Crystal frequency for monochrome video signal?

[DaveC]

80's vintage German printing equipment (offset press industry) uses a video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband video
tube monitor. (It is possible, being German and sold in the USA market, that
the video may be NTSC or PAL.)

There is no video signal on the BNC output connector.

This is used equipment being resurrected, so operational history is unknown.

There is a place on the video card labeled "Q2" that is the right shape &
size for a crystal can. The pads look like it was ripped off the board: a
short lead soldered in one pad; a hole in the other pad where a lead was
soldered (poorly, apparently!). (Rough handling is a distinct possibility:
the client is a used-equipment dealer and the fork lift is their main
tool...).

The board is populated with 80's technology, mainly 74LS' :: the crystal pads
connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial
converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz.

The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is
a multiple of the dot clock and an input to the 8275."

Maybe these clues will tell someone what frequency this crystal needs to
be...?

What frequency crystal should I be looking for?

Thanks.

 

[Jon Elson]

DaveC wrote:

80's vintage German printing equipment (offset press industry) uses a
video plug-in card (made by the manufacturer of this equipment) to
generate parameter display for the operator. The display is a standard
baseband video tube monitor. (It is possible, being German and sold in the
USA market, that the video may be NTSC or PAL.)

There is no video signal on the BNC output connector.

This is used equipment being resurrected, so operational history is
unknown.

There is a place on the video card labeled "Q2" that is the right shape &
size for a crystal can. The pads look like it was ripped off the board: a
short lead soldered in one pad; a hole in the other pad where a lead was
soldered (poorly, apparently!). (Rough handling is a distinct possibility:
the client is a used-equipment dealer and the fork lift is their main
tool...).

The board is populated with 80's technology, mainly 74LS' :: the crystal
pads connect to an 'LS04 inverter/driver and then to an 'LS96
parallel-to-serial converter. The 'LS96 spec sheet says that it can be
driver up to 25 MHz.

The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK
is a multiple of the dot clock and an input to the 8275."

Maybe these clues will tell someone what frequency this crystal needs to
be...?

What frequency crystal should I be looking for?
Put in ANY frequency, as long as it is known. Fire the gear up, and

observe the video output with a scope. measure the horizontal sync
frequency. Now, you can easily figure the ratio (up or down) to
get the desired H sweep freq, and most simple monitors should sync
to it, even if the number of vertical lines is a bit off.

Jon

 

[tm]

"DaveC" <invalid@invalid.net> wrote in message
news:0001HW.CD2EDE2600AA565EB01029BF@news.eternal-september.org...

80's vintage German printing equipment (offset press industry) uses a
video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband
video
tube monitor. (It is possible, being German and sold in the USA market,
that
the video may be NTSC or PAL.)

There is no video signal on the BNC output connector.

This is used equipment being resurrected, so operational history is
unknown.

There is a place on the video card labeled "Q2" that is the right shape &
size for a crystal can. The pads look like it was ripped off the board: a
short lead soldered in one pad; a hole in the other pad where a lead was
soldered (poorly, apparently!). (Rough handling is a distinct possibility:
the client is a used-equipment dealer and the fork lift is their main
tool...).

The board is populated with 80's technology, mainly 74LS' :: the crystal
pads
connect to an 'LS04 inverter/driver and then to an 'LS96
parallel-to-serial
converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz.

The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK
is
a multiple of the dot clock and an input to the 8275."

Maybe these clues will tell someone what frequency this crystal needs to
be...?

What frequency crystal should I be looking for?

Thanks.

Can you feed in a test signal from a signal generator and see what you get

on the display? A line in NTSC is about 64 us. If you have 80 characters x 7
dots, that's 560 dots per line or about 0.114 us per dot. That gives about a
9 MHz clock frequency. Maybe you can find a good signal generator and start
out in that range. At least it would give you a clue as to what the video
format should be.

 

Followups set to sci.electronics.repair .

In sci.electronics.components DaveC <invalid@invalid.net> wrote:

The board is populated with 80's technology, mainly 74LS' :: the
crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96
parallel-to-serial converter.

Suggestion: Identify the "output" of the LS04, remove the LS04, hook up
a function generator to the "output" trace, and start turning the knob.
At some point, something resembling video should start coming out of the
output. Continue turning the knob until the period on the video is
correct. At a guess, the answer is probably somewhere between 1 and
20 MHz.

Another way to do it: Grab the first random crystal between 1 and 20 MHz
you can find and solder it in. Look at the video output with a scope.
You will probably see something resembling either PAL or NTSC video;
compare the period of what you see to the standard, and change frequency
accordingly.

An analog color TV will have a 3.579545 MHz crystal in it. An old PC
motherboard (286 and below) will probably have a couple of crystals on
it; one is often 14.31818 MHz.

http://en.wikipedia.org/wiki/Crystal_oscillator_frequencies lists some
common PAL and NTSC crystal frequencies.

The board uses a 8275 CRT controller, and in the datasheet it says:
"CCLK is a multiple of the dot clock and an input to the 8275."

The "AC Characteristics" section gives the minimum CCLK period as
480 ns, which is 2.08 MHz. That doesn't mean you need a 2 MHz crystal
max; CCLK is one-eighth of the dot clock, so the crystal would be 16 Mhz
max. From the block diagrams on the data sheet, if the parallel bus on
the LS96 you found is hooked up to a couple of ROMs, then the clock
input to the LS96 is probably the dot clock.

Matt Roberds

 

[Michael A. Terrell]

DaveC wrote:

80's vintage German printing equipment (offset press industry) uses a video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband video
tube monitor. (It is possible, being German and sold in the USA market, that
the video may be NTSC or PAL.)

There is no video signal on the BNC output connector.

This is used equipment being resurrected, so operational history is unknown.

There is a place on the video card labeled "Q2" that is the right shape ?
size for a crystal can. The pads look like it was ripped off the board: a
short lead soldered in one pad; a hole in the other pad where a lead was
soldered (poorly, apparently!). (Rough handling is a distinct possibility:
the client is a used-equipment dealer and the fork lift is their main
tool...).

The board is populated with 80's technology, mainly 74LS' :: the crystal pads
connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial
converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz.

The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is
a multiple of the dot clock and an input to the 8275."

Maybe these clues will tell someone what frequency this crystal needs to
be...?

What frequency crystal should I be looking for?

Mono video used 15,750 Hz for horizontal sweep.

NTSC video used 15,734.34 HZ for horizontal sweep, and was often
derived from a 4X colorburst crystal at 14.318180 MHZ by dividing by
910.

The same ratio would need 14.332500 MHz for Mono.

Can't you find an old XT monochrome video card for reference?

 

[Tilmann Reh]

Michael A. Terrell schrieb:

80's vintage German printing equipment (offset press industry) uses a video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband video
tube monitor. (It is possible, being German and sold in the USA market, that
the video may be NTSC or PAL.)

If it's monochrome, we don't need to talk about NTSC or PAL and their
particular color carrier frequencies...

What frequency crystal should I be looking for?

Mono video used 15,750 Hz for horizontal sweep.

In Europe, especially Germany, horizontal frequency was 15.625 kHz and
vertical frequency 50 Hz in those days.

As others have already suggested, supply a reasonable clock to it,
measure the sync outputs and then change the frequency accordingly.
Chances are good that it's a standard and even frequency, like (for
example) 16 MHz.

Tilmann

 

[Martin Brown]

On 30/01/2013 22:26, DaveC wrote:

80's vintage German printing equipment (offset press industry) uses a video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband video
tube monitor. (It is possible, being German and sold in the USA market, that
the video may be NTSC or PAL.)

There is no video signal on the BNC output connector.

This is used equipment being resurrected, so operational history is unknown.

There is a place on the video card labeled "Q2" that is the right shape &
size for a crystal can. The pads look like it was ripped off the board: a
short lead soldered in one pad; a hole in the other pad where a lead was
soldered (poorly, apparently!). (Rough handling is a distinct possibility:
the client is a used-equipment dealer and the fork lift is their main
tool...).

The board is populated with 80's technology, mainly 74LS' :: the crystal pads
connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial
converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz.

The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is
a multiple of the dot clock and an input to the 8275."

Maybe these clues will tell someone what frequency this crystal needs to
be...?

What frequency crystal should I be looking for?

I'd try 13.5MHz first but anything in that ballpark and output the video
to a multisync monitor and you should get some sort of picture.

Old monitors don't like being driven too slowly for long periods.

--
Regards,
Martin Brown

 

[Ian Field]

"Tilmann Reh" <usenet2007nospam@autometer.de> wrote in message
news:keddia$5n4$1@dont-email.me...

Michael A. Terrell schrieb:

80's vintage German printing equipment (offset press industry) uses a
video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband
video
tube monitor. (It is possible, being German and sold in the USA market,
that
the video may be NTSC or PAL.)

If it's monochrome, we don't need to talk about NTSC or PAL and their
particular color carrier frequencies...

In PAL & NTSC; the colour carrier was a multiple of the line rate.

 

[Ian Field]

"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
news:%VqOs.7610$Sq4.6558@newsfe14.iad...

On 30/01/2013 22:26, DaveC wrote:
80's vintage German printing equipment (offset press industry) uses a
video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband
video
tube monitor. (It is possible, being German and sold in the USA market,
that
the video may be NTSC or PAL.)

There is no video signal on the BNC output connector.

This is used equipment being resurrected, so operational history is
unknown.

There is a place on the video card labeled "Q2" that is the right shape &
size for a crystal can. The pads look like it was ripped off the board: a
short lead soldered in one pad; a hole in the other pad where a lead was
soldered (poorly, apparently!). (Rough handling is a distinct
possibility:
the client is a used-equipment dealer and the fork lift is their main
tool...).

The board is populated with 80's technology, mainly 74LS' :: the crystal
pads
connect to an 'LS04 inverter/driver and then to an 'LS96
parallel-to-serial
converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz.

The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK
is
a multiple of the dot clock and an input to the 8275."

Maybe these clues will tell someone what frequency this crystal needs to
be...?

What frequency crystal should I be looking for?

I'd try 13.5MHz first but anything in that ballpark and output the video
to a multisync monitor and you should get some sort of picture.

Old monitors don't like being driven too slowly for long periods.

They don't have to be old - just have a CRT.

The scan yoke being an inductor has linear ramp current when the voltage is
applied for the forward scan period, reducing the frequency increases the
period - the inductor has time to saturate and "punch-through" the scan
transistor!

 

[Michael A. Terrell]

Ian Field wrote:

"Tilmann Reh" <usenet2007nospam@autometer.de> wrote in message
news:keddia$5n4$1@dont-email.me...
Michael A. Terrell schrieb:

80's vintage German printing equipment (offset press industry) uses a
video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband
video
tube monitor. (It is possible, being German and sold in the USA market,
that
the video may be NTSC or PAL.)

If it's monochrome, we don't need to talk about NTSC or PAL and their
particular color carrier frequencies...

In PAL & NTSC; the colour carrier was a multiple of the line rate.

Did you just figure that out?

 

[Tauno Voipio]

On 7.2.13 11:35 , Ian Field wrote:

"Tilmann Reh" <usenet2007nospam@autometer.de> wrote in message
news:keddia$5n4$1@dont-email.me...
Michael A. Terrell schrieb:

80's vintage German printing equipment (offset press industry) uses
a video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard
baseband video
tube monitor. (It is possible, being German and sold in the USA
market, that
the video may be NTSC or PAL.)

If it's monochrome, we don't need to talk about NTSC or PAL and their
particular color carrier frequencies...


In PAL & NTSC; the colour carrier was a multiple of the line rate.

Not quite.

In PAL, the subcarrier is 4.433618 MHz and the line rate is 15625 Hz,
the ratio is 283.75512, not an exact multiple.

When I studied the thing in the 60's, the explanation was to find
a frequency at as non-integer rate as possible, to get rid of
Moire effects.

--

Tauno Voipio

 

[Tauno Voipio]

On 7.2.13 11:42 , Ian Field wrote:

"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
news:%VqOs.7610$Sq4.6558@newsfe14.iad...
On 30/01/2013 22:26, DaveC wrote:
80's vintage German printing equipment (offset press industry) uses a
video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard
baseband video
tube monitor. (It is possible, being German and sold in the USA
market, that
the video may be NTSC or PAL.)

There is no video signal on the BNC output connector.

This is used equipment being resurrected, so operational history is
unknown.

There is a place on the video card labeled "Q2" that is the right
shape &
size for a crystal can. The pads look like it was ripped off the
board: a
short lead soldered in one pad; a hole in the other pad where a lead was
soldered (poorly, apparently!). (Rough handling is a distinct
possibility:
the client is a used-equipment dealer and the fork lift is their main
tool...).

The board is populated with 80's technology, mainly 74LS' :: the
crystal pads
connect to an 'LS04 inverter/driver and then to an 'LS96
parallel-to-serial
converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz.

The board uses a 8275 CRT controller, and in the datasheet it says:
"CCLK is
a multiple of the dot clock and an input to the 8275."

Maybe these clues will tell someone what frequency this crystal needs to
be...?

What frequency crystal should I be looking for?

I'd try 13.5MHz first but anything in that ballpark and output the
video to a multisync monitor and you should get some sort of picture.

Old monitors don't like being driven too slowly for long periods.


They don't have to be old - just have a CRT.

The scan yoke being an inductor has linear ramp current when the voltage
is applied for the forward scan period, reducing the frequency increases
the period - the inductor has time to saturate and "punch-through" the
scan transistor!

There is another consideration:

The scan system is resonated on the third harmonic to the line rate
to create the S-correction for the scan, slower on the edges and
faster at the middle. This is to compensate for the varying distance
between the electron gun and the screen. This means to keep the
line rate within a few percent of the nominal. The method was
populas with the monochrome tubes, but colour things often use
more sophistacated methods (parabolic correction, etc).

--

Tauno Voipio

 

On Thu, 7 Feb 2013 21:35:38 -0000, "Ian Field"
<gangprobing.alien@ntlworld.com> wrote:

"Tilmann Reh" <usenet2007nospam@autometer.de> wrote in message
news:keddia$5n4$1@dont-email.me...
Michael A. Terrell schrieb:

80's vintage German printing equipment (offset press industry) uses a
video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband
video
tube monitor. (It is possible, being German and sold in the USA market,
that
the video may be NTSC or PAL.)

If it's monochrome, we don't need to talk about NTSC or PAL and their
particular color carrier frequencies...


In PAL & NTSC; the colour carrier was a multiple of the line rate.

You mean fractional multiplier ?

The B&W contains spectral peaks at multiplies of line and field rate.
For (stationary) images, there is no energy between the spectral
lines.

The whole idea of both NTSC and PAL (but not SECAM) is to code the
chrominance signal into these "empty" spaces and thus the subcarrier
must be at some submultiple of the line rate. In PAL there is an
additional 25 Hz frequency shift, thus the same phase relationship
occurs every 4th field.

While this spectrum interleaving works pretty well for stationary
images, any movement will spread the spectral lines and luminance and
chrominance can no longer be perfectly separated, causing cross
chrominance and cross luminance problems. For this reason ties with
small details should not be used in TV studios if it is expected that
the signal could be transported through NTSC/PAL, since a tie with
only small B/W stripes would cause a quite colourful result .

 

[William Sommerwerck]

In PAL & NTSC the colour carrier was a multiple of the line rate.

Not quite.

In PAL, the subcarrier is 4.433618 MHz and the line rate is 15625 Hz,
the ratio is 283.75512, not an exact multiple.

When I studied the thing in the 60's, the explanation was to find
a frequency at as non-integer rate as possible, to get rid of moire
effects.

This is not a correct explanation -- and I'm certain your numbers are wrong
(you've rounded off the line rate).

The subcarrier HAS to be a multiple of the line rate -- specifically, an odd
multiple of half the line rate -- or the sidebands of the color signal will
not properly interleave with the sidebands of the luminance signal.

By the way, moire is not capitalized. It is not a person's name.

 

[William Sommerwerck]

The B&W contains spectral peaks at multiplies of line and field rate.
For (stationary) images, there is no energy between the spectral lines.

This is not correct, unless every line is like every other line. The normal
variation in vertical details causes the peaks to "smear" somewhat.

 

[Jan Panteltje]

On a sunny day (Fri, 8 Feb 2013 06:47:57 -0800) it happened "William
Sommerwerck" <grizzledgeezer@comcast.net> wrote in
<kf3361$9mg$1@dont-email.me>:

In PAL & NTSC the colour carrier was a multiple of the line rate.

Not quite.

In PAL, the subcarrier is 4.433618 MHz and the line rate is 15625 Hz,
the ratio is 283.75512, not an exact multiple.

When I studied the thing in the 60's, the explanation was to find
a frequency at as non-integer rate as possible, to get rid of moire
effects.

This is not a correct explanation -- and I'm certain your numbers are wrong
(you've rounded off the line rate).

The subcarrier HAS to be a multiple of the line rate -- specifically, an odd
multiple of half the line rate -- or the sidebands of the color signal will
not properly interleave with the sidebands of the luminance signal.

By the way, moire is not capitalized. It is not a person's name.

In PAL 25 Hz is added to the color subcarrier to force the interference pattern
caused by chroma in the BW picture to move, so it becomes less visible.
From:
http://en.wikipedia.org/wiki/PAL:
<quote>
The 4.43361875 MHz frequency of the colour carrier is a result of 283.75 colour clock cycles per line plus a 25 Hz offset to avoid interferences.
Since the line frequency (number of lines per second) is 15625 Hz (625 lines × 50 Hz ÷ 2),
the colour carrier frequency calculates as follows: 4.43361875 MHz = 283.75 × 15625 Hz + 25 Hz.
<end quote>

 

[Rich.]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:kf3361$9mg$1@dont-email.me...

By the way, moire is not capitalized. It is not a person's name.

Maybe not the way he used it, but it is a girl's first name.
http://www.thinkbabynames.com/meaning/0/Moire

 

[Spehro Pefhany]

On Fri, 8 Feb 2013 10:39:39 -0500, "Rich." <rcres@XXnewsguy.com>
wrote:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:kf3361$9mg$1@dont-email.me...

By the way, moire is not capitalized. It is not a person's name.

Maybe not the way he used it, but it is a girl's first name.
http://www.thinkbabynames.com/meaning/0/Moire

When two patterns of lines
cross to form new designs,
that's a moiré.

 

[tuinkabouter]

On 2/8/2013 7:48 AM, Tauno Voipio wrote:

On 7.2.13 11:35 , Ian Field wrote:


"Tilmann Reh" <usenet2007nospam@autometer.de> wrote in message
news:keddia$5n4$1@dont-email.me...
Michael A. Terrell schrieb:

80's vintage German printing equipment (offset press industry) uses
a video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard
baseband video
tube monitor. (It is possible, being German and sold in the USA
market, that
the video may be NTSC or PAL.)

If it's monochrome, we don't need to talk about NTSC or PAL and their
particular color carrier frequencies...


In PAL & NTSC; the colour carrier was a multiple of the line rate.


Not quite.

In PAL, the subcarrier is 4.433618 MHz and the line rate is 15625 Hz,
the ratio is 283.75512, not an exact multiple.

As far as I know it is
283.75 fH + 1/2 fV = 283.75 fH + 25 Hz = 4433618.75 Hz

I don't recall why. But Google has the answer:
<http://www.db0anf.de/app/bbs/messages/show-460135PA2RHB>
To make the dot pattern that results from the colour subcarrier almost
invisible, we need to satisfy this equation:

4*fc - 2*fr fl = line frequency (15625 Hz)
fl = ----------- fc = colour subcarrier frequency
n fr = frame rate (50 Hz)

This will ensure that dark and light dots cancel each other as much as
possible between alternating lines and between alternating frames.

The number n must be odd, and high enough to get a high enough colour
frequency. It was chosen to be 1135.

We get 4*fc - 2*fr = 1135 * 15625
fc = 1135 * 15625/4 + 25 = 4433593.75 + 25 = 4433618.75 Hz


Note: when colour television was first on the air, we did not have the
25 Hz offset yet. And although the dot pattern should have cancelled over
the screen, it was visible and you could tell, from watching your old
black and white screen, that a colour transmission was on.
After adding in the 25 Hz "time compensating" offset, this was no more.

The "integration time" for the screen is 4 frames, or 80 milliseconds. If
you could photograph the screen with that as the exposure time, the dot
pattern would be absolutely invisible.
If you took a picture with an exposure time of 2 frames (40 ms), or in
other words exactly one complete screen, you could see the residual dot
pattern.

 

[Fred Abse]

On Fri, 08 Feb 2013 08:55:32 +0200, Tauno Voipio wrote:

The scan system is resonated on the third harmonic to the line rate to
create the S-correction for the scan, slower on the edges and faster at
the middle.

That's yet another version of the widely-held misapprehension about
horizontal output harmonic tuning.

The *leakage inductance* of the flyback transformer is resonated at either
the third (monochrome), or fifth (color) harmonic of the "flyback
frequency", which is the reciprocal of twice the flyback time, somewhere
around 3, or 5 times 50kHz for NTSC/CCIR 525/625 line TV, assuming 10
microsecond flyback.) This has the effect of flattening the peaks of the
(half-sine) flyback pulses, and can be seen as either one or two small
dips in peak flyback voltage. In early tube designs, this was done with a
small winding underneath the HV winding, which was resonated with a
capacitor. In later designs with diode-split windings, it was done by
carefully controlling interwinding capacitance.

S-correction is a separate issue, achievable with a suitable capacitor in
series with the actual scanning current.


--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)