[sdiy] The fatman is finished...

[Scott Gravenhorst]

Gabriel Lindeborg <gabriel.lindeborg at sverige.nu> wrote:
>Hi Harry!
>
>Seems to be an all digital end error since the oscillators filter and 
>amp. works fine, provided that they should be audiable when I crank the 
>VCA Velocity pot up (I think they should, its a VCA bias right?).
>At the moment I suspect a sinister eprom...

I know you said you've checked soldering and part orientation, but please just 
make sure, and with soldering, I would stongly suggest using a reasonably high 
power magnifier such as a jeweler's loupe.  I use a telescope eyepiece.  It 
does sound like a digital problem and it could easily be a bad EPROM.  You can 
static protectively package and mail that back to PAiA for them to check, if 
it's bad, they'll replace it.  Of all the digital parts that could be bad, the 
EPROM having corrupt content is probably most likely.  New parts are rarely 
bad, though it can happen.  The most common cause of problems with kits is 
builder error, which is why I suggest making absolutely sure that part values 
and orientation is correct and that soldering be intensely scrutinized.  Any 
solder point that you are unsure of should be reflowed.  Make sure that the 
solder has adhered to the metal pins.  Pins with oxide on them can look sort of 
soldered, but the oxide coating can prevent electrical contact.  Also make sure 
there are no solder bridges.  Another thing to check is hairling cracks or 
scratches in etched lands.  These are easily fixed with a short piece of bare 
copper wire and a drop of solder.

Unfortunately, there's not very much troubleshooting you can do with the MCU 
part of this, especially without a scope.  And even with a scope you can make 
sure all of the lines that should be toggling are doing so, but if the EPROM 
data is corrupt, you really can't know it without having a way to verify the 
data.  Reseat the IC packages perhaps.

Best of luck.


>
>//Gabriel
>
>harrybissell wrote:
>
>> If you don't have a signal tracer... try making a divider of a 100K and a 10K
>> resistor with the signal taken from across the 10K going to your amp
>> (turned down REAL low to start with).   That will work as a signal tracer for
>> your
>> needs. Then do what Scott suggested.
>> 
>> I have a cable with these resistors installed in the plug (amp end) and two
>> MINI HOOKS
>> on the other end (signal / ground).
>> 
>> WARNING: This is assuming a guitar or similar amp that has a capacitor in
>> series with the
>> input. A direct coupled amp could FRY speakers if you hooked up DC signals
>> (and with a
>> signal tracer, you can - easily)
>> 
>> Of course you should be flogged for not having a scope but that is another
>> story :^P
>> you will be given a break since its a Fatman
>> 
>> H^) harry
>> 
>> Gabriel Lindeborg wrote:
>> 
>> 
>>>Hi Scott!
>>>
>>>Scott Gravenhorst wrote:
>>>
>>>>Hi Gabriel,
>>>>What test equipment do you have access to?  A scope is really helpful if
>>>>you have on or can borrow one.
>>>>
>>>
>>>No scope for the weekend...
>>>Dig. Multimeter at hand.
>>>
>>>
>>>>The MIDI LED flashing is good.
>>>>
>>>>Does the GATE LED come on?
>>>
>>>No...
>>>
>>>
>>>>Have you tried using each MIDI channel one at a time each in turn?  (If
>>>>there's something not right with the dip switch, you'll discover it this
>>>>way).  If you find a DIP setting that causes the GATE LED to light when
>>>>a key is down, you've got the MIDI channel set to the one the FatMan is
>>>>actually listening to.  If the setting doesn't look right, there's
>>>>something amiss with the DIP switch.
>>>
>>>Tried all channels multiple times, no success.
>>>
>>>
>>>>The GATE signal is required or the ADSR won't cycle.  The ADSR supplies
>>>>the required signal to the VCA control input.
>>>>
>>>>I read your other message, sounds like you have at least used a signal
>>>>tracer.  The VCOs output a constant signal regardless of whether a key
>>>>is down or not.  Check the output of the VCF, it should also have a
>>>>constant output.
>>>
>>>I simply turned up the VCA Velocity, no problemo with the oscillators
>>>vca or filter...
>>>
>>>The CVs changes every time I turn it on, the gate remains 0V.
>>>The uP seems to function as the address lines seem to stay of 5V or 0V
>>>sadly at fixed value, could indicate a loop (could also indicate
>>>somethings really wrong or that everythings ok...).
>>>Vcc to logics all 4,8-4,9V.
>>>The uP output at o14/pin4 to gate/envelopes stays at 3,6V all the time.
>>>The uP output at o13/pin3 to envelopes stays at around 1,8V.
>>>
>>>
>>>>Let me know about the above questions, I'll have more depending on the
>>>>answers.
>>>
>>>That´ll be great!
>>>
>>>//Gabriel
>> 
>> 
>> 
>

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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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