Author Topic: Earthquaker devices bitcommander  (Read 1413 times)

Steve Connochie

Earthquaker devices bitcommander
« on: July 09, 2018, 04:15:14 PM »
Hello looking for a bit of advice on this build.http://tagboardeffects.blogspot.com/2015/09/earthquaker-devices-bit-commander.html. I've built it and it appears to function sort of ok. But very noisey squeels and pops a bit so I started debugging. I removed the ground connection from the level pot as an experiment as the pots are all connected via base 1 to the common ground but that was horrendous. But my main concern is with the 386 chip I was alarmed by the temperature it reached in a matter of seconds and disconnected the power supply incase the thing burst into flames. There are definitely no shorts and I'm confident the build is correct but don't want to continue unless this heating is normal. Any help will be much appreciated. Steve

thehallofshields

Re: Earthquaker devices bitcommander
« Reply #1 on: July 09, 2018, 06:24:01 PM »
386 getting hot is a common problem. I don't recall what the usual causes are though.

pinkjimiphoton

Re: Earthquaker devices bitcommander
« Reply #2 on: July 09, 2018, 10:38:23 PM »
so far, every 386 i've had get wicked hot, i had a short somewhere near the chip.

pics? voltages please?
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dschwartz

Re: Earthquaker devices bitcommander
« Reply #3 on: July 09, 2018, 10:42:24 PM »
My bet is the 386 is oscillating...
Place a big cap (eg 100uF) between the power pins of the 386
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Steve Connochie

Re: Earthquaker devices bitcommander
« Reply #4 on: July 10, 2018, 10:06:41 AM »
Thanks for the input I'll go round the tracks again to ensure no solder shorts before firing it up tonight and get some voltage readings. Am I right in saying the cap goes across pins 6  and 4 Vs and ground.

duck_arse

Re: Earthquaker devices bitcommander
« Reply #5 on: July 10, 2018, 11:07:54 AM »
is there a circuit diagram? how come pin 2 isn't connected to ground?
Last Edit: Soon at 09:27:12 by someone sensible

Steve Connochie

Re: Earthquaker devices bitcommander
« Reply #6 on: July 10, 2018, 03:35:07 PM »
Here's the diagram that appears elsewhere in the forum I've just come across it myself. It's a verified layout I must have messed up somewhere need to redouble my checks before connecting again I don't want to cook my build🤣


Steve Connochie

Re: Earthquaker devices bitcommander
« Reply #7 on: July 10, 2018, 07:24:28 PM »
I've scraped between the copper strips thoroughly once more, checked the layout rewired the pots to no avail still squeals pops and whines, I'm sure it's worse than before as only the up and level pots appear to have any influence on the output. I haven't done anything to address the temperature of the 386 based on comments here and elsewhere they do run hot don't like it but will live with it for now. I don't really know what voltages I should be checking or their values so here is what I've measured at each of the chips for starters.
386
Pin
1&4- 0
2&3- 0.08
5- 3.68
6- 8.91
7- 4.44
8- 0.62

TL072
1&5 - 3.68
2&3- 3.79
4- 0
6&7 - 3.83
8 - 8.1

4024BE
All zero volts except
1&2 - 0.03
6&11- 8.89
14- 3.09
They seem all over the shop to me but I don't really know what I'm doing🤔 and here's a couple of pics incase someone can spot my mistakes and yes my soldering is total pants. Thanks in advance for any assistance






« Last Edit: July 10, 2018, 07:48:10 PM by Steve Connochie »

duck_arse

Re: Earthquaker devices bitcommander
« Reply #8 on: July 11, 2018, 10:42:56 AM »
try grounding pin 2 of the 386. another something - pin 14 of the 4024 should be connected to V+, yours says 3V. how come?
Last Edit: Soon at 09:27:12 by someone sensible

Steve Connochie

Re: Earthquaker devices bitcommander
« Reply #9 on: July 11, 2018, 05:38:05 PM »
Must have made an arse of pin14 it is 8.98v. Tried grounding pin 2 chip still gets hot and no change to the output. Definitely something wierd going on I noticed while poking around if I bring my finger close to the input wire no physical contact there is a hissing squeal! Think this one's for the bin, already wasted enough money and time and no further forward Begining to suspect the quality/authenticity of the chips.