US - UK Mains Voltage and Frequency

[magikarp99]

Does anybody know if VHS players are dependent on mains frequency?

It seems that UK VTRs use PSUs that are compatible with both UK and US mains voltages and frequencies. But US VTRs are US only. This would suggest they aren't frequency dependent, but I'd like confirmation before I go damaging my electronics.

For clarity I want to plug US equipment into UK mains. I can handle voltage difference with a transformer, but frequency converters are expensive.

[smrpix]

If the equipment does not say it is rated for 240v do not plug it into a 240v mains. Frequency has nothing to do with it.

[magikarp99]

Uhhh... I just said I would use a voltage transformer. So voltage difference doesn't matter, as I can supply a 120V connection. But US mains uses 60Hz, and UK mains uses 50Hz.

[smrpix]

Uhhh... I just said I would use a voltage transformer. So voltage difference doesn't matter, as I can supply a 120V connection. But US mains uses 60Hz, and UK mains uses 50Hz.

Your original statement was ambiguous.

For clarity I want to plug US equipment into UK mains. I can handle voltage difference with a transformer, but frequency converters are expensive.

But actually, there's no point in over-discussing it. Every piece of electronic equipment lists what it can handle. VTRs typically step down the voltage internally.

[magikarp99]

Your original statement was ambiguous.

For clarity I want to plug US equipment into UK mains. I can handle voltage difference with a transformer, but frequency converters are expensive.

But actually, there's no point in over-discussing it. Every piece of electronic equipment lists what it can handle. VHS decks typically step down the voltage internally.

For clarity I want to plug US equipment into UK mains. I can handle voltage difference with a transformer, but frequency converters are expensive.

..

[smrpix]

That's my point -- depending on what you emphasize it can be read differently.

[redwudz]

Within the input specifications of a modern power supply, frequency and input voltage aren't really that critical as the PS converts it all to DC regulated voltages.
For timing, most often there is an internal oscillator that generates the timing signal, independent of the line frequency.

[magikarp99]

Thank you for the input. This is what I figured too. I have been told to be careful, and check that the internal transformer doesn't overheat, but aside from this I shouldn't expect any issues.

[jman98]

Within the input specifications of a modern power supply, frequency and input voltage aren't really that critical as the PS converts it all to DC regulated voltages.

Therein is the problem. You said modern power supply. I'm pretty sure an old US VCR (does ANYBODY even use the term VTR like the OP does?) does not have what you would call a "modern power supply". In the 2000s it was not difficult at all to find all kinds of US sold electronic equipment that could not handle electricity at European voltages. Some of that was deliberate to protect foreign sales channels. Some was due to cheapness or laziness by the manufacturer.

[magikarp99]

This is a pro model, still in production in 2002. So it is almost certainly okay.

[smrpix]

This is a pro model, still in production in 2002. So it is almost certainly okay.

So, what does it say on the back?

[jimdagys]

Frequency has nothing to do with it.

Incorrect. I had a vcr running off a power inverter that I could adjust the frequency. Any deviation from 60hz (like 59 or 61 caused an obvious difference in brightness of the picture.

[smrpix]

Frequency has nothing to do with it.

Incorrect. I had a vcr running off a power inverter that I could adjust the frequency. Any deviation from 60hz (like 59 or 61 caused an obvious difference in brightness of the picture.

Most electronics that can handle the voltage variations convert to dc and step-down. I could have been more precise. We still don't know OP's actual situation.

[netmask56]

I have a number of US 120v only pre-amps and they run ok via a step down transformer, but you might run into trouble with the motors in the VCR. They possibly may not like being run with a 50Hz voltage even if the volts are ok at 120v and vice versa UK gear running in the US via a step up xformer but wrong freq. Unless there is documentation then all you can do is do an experiment and cross fingers and toes that you don't smell anything from the VCR!

[turk690]

Does anybody know if VHS players are dependent on mains frequency?

In my experience, after around 2000 (or even before), domestic VCRs internally have high-efficiency switch-mode power supplies (SMPS). The AC mains is directly rectified and fed to a power oscillator running roughly anywhere from 50KHz to 1MHz, then stepped down and filtered to the appropriate voltages required. The mains frequency is irrelevant at that point.

It seems that UK VTRs use PSUs that are compatible with both UK and US mains voltages and frequencies. But US VTRs are US only. This would suggest they aren't frequency dependent, but I'd like confirmation before I go damaging my electronics.

VCRs (and a whole lot of other domestic electronics) are made in the Far East, where, to be as efficient as possible, they designed SMPS that are one size fits all so that they work wherever plugged. Where it was before a costly specialty, SMPS are now routinely autovolt (if it states that it can be plugged into any 100-240Vac, 50/60Hz electrical mains outlet). The main bridge rectifier filter capacitor in this case is mostly a 400V or 450Vdc device, to accomodate the probability that it's gonna be plugged to a 220V or 240Vac outlet (which makes the primary B+ side of the SMPS around 360Vdc). The very same SMPS intended for use in North America (or Japan) has said capacitor only a 200V or 250Vdc device, because plugging it to 120V mains only creates a primary B+ of 180Vdc. The North American counterpart will therefore be labeled as strictly 120Vac, 60Hz only because it will blow up otherwise. So go use the step-down transformer; fear not.

I have been told to be careful, and check that the internal transformer doesn't overheat, but aside from this I shouldn't expect any issues.

The internal step-down transformer in the SMPS circuitry of current typical consumer & pro VCRs has a ferrite EI core and probably occupies a space on the PCB no larger than 1 or 2 cubic inches. It scarcely overheats. What is more likely to overheat are the SPMS power transistors and filter capacitors (the latter dying a slow death from day1).

[2Bdecided]

Just over a decade ago, I ran 40 NTSC VCRs and 40 NTSC TVs on 50Hz 110V. One TV flickered badly. One VCR (which was, as we say in the UK, knackered) was slightly closer to failure. Other than that, everything was happy with 50Hz.

I had a 60Hz 110V generator, but didn't need it except for those two items.

Cheers,
David.