please help! ic20 getting hot! SOLVED!!!

[LoopStar]

Hi everyone!

I'm building a x0x from self sourced parts. As some of the orders got delayed, I started building with what I got. Today, the rest of the parts arrived and I soldered those last parts in. When I plug in the x0x theres a hum coming out of the headphone jack. nothing else happens. The voltages at j4 are correct, but ic20 gets really hot. Also, testing the voltage across c3 gave me ~4V. Everything fine with c5 though: 13,47V. Any suggestions what could be wrong?

[Localboy]

Sounds like a short on your 5V rail. Measure between the center pin and the outer pins, is there zero ohms? Then look for solder shorts or maybe a backward polarity capacitor.

[LoopStar]

Sounds like a short on your 5V rail. Measure between the center pin and the outer pins, is there zero ohms? Then look for solder shorts or maybe a backward polarity capacitor.

Nope. I'm not good at using my multimeter, so I don't know if the ohm-values I've measured are correct. In any case, I didn't get zero ohms. I also measured the voltages of the 7805:
middle pin => right pin => ~5V
left pin => middle pin => 1v

While I was checking, I found out, I only get 1V across c6, not ~5V. Strange...

[Localboy]

The pin on the 7805 connected to C3 should have 8V or more. The pin connected to C6 should have 5V.Middle pin is Ground. Since you are getting 1V out of the 7805 which supplies the the regulated 5V supply, it is being pulled low (too much current is being drained), therefore something on the 5V supplied circuitary is a incomplete short (because you have 1V and not 0V)
The 5V supplies the digital/sequencer/buttons/LEDs/USB chip/Midi. Remove the 7805... does C3 go back up to 8V or more? The 7805 can supply around 1 Amp, so the resistance over C6 would be less than 5 ohms, if it is being pulled low. Disconnect main board (still less than 5 ohms... check usb and midi. Otherwise check the other parts of the circuit mentioned.

[LoopStar]

Here's what I did: I've unplugged all the jumper-cables and re-checked the powersupply. Everything seems to be back to normal. I'm getting 5V out of the 7805 with ~14V going in. The Voltage across the large caps is ~14V again. The voltage across C6 is back to 5V, too. Also the values at J4 are back to normal. Everything seems to be fine, so I guess I'll start to do some checking of the vco next. I'll post the results later this evening!

UPDATE:

While examining my x0x I found two ICs that I seem to have soldered the wrong way: IC4 & IC5
Could this lead to the behaviour my x0x showed when I started this thread?

[subatomic]

ICs the wrong way can be bad. often frying those ICs, since power (VC+ and GND) is connected to non-power pins on the ICs...

[LoopStar]

ICs the wrong way can be bad. often frying those ICs, since power (VC+ and GND) is connected to non-power pins on the ICs...

That pretty much didn't matter too much, because I decided to cut the legs of the ics instead of trying to desolder the thing in one piece. Today I got my replacement ICs and soldered them in... now it works! wooooooooooohooooooooooooooooo!

Thanks to everyone in the forum for helping!

My x0x looks like this:


and sounds like this:
http://www.loopstar.eu/audio/mp3/x0x/x0x-test4.mp3

[Localboy]

Excellent. Now make the clone tubescreamer;-).

[tupinamba]

Hi Everyone,
This is my first post and I'm a total n00b so please be indulgent...
I've assembled a X0xb0x kit bought to x0xsh0p.de and I'm experiencing the same problem as LoopStar.
I also put IC4 (but not IC5) the wrong way at first and the 7805 was getting VERY hot VERY quickly...
I unsoldered IC4, put a socket instead an used a brand new 74HC595. Now the 7805 does not overheat but I can't get any sound at all. Leds light up randomly, some bright, some dim...
As banned from x0xsh0p told me I may have fried the microcontroller, I tried to connect to the x0xb0x via USB to see if I could get anything.
But here again no way : I cannot get the x0xb0x to be recognized by my OS (using Windows XP in this case). I installed the driver (CDM20814_Setup.exe) but I cannot see anything in the Device Manager (no "Ports (COM&LPT)" section !). c0ntr0l does not see anything. System does not react when I power up the x0xb0x in Bootload mode, USB cable being connected.
I have to mention that I had the USB chip soldered to the board by a professional so I guess it's been done right.
I'm really stuck here... so if anyone has any clue...
Thanks in advance.

[guest]

there is a good chance you fried the micro

make sure there is 5v on pin9 and pin40 of the micro

does your computer detect that there is a usb device connected
can you find it in the attached devices list
that should work regardless of the micro

[tupinamba]

That's what I call a fast answer ! Thanks !
The system does not react at all when I plug in the power supply, Bootloader on and USB cable connected.
I don't even have a "PORT" section in my device list !
My computer is an ASUS laptop.
I checked voltages : I do get 4.99V on pins 9 and 40 of the µcontroller.
So those are to different issues, right ? That's my luck...

[guest]

yes most likely two different issues
you could try removing the microcontroller
and seeing if the computer finds the device

[guest]

here are the voltages for the usb chip
http://forums.adafruit.com/viewtopic.php?p=9136

did you get the usb chip soldered at x0xsh0p.de
do you know if they tested for functionality

[tupinamba]

Hi,
I got the USB chip soldered by a professional company through my work (they slipped the chip & board with other stuff to be soldered) so I guess nothing happened there...
I removed the µcontroller, connected the USB cable (it provides 5V on Pin 1), the power supply and checked the USB chip voltages.
I get some weird results :

pin / normal voltage // my values
1 / 0 // 4.64
2 / 5 // 5
3 / 5 // 5
4 / 3.3 // 0.24
5 / 3.3 w. data // 0.01
6 / 3.3 // 3.46
7 / 3.3 w. data // 0.01
8 / 0 w. data // 0.01
9 / 0 // 0
10 / 5 // 0.07
11 / 0 // 0.07
12 / 0 // 0.01
13 / 5 // 5
14 / 5 // 5
15 / 5 // 0.08
16 / 0 // 0.07
17 / 0 // 0
18 / 5 // 4.62
19 / 5 // 4.62
20 / 5 // 4.62
21 / 0 //0.07
22 / 5 // 4.62
23 / 5 // 0.07
24 / 5 // 4.63
25 / 5 // 0
26 / 5 // 5
27 / clock // 1.64
28 / clock // 2.37
29 / 0 // 0
30 / 5 // 4.8
31 / 0 // 0
32 / 0 // 4.62

The big differences are Pins 1, 4, 10, 15, 23, 25 and 32. Is there something relevant here ?

[guest]

turn the power off
and measure the resistances of r6 through r10
and make sure they match the schematic
then measure the resistance to ground
on pin4 of the usb chip

then plug it back in to the computer
and measure the voltage on all 4 pins of the usb jack
make sure there is 5v on one of the end ones