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From: Andreas Meerbann on 26 Jan 2010 03:59
Hi Paul,

What TV are you using?
Maybe it's just the TV that does not catch the RF Signal from the
modulator when doing the autoscan. You could try a manual tune to the
UHF channel (I think it was channel 39?) or you might try the
following:
Tune your TV to one of the working C64S and save the tuner setting to
a program number in the channel list. Then desolder the RF modulator
from the working C64S and mount it into your formerly-NTCS-C64S. Then
check with the already tuned TV if you can see anything on the
previously stored program number.
In case there is nothing visible (noise rather than a valid signal)
you should first measure the power supply voltages of the modulator.
In case there is at least a black screen or a distorted picture, the
modulator seems to do at least something and it's worth checking the
other connections (I think you've cut away parts of the mainboard,
right? This could easily have damaged some signal lines with shortcuts
or open circuits - just think of your experience with the serial
port...

Regards,
Andreas

PS: you're learning a lot about electronics in the moment, right? It
reminds me to the first steps in electronics famous Jeri Ellsworth did
in her parent's home ;-)
From: Paul Förster on 27 Jan 2010 12:49
Hi Sam,

> I think those articles are usefull:
> http://www.mayhem64.co.uk/convert.htm
> http://webspace.webring.com/people/sp/profdredd/pal64/palc64.html
> http://starbase.globalpc.net/c64/np-diff.html

.... unfortunately, they are not useful because they seem to refer to
the old boards. I can't find for example the 15 (or 16 respectively) pF
cap on the C64C board. The second link even talks about different
kernal and character ROMs. But AFAIK there are no differences between
the U.S. and European ROMs...

The only of these three links I can do something with is the first. To
be more precise, the instructions on how to tune the thing are
interesting, though the text also refers to the old board.
--
cul8er

Paul
paul.foerster(a)gmx.net

From: Paul Förster on 27 Jan 2010 13:17
Hi Andreas,

> What TV are you using?

.... a Philipps that I received from a friend not too long ago.

> Maybe it's just the TV that does not catch the RF Signal from the
> modulator when doing the autoscan. You could try a manual tune to the
> UHF channel (I think it was channel 39?) or you might try the
> following:
> Tune your TV to one of the working C64S and save the tuner setting to
> a program number in the channel list. Then desolder the RF modulator
> from the working C64S and mount it into your formerly-NTCS-C64S. Then
> check with the already tuned TV if you can see anything on the
> previously stored program number.

.... that is exactly what I did.

> In case there is nothing visible (noise rather than a valid signal)
> you should first measure the power supply voltages of the modulator.
> In case there is at least a black screen or a distorted picture, the
> modulator seems to do at least something and it's worth checking the
> other connections (I think you've cut away parts of the mainboard,
> right? This could easily have damaged some signal lines with shortcuts
> or open circuits -

.... it should be far away enough from the cut away part. But I'll
check. Also, the original NTSC modulator (which is present but has no
RF out anymore) does something. It gives a picture on my monitor (not
TV!) and sound. So it should have power. But I'll check nevertheless.

> just think of your experience with the serial port...

.... better don't remind me of that one. ;-)

> PS: you're learning a lot about electronics in the moment, right? It
> reminds me to the first steps in electronics famous Jeri Ellsworth did
> in her parent's home ;-)

.... yes, I'm learning a lot but not because I want to relive Jeri's
childhood. After all, I don't burn dolls... :-P
--
cul8er

Paul
paul.foerster(a)gmx.net

From: Andreas Meerbann on 28 Jan 2010 03:08
> ... yes, I'm learning a lot but not because I want to relive Jeri's
> childhood. After all, I don't burn dolls... :-P
well... that's what she does NOW - roughly 25 years later! So you see
what future you are facing ;-)

But back to the issue: Please check the supply voltages of the
modulator (I think it takes both 12V and 5V AFAIR). You should be able
to see that from the schematic

Andreas
From: Paul Förster on 28 Jan 2010 12:32
Hi Andreas,

> well... that's what she does NOW - roughly 25 years later! So you see
> what future you are facing ;-)

.... no. I read an interview somewhere that she got dolls from her dad
when she was a child and that she did cruel things to them like
"material tests" (beheading, burning, etc.). She kept begging her dad
for a computer until he finally gave in. So, that was decades ago.

> But back to the issue: Please check the supply voltages of the
> modulator (I think it takes both 12V and 5V AFAIR). You should be able
> to see that from the schematic

.... the schematics say pin 1 is +5V coming in thru a curly line which I
would say could be a cap. The case and pin 3 is ground. I wonder why it
is pin 3 and not 2 which would be more logical...

Anyway, I'll probably check in the next few days, if I find the time.
--
cul8er

Paul
paul.foerster(a)gmx.net

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