How important is power frequency for VCRs? (50Hz vs 60Hz)

[fHomeVideo]

Hey y'all

I just got a package from lordsmurf himself with a full NTSC workflow since my home tapes were made with NTSC cameras. As soon as I buy some extra HDDs I will be ready to start archiving.

The JVC SR-V101US asks for 120V 60Hz, logically.
However, I live in a 220V 50Hz country. I already own a transfomer for 110/120V equipment, but I don't think it converts the frequency from 50 to 60.

Is the frequency difference a problem? Sync issues, electrical issues? I found a thread where a user says frequency is important but no further elaboration.

I tried googling for transformers that also convert frequency (that are sold in my country) but I haven't found any in my first couple of searches.

Thanks!

[lordsmurf]

Well, that gave me a mental pause. I've not had to think about step converters in decades.

So I asked Gemini, and the AI answered:

Quote:

You cannot simply use a plug adapter; you will fry the VCR.
- Voltage: You need a Step-Down Transformer (220V to 110V). Ensure it is a transformer, not a cheap "travel converter" meant for hair dryers.
- Frequency (The 50Hz Problem): Most VCRs from the 1990s and later use internal quartz crystals for timing, so they often don't care about the 50Hz vs 60Hz difference for the video speed. However, the internal transformer will run hotter.
- Recommendation: Use a transformer rated for at least double the wattage of the VCR (e.g., if the VCR is 25W, use a 50W+ transformer) to handle the extra heat.

The "run hotter" worries me, but it may be AI slop, as I don't remember that being a consequence. The converter gets hot, but I don't remember the VCR getting unusually hot.

Do they even make step-down transformers for less than 100W? You want the standard "heavy brick" unit that the size of 3x+ VHS tapes (~$75, 500W+). Some are "dongle" type design (100-250W), about half the size of the bricks. Do not use the junky "wall plug converter" (made in China) with zero protections.

Your main worry, outside of not frying the gear, is noise spew. I think it's more of an issue with PAL gear in NTSC, but it can happen the opposite direction.

I don't recall if V101 had a PAL-type 100-240V PSU. Most NTSC decks only work in NA/Japan, while most PAL decks work anywhere.

[fHomeVideo]

Yeah, I got a similar reply from Gemini. I'm hoping some humans can confirm before I plug in the machine.

Quote:

In modern VCRs (produced after the mid-1980s), the internal timing is controlled by a Quartz Crystal Oscillator, not the 50Hz/60Hz frequency of the power line.
Motor Speed: VCR motors (drum and capstan) are governed by internal Servo Loops. They compare the speed of the motor to an internal reference frequency. They do not "slave" to the power line frequency like an old wall clock or an AC motor in a dryer might.
Capture Sync: The video signal itself (NTSC 60Hz or PAL 50Hz) is generated internally. The 50Hz power from your wall will be rectified into DC voltage by the VCR’s power supply before it reaches the sensitive video circuits.

Heat:
The only potential issue is that the VCR's internal power transformer is designed for 60Hz. When you run a 60Hz transformer on 50Hz, it becomes slightly less efficient and runs hotter.
Lower frequency (50Hz) allows the magnetic core to "saturate" more easily.
Since your VCR only draws 19W, the extra heat will be negligible. If it were a 500W amplifier, it would be a problem; for a VCR, it is almost always within the safety margin.

Service manual does mention servo motors, mentions a crystal (not quartz nor oscillator), does not mention magnetic core or DC rectification (does mention regulation).

I already own a 300W step-down 220to110 transformer so I'm super covered Watts-wise.

I read on reddit of a guy who used car inverters that do 12V to 120V 60Hz for another kind of device, meaning you have to either get car batteries or step down from 220V to 12V first, but I'm hoping to avoid that if possible.

Regarding noise, I would likely test for noise once I know it's electrically safe to plug in and that sync/timing won't be an issue.

[aramkolt]

My understanding is that for switching power supplies, as long as they are rated for the voltage in question or more, the frequency of AC should not matter between 50 or 60Hz. Essentially what happens in most modern VCRs (having switching power supplies), Input AC voltage is immediately rectified into DC and then stored as a DC voltage in the main filter cap as a very first step. From there, a switching regulator pulses that DC into a smaller transformer at high frequencies resulting in AC output that is then rectified back to DC again (and into capacitors on the secondary side) at the various voltages that the VCR needs to function. The frequency of the switching transistor (often a MOSFET) is determined though a feedback loop from the secondary side through an optocoupler if the voltage is dropping too much on the output from current draw from the rest of the circuit.

[lordsmurf]

In the early 90s, there was a silent switching to worldwide PSUs, and the 50Hz vs. 60Hz starting to be generated within the device, rather than rely on external power to control it.

I think "quartz crystal oscillator" refers to an IC on the mainboard. It's part of the power/timing mechanics of the board.

But I'm going off shaky memory here, so I wanted to refer to my favorite book, "VCR Troubleshooting and Repair" by Capelo. So I leveraged Gemini again, pushing back with what I know, and giving it instruction to only look at that reference book for answers. (*I had verified it could access that book before even asking my prompts. And it did, because AI all trained on stolen books and online data.)

And Gemini confirmed my memory is correct here.
- "heat" was AI slop, any heat draw beyond norms is negligible for VCRs
- the "crystal" is an IC -- though it's still "clear as mud" on the details, still some AI slop going on

If I were you, I'd plug it in (to the 110 output of the step converter). I think we did the DD on it, all looks good.

The only question now is noise spew from the step converter. Lots of those are "industrial" in nature, not intended for AV type gear. So electrical line noise was not the focus. But again noting that NTSC "220 device to 110 power" seems to be more problem than PAL "110 device to 220 power".

[timtape]

Yes for the later SMPS VCRs the 50/60 Hz is not the issue but possibly the mains voltage may is. I would only supply 240vac to the VCR if the owners manual and the label on the back of the VCR clearly stated that 220/240 vac input was permitted.

[radiokom]

I would be careful if it says only 60hz and not 50/60hz. If frequency is not important, manufacturers will almost always specify 50/60hz. There may be problems with the power supply. So I would bring it to technician who is familiar with switching power supplies and can determine what problems may occur (or not).

[radiokom]

Quote:

Originally Posted by timtape

Yes for the later SMPS VCRs the 50/60 Hz is not the issue but possibly the mains voltage may is. I would only supply 240vac to the VCR if the owners manual and the label on the back of the VCR clearly stated that 220/240 vac input was permitted.

120V instead of 220/240 is not so critical, it simply will not work in most cases. But 220/240 instead of 120 may fry PS immediately. At least I fried my Branson ultrasonic cleaner (manufactured in about 2006) PS in seconds because it has the same standard 3 pin power socket and I accidentally forgot about transformer. Repair was PITA.

[lordsmurf]

Quote:

Originally Posted by radiokom

But 220/240 instead of 120 may fry PS immediately.

OP has a step-down converter.

[vwestlife]

Video has never been linked to the AC line frequency, at least not since NTSC color was introduced in the early 1950s and required the refresh rate to be changed from 60 Hz to 59.94 Hz.

At worst, maybe the VCR's built-in clock won't keep accurate time, if it was designed for 50 Hz and you run it on 60 Hz, or vice-versa.

[fHomeVideo]

Thanks for the replies!

aramkolt: good to hear that. seems consistent with the text I can read on the PCB
lordsmurf: I will definitely test for noise when it goes online
radiokom: I'm going to take that suggestion to ask an old-school technician if I can find one in my area.
timtape: the label on the back and the user and service manuals explicitly say 120V 60Hz
vwestlife: sounds like good news.


Just in case I briefly popped open the top of the VCR to take a few pictures of the PCB.

In there I saw:
-a 068uF 275V capacitor
-a 250V fuse
and three indications of voltage printed on the PCB
-1.25A/250V (closest to the power cord and the fuse)
-1.5A/125V (later in the circuitry)
-1.5A/125V

The capacitor and the fuse give me some peace of mind regarding the use of a step-down transformer as a safety measure and regarding the potential irrelevance of power frequency, since it looks like it might even be able to take 220V if I wanted.

I've attached pictures of the internals, in case it helps anyone provide further insight.

Fuse + capacitor
fuse.jpg

Printed voltage numbers

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voltages.jpg

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[latreche34]

If anything I would be concerned about the life of components if they run at a different frequency, namely capacitors and VFD, But I don't know for sure, I have two of the HR-S7600AM and it is designed to run on both 120-240V 60/50Hz by design from the factory as it is true 525/625 scan.

[vwestlife]

That's a switching power supply. 50 vs. 60 Hz AC power makes no difference to it.

[radiokom]

Quote:

Originally Posted by vwestlife

That's a switching power supply. 50 vs. 60 Hz AC power makes no difference to it.

In theory. But why it is not marked as 50/60hz? It is not modern switching power supply, so who knows.

[aramkolt]

It probably isn't marked that way because that isn't the native frequency of the power that is expected at the voltage listed. They could have been a little less specific and said 240VAC and not mentioned the frequency and been fine I think.

A lot of 220VAC equipment works fine on 120VAC even if not listed, though it probably could be opltimized by making the main filter cap larger since the duty cycle may be a bit higher. You usually shouldn't do the reverse and try a 120VAC machine on a higher voltage as the capacitors and startup ciruit may not tolerate higher voltages, but you're very unlikely do do harm with a lower AC voltage.

I just recently got a DVR-560H and apparently those were only listed as 220/240V, though interestingly they did list both 50 and 60Hz, but it does work just fine on 120VAC. Also says it's a PAL unit, but it also works with NTSC signals. So I guess lesson is you can't always fully trust the label. I did get it from the USA, and all of the content on the HDD it is NTSC so I'm sure the prior owner used it the whole time on 120VAC without any problems. Interestingly, I see they used it to capture laserdiscs which is something I was also curious to try.

[aramkolt]

After looking at the pictures, yeah, you definitely don't want to try to run that on 220V, the main filter capacitor being rated for 275 actually isn't high enough for 240V equipment since it most likely will charge to about 1.4x (square root of 2) the line voltage, so in this case something like 330V. In most cases, you'll see switch mode power supplies with main filter caps rated for either 350V or 400V for this reason. Fuses are designed in such a way that they are more sensitive to the current than the voltage rating and I think the voltage rating has mostly to do with the material choice within the fuse.

Frequency difference is fine though using a step-down transformer or VARIAC. I personally like variacs because you can fine tune the voltage to whatever you want. I remember buying a 120V to 100V step-down transformer and I was still getting closer to 110V which, while an improvement, seemed to defeat the purpose of feeding rarer Japanese equipment 100V (since that's what they use there) for the effort involved. Japan's grid is allowed to fluctuate up to 110V I think, but still would rather be gentler on components on old/rare stuff like WVHS players that were more common in Japan. USA grid voltages often can vary between 117-127V I've found, but it generally depends on what other loads are on the grid, so it's more likely to be lower say in the summer when everyone is running air conditioners just as an example.

I also see lots of my least favorite capacitor brand in there - the robin's egg blue Lelons. Woof. I think I dislike those just about as much as ELNAs. Certain series of ELNAs can be ok (like bipolar caps and stargate/audio grade lines), but their general purpose ones and even main filter caps I've seen fail far too often, so I'll usually replace those on sight in power supplies or high-heat areas. If it works fine, there's not an immediate need to swap them, I'd just suspect those first if you ever do have issues.

[dpalomaki]

There is no single answer. It depends on the design of the unit in question. A knowledgeable electronics expert would need to study the circuit schematic and component specs to determine whether or not it is safe to operate the machine at other than name plate/owners manual voltages and frequencies. And, while not an issue for old gear, operation out of the nameplate parameters would void warranties. In any case finding repair services for old gear is problematic if you zap it.

A quick look art several pieces of gear I have indicate:
- Pana AG-1980 & AG-1970 specify 120 volt 50-60 hz
- JVC HR-S9600U reads 120 volt, 60 Hz
- Toshiba D-KR10 120 volt, 60 Hz
- HR-S3500 120 volt, 60 Hz
- Pana PV-V4524S 120 Volt, 60 Hz
- Sony DHR-1000, 120 Volt, 60 Hz
- Sony EV-S7000 NTSC, 120 volt, 60 Hz
- An old Marantz receiver supports 120 volt, 50-60 Hz
- my DELL monitors support 100-240 Volt 50/60 Hz
- but my ToshibaTV wants 120 Volt, 60 Hz
- A Videonics power supply for an MX-Pro reads 100-240 Volt, 43-63 Hz

Some gear includes voltage selection switch/jumpers,
- A TEAC cassette deck I have supports 100, 120, 220 and 240 volt 50-60 Hz

In a past life I was responsible for an electrical distribution system, includinp power transformers, built for 2400 volt, 25 Hz power. It was converted to 60 Hz power and transformers were down-rated some what for increased heating losses due to frequency changes. However, large distribution power transformers designed for 60 Hz would not have worked for 25 Hz power.

Transformer properties are voltage and frequency dependent. A lower frequency requires more turns and/or iron to operate at the same voltages. Whether or not there is enough "over build" in your gear to work well at 50 Hz is the question. Your gear, your risk, your decision.

The 50/60 Hz raster choices were keyed to regional power line frequencies as a way to mitigate issues with power supply ripple and lighting flicker.

[aramkolt]

Agree that for power supplies that use transformers (linear power supplies or AC to AC ones), that the characteristics of the transformer can matter a lot with frequency, particularly if using a frequency that is much lower than 50/60Hz, such as 25Hz.

My understanding is that the lower the frequency of AC mains that the transformer has to be (much) physically bigger in order to saturate the transformer's coil and get an equivalent amperage output to mains AC at a higher frequency.

With switch mode power supplies, there is no transformer as a first stage and voltages are immediately stored as DC in the main filter cap, so the starting frequency doesn't really matter as long as the voltage can be handled by the capacitor and the capacitance is high enough that it doesn't drain sufficiently low from being pulsed before the next sine wave of AC power arrives to charge the filter cap via usually a full bridge AC->DC rectifier.

From the DC main filter cap, that DC voltage gets pulsed very quickly into a small transformer as a square wave (in the Kilohertz or Megahertz range). The extremely fast pulsing allows the inverse of needing a big transformer for low frequencies - the transformers in switch mode power supplies are actually quite small for the amount of power they can deliver which saves on material costs and weight.

Main downside to switch mode power supplies (outside of being far more complex) is that they are often electrically noisy since they pulse so fast and can cause RF interference and sometimes electrical noise on the actual power supply outputs depending on how they get smoothed.