jwillans

I've got hold of a 12V lamp and done some further testing. Here is a photo of my configuration: The PS is fed into the connection block on the right. The positive terminal of the PS goes to the lamp (red wire), and the negative terminal of the PS goes to the ground pin of J3. The negative terminal of the lamp (black wire) is connected to D0 of J3. As can be seen from the photo the lamp is off, even though I have sent messages to switch it on. There are two ground pins on J3 labelled vs, looking at the tracing one goes to common ground, this is the one currently connected in the photo. The other vs goes to "free wheeling diodes" (whatever that means), if this is also connected to ground then the bulb comes on continuously regardless of messages sent or even if the core has power. Should this be left disconnected? Thanks, James

Thanks for your continued help. I'm going to do as you suggest, I'll get a physical lamp and connecting it. In the meantime I would appreciate it if you could make sure I have understood correctly. Ground of the PS is connected to ground on the ULN2803, the outputs of the ULN2803 switch ground on and off. Therefore, if I connect the multi-meter to the positive of the PS and an output pin of the ULN2803 then I would expect to get a + V reading if the ULN2803 has ground switched on and a 0 reading if the output is switched off? If this is the case, I am always getting a + V reading regardless of whether it is switched on/off. I can't understand why having a physical lamp/resistor in place of the multi-meter would lead to a different reading? Thanks again, James

Some further info that may help. I have connected the PSU ground to both the Vs pins on the Smashtv dout J3, however looking at the board this takes one ground as input into pin 9 (which is ground) but also pin 10 of the ULN2803, which according to the datasheet is "free wheeling diodes". Is this correct, I'm not sure what free wheeling diodes are? James

Thanks guys. Well this is frustrating, I have uploaded midiox128 and connected in the described way, I am using a multi-meter to test the lamp voltage, since these cannot yet be connected, but I'm not getting the result I expect. The PS ground is connected to Vs on J3, all the output pins on J3 read the output voltage (12V) when the unit is powered up. Sending midi messages does not seem to change this state (90 30 7F/90 30 00). Note that the output on J4-J6 are Any thoughts on what might be going wrong/things to check? James

Is there a utility that I can enter midi messages in hex form and send them. I'd like to test my dout module but I can't work out how I can send something like: 90 30 7F I've tried midi-ox but there is no facility for entering hex midi controller messages as far as I can see. Thanks, James

The core you show is mine, and it seems to work (although I have not connected external modules yet). C1 and C2 should be 33pf and C7 and C8 should be .1uf. I'm fairly sure mine are the correct way around. James

One final question (I promise), is there a sensible place to connect the 12V PSU ground on the DOUT (i.e. vs on J2 since this module is the end of a chain)? James

Thanks for your response Reiner, it sounds like standard midio128 will work okay for my purposes. James

Thanks everyone, especially David - those are exactly what I need. James

Hi Reiner, I'm currently building a midibox to support a Hauptwerk console I am working on. In this, I will be controlling stop lights as well as recieving momentary stop control signals from the console all using midio128. I was anticipating simply configuring the midio128 script, to couple input/output events to input/output midi messages, and then compiling it to a syx file. What tricks does your program do that I might need to consider? Thanks, James

Fairly new to PCB assembly. I've seen the legs which effectively bolt to a surface and then the PCB screws into these. Is there an equiavlent where the leg can be glued/stuck to a surface? Ideally I would want plastic ones so the PCB can clip onto the leg? Many thanks, James

Hi Lylehaze, I tried uploading the application and all indications seem to be that it uploaded okay. I've not yet built any of the core modules, so I cannot test whether the application is behaving as expected. Your midi activity monitor looks a useful debug tool although I didn't have the components to hand to build it. Many thanks for all your help with this, I really appreciate your support. James

Thanks for your continued help. I have made some progress, I decided to check my soldering, and resolder any joints in doubt. Now when I reconnect to the PC I get a single message: 00000008477756 ms | Sysex message: F0 00 00 7E 40 00 01 F7 when the power is connected to the core, then nothing!! If I disconnect and reconnect core power then I get a further message, what might be this symptomatic of? James

Thanks! I've now moved from one problem to the next, I'm not sure whether I should start a new thread for this elsewhere - please let me know if so. I've connected the core to the PC but I get no input requests from it, the bootstrap loader has been burnt on the PIC by smashtv so should be there. I have verified that the midi card and cable work by connecting another midi device, this displays output in the MIOS window, so all is well here. I have started working my way through the newbie troubleshooting section. All my voltages are correct according to the following diagram: http://www.ucapps.de/howtodebug/mbhp_core_extract_measuring_vdd.gif I'm curious to know whether the "when nothing is sent voltage" (on pin 25 of the PIC) should change when message is sent via midi out? If so, could my constant 5V be an indicator that requests are not being sent from the PIC? I'd like to check that the bootstrap has for sure being burnt, but didn't understand what "use the verify function of IC-Prog/P18" referred to in the troubleshooting guide? Many thanks, James

I resoldered the 7805 and all is now well with the test voltages 5.01, can now move to the next stage of plugging it into midi. Many thanks Lylehaze. James

Hi Lylehaze, I appreciate all your help, I think I am making progress. I have just remeasured the voltages on the 7805, but using the middle pin rather than tab and I get: pin 1 - middle = 10.52V pin 3 - middle = 5.02V So that looks fine. I now get values on the IC sockets, but each of the tests reads 7.4V where it should read 5V. James

Hi LyleHaze, I'm not sure which is pin 1 and 3, but I get -0.52V on the one closest to the midi sockets (back) and 2.68V on the one closest to the front. It does not get hot, or even warm and there were no sparks! Following another thread with similar problems, I've also tested the rectifier + to - gives 10.62V ~ to ~ gives 11.83V (almost the same as the input on J1). Something isn't right!! James Edited: clarified regulator voltages.

Some images to help me diagnose: Many thanks for any help offered, James

Hi, I have just built my first core using a smash tv kit. I've checked and double checked and all the components seem to be correctly inserted and well soldered. However I am not getting any voltages on the ICs when I apply the standard tests. J1 is connected to a unregulated 500ma AC Adapter which is set to 7.5V. This is spitting out DC, but I understand from the documentation that this does not matter that DC power is being fed into the rectifier.. When I check voltage on J1, it is a little odd since it is 11.86 even though it is set to 7.5V on the variable notch on the PSU. Could this be a problem? I've tried measuring the voltage at the regulator and I get nothing! Help, James

Thanks JimHenry. James

Thanks JimHenry, I really appreciate your continued advise. Just a final clarifications: the ULN2803 do not require their rectified input to be smoothed and regulated? Thanks again, James

I have received a core module + a dout. I plan to order the extra components to start experimenting with the lamps in the coming weeks. I'd just like to outline what I am planning to do, to make sure I have it straight. I am planning to use two transformers fed from the mains. The first transformer will provide 5V directly into the core module (my understanding is that the core module will do the rectification/smoothing/regulation). The second transformer will provide 12V to a custom circuit which will do similarly rectify, smooth and regulate this current, this will be fed into the high voltage pins of the ULN2803 mounted on the dout. 1) The current provided by the second transformer is being fed to lamps via the ULN2803. Given these are just lamps, can I do away with the rectifiction, smoothing and regulation on this supply. I am assuming this won't effect the ULN2803s, but will it have an impact since the ground will be shared across the first transformer (this may relate to the second question)? 2) At what point in the circuit should the ground be shared? 3) I've heard about ground loops, is this something I should be concerned about in the scenario described above? Thanks for your patience, James

Hi, Can somone advise me on what plug I need to attach to the following socket (which is mounted on a PCB): Thanks, James

JimHenry - Thanks for your continued advise, I guessed that this would be the best solution. Excuse the naive question but, if I was to break the traces on the PCB using a knife, how would I go about adding a new terminal to that trace that I can interface to? Is there a well documented approach to doing this? Thanks, James

As part of the organ I am buildng, I have aquired a bank of 16 illuminated rocker tab switches which come mounted on a single PCB. Tracing the PCB to the connecting socket it seems that they are arranged as a scan matrix of 4 * 4. Is there an approach to using a scan matrix of this type with the DIN modules? Thanks, James