moebius

mb944: Go to http://coinoptech.com/mbhp/ Or email Smash directly. Bye, Moebius

Oh course not -mee stuupid! Signal should go straight to +input and that Ra (Ra+trimmer) goes from -input to ground... (and Rf is in feedback path from output to -input of opamp) Head bangin' time...

Bloody mess... If Ra+trimmer are about 1,5kOhm and Rf 1kOhm.. and opamp input voltage is 2,2v it should give out around 3,67v.. +/-12v power supplies are ok.. (start with higher trimmer values first..) What the f**k is going on there?!

Ra + trimmer? Those are in series, yes? Opamp powered, with?

Ra, Rf.. are those measurement after the buffer?

Sounds like voltage measurement time, on "live" circuit.. check how much voltages are after buffer.. And Casio turned off you can measure resistor values..

For that opamp you'll need bipolar supply.. isn't there any on board? (How are those opamp powered?) Bye, Moebius

Ups, didn't check the lettering and the symbol is confusing ;D Yeah, TL072 should be just okay for this task. Bye, Moebius

http://www.ucapps.de

It was too good to be true ;) Think the markets for non-pro user installations.. "I guess we take that one - It's a well known brand and anything" ;D What's complicated? Simple opamp buffer circuit, one non-inverted, one inverted, from the same mono input signal, can be used to split it to inverted and noninverted signals, before power amp inputs.. (NE5532, anyone?) Then speaker (<- With enough impedance) leads are connected to the positive (hot) poles of the amplifier speaker outputs. (See Rowans post) Then put on your favourite pumpin' record and see those cones moovah'.. Bye, Moebius

Looks like it, yeah! Now go and blow up your Casio, Moebius ;D p.s. Of course your going to connect CV input wires from the TIP of the plug, right?

Hi, Looking good, expect: res buffer, connect the other end going to ground to wiper instead. (In curret configuration it acts like voltage diviner, not variable resistor..) (and if you like, you can leave ot IC2. For frequency buffer, just put ext. cv thru 47K resistor and insert it in vcf side of that resistor following that opamp. Bye ya, Moebius

That was a single INVERTING opamp, outputting negative voltages.. If you use single non invering opamp: Use 1kOhm for Rf and 1kOhm (restricts gain to 2) + 100Kohm trimmer in series for Ra. Then you can adjust gain from very little boost to BIG boost.. (I hope vcf survives - Don't blame me) ;D And why not? I don't know how often uC scans that dial ect. But I think you could make it even so, that it has own pot for each parameter - when some parameter is changed, first midibox checks if "datawheel" is on that parameter, if not changes to that parameter, and then enters to data mode (?) and uses pot value to update parameter... (of course midibox could also read what's the value on display ;)) this kind of application would have many uses for other equipment also.. Bye, Moebius p.s. That logic probe is more like of a toy..useful one of course but to see how uC controls that Music LSI you'll need (probably) MHz capable device, that can log bus wide data.

Hmm.. *Whisling*... It MIGHT be just a feature vcf chip (New Japan Radio doesn't even remember to have manufactured this part, no datasheet) - or just lame design by Casio not to make home keyboardist scared :P You can try boosting resonance voltage.. You can modify that buffer (uC -> resonance) to be a low gain non-inverting opamp circuit or use two inverting opamp circuits in series.. (with adjustable, but low gain) use something like: http://www.vwlowen.demon.co.uk/java/opamp.htm Yes, but it's too hard ;) (Must have pro gear like datalogging logic analyzer) Bye, Moebius

HD44780 compatible LCD controllers: [table] [tr][td]Controller: Â [/td][td]Manufacturer:[/td][/tr] [tr][td]HD44780 Â [/td][td]Hitachi[/td][/tr] [tr][td]KS0066 Â [/td][td]Samsung[/td][/tr] [tr][td]KS0076 Â [/td][td]Samsung[/td][/tr] [tr][td]KS0070 Â [/td][td]Samsung[/td][/tr] [tr][td]S6A0069 Â [/td][td]Samsung[/td][/tr] [tr][td]LC7985NA Â [/td][td]Sanyo[/td][/tr] [tr][td]SED1278 Â [/td][td]Epson[/td][/tr] [tr][td]NT3881D Â [/td][td]Novatek[/td][/tr] [tr][td]SPLC780 Â [/td][td]Sunplus[/td][/tr] [tr][td]MSM6222 Â [/td][td]OKI[/td][/tr] [tr][td]NJU6408B Â [/td][td]NJR[/td][/tr] [tr][td]NJU6468 Â [/td][td]NJR[/td][/tr] [tr][td]NJU6470 Â [/td][td]NJR[/td][/tr] [tr][td][/td][td][/td][/tr] [tr][td]Possibly: Â [/td][td][/td][/tr] [tr][td]UM3881B Â [/td][td]UMC[/td][/tr] [tr][td]T7934 Â [/td][td]Toshiba[/td][/tr] [/table] If your LCD has one of these chips, there are good changes to get it work. These chips have similar instruction set, data bus and timings are like original HD44780 (or faster, which shouldn't matter) BUT this only means that controller chip is compatible with driver designed to HD44780 Â 8) It's simply easier to get a display that has datasheet available. Common problems, if it isn't your soldering: First: There is no common standard for display connector - You should get your LCDs datasheet to see, what the pinout is. Second: Your display may need negative contrast voltage. (Watch out for Vee pin.) (check post by Smash: http://www.midibox.org/cgi-bin/yabb/YaBB.cgi?board=troubleshooting;action=display;num=1099022402) Third: Backlight not working? Maybe it's Electroluminescent (EL) type. And it's also good to know, that at least HD44780 displays can be initially programmed to different character sets - maybe your dirt cheap surplus display just talks greek to you ;D Bye, Moebius (Sources: http://www.idwusa.com/frameset.htm?products/catalog/ModuleTypes/CharacterType/Specifications/DotCharacterPatterns.htm&1 NJR part cross reference ect.)

Hi, read bridging part CAREFULLY: http://www.rocketroberts.com/techart/amp.htm A good one.. LOL, AAHhhah! Bye, Moebius

Ahemm.. ;) Leave 741s, no need for those.. (And actually with THAT circuit you would be inserting max -10v to resonance input that originally swinged between +0,8 and +2,2v :D) Then: use separate resonance controls for melody / chords VCF. (To external cv ins) And there's no need to insert many external CV's to frequency controls, just put one per vcf and insert it to the place (b) as seen in the manual.. And making CV balanced.. yeah.. Kind of like that ;) Making that mbhp_aout_balanced_cv.pdf circuit creates an offset voltage. And then it's connected to the AOUT board. (replacing one "jumper" with resistor).. Be sure that you have most recent AOUT schematics so you see how it's connected. Bye, Moebius

Sorry for confusing you.. Nope. You build that buffer circuit as you had it in your picture. But, you probably don't have to do additional scaling to ext. cv voltages, if you MODIFY AOUT, by omitting those R_y, R_p resistor in AOUT board and putting wirelink in place of R_x (then it equals the buffer you made in HT-3000, that's what I meant) - It will give you 'bout 0-2,048v out. Then (There's only reference to this at forum, sooo..) adding http://www.ucapps.de/mbhp/mbhp_aout_balanced_cv.pdf you simply make external cv to be 'bout 0v at CC64, -1,024v at CC0 and +1,024v at CC127... This would mean, that when ext. control is in mid. point it doesn't affect HT-3000, and lower values make resonance go down and higher values make it go up.. Bye, Moebius

Hi, I guess that accuraty isn't that important here, so I think you can use voltages from AOUT directly - just omit resistors R_y and R_p and replace resistor R_x with wire link will give you output voltages from 0 to 2,048v. (Yes, it's the same buffer circuit ;)) I think using AOUT_balanced for CVs is smart thing to do - midpoint would then give zero external modulation ect.. Bye, Moebius p.s. Hmm.. basic analog delay.. well, voltage controlled ones are way cooler ;D

Yup, The upper section in the pic looks right ;) And for the companders - Take a look at http://www.generalguitargadgets.com/index.php?option=content&task=view&id=140&Itemid=156 Circuit around SA571 (or 570) is compressor after input and expander before output buffer. Should be easy to adept to HT-3000 chorus.. Compressor before LPF part of the BBD input and Expander after the LPF part at the BBD output.. Bye, Moebius

Hi, MBHP_JDM is just an adaptation of a original JDM programmer: http://www.jdm.homepage.dk/newpic.htm Get a 18pin "machine pin" ic socket (these are harder to break ;)), compare the original JDM schematics and MBHP_JDM one - all the signals needed to program 16F84 can be taken from the socket of a MPHP_JDM. So, use jumper wires to connect 18pin socket like in original schematics and leave some wires longer - to be plugged into MBHP_JDM.. (some additional wiring stuff is included for serial EEPROMs, but I'm no expert and don't know what to leave out..) Bye, Moebius

Well, Opamp feedback (from output) goes to the - terminal (pin2, in this case). And leave the pot out.. (and opamp of course is powered +/- something ;)) And ext. cv must have Ground connection.. Otherwise it looks good. You could use two inverting opamps to scale ext. cv to 0,5-2,2v inside the machine so it would accept 0-5v modulation or whatever you like, with biasing it can also be used with bipolar modulation, or use 2,5v as point with no external modulation. So, it's going nice, Moebius p.s. No wonder Chorus is noisy, there is no "compander" noise reduction.. By the way, if your going to bypass that, can I have the chips ;)

It's the metal cover over the PCB, it's bend so it touches some of the chips on the board and transfers heat to dissipate from a larger area. Bye, Moebius

Well, as this thread is dead ;) (or let's say problems solved) I use it as an excuse to blaa blaa.. Checking your own work is a one thing - but doing it to somebody other.. ;) Once you get used to a soldering iron (and that is MUCH easier with a proper one), you know when you have done a good job, and where problem might be.. I once went to meet this service technician, focusing to audio stuff "only", and he had a gig, so I went along.. The problem was described as "one channel on studio monitoring system being damped" - yeah, that it was, left monitor channel was down at least -6dB compared to right one. With physically switching speaker cables problem was isolated to this World Famous active nearfield monitor (Finnish brand ;)).. After voltage measurement and opamp replacement procedure (HIS standard: not an advice nor recommendation. He's got over 20 years experience on the field - knowing the failure rate of opamps (and the rate he's charging), It's just "cheaper" to check, if there isn't power problems and replace all opamps and see if it helps, than do a time consuming fault hunting, just to see it was a blown opamp), problem was still there. He was about to take it to his lab and do the proper checking with scope ect... but then I had a hunch and suggested, that he would resolder leads of a power resistor (10w or so) on the power supply. It actually worked ;D There wasn't any signs of a cold solder joint or anything. PS voltages looked good with a DVM. Probably years of use and heat generated by that resistor had revealed a cold solder joint left from manufacture, that injected a nasty ripple voltage (which you couldn't see with a DVM) to the power lines causing improper functionality.. Problem solved: Boy, Did I feel good ;) ---- Another thing: I have been repairing a Korg Polysix... Anyone of you having a 20 years (or so) old synthesizer with patch storage - Watch out! There are a good changes that it uses a Ni-Cad battery as a memory backup.. As those get old, they stop working, but loosing your custom sounds isn't the worst thing: They will eventually spill their guts out to your precious synth PCB.. This can corrode copper traces so badly that it's very hard to repair.. SO check and change Ni-Cad batteries, NOW! If there is already corrosion, it must be scraped off. I secured bare copper traces from oxidation with solder plating. Bye, Moebius

Hi, I haven't realized that those old Casios were that hot beasts.. even a nice (?) analog chorus there ;) Well, only one vcf per part, but anyway... Looking at schematics and functional description - I would insert additional filter frequency (thru resistor) control voltage at point (b) as seen on page 19. (That's pin7 at LA6358-2, for melody part and pin1 at LA6358-3 for chord part, page 3).. Original voltages are scaled between 0,8v <-> 2,6v.. and additional voltages should be scaled the same (?!). For resonance control, lift the side of the 220k resistor that connects to uC side. Add an non-inverting unity gain buffer circuit between lifted resistor leg and uC. (We don't want to know what that processor thinks about seeing external voltages on it's output pins.. ;)) Then insert resonance CV at buffer output (lifted resistor leg).. It's scaled between 0,5v and 2.2v but I think that you can go at least bit higher than that ;) But study circuits yourself and see if I make any sense here ;)) Bye, Moebius