deletemeplease

Can anybody explain to me roughly how to test circuits? I'm able to follow the instructions TK gave on ucapps.de but my core doesnt work and it would be interesting to learn how to test the circuit properly. At the moment all i use my multimeter for is continuity checks, which doesn't really tell me an awful lot about the circuit! ::) I read this site http://www.doctronics.co.uk/meter.htm which told me a little about using the multimeter's functions (and i also got the resistor colour code converter - which helps you work out what resistor you have in your hands). Any tips would help! Thanks! Paul

Is it too late to reserve 8 encoders? EDIT: Never mind! A friend said he has some spare! ;D

I have a spare PIC16F874 and 20 mhz crystal. Â would it be possible to burn a firmware (after i've replaced the crystal) just to test the midi out (like send a sysex on power on)? That way i would know if it was my crystal thats causing the problems? I started building my box last year using the .pdf midibox 16 guide and that didnt work, but that could have fried my lcd i guess? Well if the midi output works with my old pic, then i'll buy a new lcd :D

The crystal i use is parallel cut. But the circuit still doesnt work ??? ??? ??? I have no clue why not.

That would explain why the output doesnt work ::) Nat - The circuit wont output anything if the crystal is wrong as the PIC needs the proper crystal to function properly (i think)

Hey mate :) I didnt have anything connected at the when i was getting strange voltages, because i was just testing the volts between pins on the IC. Yeah i'm using that same crystal, i was begining to get the feeling that that was the problem! :-/ I checked the connection between pin 3 (+5v) of the 7805 and B+ / Vd of the core lcd jumper pins, and thats fine, so presumably the LCD *should* light up when i apply voltage, even if it displays nothing right? I'll try find another crystal (my local supplier is out of stock) but farnell offers 3 x 10 mhz crystals and i dont know which are serial and which are paralell cut - http://uk1.farnell.com/Search/level_5.jhtml?PRODID=47684&SKUID=45669 ^ That's the order page, but it doesnt say (neither does the datasheet) whether crystals are serial or parallel cut :'(

YO! No the circuit doesnt send any sysex on start up, which makes me think there is a problem some where on the board (i don't get a sysex string even if the lcd is not connected). As for the LCD, i tested it by plugging my cable in and checking the connection between the bottom of the core board (where the jumper pins where soldered) and each individual pin on the LCD. Hard work when the pinning isnt straight forward! ::) Right.. i'll go check the connections on my core again :)

Ello.. me again ;D I plugged in my lcd, and nothing happens when i apply power, the backlighting doesnt come on (and no characters are displayed). I programmed the PIC by using the JDM programmer over the connection to J3 on the core, which verified that the bootloader was loaded properly. Should the LCD light up when power is applied to it, regardless of if everything is set up correctly (as long as power is being supplied to VDD and VSS and LED- and LED+)? I think something is drastically wrong with my circuit - i sent the following sysex string: F0 00 00 7E 40 00 0D 02 00 0B 0A 00 00 00 01 00 00 00 00 F7 in order to see if the PIC thought there was an lcd connected, but i got no response. I'm getting fed up again  :-/ Thnx! EDIT: Damn i forgot to say - i checked the connections for the LCD and thats all fine, i checked the voltage across Pin 1 and 2 of the LCD (Vss and Vdd) and that was a healthy 5v, as was the voltage across pin 15 + 16 - A(LED+) and K(LED-).

Yes that works ;D Yet another time when i should have read the instructions slowly :-/ THANK YOU ALL!

Ok, but arent Electolytic Cap's polarised? I dont want polarised do i? Worth a try though isn't it ;) Ahh I understand! Oh shoot! i just checked and i was using J2!!!!!!!!! HAHAHA! I thought that was J1 (the one next to the 7805)... well that would explain my problems. ::). I'm such a retard. heh Right i'm off to go solder it properly! Thanks for your help everyone! :-*

Ok i'll try that :) Thanks!

Everything I have is either wrong voltage or more than 1amp! >:( Right well theres nothing more that i can do tonight.. i'm gonna sleep and hopefully it'll have fixed itself by morning! ;D

I haven't got another one  ::) :EDIT: Hmm. .i tried my soundcard supply (9v) and that yielded the same results but thats rated at 1amp as well. The thing that confuses me is the fact that mains polarity is meant to be unimportant, yet i get 2 different sets of results depeding on if i use + or -. hmmm ???

Ok so i dropped the voltage from 9 volts in my first experiment, to 7.5 volts. Â These are my results: +ve IC1:MCLR(1) - IC1:Vss(12) = 7V IC1:Vdd(11) - IC1:Vss(12) = 7V IC1:Vdd(32) - IC1:Vss(31) = 7V IC2(8) - IC2:(5) = 7V -ve IC1:MCLR(1) - IC1:Vss(12) = 2.5-3V IC1:Vdd(11) - IC1:Vss(12) = 2.5-3V IC1:Vdd(32) - IC1:Vss(31) = 2.5-3V IC2(8) - IC2:(5) = 2.5-3V :-/ At 6v i get 6v for +ve, 2.5-3v again for -ve. I'm starting to think this is something to do with my 7805. Â My power supply is capable of 1.2A i think so i'm guessing thats whats being sent into the circuit, which would explain the heat being generated by the 7805 so i dont know if thats got anything to do with it. ??? I'm stumped..

Thanks for the advice nat. Yes its definately a 7805 "L7805ACV" to be precise :) Not sure if my crystal is serial or parrallel cut (just pouring throught the datasheet now). But would this have any effect on the voltage? I think the voltage difference must be due the the bridge rectifier, so i'll see if i can find the proper one in farnell somewhere, which could take a few hours.. :'( Thanks for your suggestions tho nat..

I'm not sure. I don't know how to test for that :-/ One more part i forgot to mention was my crystal - it is a 10 mhz, but doesnt look like my 20 mhz one its about a quarter of the size. Damn Farnell and their too much choice! (my crystal is Farnell order code: 485-081) My crystal looks like the one on the left <-- Well I could say I'm dissapointed that my core doesn't work, but as it's the second time i've built it, i'm just glad the voltage is running through it!! ::)

Yo I finished building my Core today and I just came to testing it and i'm getting very strange results! I tested with Pin 1 being positive (+ve) and negative (-ve) and recorded the following results: Pin 1 - +ve IC1:MCLR(1) - IC1:Vss(12) = 9V IC1:Vdd(11) - IC1:Vss(12) = 9V IC1:Vdd(32) - IC1:Vss(31) = 9V IC2(8) - IC2:(5) = 9V Pin 1 - -ve IC1:MCLR(1) - IC1:Vss(12) = 1.5-1.6V IC1:Vdd(11) - IC1:Vss(12) = 1.5-1.6V IC1:Vdd(32) - IC1:Vss(31) = 1.5-1.6V IC2(8) - IC2:(5) = 1.5-1.6V Now, I did use a couple of different parts which could explain the strange results. These are the different components i used (same values but different types.. don't know if it makes a difference) C4 - 100nF Resin-Dipped Ceramic Capacitor C6 - 330nF Resin-Dipped Ceramic Capacitor X1 - W005 bridge rectifier* The spec of the W005 bridge rectifier is : Part - W005, PIV- 50V Ifav. - 1.5A Max RMS- 35V Max cap- 5000µF Max Vf per diode- 1.1V/1A I was going to use 4 1N4001's but i was unsure of how to solder them. I posted an idea of how to connect them, but no-one could tell me if it was right! See- http://www.midibox.org/cgi-bin/yabb/YaBB.cgi?board=parts_q;action=display;num=1058810967 Also the 7805 got extremely hot quickly. I've checked my soldering, and checked the positions of the parts (and polarity) and that's all fine. Any suggestions!?

Good suggestions ;D. I'm thinking about making up a floorboard as i got a J-Station, and I could do with some live switching! :D

I was just looking on the eDrum website which uses similar components for that circuit, and it said the bridge rectifier W005 would be suitable as a replacement. Part - W005, PIV- 50V Ifav. - 1.5A Max RMS- 35V Max cap- 5000µF Max Vf per diode- 1.1V/1A What do you think? :-/

I have to use 4 1N4001's on my core circuit because I can't find any UK supplier of B40C800 bridge rectifier. Now, I'm a little unsure how to connect up the 1N4001's - is this correct: Thanks!

So I got a desolate PIC16F874 since i'm rebuilding my MIDIbox with a PIC18F452 :). Anyone know of any fun circuits that require that PIC16F? It seems a shame to just throw it in box of spare components, when it could be doing something useful! (I tested my JDM programmer today - WOOOOOOOOO! it works!)

i dont know if this is whats wrong but hold control and use your mouse scroll wheel? ;)

Ahhh! I see ::) Thanks buddy!

My LCD is specified as follows: Pin - Symbol 1 Â - Â VSS 2 Â - Â VDD 3 Â - Â Vee 4 Â - Â Rs 5 Â - Â R/W 6 Â - Â E 7 Â - Â DB0 8 Â - Â DB1 9 Â - Â DB2 10 Â - Â DB3 11 Â - Â DB4 12 Â - Â DB5 13 Â - Â DB6 14 Â - Â DB7 15 Â - Â A(LED+) 16 Â - Â K(LED-) I've drawn a wiring diagram here : http://homepage.ntlworld.com/keith.williamson/misc/lcd.jpg (40kb) Is that wiring correct? Do I need the green lead to be connected like that? TIA! EDIT: Oh i forgot to mention I'll be using it with the MBHP core, with a PIC18F452 if that matters ::)

From the looks of it, and my experience of .tk urls it's just using url forwarding. So essentially it's the same site, hosted on the same server, but with a different name - which all helps in catching the eye of passer's by. More information about .tk addresses can be found at http://www.dot.tk/ they are free and help out a rural community! Why not check em out?