Author Topic: 120 and 240VAC: how compatible?  (Read 1262 times)

Rob Strand

Re: 120 and 240VAC: how compatible?
« Reply #20 on: July 30, 2022, 06:40:15 PM »
Quote
2) The previous owner had clipped the normal plug end off the power cable, and replaced it with a pin jack like what we used to see on the end of the power-supply cables in our computers that would go to hard and floppy drives.
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Rob Strand

Re: 120 and 240VAC: how compatible?
« Reply #21 on: July 30, 2022, 09:16:17 PM »
I'm always pleasantly surprised if transformer wire colours conform 100% to the schematic. Those colours can change between production runs. Manuals don't get updated for it, presumably official service centres get a memo about it.
Anyway, that's why I picked up on the 3rd wire as an easy tell whether you have a 220/240 traffy, no matter what the colours might be.
Very true.   Documentation from Japan is pretty good, usually brief but concise.

Philips consumer products often had many versions.   They *did* have the documents for each version however more often than not the version didn't actually match the exact product.   Not really Philip's fault, users didn't know what version they had, or that there was a different version.   I remember once they updated one of their tweeters to a current model driver and it was about 3dB more sensitive than the original.  The documents accurately showed the change but engineering-wise it was wrong!  30 years later a guy on the web measured the frequency response and was wondering why it wasn't flat!
« Last Edit: July 30, 2022, 09:20:02 PM by Rob Strand »
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Ice-9

Re: 120 and 240VAC: how compatible?
« Reply #22 on: July 31, 2022, 04:08:17 AM »
Mark, The only way to know what is going on and how to sort it out is to open up the rack and have a look at what has been modified internally (or not). I wouldn't be wiring any mains up to the unit until I knew what was inside, when it comes to mains voltages, never trust someone's vague memory of what they have changed. Check this out for yourself after all it is only a few screws to open up the box. 

Once open you it will be obvoius what transformer is fitted and what you need to swap. Rob posted a link to a transformer on Reverb.com for about $10 if you didn't see that a few posts above. 

It's pointless trying to work out how to fix something if you haven't even looked inside yet to see what you might or might not need as it might be correct for 110v already. Get that box opened up :)
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matopotato

Re: 120 and 240VAC: how compatible?
« Reply #23 on: July 31, 2022, 05:15:29 AM »
Mark. <snip>  Get that box opened up :)
...and post some pics. We like 'em...
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anotherjim

Re: 120 and 240VAC: how compatible?
« Reply #24 on: July 31, 2022, 06:37:24 AM »
Are these the computer-type connectors used?


I don't think there is anything badly wrong with using those Molex-type connectors for AC power (within the designed rating). IIRC, you could get insulating boots to cover the rear wire entry. For instance, the spin motor of the old 8" floppy drives was AC mains powered off a 3pin Molex.

The thing with them is you really must use a proper crimping tool and also the removal tool to correct mistakes. And, of course, make very sure the connector can't fit in any that it shouldn't. The cost of an official crimping tool will make your eyes water.

Anyway, all that is FYI. It has to be better to use a normal AC connector, even in a rack.



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anotherjim

Re: 120 and 240VAC: how compatible?
« Reply #25 on: July 31, 2022, 06:51:58 AM »
..don't some 110v/60Hz places get x2 balanced supply phases so heavy loads can run off 220v .....

Not on the same outlet.

I didn't think it would be, but a purpose-built studio might include a 240v feed to allow for foreign gear? I don't know as the situation doesn't arise where I live, but 110v is standard for industrial power tools so 240v/110v transformers are easy to get and cheap if we want 110v (ignoring the 50-60Hz difference).
My point is that it might have been used at 240v but couldn't use a domestic type outlet hence the "non-standard" connection.

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Ben N

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Re: 120 and 240VAC: how compatible?
« Reply #26 on: July 31, 2022, 10:19:31 AM »
The part number on the tranny in the Reverb setting that Rob linked clearly shows the part number corresponding to the 117V transformer on the schematic. Seems a pretty simple matter to just look at the legend on the part, regardless of the color of the primary wires.

PRR

Re: 120 and 240VAC: how compatible?
« Reply #27 on: July 31, 2022, 04:23:18 PM »
...where I live, ..110v is standard for industrial power tools so 240v/110v transformers are easy to get and cheap...

The yellow job-site boxes?

That is very specific to UK code and a few UK-derived markets? I'm not even sure they do it in Hong Kong or Australia?

That's 230V:110V. Mark needs the other way. Yes the iron is reversable... but too hot this summer to mess with it.

And 110V center tap is a funny beast. Yes it is only <70V to dirt but a lot of gear never contemplated both sides being "live". Aside from hum, I have read of fancy audio making a conflicting assumption and smoking a many-$K DAC.

Mark wants (maybe!!) 230V. He can sure take that off his dryer circuit but the cable has to be big enough to blow a 30 Amp breaker, so not that lamp-cord. Under NEC code such a circuit must be a single outlet (OK today but what if more 230V bargains follow Mark home?) And again a US/CAN dryer circuit is effectively cent[re|er]-tap. And we don't know what mods the previous genius did.

I did find out what is inside the yellow box, and where the earths should run.
https://www.youtube.com/watch?v=2t_JR0CxctQ
I had heard the box was filled with sand+binder for control of heat and fire, but maybe not in this model?
« Last Edit: July 31, 2022, 04:25:48 PM by PRR »
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PRR

Re: 120 and 240VAC: how compatible?
« Reply #28 on: July 31, 2022, 04:53:15 PM »
This is like what he should want (assuming the 230V notation is correct):
https://www.aliexpress.com/item/2251832799825022.html?gatewayAdapt=4itemAdapt
Under 20 bucks, shipped by slow-boat. I don't know the trustworthiness. He may be safer going to the local international airport traveler's store so he knows who to blame if it burns-up.

Unusually, this one goes both ways. Set the switch!!

There is ANOTHER converter rated 240V:120V 1,000 Watts, in a smaller box which sure can't be a 1KW winding. These are only for "heater" loads, irons and hair-dryers. They switch on/off rapidly to give the heating effect of 120V from 240V power.
« Last Edit: July 31, 2022, 04:57:27 PM by PRR »
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Rob Strand

Re: 120 and 240VAC: how compatible?
« Reply #29 on: July 31, 2022, 07:26:58 PM »
Quote
Are these the computer-type connectors used?
...
I don't think there is anything badly wrong with using those Molex-type connectors for AC power (within the designed rating).
OK for inside equipment but not for external cables.   External cables and connectors have a whole heap of safety requirements.  That's why most companies stick to standardized mains connectors.

As an example imagine someone cuts their (external) power cable and joins them back again using a terminal block
https://www.cdlmicro.co.uk/cdl-tbk-10a-10a-12-way-terminal-blockcable-connector-strip-for-electrical-connections-black.html
Suppose the terminal is mains rated (I don't know if that one is).   While it's OK to do mains wiring inside equipment with a terminal block it's not OK do mains wiring outside of the equipment using the same terminal block.  Same goes for connectors.

Moreover, if you submitted a product for safety testing with a terminal block joining the wires it would be rejected
for sure.   That means the method of construction doesn't comply with safety standards.

Even from a common sense point of view many connectors aren't safe if pulled or if they are exposed to humid environments.

Quote
The cost of an official crimping tool will make your eyes water.
Indeed, some have insane prices like > $1000.   If a cable manufacturer doesn't have the right tools it can blow-out costs for small runs.
« Last Edit: July 31, 2022, 11:51:17 PM by Rob Strand »
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