26 Feb
2012
26 Feb
'12
11:05 a.m.
So, my UK101 sold for a healthy ?224, which I am very happy about indeed.
However, it's to a buyer in the USA and he wants me to split the
bundle and send just the computer - he does not want the monitor.
He claims that although the computer will run on a 240-to-120V
transformer, the monitor will not, as US DC is 60Hz and European is
50Hz.
Is this correct? It's news to me.
I don't really want to split the package up, TBH - I am not sure that
the monitor is worth much on its own.
--
Liam Proven ? Profile: http://lproven.livejournal.com/profile
Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven
MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven
Tel: +44 20-8685-0498 ? Cell: +44 7939-087884
26 Feb
26 Feb
11:27 a.m.
On Feb 26, 2012, at 2:05 PM, Liam Proven wrote:
So, my UK101 sold for a healthy ?224, which I am very
happy about indeed.
However, it's to a buyer in the USA and he wants me to split the
bundle and send just the computer - he does not want the monitor.
He claims that although the computer will run on a 240-to-120V
transformer, the monitor will not, as US DC is 60Hz and European is
50Hz.
Is this correct? It's news to me.
It's certainly true about US mains vs. UK mains. Whether or not it
makes a difference for the monitor is another question, though the specs
for the monitor will probably inform that. One can get mains transformers
to convert 240v to 120v, but that obviously will not change the frequency
of the AC.
Most consumer equipment doesn't care that much, but plenty of things do;
I would imagine most 50Hz gear would operate on 60Hz because it will
reduce the ripple, but that is not universally true. Most clock radios,
among other things, will function incorrectly because they use the zero
crossing of the AC waveform as a clock, so if you move from 50Hz to 60Hz
(or vice versa), you're off by a fifth or sixth.
One possible solution is to run the monitor off a UPS; they sometimes
convert the mains to DC and convert the DC to AC again, so if you had a
UPS that would run off 240V at 60Hz, it might convert to 50Hz on the
other end. It might not. It would depend on the UPS.
Again, it's also possible that the monitor may run OK at 60Hz. Either
way, I would imagine the monitor will cost a fortune to ship overseas.
- Dave
11:30 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of Liam Proven
Sent: 26 February 2012 19:06
To: General Discussion: On-Topic and Off-Topic Posts
Subject: UK versus US monitor question
So, my UK101 sold for a healthy ?224, which I am very happy
about indeed.
However, it's to a buyer in the USA and he wants me to split the
bundle and send just the computer - he does not want the monitor.
He claims that although the computer will run on a 240-to-120V
transformer, the monitor will not, as US DC is 60Hz and European is
50Hz.
Is this correct? It's news to me.
It used to be the case that TVs synced to the mains frequency but I don't
think that?s been the case since we went 625 line. Which Monitor was it?
I don't really want to split the package up, TBH -
I am not sure that
the monitor is worth much on its own.
Prossibly trying to avoid shipping costs to the US. By default the UK101
produces 50Hz frame sync so he will need a monitor that syncs to 50Hz, not
60Hz as most US monitors do. From the brief web page I read the UK101 also
produces PAL not NTSC so he will need a PAL monitor or tweak the UK101.
--
Liam Proven ? Profile: http://lproven.livejournal.com/profile
Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven
MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven
Tel: +44 20-8685-0498 ? Cell: +44 7939-087884
12:13 p.m.
It used to be the case that TVs synced to the mains
frequency but I don't
Was it?
think that=92s been the case since we went 625 line.
Which Monitor was it=
?
Both 405 line (System A) and 625 line (System I) TVs over here have a
50Hz vertical scan rate (or close to it), but AFAIK they all synced to
pluses i nthe video signal. Certainly the schemaitcs for systme A TVs
that I've just looekd at confirm this.
While there are advantages i nhavign the vertical scan rate cloe to the
mains frequency, it's not requried, and you should ahve no problems
running a 50Hz vertical monitor off 60Hz mains of vice versa if the PSU
in the monitor can handle it. I've vertainly run plenty of US-spec
montiors over here.
I don't really want to split the package up,
TBH - I am not sure that
the monitor is worth much on its own.
=20
Prossibly trying to avoid shipping costs to the US. By default the UK101
produces 50Hz frame sync so he will need a monitor that syncs to 50Hz, no=
t
60Hz as most US monitors do. From the brief web page I read the UK101 als=
o
produces PAL not NTSC so he will need a PAL monitor or tweak the UK101.=20
1:08 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of Tony Duell
Sent: 26 February 2012 20:14
To: cctalk at classiccmp.org
Subject: Re: UK versus US monitor question
A long time ago...
It used to be the case that TVs synced to the
mains
frequency but I don't
Was it? think that=92s been the case since we went 625
line. Which
Monitor was it=
?
Both 405 line (System A) and 625 line (System I) TVs over here have a
50Hz vertical scan rate (or close to it), but AFAIK they all
synced to
pluses i nthe video signal. Certainly the schemaitcs for systme A TVs
that I've just looekd at confirm this.
While there are advantages i nhavign the vertical scan rate
cloe to the
mains frequency, it's not requried, and you should ahve no problems
running a 50Hz vertical monitor off 60Hz mains of vice versa
if the PSU
in the monitor can handle it. I've vertainly run plenty of US-spec
montiors over here.
> I don't really want to split the package up, TBH - I am
not sure that
the
monitor is worth much on its own.
=20
Prossibly trying to avoid shipping costs to the US. By produces 50Hz frame sync so he will need a
monitor that
syncs to 50Hz, no=
t
60Hz as most US monitors do. From the brief web page I read
the UK101 als=
o
produces PAL not NTSC so he will need a PAL monitor or
tweak the UK101.=20
Eh? I didn;t think the UK101 produced any form of colour
output, which is
what PAL would specify. Most likely that's a page that
incorrectly uses
'PAL' to mean '50Hz vertical'.
-tony
27 Feb
27 Feb
12:48 p.m.
It used to be the case that TVs synced to the mains
frequency but I don't
Was it? 
3:14 p.m.
On 2/27/2012 1:48 PM, Tony Duell wrote:
A long time ago...
OK, I am sceptical. What do you mean by a 'long time ago'?
Unti lthe coming of the National Grid, different areas would be supplied
with mains at slightly differnet frequencies (even assuming it was
supposed to be nominally 50Hz), and therre would eb no phase relationship
at all. So usign that for any form of TV synchronisation is a non-starter.
So that really limits us to post-WW2 TVs. The oldest book of schematics I
have is dated 1953, but it contains models going back to 1948. Not one
attempts to derrive the vertical sync signal from the mains as far as I
can see.
I think it goes back more to the spinning disk TV format from the late 30's.
http://www.tvhistory.tv/index.html Dig here for more history on TV
It used to be
the case that TVs synced to the mains
frequency but I don't
Was it? But I am a scientist... So while I have not found such
a TV, I an't say
they don't exist. So I would ask you to state the make and model of one
or more TVs that derrived the vertcal sync signal from the mains, so that
I can track down the scheamtics and see what they did.
-tony
Ben.
4:54 p.m.
ben wrote:
I think it goes back more to the spinning disk TV format from the late
30's.
http://www.tvhistory.tv/index.html Dig here for more history on TV
Even those had
to be synchronized to the broadcast, NOT to the mains
frequency.
5:06 p.m.
On 2/27/2012 5:54 PM, Eric Smith wrote:
Ben.
ben wrote:
A quick scan leaves you wondering, is the broadcasting device (
mechanical camera)
tied to to the mains frequency. I found a good bit on the receivers, but
not on the cameras.
I think it goes back more to the spinning disk TV format from the late
30's.
http://www.tvhistory.tv/index.html Dig here for more history on TV
Even those had
to be synchronized to the broadcast, NOT to the mains
frequency. 
28 Feb
28 Feb
5:59 p.m.
Eric Smith wrote on Mon, 27 Feb 2012 16:54:50 -0800
ben wrote:
My impression is that this isn't quite true. You have to synchronize to
the frequency of the broadcast and also to the exact phase of the
broadcast. We are used to handling both with a single circuit, but they
are separate issues. Though modern recreations of mechanical TV
receivers seem to favor DC motors, many original devices used
synchronous AC motors instead. So if the broacast was using the mains as
a reference the receiver would, after a start up period, be in sync in
terms of frequency.
The phase difference between the sender and receiver would be arbitrary,
of course. The way to solve that is to have the viewer adjust some knob
until the picture looked right. One solution is to have the knob add
some friction to the motor when pressed, causing the rotation to fall
slightly allowing the picture to drift into the desired position.
My father started working at RCA in 1957 and tells me that hybrid
receivers (with electronic horizontal circuits and mechanical vertical)
were still common at that time. I found absolutely nothing about them
online. Even museums that list their TV receivers seem to jump directly
I think it goes back more to the spinning disk TV format from the late
30's.
http://www.tvhistory.tv/index.html Dig here for more history on TV
Even those had
to be synchronized to the broadcast, NOT to the mains
frequency. from full mechanical models to fully electronic ones.
http://www.earlytelevision.org/
I did see a hybrid camera at this site near the bottom of
http://www.earlytelevision.org/safar_studios.html
Anyway, even after mechanical and hybrid sets were forgotten there was
enough line noise in typical power supplies to make it a good idea to
keep the picture synchronized with the mains. And even today, with nice
switching power supplies, having the TV run at the line rate makes the
terrible noise that appears on the screen when someone turns on a
blender in the next room remain a stationary line instead of moving all
over.
-- Jecel
6:48 p.m.
On Tue, 28 Feb 2012, Jecel Assumpcao Jr. wrote:
My father started working at RCA in 1957 and tells me
that hybrid
receivers (with electronic horizontal circuits and mechanical vertical)
were still common at that time.
outside of museums??!?
1957??!?
I didn't buy my first NEW TV until 1961 (Philco 17" "portable", WITH
UHF!), so I don't have first hand knowledge of what was available in 1957,
but the barely working clunkers in Goodwill, etc. were not mechanical.
OTOH, some of the first REMOTE CONTROL TVs (a little later) had a motor to
TURN the channel selection knob!
10:39 p.m.
On 28 Feb 2012 at 18:48, Fred Cisin wrote:
On Tue, 28 Feb 2012, Jecel Assumpcao Jr. wrote:
I can't say that I've ever seen one that way, including pre-war "kit"
models, like the Meissner (they of "signal shifter" VFO fame):
http://www.myvintagetv.com/meissner101153.htm
Our 1948 10" Philco tabletop certainly didn't use that scheme (had a
huge transformer in it though). And neither did our "big screen"
1953 RCA set.
Perhaps he's thinking of the CBS color system with the motor-powered
wheel:
http://www.novia.net/~ereitan/Color_Sys_CBS.html
--Chuck
My father started working at RCA in 1957 and
tells me that hybrid
receivers (with electronic horizontal circuits and mechanical
vertical) were still common at that time.
outside of museums??!?
1957??!? 
10:04 p.m.
--- On Tue, 2/28/12, Jecel Assumpcao Jr. <jecel at merlintec.com> wrote:
My father started working at RCA in 1957 and tells me
that
hybrid
receivers (with electronic horizontal circuits and
mechanical vertical)
were still common at that time. I found absolutely nothing
about them
online. Even museums that list their TV receivers seem to
jump directly
from full mechanical models to fully electronic ones.
I think you might have misunderstood something about that. All electronic television was
well and truly common by 1957. In fact, RCA had color sets on the market in 1955.
Even in the late 40's, television was all electronic. Electrostatic deflection,
however, was quite common back then - perhaps that's what he meant. Instead of
magnetic coils to deflect the beam, early small screen sets used electrostatic tubes, with
deflection plates in them. Most oscilloscopes used electrostatic tubes for a long time
thereafter, but as television sets got bigger, they went to all magnetic deflection.
-Ian
10:26 p.m.
On 2012 Feb 28, at 10:04 PM, Mr Ian Primus wrote:
--- On Tue, 2/28/12, Jecel Assumpcao Jr. <jecel at
merlintec.com> wrote:
I don't have examples, but to give him the benefit of the doubt,
perhaps he was referring to special cases such as projection TVs or
some-or-other studio equipment. Working in RCA he might have been
seeing stuff most people wouldn't.
My father started working at RCA in 1957 and
tells me that
hybrid
receivers (with electronic horizontal circuits and
mechanical vertical)
were still common at that time. I found absolutely nothing
about them
online. Even museums that list their TV receivers seem to
jump directly
from full mechanical models to fully electronic ones.
I think you might have misunderstood something about that. All
electronic television was well and truly common by 1957. In fact,
RCA had color sets on the market in 1955.
Even in the late 40's, television was all electronic. Electrostatic
deflection, however, was quite common back then - perhaps that's
what he meant. Instead of magnetic coils to deflect the beam, early
small screen sets used electrostatic tubes, with deflection plates
in them. Most oscilloscopes used electrostatic tubes for a long
time thereafter, but as television sets got bigger, they went to
all magnetic deflection. 
10:43 p.m.
I don't have examples, but to give him the benefit
of the doubt, perhaps he
was referring to special cases such as projection TVs or some-or-other
studio equipment. Working in RCA he might have been seeing stuff most people
wouldn't.
I have a LOT of 1950s tech docs on RCA television equipment, and I
have never seen any hybrid mechanical systems mentioned in them.
Perhaps he might be confusing the television for radar indicators. In
the mid 1950s, there were still some PPI scopes with the rasters
scanned mechanically, by rotating the yoke. This was a very common
method to get the rotating raster back in the 1940s, but started to be
replaced by all electronic sweep generators in the 1950s. The last use
I can think of for these rotating yokes was on the SAGE gap filler
nodes, made by Westinghouse - up to seven yokes on seven tubes
spinning in sync.
--
Will
29 Feb
29 Feb
2:40 a.m.
On 2012 Feb 28, at 10:43 PM, William Donzelli wrote:
I'm not having much luck finding examples of actual models, and I
don't know about RCA specifically, but TMU there were theatre or
large-screen projection TVs made with Kerr cells (for light
modulation) and rotating mirrors (scanning) for display of the
standard TV signal around that era. I thought Scott made a home TV of
this form (40s). As such, there were mechanical-scan systems aside
I don't
have examples, but to give him the benefit of the doubt,
perhaps he
was referring to special cases such as projection TVs or some-or-
other
studio equipment. Working in RCA he might have been seeing stuff
most people
wouldn't.
I have a LOT of 1950s tech docs on RCA television equipment, and I
have never seen any hybrid mechanical systems mentioned in them.
Perhaps he might be confusing the television for radar indicators. In
the mid 1950s, there were still some PPI scopes with the rasters
scanned mechanically, by rotating the yoke. This was a very common
method to get the rotating raster back in the 1940s, but started to be
replaced by all electronic sweep generators in the 1950s. The last use
I can think of for these rotating yokes was on the SAGE gap filler
nodes, made by Westinghouse - up to seven yokes on seven tubes
spinning in sync. from the very early (20s-30s) experimental systems and
the CBS
sequential-field colour system.
5:27 a.m.
I'm not having much luck finding examples of
actual models, and I don't know
about RCA specifically, but TMU there were theatre or large-screen
projection TVs made with Kerr cells (for light modulation) and rotating
mirrors (scanning) for display of the standard TV signal around that era.
I would not call these "still common at that time" (1957).
--
Will
12:55 p.m.
I'm not having much luck finding examples of
actual models, and I
don't know about RCA specifically, but TMU there were theatre or
large-screen projection TVs made with Kerr cells (for light
modulation) and rotating mirrors (scanning) for display of the
standard TV signal around that era. I thought Scott made a home TV of
this form (40s). As such, there were mechanical-scan systems aside
We had back-projection home TVs over here -- White-Ibbotson was the best
known. But they used a small convntional CRT (2" screen) with a highr
than normal EHT (25kV or so) in a Schmidt-type optical assembly. No
mechanical scanning.
Did you have 'mirror in the lid' TVs in the States? Due to the small
defleciton angle, the CRTs in early (1930's) TVs wrre very long from base
to screen. Some mnufactuered stood them vertically with the screen on top
and had a front-silvered mirror in a hinged lid on top of the cabinet.
For viewing you lifted the lid to the 45 degree position and viewed the
refleciton of the screen in the mirror.
(Yes it would be back-to-front compared to what was actualyl on the
screen, but having one of the defleciton coils revesed mant the picutre
you actually saw was the right way round)
Again fully electronic scanning.
-tony
2:07 p.m.
On Wed, 29 Feb 2012, Tony Duell wrote:
Did you have 'mirror in the lid' TVs in the
States? Due to the small
defleciton angle, the CRTs in early (1930's) TVs wrre very long from base
to screen. Some mnufactuered stood them vertically with the screen on top
and had a front-silvered mirror in a hinged lid on top of the cabinet.
For viewing you lifted the lid to the 45 degree position and viewed the
refleciton of the screen in the mirror.
(Yes it would be back-to-front compared to what was actualyl on the
screen, but having one of the defleciton coils revesed mant the picutre
you actually saw was the right way round)
Again fully electronic scanning.
My grandparents had a tiny portable one of those. I haven't seen it in
close to 50 years, but I heard that my cousin has it, and he's enough of
an elctronics hobbyist to appreciate it.
1 Mar
1 Mar
4:34 p.m.
William Donzelli wrote on Wed, 29 Feb 2012 01:43:16 -0500
I asked my father for more details and he confirmed what several here
guessed: he meant that they had lots of those old mechanical TV sets in
the RCA lab (Marion, Indiana) when he arrived there in 1957/58. So this
was in a kind of museum, not stuff that was being sold.
When I tried to get him to explain how it would be possible to have a
mechanical vertical part and an electronic horizontal part we came to
the conclusion that the sets he was remembering were actually the fully
mechanical ones with the traditional spiral of holes from before World
War II.
On a related subject, I have seen a few videos of modern recreations of
mechanical TVs on Youtube and feel they are a bit misleading. They are
being fed a signal created from a good video source, so the images we
see are far better than what you would get from a mechanical camera.
That is like showing off a SInclair ZX Spectrum hooked up to a SD card
and playing a video (you can see that on Youtube too) - it gives you a
wrong idea of what using the device was like when it was new.
-- Jecel
I don't
have examples, but to give him the benefit of the doubt, perhaps he
was referring to special cases such as projection TVs or some-or-other
studio equipment. Working in RCA he might have been seeing stuff most people
wouldn't.
I have a LOT of 1950s tech docs on RCA television equipment, and I
have never seen any hybrid mechanical systems mentioned in them.
2 Mar
2 Mar
12:56 p.m.
William Donzelli wrote on Wed, 29 Feb 2012 01:43:16 -0500
I asked my father for more details and he confirmed what several here
guessed: he meant that they had lots of those old mechanical TV sets in
the RCA lab (Marion, Indiana) when he arrived there in 1957/58. So this
was in a kind of museum, not stuff that was being sold.
Ah, that makes a lot of sense
I
don't have examples, but to give him the benefit of the doubt, perhaps he
was referring to special cases such as projection TVs or some-or-other
studio equipment. Working in RCA he might have been seeing stuff most people
wouldn't.
I have a LOT of 1950s tech docs on RCA television equipment, and I
have never seen any hybrid mechanical systems mentioned in them.
When I tried to get him to explain how it would be possible to have a
mechanical vertical part and an electronic horizontal part we came to
the conclusion that the sets he was remembering were actually the fully
mechanical ones with the traditional spiral of holes from before World
War II.
There were single-axis CRTs made for speical purposes, there's one in
that Tektronix printer used with their storage-tube displays. Inm that
device the other axis is provbided by moving the paper pwas the end of
the CRT.
You could make a TV with such a CRT and a rotating mnirror drum to give
the other scan axis (prsumably the slower one). Whether this was ever
done I don't know, I've not heard of it but then vintage TV is nto my
speciality.
On a related subject, I have seen a few videos of modern recreations of
mechanical TVs on Youtube and feel they are a bit misleading. They are
being fed a signal created from a good video source, so the images we
see are far better than what you would get from a mechanical camera.
That is like showing off a SInclair ZX Spectrum hooked up to a SD card
and playing a video (you can see that on Youtube too) - it gives you a
wrong idea of what using the device was like when it was new.
Indeed. Which is why (to get this on-topic) I think it's important to
preserve as much of a vintage computer system as you can, not just the
processor.
By all means inteface a mdoern storage dervive to it for day-to-day use.
And hook up a mdoern printor or an interfave to a PC that grabs the data
intended to go to the pritner rather than running a clatterign mechanical
thing all the time. But keep the old cassette tape unit, the thermal
pritner tht fades if you looks at it wrong, the clattering ASR33, etc
jsut so you can rememebr (and demonstrate) what the system was really
like to use.
-tony
29 Feb
29 Feb
12:48 p.m.
My father started working at RCA in 1957 and tells me
that hybrid
receivers (with electronic horizontal circuits and mechanical vertical)
Are you sayig these sets had a single-azis CRT to provide the horizontal
scan and a mirror drum or similar to provide the vertical scan?
Kersqueeble. I have never seen anythign like that over here. From the mid
19830s onwards all our TVs were fully electronic.
I did heard of some CCD-based camers which had a single-axis CDD
(considerably simplerand easier to driv than a 2-axis one) that was
mechancially scanned acorss the iamge (or used a mirror to do the same
thing), but that's rather differnet.
keep the picture synchronized with the mains. And even
today, with nice
switching power supplies, having the TV run at the line rate makes the
A number of TVs and monitors ran their SMPSUs at the horizontal scan
rate. The DEC VR241 colour monitor is one such -- it's a Hitachi chassis.
The power supply is driven from the horizotanl oscillator, at least once
it's all got going (and $deity help you if you have to trace a startup
fault on that thing). One manufactuer in Europe had that they called the
'IPSALO circuit'. That was an acronym for 'Integrated Power Supply and
Line Output' -- 'Line Output' is what you woudl call 'Horizontal
Output'.
Yes, the chopper transformer and flyback transformer were one and the
same. IIRC< the vetical defleciton coils were o nthe output side of the
pSU isolation barrier, the horizontal deflection coils were on the mains
side. Just a little trap for the unwary...
-tony
28 Feb
28 Feb
11:17 a.m.
[TV getting vertial sync from tha mains]
I think it goes back more to the spinning disk TV
format from the late 30's.
http://www.tvhistory.tv/index.html Dig here for more history on TV
According to all the published information I have 9including
instructions for buildign such a receiver and scheamtics published at the
time, there was no vertical synchronisation in this system.
The drive motor for the disk had a synchronistation device conisiting of
a toothed wheel between the poles of an electromagnet. This provided a
line synchronaistion, ensurign the picture lines started in the right
place but which line started the frame wasn't specified. Rather the
viewer had to mnually retard the disk (press a thumb on it) until the
picture didn't ahve a bar across it.
-tony
27 Feb
27 Feb
3:36 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of Tony Duell
Sent: 27 February 2012 20:49
To: cctalk at classiccmp.org
Subject: Re: UK versus US monitor question
A long time ago...
OK, I am sceptical. What do you mean by a 'long time ago'?
Unti lthe coming of the National Grid, different areas would
be supplied
with mains at slightly differnet frequencies (even assuming it was
supposed to be nominally 50Hz), and therre would eb no phase
relationship
at all. So usign that for any form of TV synchronisation is a
non-starter.
So that really limits us to post-WW2 TVs. The oldest book of
schematics I
have is dated 1953, but it contains models going back to
1948. Not one
attempts to derrive the vertical sync signal from the mains
as far as I
can see.
But I am a scientist... So while I have not found such a TV,
I an't say
they don't exist. So I would ask you to state the make and
model of one
or more TVs that derrived the vertcal sync signal from the
mains, so that
I can track down the scheamtics and see what they did.
Perhaps as amateur sync gen, there is reference to mains sync here:-
http://vss.pl/cq_tv/cq-tv31.pdf
But I think that's for the sync generation at the camera. I did think the
Pye V4 used mains to sync frequency (NOT PHASE) but when I looked it up it
didn't. Then I also recall the horrid problems most TV's of that age had
with frame sync. I seem to remember one of the Apollo moon shots being
described in terms of a number of TVs with no adjustment to frame sync.
It used to be the case that TVs synced to the mains
frequency but I don't
Was it? -tony
28 Feb
28 Feb
11:21 a.m.
Perhaps as amateur sync gen, there is reference to
mains sync here:-
http://vss.pl/cq_tv/cq-tv31.pdf
But I think that's for the sync generation at the camera. I did think the
Yes, and hat makes sense. Havign the vertical sync of a small
closed-circuit system or an amateur TV system locked ot the mains means
that if there's any maind hum/ripple in the video signal (and given the
verty small signal from the target of a vidicon tube, it's likely there
will be), havinf the signal mlocked ot the mains means you have a static
'hum bar rather than one that drifts up and down the picture. The former
is a lot less annoying.
But that's not the samething as suggestign a TV receiver would sync to
the mains rather than some sync pulse in the incoming signal
-tony
26 Feb
26 Feb
1:10 p.m.
Dave wrote:
It used to be the case that TVs synced to the mains
frequency but I
don't think that?s been the case since we went 625 line.
Despite some claims,
I've never seen credible evidence of the existence
of a TV that "synced to the mains frequency", even for the 405-line
system. I think it's an urban legend. TVs sync to the recovered vertical
sync pulse of the incoming video signal.
It's certainly possible that a TV designed for 60 Hz mains might have a
power supply that has problems with 50 Hz, and rather less likely the
other way around, but that has nothing to do with the field rate of the
video signal, which has no inherent synchronization to the mains.
There are, on the other hand, several reasons why the broadcast field
rate iwas chosen to be the same as the mains frequency. However, even
those reasons are questionable, since NTSC color broadcasting has always
been done with a field rate that is 0.1% lower than the mains frequency,
yet the slow beat between the mains frequency and the field rate has
never caused a problem.
3:35 p.m.
On Feb 26, 2012, at 4:10 PM, Eric Smith wrote:
Dave wrote:
Indeed, I doubt it would even work. It would require your video
generator to be in sync with the mains frequency, which is something
I'd find unlikely at best even before we dropped the frequency for
NTSC color video.
- Dave
It used to be the case that TVs synced to the
mains frequency but I don't think that?s been the case since we went 625 line.
Despite some claims, I've never seen credible evidence of the existence of a TV that
"synced to the mains frequency", even for the 405-line system. I think it's
an urban legend. TVs sync to the recovered vertical sync pulse of the incoming video
signal.
12:08 p.m.
So, my UK101 sold for a healthy =A3224, which I am very happy about indee=
d.
I really am goign to have to look for another hobby...
However, it's to a buyer in the USA and he wants me to split the
bundle and send just the computer - he does not want the monitor.
He claims that although the computer will run on a 240-to-120V
transformer, the monitor will not, as US DC is 60Hz and European is
50Hz.
Is this correct? It's news to me.
It's very likely to be incorrect.
Yes, UK mains is 50Hz and US mains is 60Hz. Almost all monitors simply
produce one or more DC rails from this [1]. Provided the PSU in the
monitor will handle 60Hz -- and for any reasoable PSU design if it'll run
on 50Hz mains it'l lrun on 60Hz mains --then the monitor would be fie on
240V 60Hz. If not, then it would be a fairly easy job to convert it.
[1] An amazing number of small (12" or so) monochrome monitors, and not
jeust TV tarte ones, produve 12V from the mains by one of a number of PSU
circuits. This 12V is used to power the CRT heaters amd the lowe-power
cirucitry, the high voltages for the CRT electrodes and the video output
stage come fro mthe flyback transformer (itself powered from the 12V DC
supply). If it's that sort of design it doesn't much matter where the 12V
DC comes from.
Do you knw othe make and model of the monitor, just in case one of us has
ocme across it and has a scehamtic to hand?
A seconadary issue is the vertical sync rreqeucny of the machine. TV
cvertical rates are essentially the same as the main frequency i ntyhe
country to prevent problems wither with the CRT image beating against the
room lighing and cuasing flicker or to reduce the visible effects of
ripple from the mains PSU gettign into the video circuitry. So if the
buyer wishes to use the machine in the States he will presumably need a
monitor that can handle 50Hz vertical. Most small mono monitors can, and
in any case the mofification is not complicated. But I'd want to kepe the
oroginal monitor if possible.
I don't really want to split the package up, TBH - I am not sure that
the monitor is worth much on its own.
I suspect the _real_ reason is that the monitor is ratehr more delicate
than the rest of the machine, and would be fairly expnsive to ship.
-tony
27 Feb
27 Feb
5:58 a.m.
On 02/26/2012 02:08 PM, Tony Duell wrote:
I suspect the _real_ reason is that the monitor is
ratehr more delicate
than the rest of the machine, and would be fairly expnsive to ship.
Delicate and heavy... but I think the issue of hooking a display intended
for NTSC up to a system designed to produce PAL is a bigger one, surely?
I'm expecting that's going to bite me with a lot of my collection when I
eventually ship it over to the US (although one of the things coming over
will be an ACW, so at least I'll be able to tap into its built-in display
for some systems if needed)
cheers
Jules
1:19 p.m.
On 02/26/2012 02:08 PM, Tony Duell wrote:
For monochrome (so not PAL!), it's not much of a problem. The video
signals are the same voltage levels, and the horizontal sync frequencies
are very close -- close enough that most times the 'wrong' monitor will
sync anywaym if noy, it's kist a twak of the horizontal hold control.
Most of the time the other vertical rate is within the range of the hold
control (of ovbvoious reoasns, the same monitor chassis was sold
worldwide), if not the vertical section is genreally easy to modify.
Colour video is a differnet issue of course. RGB has few problems, but
interconverting between NTSC and PAL encoding is 'fun'.
I suspect the _real_ reason is that the monitor
is ratehr more delicate
than the rest of the machine, and would be fairly expnsive to ship.
Delicate and heavy... but I think the issue of hooking a display intended
for NTSC up to a system designed to produce PAL is a bigger one, surely?
I'm expecting that's going to bite me with a lot of my collection when I
eventually ship it over to the US (although one of the things coming over
will be an ACW, so at least I'll be able to tap into its built-in display
for some systems if needed)
As I am sure you know that's a TTL input RGB monitor at normal UK TV
rates. It's actually a Microvitec chassis nad very similar to some of
thei stnadalone monitors. You may be able ot coifugre it for analogue RGB
inouts (at whcih point it'll not longer take the output of the BBC B+
board in the ACW).
-tony
10:10 a.m.
On 26 February 2012 20:08, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
(?)
So, my UK101 sold for a healthy =A3224, which I am very happy about indee=
d.
I really am goign to have to look for another hobby... Do you knw othe make and model of the monitor, just in
case one of us has
ocme across it and has a scehamtic to hand?
From the listing:
?
A little more info about the screen & its box. NB. I am not sure this
is the original box for the screen. The CRT is in what must be the
original polystyrene packing foam, and this fits snugly into the box
but protrudes slightly. However, visibly, when the box was sealed, the
contents did bulge out of the top. The flaps were torn open and part
is missing, but they did not close 100% even when new.
The following text is printed (quite roughly) on the monitor box:
XM226 16
9204
MOTOROLA DATA PRODUCTS
#155 HARVESTER RD., WEST CHGO, IL. 60185
TO:
REDIFON COMPUTERS LTD
17-27 KELVIN WAY
CRAWLEY, SUSSEX ENGLAND RH13 2LY
PO# RA27731
FO# I100416
And the following is handwritten:
200K pot
040.012-0
There is also the tattered remains of what I think is a shipping
label, slightly slug- or snail-eaten.
?
Googling the model number bizarrely gives me this repost:
http://www.holidays.net/store/Complete-Compukit-UK101-with-case,-VDU,-manua…
That is bizarre and annoying.
Anyway, it's a Motorola XM226-16, service #HS.01620-006, serial #9200
5237, manufactured July 1979.
I suspect the _real_ reason is that the monitor is
ratehr more delicate
than the rest of the machine, and would be fairly expnsive to ship.
Indeed. And I don't really want to split it.
--
Liam Proven ? Profile: http://lproven.livejournal.com/profile
Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven
MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven
Tel: +44 20-8685-0498 ? Cell: +44 7939-087884
1:24 p.m.
On 26 February 2012 20:08, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
(?)
Quite simple. The price of vintage computes has gone through the roof
recently - -\pounds 224 for a simple-=ish single-board 6502 system for
example, and ther;es no way I have that sort of money to spare .
It was fun when I could pick up some interestign machines for a few 10's
of pounds, or when poeple would give them to you, but not any more. I've
got some more projects to do with wht I already have, but after that I'll
be working on soemthing else -- if I can find soemthing else.
>
> So, my UK101 sold for a healthy =3DA3224, which I am very happy about =
indee=3D
d.
I really am going to have to look for another hobby... Anyway, it's a Motorola XM226-16, service
#HS.01620-006, serial #9200
5237, manufactured July 1979.
Is that on the monitor itself, or just on the (possibly incorrect) box?
If it is a Motorola unit, I would be _very_ suprised if it couldn't be
got to work on 60Hz mains.
-tony
4447
days inactive
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31 comments
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ard＠p850ug1.demon.co.uk -
bfranchuk＠jetnet.ab.ca -
cclist＠sydex.com -
cisin＠xenosoft.com -
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eric＠brouhaha.com -
fraveydank＠gmail.com -
hilpert＠cs.ubc.ca -
ian_primus＠yahoo.com -
jecel＠merlintec.com -
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