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PAL Amiga Monitor on US Power?

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EagleTG

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Sep 19, 2015
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Near Allentown, PA
I was lucky enough to score a PAL Amiga 500 along with a UK import monitor on CraigsList a while back. I had no idea it was PAL until I went to pick it up and saw the plugs. I was quite excited as PAL was my preference, but I thought one would be really hard to find.

For what it's worth, the monitor is a Philips CM 8833. I'm interested in plugging this into US power, but am concerned for a few reasons. First, based on the power requirements of the monitor, I picked up a 500W step-up transformer (should be plenty even for dealing with the inrush current requirements). I am a bit concerned relating to the 50Hz / 60Hz differences between power across the pond and here in the US. I know the converters don't deal with changing frequencies, so I will be feeding 60Hz to the monitor that is expecting a 50Hz signal. I know some appliances can deal with this pretty well but am concerned as I know the inner electronics of some monitors actually derive the sweep frequency from the input power.

So, I'm looking for some suggestions. I've Googled this like crazy, and naturally have decent Google-Fu, this time I'm not finding anything useful. I can't be the first person to want to do this.

It boils down to two questions for me. Am I going to blow this monitor up? Will it still run at PAL frequencies?

Thanks again to anyone who can help. :)
-Todd
 
It's a very good thought, but by this time period monitors were a bit smarter than that.
I wouldn't worry about it. Should be fine with a step up transformer.
 
Looking at a schematic, it shows a strictly 50Hz AC input rating. However, the AC only feeds a full wave rectifier bridge to generate the primary unregulated DC power. The AC power frequency goes nowhere else so won't affect PAL operation or power supply regulation. In my opinion, applying 50Hz AC will not damage the monitor but I don't want to be responsible for what happens. I did CRT display repair for over 20 years but that was in the USA so never dealt with European models. Of course, wait for other opinions before acting on mine :)

Larry G
 
EagleTG said:
I know the inner electronics of some monitors actually derive the sweep frequency from the input power.
Click to expand...

Surely all monitors must sync to the video signal they receive? I don't see how they can correctly display anything any other way.
 
EagleTG said:
...the monitor is a Philips CM 8833. I'm interested in plugging this into US power, but am concerned for a few reasons. First, based on the power requirements of the monitor, I picked up a 500W step-up transformer...
Click to expand...
I don't have that PAL monitor, but a few years ago I did bring back a PET 8296-D from Europe. That PET has a built-in monitor. I used a 500W step-up/step-down transformer from PowerBright.com in order to get the 220V needed. The computer worked perfectly, as did its built-in monitor.

FCUG celebrating 34 years this month,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm
 
TV refresh rates have never been driven directly by the AC mains power line frequency, since in the early days there were several different AC mains frequencies in use in North America: 50 Hz in Southern California, 25 Hz in Eastern Canada and upstate NY, and 60 Hz everywhere else -- as well as 36-volt DC farm windmill generator systems, and pockets of Edison's 120-volt DC system in New York City.

Some computers use AC cooling fans and some early 8-inch hard drives used a spindle motor powered directly off of the 120/240-volt AC mains, but other that that, everything in a computer or monitor runs on DC power, and thus is unaffected by the incoming AC mains frequency.
 
vwestlife said:
TV refresh rates have never been driven directly by the AC mains power line frequency, since in the early days there were several different AC mains frequencies in use in North America: 50 Hz in Southern California, 25 Hz in Eastern Canada and upstate NY, and 60 Hz everywhere else -- as well as 36-volt DC farm windmill generator systems, and pockets of Edison's 120-volt DC system in New York City.
Click to expand...

Frequencies ranging from 16⅔ to 133⅓ Hz have been used over the 100+ years electricity has been generated. 400 Hz is the standard for aviation.

Some computers use AC cooling fans and some early 8-inch hard drives used a spindle motor powered directly off of the 120/240-volt AC mains, but other that that, everything in a computer or monitor runs on DC power, and thus is unaffected by the incoming AC mains frequency.
Click to expand...

The Commodore 64 uses the mains frequency to generate a time of day clock. Hardly anything uses it but that clock needs to be present for 100% software compatibility.
 
I think the main reason why refresh rates are matched to AC rates is to avoid interference (even today you have settings like that on monitors, TVs, digital cameras etc).
The CM8833 is a dual-standard monitor anyway, and can handle both 50 Hz and 60 Hz input signals (I am in a PAL country, using mine as a CGA monitor, which is 60 Hz).
Whether it runs as expected on 60 Hz AC, I'm not sure, but I suspect it would.
 
TVs have been made that operate from the line frequency. I don't know about mass production though.

TV came a very long way. I think most people don't realise there is a whole history, starting with mechanical television.
 
cthulhu said:
The Commodore 64 uses the mains frequency to generate a time of day clock. Hardly anything uses it but that clock needs to be present for 100% software compatibility.
Click to expand...

The Amiga uses it for something too. I can't recall what at the moment.
 
Thanks guys, you gave me the confidence to give 'er a try. I first gave the capacitors a once-over with the trusty rusty ESR meter, everything looked good so I plugged it in and hit the button.

A picture is worth a thousand words:
amigamonitor.jpg


Awesome!
 
FWIW, if you are using analog RGB output from the Amiga (which I imagine you are) then a PAL-specific monitor is not a requirement. Any of the US 1084s will sync at 50hz. PAL is really only necessary for broadcast or composite/s-video signals.
 
geoffm3 said:
FWIW, if you are using analog RGB output from the Amiga (which I imagine you are) then a PAL-specific monitor is not a requirement. Any of the US 1084s will sync at 50hz. PAL is really only necessary for broadcast or composite/s-video signals.
Click to expand...

Upgrade to (if it isn't already) ECS, and it can do PAL or NTSC, at the user's discretion. (ECS might not even be necessary, I seem to remember playing at least one PAL game on an NTSC A500 I had that I don't think I upgraded).

geoffm3 said:
I think same thing there... TOD on one (both?) of the CIAs.
Click to expand...
Most likely; I don't know what else it would be.

I do recall there was a jumper setting to use the line frequency, or, an on-board oscillator, for whatever it was. Only because I remember having to change the jumper when I started using an ATX power supply.
 
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