Speaker hiss so the TDA2050 ok, +/-20V. +/-9V and 3.3V for the digital
all there. No front LEDs lit
There was some throughput of hum when I first connected a jack to the
input but nothing since , nor feeding test signal direct into the 2
lines from the 072 first opamp , conveniently discretely isolated on
that end of the board. I've been bench testing without the connection to
the front panel click switches+LEDs, to avoid taking all that part. Next
thing to try, but anyone know if a break in that ribbon to the front
panel , or my full disconnection, can cause the Philips system uC to
stop functioning, by lack of load or continuity?

probably something to do with 3 very iffy looking chassis ground
contacts at the 3 front panel sockets, will wire between them and see
how things pan out. May even need a footswitch connected to the amp to
do anything.

"N_Cook" wrote in message ...

probably something to do with 3 very iffy looking chassis ground
contacts at the 3 front panel sockets, will wire between them and see
how things pan out. May even need a footswitch connected to the amp to
do anything.



You shouldn't need a footswitch.

Is this one of those amps where the buffered input goes into a Codec, and
the Codec output goes to the TDA?
Everything else just number crunching?



Gareth.

3 ground contacts bridged, no difference.
Probably like Roland Cube pot problems. All pots except the master , are
used as digital controls, 0 and 3.3V dc on the ends. Amazingly only one
of the 7 "digital" pots you can turn down to a few ohms , all others
many DVM-R ,Ks to megs and wavering. As there is polling signals on the
front panel switches the main uC must be ok , for that anyway, and I
assume there must be a control logic that locks out the whole system if
the ADC voltages are wavering about , beyond some set minimum for the
user doing an adjustment of one perhaps at a time

Replaced the worst 2 pots with fairly stable minimum few 100s of ohms
settings of the rest, no LEDs.
I'm now assuming the inbuilt flash memory of the
P89LPC936F is corrupted as distinct from the RAMs. There is a vacant
header for in-cct programming with RST on the overlay. This line goes
to the INV-RST pin of the uC and according to the datasheet a LOW on
there will reset the uC, but no change still no LEDs. It looks as though
to erase the flash , needs a Chip Erase command via in-cct programming,
so that looks like the end of this usual digital farting about. One more
effort ,Cannot find "factory reset" for Line6 spider stuff, will try 5
seconds on each at power-up and then 2/3/4 of the adjascent ones.

"N_Cook" wrote in message
...
Replaced the worst 2 pots with fairly stable minimum few 100s of ohms
settings of the rest, no LEDs.
I'm now assuming the inbuilt flash memory of the
P89LPC936F is corrupted as distinct from the RAMs. There is a vacant
header for in-cct programming with RST on the overlay. This line goes to
the INV-RST pin of the uC and according to the datasheet a LOW on there
will reset the uC, but no change still no LEDs. It looks as though to
erase the flash , needs a Chip Erase command via in-cct programming, so
that looks like the end of this usual digital farting about. One more
effort ,Cannot find "factory reset" for Line6 spider stuff, will try 5
seconds on each at power-up and then 2/3/4 of the adjascent ones.



Hold Clean channel button and power on.

User manual he
http://l6c.scdn.line6.net/data/6/0a0...ev%20A%20).pdf



Gareth.

On 18/03/2014 12:05, Gareth Magennis wrote:
"N_Cook" wrote in message
...
Replaced the worst 2 pots with fairly stable minimum few 100s of ohms
settings of the rest, no LEDs.
I'm now assuming the inbuilt flash memory of the
P89LPC936F is corrupted as distinct from the RAMs. There is a vacant
header for in-cct programming with RST on the overlay. This line goes to
the INV-RST pin of the uC and according to the datasheet a LOW on there
will reset the uC, but no change still no LEDs. It looks as though to
erase the flash , needs a Chip Erase command via in-cct programming, so
that looks like the end of this usual digital farting about. One more
effort ,Cannot find "factory reset" for Line6 spider stuff, will try 5
seconds on each at power-up and then 2/3/4 of the adjascent ones.



Hold Clean channel button and power on.

User manual he
http://l6c.scdn.line6.net/data/6/0a0...ev%20A%20).pdf



Gareth.



Did that, still dead so some other problem perhaps. I can see why no
audio throughput. The AK4552 audio ADC\DAC is held off at p13 by the big
DSP which presumably is held dead by the system uC. Its times like this
that I feel there is something dead simple, for just a bit of inside
gen. I think I'll rassemble in the chassis , perhaps there is some
hidden ground plane that connects to one of the fixing points.
As there was some audio for half a second on first connecting an input
there cannot be something permanently failed

"N_Cook" wrote in message
...
On 18/03/2014 12:05, Gareth Magennis wrote:
"N_Cook" wrote in message
...
Replaced the worst 2 pots with fairly stable minimum few 100s of ohms
settings of the rest, no LEDs.
I'm now assuming the inbuilt flash memory of the
P89LPC936F is corrupted as distinct from the RAMs. There is a vacant
header for in-cct programming with RST on the overlay. This line goes
to
the INV-RST pin of the uC and according to the datasheet a LOW on there
will reset the uC, but no change still no LEDs. It looks as though to
erase the flash , needs a Chip Erase command via in-cct programming, so
that looks like the end of this usual digital farting about. One more
effort ,Cannot find "factory reset" for Line6 spider stuff, will try 5
seconds on each at power-up and then 2/3/4 of the adjascent ones.



Hold Clean channel button and power on.

User manual he
http://l6c.scdn.line6.net/data/6/0a0...ev%20A%20).pdf



Gareth.



Did that, still dead so some other problem perhaps. I can see why no audio
throughput. The AK4552 audio ADC\DAC is held off at p13 by the big DSP
which presumably is held dead by the system uC. Its times like this that I
feel there is something dead simple, for just a bit of inside gen. I
think I'll rassemble in the chassis , perhaps there is some hidden ground
plane that connects to one of the fixing points.
As there was some audio for half a second on first connecting an input
there cannot be something permanently failed



These have built in noise gates, make sure your signal is big enough to turn
it on!

(I assume though the noise gate would not actually be muting the DAC via pin
13)

Oh and I've just thought, occasionally amps have a mute that is operated by
the switched input jack socket - injecting a signal further down the line
might not work.



Gareth.

Wasted too much time on this. Annoying as the datasheets are available
for all chippery, including the DSP and a serial flash memory so 2
distributed memory and 2or 3 on the uC.
What I thought was polling of the front switches was floating lines to
the uC, they never get committed to an input or output state, oscillator
is fine .

If there is a strong signal on the input then at powerup or powerdown
some low output for half a second, explains the initial hum signal heard.
There is a mute line, to pin91 , GPIO(0) overlay labelled "guitar
sense" grounded if no jack inserted