Region Conversion

[Dubis7]

I have an opportunity to pick up an RCA 8-PT, but it's in India. From what I understand, it'll be PAL format, want 230V from the wall outlet, and have a different power cord. Will it be possible to convert it to NTSC, 115-120V, and provide a standard US cord? How difficult would that potentially be?

[ChrisW6ATV]

I would get the set first, then figure out how and when its existing conversion work was done (unless RCA made any such sets originally). If it was converted (or manufactured thatway) in the 1950s, it will be far more interesting to keep it as is and adapt to it externally. You can do so with 110-220V step-up transformers typically, and maybe a multi-standard VCR or video converter.

[Eric H]

Those sets are common as dirt right here in the U.S. probably much easier to just get one here?

[Electronic M]

No guarantees it is not currently set up to do NTSC with 120VAC.....It was not uncommon for non-technically informed folks to move to another country bring a TV with them, and then wonder why it does not work in it's new home. That could have been bought in the USA moved there and left to sit when it did not work there.

[Dubis7]

It's in India currently, and from what I understand was bought there. A friend is traveling to the US in a few years, though, and was saying I could have it if I wanted.

[colectorad]

Originally Posted by Dubis7

I have an opportunity to pick up an RCA 8-PT, but it's in India. From what I understand, it'll be PAL format, want 230V from the wall outlet, and have a different power cord. Will it be possible to convert it to NTSC, 115-120V, and provide a standard US cord? How difficult would that potentially be?

Assuming it's been restored:

1.) Power it with a ~120VAC->~240VAC boost transformer. Plug adapters are often included.

2.) Connect any RF video signal and adjust the 'vertical hold' control until the picture stabilizes. This is a B&W set, so PAL->NTSC conversion is pointless.

[Dubis7]

Ah, so PAL/NTSC only applies with color. I wasn't aware.

I have this nagging idea that power transformer sets will take whatever wall voltage they receive and turn it into the voltage the set wants, but that's probably not true. I'm not sure where I got that idea from. Would converting it to accept American wall voltage be as easy as having a power transformer under the American specs produced and swapping it in, or are there more complexities?

[bandersen]

Originally Posted by Dubis7

Ah, so PAL/NTSC only applies with color. I wasn't aware.

No, there's more to it than just color. Checkout this chart: http://www.diffen.com/difference/NTSC_vs_PAL

Different vertical and horizontal frequencies, number of scan lines, bandwidth and sound carrier. PAL is higher resolution (625 vs 525 scan lines) so needs more bandwidth. Probably the circuits have enough range it can handle an NTSC signal though.

[dieseljeep]

Originally Posted by bandersen

No, there's more to it than just color. Checkout this chart: http://www.diffen.com/difference/NTSC_vs_PAL

Different vertical and horizontal frequencies, number of scan lines, bandwidth and sound carrier. PAL is higher resolution (625 vs 525 scan lines) so needs more bandwidth. Probably the circuits have enough range it can handle an NTSC signal though.

I understood that the B/W standard for anything other than NTSC, was known as CCIR.
I have a small, solid state Sony B/W set that has two switches on top, one for 120/240 volts and one for the region. Don't remember what it was labeled as. It also has channel 1 and also UHF.
I bought it, as it was different and interesting.

[Electronic M]

Originally Posted by Dubis7

I have this nagging idea that power transformer sets will take whatever wall voltage they receive and turn it into the voltage the set wants, but that's probably not true. I'm not sure where I got that idea from. Would converting it to accept American wall voltage be as easy as having a power transformer under the American specs produced and swapping it in, or are there more complexities?

There are such things as constant voltage(also called saturable-reactor among other things) voltage transformers that can take a wide range of (sometimes fluctuating) input voltages and produce a steady output, but the only sets I know of them being used in are pre-Emerson-takeover Dumonts, and early Solid State sets (mostly Zeniths). Many European market radios had a tapped 240V input winding, and had a line voltage selector switch that would allow you to select the tap for your local line voltage (110,120,210, 240, etc), but I doubt an American made product would have that.

You can find (or have made) a proper power transformer for that set.

I wonder if the original design used a power transformer? Most portable sets tend to be transformerless Hot chassis designs. Most hot chassis used doublers for B+, and series string heaters. If it has two heater strings 240V operation is easy to achieve....Simply chop some parts from the doubler to make it a simple half wave rectifier, double up the filter caps, series pairs of any parallel heater chains with the same current, or add a dropping resistor to the chain.

Techs in various countries had lots of clever and stupid ways of making foreign sets work.....To definitively know for sure what work fixing it will entail, a comparison of it's present wiring to the schematic is in order.

[maxhifi]

Double post

[maxhifi]

as well as the above, with ntsc, the blackest signal is 0V while wirh PAL a full white signal is 0V. The advantage being that with a PAL signal interference is less noticeable.

[Dubis7]

http://antiqueradio.org/art/RCA8-PT-7010-SVC.pdf

Checking the schematic, it does have a power transformer. I'm actually familiar with the European selectable input transformers - my Norelco tape recorder has one.

So, besides the possibility of modifying the circuits to match the NTSC standard more fully, it sounds like getting this to run in the US is just a matter of having a new transformer made and swapping it in.

I wonder how difficult it would be to MAKE that NTSC conversion. Even if it would technically work as is, it would save a lot of headache in the future to make it match other American sets, though having a region frankenset would be kinda neat.

[dieseljeep]

Originally Posted by Dubis7

http://antiqueradio.org/art/RCA8-PT-7010-SVC.pdf

Checking the schematic, it does have a power transformer. I'm actually familiar with the European selectable input transformers - my Norelco tape recorder has one.

So, besides the possibility of modifying the circuits to match the NTSC standard more fully, it sounds like getting this to run in the US is just a matter of having a new transformer made and swapping it in.

I wonder how difficult it would be to MAKE that NTSC conversion. Even if it would technically work as is, it would save a lot of headache in the future to make it match other American sets, though having a region frankenset would be kinda neat.

If you do get the set, find another set for parts, even if it doesn't work.
Trying to get a custom transformer made, would be extremely expensive.

[Electronic M]

Originally Posted by dieseljeep

If you do get the set, find another set for parts, even if it doesn't work.
Trying to get a custom transformer made, would be extremely expensive.

It would probably be cheaper to have an external step up transformer....Could make one with a beefy transformer from a newer piece of gear....Many had 2 120V primary windings that could be configured for 120V or 240V duty by parallel or series connection respectively....You could wire the dual primaries for step up auto-transformer duty, and power it on the cheap.