sequencer won't work, need some help

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evostars
 
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sequencer won't work, need some help

Post by evostars »

Hi,
I've build my x0xb0x, checked the VCO and VCF, and checked all the polarities, and IC's. Power is fine, there are no shorts, and there is no trash. I looked over the board several times. The wire connectors are also fine.

But the problem:
-when i power up, all the lights go on, but there is no sound or interaction possible. When I power of and on again within a few second, a section of the led lights is off. After a few of these reboots, all leds are off.

When i try to connect with the CPU with USB/conbox, the CPU isn't there.

I bought a new CPU, with sokkOS 1.9.1 on it, so that should be fine (first CPU had no bootloader).

I checked the analog voltages, but havent checked the digital section, because I haven't got them(reference).

I spent a lot of time measuring and looking for errors, but didn't find the error.
My hope is running low. But I won't give up. This monster will work!

Does anyone recognize this problem?

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phono
 
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Re: sequencer won't work, need some help

Post by phono »

make sure you dont have the selection knob on backwards which may put you in bootloader mode instead of what you intended

evostars
 
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Re: sequencer won't work, need some help

Post by evostars »

phono wrote:make sure you dont have the selection knob on backwards which may put you in bootloader mode instead of what you intended
well the knob doesn't go on backwards, and more so, the position of the knob, doesn't make ANY difference. all the leds are on, and there is no interaction or sound.

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mmm
 
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Re: sequencer won't work, need some help

Post by mmm »

The processor probably doesn't run.

The nice thing about the digital part is that it has so few components. For the processor to execute its program it needs the following things:

- supply voltage
- reset voltage
- clock

Check if all those are present at the processor

- supply voltage is on pin 40 (ground is pin 20)
- reset line is pin 9
- clock is on pins 18 and 19

My suspicions would run towards the resonator (read: the clock) because I've seen this problem before.

evostars
 
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Re: sequencer won't work, need some help

Post by evostars »

Thanks MMM
I'll check the resonator. I've got a spare so that would be nice!

evostars
 
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Re: sequencer won't work, need some help

Post by evostars »

eh, how do you test a 16MHz resonator?
I've got a scope, should I see a sinus or block, between tthe to outer pins, or from pin to earth?
never tested one before...

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altitude
 
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Re: sequencer won't work, need some help

Post by altitude »

what is your +5 rail reading? Check that first. I've seen a number of those Chinese boards with bad etching in the digital section

evostars
 
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Re: sequencer won't work, need some help

Post by evostars »

Altitude wrote:what is your +5 rail reading? Check that first. I've seen a number of those Chinese boards with bad etching in the digital section
first thing I checked. their good.

Tomorrow I'll put in a new 16MHz crystal. The resonator had 3 pins, the crystal only 2, does that make any difference?
should I put in 2 22pF to ground?

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altitude
 
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Re: sequencer won't work, need some help

Post by altitude »

yeah, there is a difference.. you will need 2 caps with a regular crystal. Each leg of the crystal gets a cap to ground. Make sure you get a parallel cut one, not series cut and check the spec sheet for the right cap value. Use NP0/C0G grade caps. The resonator has its middle pin to ground and does not need caps (why it was used)

evostars
 
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Re: sequencer won't work, need some help

Post by evostars »

Altitude wrote:yeah, there is a difference.. you will need 2 caps with a regular crystal. Each leg of the crystal gets a cap to ground. Make sure you get a parallel cut one, not series cut and check the spec sheet for the right cap value. Use NP0/C0G grade caps. The resonator has its middle pin to ground and does not need caps (why it was used)
Parallel cut? Series cut? Whats that?

evostars
 
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Re: sequencer won't work, need some help

Post by evostars »

The atmega162 says 12-22 pF with a crystal, so thats good.
Exciting! Maybe today its going to work!
:)

evostars
 
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Re: sequencer won't work, need some help

Post by evostars »

evostars wrote:The atmega162 says 12-22 pF with a crystal, so thats good.
Exciting! Maybe today its going to work!
:)
I found a really intersting link, it's off topic, but wanted to share
http://www.BANNED.com/xoven.htm
A (electronic) oven te keep a XTAL stable!
How nice :lol:

evostars
 
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Re: sequencer won't work, need some help

Post by evostars »

Ok, when i measure the 6 Mhz of the IO board, i see a sinus.
But at pin 18 and 19 of the 162 no signal.
Pin 18 is 0 volts
Pin 19 is 141 mV
Still no luck today. New crystal doesnt change anything.

evostars
 
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Re: sequencer won't work, need some help

Post by evostars »

Ahrgggg
Why?
:cry:

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mmm
 
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Re: sequencer won't work, need some help

Post by mmm »

I take it you have checked pin 9 of the processor first?

If that looks ok you need to check if there is a short. Suspect would be pin 18 against ground; but check bopth pin 18 and 19 against ground and each other; and also check continuity between the pins and the resonator.

And don't worry too much.

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