please help! ic20 getting hot! SOLVED!!!

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tupinamba
 
Posts: 59
Joined: Fri May 06, 2011 5:30 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by tupinamba »

Values are 0.027k for both...

guest
 
Posts: 3155
Joined: Fri Feb 17, 2006 5:35 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by guest »

well its probably a bad chip then
although i wouldnt worry about it too much
until you get the new microcontroller in
the only thing usb is really good for
is reloading new firmware
and hopefully youll never have to do that

tupinamba
 
Posts: 59
Joined: Fri May 06, 2011 5:30 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by tupinamba »

OK, thanks.
I'll get another microcontroller and see where we go from here !

tupinamba
 
Posts: 59
Joined: Fri May 06, 2011 5:30 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by tupinamba »

Bad news : Christian from x0xb0x.de had the microcontroller tested and it is OK. So back to nowhere...
Do you have any clue about what could have been damaged by putting the IC4 backwards in the first place ? I tested with a new cIC4 chip but nothing better...

guest
 
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Re: please help! ic20 getting hot! SOLVED!!!

Post by guest »

i reread our posts
and it doesnt seem like we did much
microcontroller debugging
so lets start with that

when you turn the x0x on
do different leds come on
when you restart it
or does it generally go to the same state

does moving the mode knob
change anything at all
does the tempo led blink
in any of the modes

what are the voltages
on pins 8 18 19 20 40
of the microcontroller

remove ic2 and see what happens

tupinamba
 
Posts: 59
Joined: Fri May 06, 2011 5:30 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by tupinamba »

Thanks again for your precious help!
I'll run the tests when the microcontroller is back from Germany...

tupinamba
 
Posts: 59
Joined: Fri May 06, 2011 5:30 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by tupinamba »

I got the microcontroller from Christian today and ... IT WORKS ! ! ! :D
Sound finally came out of the x0xb0x two hours ago and it can't stop playing with it.
I tuned it using an instrument tuner and it's pretty good. I still have to calibrate it but it already sounds amazing !
The only issue (apart from the USB which is not a priority) is about the leds : some of them don't light up at all and other are dim:

> Don't light up :
Steps 1 & 2
C note
Tempo
Run
Chain
Prev
Next

> Are dim :
Steps 10 to 16
Notes A, B, C'
Rest
Down
Up
Done
Accent
Slide

There seems to have something geographical... Do you have any idea of what could be wrong ?

guest
 
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Re: please help! ic20 getting hot! SOLVED!!!

Post by guest »

its strange that the micro fixed it
as you said that x0xsh0p said nothing was wrong with it
perhaps it just needed a trip around the world

the ones that done light up
are on ic4
which is odd
because its the first shift register in the line
so all the data has to pass through it
to get to the other leds

hold down the c button
and check that the c led is not getting any voltage
and follow its line back through the resistor
and check directly on its output pin from ic4
if its not outputting 5v
you might just want to try replacing ic4

the remainder of those
are spread over ic6 ic7 and ic8
so im not sure if there is a common cause
turn off the power
and measure the resistance of the resistors
that lead to the bad leds
and compare it to some good ones
it could just be a bunch of bad leds as well
make sure the chips are outputting 5v
are all the chips labelled the same

tupinamba
 
Posts: 59
Joined: Fri May 06, 2011 5:30 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by tupinamba »

Hi,
Yes, it's strange that it works now although the chip was OK...

First tests :
Leds that don't light up get 0v
Leds that light up dimly get 1.8v
Leds that light up OK get 1.9v
I changed IC4 but nothing better with new chip...
I'll investigate further later today.

Thanks again !

guest
 
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Joined: Fri Feb 17, 2006 5:35 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by guest »

have you traced the voltages back up the resistors
and up to the shift register
if it is giving 5v
then try replacing the led

tupinamba
 
Posts: 59
Joined: Fri May 06, 2011 5:30 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by tupinamba »

I Might have a clue on what's going on...
There seemed to be a mistake in the resistors I got for the control surface and 1k resistors were mixed with 10k. So that would explain the brighter leds (and the dim ones would be a problem). I got 1k resistors from R117 to R260 or so...
Could this also explain the leds that don't light up ?
I traced back the "C" led that don't light up to pin 15 from IC4 and this pin never gives the 5v required. IC5 is a 74HC595 but not the same brand as the others.
Are there different types of 74HC595 ? Could this explain something ? Or are the resistors the key ? (i.e. could they be the reason why IC4 doesn't behave as it is supposed to do ?)

guest
 
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Re: please help! ic20 getting hot! SOLVED!!!

Post by guest »

different resistors
would definitely give different brightness

does the c key play a note in keyboard mode

turn off the power
and measure the value of the resistor
that goes to the c key
and then put one meter probe on pin15
and the other on the led
and make sure all the traces are good too

brand of the chip shouldnt matter
when you tried replacing that chip
did you use one from the same supply
ive definitely seen multiple bad chips before

if you have your parts socketed
you can take out one of the good ones
and drop it in and see what happens

tupinamba
 
Posts: 59
Joined: Fri May 06, 2011 5:30 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by tupinamba »

I'm a little confused...
I changed most of the resistors to 10k and it seems to solve the brightness issue... But nothing on the dead leds.
"C" note produces sound alright.
Leds that don't light up are OK, I tested each of them
The 74HC595 are from Smashtv for a Midikit project. I tested three of those...
One thing is shure : IC4 doesn't give 5v when buttons pushed / switches turned ("C" note, "prev", "next", "run", "chain", 1st and 2nd steps, tempo).
One other thing : there is always 5v on IC4 pin 14 (SI) (stands for Serial In?) (plus the normal 5v on pins 10 (SCLR) and 16 (Vcc).
I'll get all the 1k resistors changed to 10k tomorrow (no more left!) but I don't think that's the problem...

guest
 
Posts: 3155
Joined: Fri Feb 17, 2006 5:35 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by guest »

there must be a fault in the pcb then
if youre confident the chip is ok
which seems reasonable
as all the data for the rest
must first pass through ic4

turn off the power
and measure the resistance to ground
from the output pins of ic4
perhaps there is a short some place

tupinamba
 
Posts: 59
Joined: Fri May 06, 2011 5:30 am

Re: please help! ic20 getting hot! SOLVED!!!

Post by tupinamba »

All resistors replaced. No more brightness issue... But still no light on the same leds !
I checked resistance to ground from the outputs but they seem fine (i.e. the same as the other 74HC595 ICs on the board).
The only thing that could be weird is pin 14 which always gets 5V. It's connected to IC2 (pin 5) and IC3 (microprocessor) (pin 6). Is this normal ?

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