmail.com> wrote in message news:605af8cc-4dd2-4781-8eba-904ae94f4163@googlegroups.com...   >> The board is a nonsense piece of design.   > ** No it is not.       So, would that be more or less so than your opinion of the HK board ? And I quote from your post -   >> > valves I have ever seen or ever need to be.   >> You miss the point   > ** There was no point get - you lunatic.   Not in your wobble-eyed head ...       >> > ** FFS - there is nothing improper about the set you have.   >> I didn't say that there WAS.   > ** You did, three or four times.   Err, no, I didn't ...       > ** Believe them.       >> But that doesn't mean that they don't also fail as a result of >> something else as well.   As I said ...       > ** Sheer, paranoid fear of the new.   Oh fuck off back under your stone you obnoxious arsehole. I've been in this game for 45 years. Nothing has come along in that time to make me paranoid, and this isn't going to be the first       > You will find there is a very high resistance between the output valve > grids and the bias PCB circuitry and the cathode resistors are protected > from over-current too.   There is a couple of hundred k. Hardly a "very high resistance".       > What a dickhead.   You know, you really are a sad fool, Philip. Just about any thread that anyone starts that runs for longer than a couple of days, sooner or later, there you are running your dumb - and usually foul - gob off. The trouble with you is that you have this pathetic need to try to sound superior to everyone, when in truth, you are often at least misguided, if not downright wrong. Just because something is your opinion, it doesn't necessarily make you right and everyone else wrong. Your main failing is that you do not read things properly, and then go off on one of your ill-conceived rants, based on what you *thought* you read. When your error is pointed out, you then start madly snipping in an attempt to cover up what *you* said in reply to what the poster *actually* said, and then start leveling a tirade of abuse , peppered with expletives, capital letters, exclamation marks and asterisks, at anyone who dares to challenge you. Some of the more 'delicate' posters cave in at this, but I don't know why you keep trying it with me. You've tried this crap with me on many occasions, and I would have thought that you would have worked out by now that I am not intimidated by you. But then again, maybe your brain is either so faulty, so drug-rotted, or so alcohol-soaked that you can't remember from one day to the next who you have already unsuccessfully had a go at.   Go get some help. Seriously.   And, unless anyone else has got any sensible comments or questions, I'm done with this now. The amp is fixed. I'm reasonably happy that there are no further issues, and it will be returned to its owner today.   Arfa

mroberds@att.net: Nov 19 04:33AM > So you input a latitude and longitude and the application returns a > date and time when 3 or more GPS satellites are within (selectable) > say 30, degrees of the zenith.   This doesn't let you select the degrees-from-zenith, but you can get a good idea by looking at the 2D or 3D map.   http://in-the-sky.org/satmap.php   > Wish to determine the height of a patch of ground.   Pretty much anywhere in the UK should have decent GPS coverage - take a GPS receiver to the spot and let it sit there for a while. GPS altitude is not as accurate as latitude and longitude, but the longer you can keep the receiver still, the better it will get.   If you have really a lot of time, let it sit there for many hours logging data, and plot the results... there will be a definite distribution and you can pick the number closest to the center. If you dig into the settings enough, some receivers have options for stationary vs pedestrian vs vehicle - this tweaks the averaging/filtering that they do on the raw data, and may help you get a reliable answer sooner.   > It is away from roads, so daftlogic.com etc and old OS maps (before > they got precious with their data) and proper spot heights, is no use.   Google Maps has a "terrain" feature. You can only see the contour lines in a specific zoom range - at roughly 1.5" to 1000' scale, I get 100 m major contours and 20 m minor contours. Zooming out one mouse-wheel to roughly 1.5" to 2000' scale, I get 200 m major and 40 m minor. Two more mouse-wheels out and no contours at all.   Oh, this one is better. http://openstreetmap.org and click the "layers" icon (a stack of paper) at the right and select "cycle map". 50 m major contours and 10 m minor ones if you zoom in enough, at least in England and Scotland.   Matt Roberds

N_Cook <diverse@tcp.co.uk>: Nov 19 08:40AM On 18/11/2014 11:52, Pat wrote: >> . It is away from roads, so daftlogic.com etc and old OS maps (before >> they got precious with their data) and proper spot heights, is no use.   > Google Earth?   I'll try again later today. ISTR that whan it first came out, I tried it on a piece of ground with known survey-level and it came back rubbish. Like anything based on google maps, (just linear interpolation between road junctions so doesn't catch humps and dips )

N_Cook <diverse@tcp.co.uk>: Nov 19 08:45AM > contours and 10 m minor ones if you zoom in enough, at least in England > and Scotland.   > Matt Roberds   I've tried that, in effect. Known survey-level piece of ground and for ten minute sessions on 3 days. However I averaged the results, the answer was no better than .5m or so of the known surveyed level. I wanted to repeat this on some day and time with known good zenithal satellites, get a good agrreing result, and then move to the unknown patch of ground on another day, but again zenithal for that spot, it is not nearby to me

You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com.