e-licktronic Forum

I can't believe, I'm not the only one with this issue. I removed the LCD and all solder residue and I'm still getting the same results. By constantly probing with my MM I found that if I place one probe on any ground point or 5 volt in the sequencer section and touch the middle pin of Q43, 46, and 49 of the snare drum section that they are also connected. There has to be some place on the board where the 5 volt and ground plane are touching or intersected. I've been at this for over 2 weeks and I'm still mystified, and getting quite frustrated to have such a perfect looking Nava be entirely useless. One good thing came out of this. De-soldering components was the only thing I didn't love about working with electronics, but after getting that small De-soldering station and being able to remove a 16 pin component such as the LCD in less than 5 minutes is almost worth the aggravation I'm facing with this 5 volt/ground short. I will immediately post here when I get to the bottom of this, there's NO way I'm giving up, way too much time and money has gone into this build.

Itchy, this is in regards to your post. I thought about your post as I was again examining my board,(with no progress). I'm getting all my readings without having the IO board plugged into the main board. Since we're getting a short between 5v to ground without power being connected it can't be any good for the rest of your components to add power to the board. I haven't plugged my two boards together since the first time I noticed this two weeks ago. I hope you're not ruining all those sensitive electronic parts. I'm sort of at a dead end right now since I've gone over both sides of the board with a high power- lighted magnifying glass, the same way I soldered the entire board so I would avoid making any mistakes. lot a good that did. I'm waiting for Vincent's reply. I'm beginning to think it happened during the manufacturing of the boards especially now that I'm not the only one with this issue. I need an x-ray machine I'm even dreaming about this now. I have to get this resolved, two weeks is to long to not be able to figure this out!! I hope you didn't ruin anything. I would just unhook the IO board and check for continuity with your multi meter, at least you won't do any more harm, but what do I know I'm certainly not an expert, just a guy who loves to build things. Good hunting.

Yes and thanks for your concern! I have made some more short tests with it all plugged in, Im not getting any serious heat issues other than ic113 as I mentioned earlier so fingers crossed, but probably there are more fails to come as this gets sorted out eventually ... but also figured that its better to wait for a reply from Vincent, before the whole board is on fire. WelI anyway, would be nice to see it in action soon, especially now since the nice metal case just arrived! hehe yeah an x-ray would be great

Update: just removed ic113 the one with heat problems and now the GND and 5V is no longer shorted.. (the gnd & vcc is shorted on the chip..) I probably fried it when I was troubleshooting the midtom or something.. Don't have any other 595 to test with atm, and the mt is dead anyway.. new parts ordered but shipping takes forever

How is this possible?
I am not understanding why still the problem exist? After removing LCD the problem should solve.

I wish I had some answers, man do I wish! I was thinking the short had to come from the LCD but it had no effect, the pads are clean and perfect condition, It's really strange. No matter where I place my probe from my MM, whether it's on something that is supposed to be 5 v such as pin 8 of J2 and then touch the other end on anything that's supposed to be grounded, including all the the grounds of the pots in the main section, it beeps. I can also take one probe and touch it on anything 5 v or ground and then on every 16 pin IC, and pins- 8 and 16 are connected. On IC 115 the (24LC1025) pins 1-4 and 8 are also connected to all grounds and 5 volts. It's really quite amazing, when I have my DMM set for continuity testing where it beeps when it has makes a connection, You could probably touch well over half the contact points of the board ( except for the + or - 15 volt) and have it beep and it's very annoying. There is absolutely NO solder joints touching one another, I have never looked over a circuit board this hard and long in my life, I can't even see anything that looks suspicious and I was hoping I would just so I could try something, but the board looks perfect... Just to be random, I set one end of the probe in pin one of the LCD, (doesn't really matter since 1 & 2 and 15 & 16 are all connected) and placed the other on D1 in the Bass drum section and it's connected. I don't know if I mentioned this but I used sockets for nearly all the IC's and I'm really glad I did. If I end up having to purchase a new board and components at least I won't need IC's, knobs and a metal case. God, I sure hope it doesn't come to that.

Edit...ok forget what I wrote. You said you have the connection without the IO board connected which is not true for my board...
I've got a different error somewhere and I don't test continuity under power normally. Stupid mistake/coincidence on my part...

Check Mate wrote:I have the same issue with Ground and 5V connected (under power only). It goes away as soon as I pull IC 118. I still have an issue with my Snare which goes into a feedback as soon as I stop the sequencer after I switched transistor legs of Q43/46/49.
Unfortunately I didn't check when everything was still fine.
I suspect that maybe IC 118 is broken. I ordered some spare ones and will swap the old one for a new and report back what happened!
On my part it is mostly trial and error since I have no help with my Snare problem and I'm not up to really reading schematics/circuits.

Do you check continuity while powered? I don´t think that is advisable.

I certainly don't, that's why my IO board is not even near the main board. As soon as spotted the 5 v to ground short I knew there was not going to be any power placed on that board until I can locate it. Unless some miracle happens I don't see how I'm going to figure this problem out. I've been spending about 2 hours a day going over and over every point of contact I can see, and still it all looks perfect.

Itchy wrote:Update: just removed ic113 the one with heat problems and now the GND and 5V is no longer shorted.. (the gnd & vcc is shorted on the chip..) I probably fried it when I was troubleshooting the midtom or something.. Don't have any other 595 to test with atm, and the mt is dead anyway.. new parts ordered but shipping takes forever

I had to experience the same issue today: 5v and GND are all connected in the sequencer. Will desolder some ICs tomorrow and hopefully this will fix the continuity like it did with your Nava...