I have been using a little integrated amp (Teac a-h500i) in my workshop for a while now, just to have some tunes while I’m working, it’s hooked up to a pair of mini speakers, Gale 3010S, it sounds fine. I bought the amp a few years ago, local sale, and I’ve never had any problems with it.
While I was moving things around today, I looked at the rear of the amp and noticed that the label on the back reads ‘230v. 50 Hz’, which of course is not what we have here in Canada. The amp doesn’t appear to have a voltage selector switch anywhere, yet it seems to be functioning just fine on our mains of 120v, 60 Hz, without a step up transformer.
Two questions, is this safe to use as is? And am I doing any damage to the amp like this?
Tom
While I was moving things around today, I looked at the rear of the amp and noticed that the label on the back reads ‘230v. 50 Hz’, which of course is not what we have here in Canada. The amp doesn’t appear to have a voltage selector switch anywhere, yet it seems to be functioning just fine on our mains of 120v, 60 Hz, without a step up transformer.
Two questions, is this safe to use as is? And am I doing any damage to the amp like this?
Tom
Depending on amp construction, it could work this way.
Probably You are listening to half the Wattage the amp would produce, since the rail Voltages are at half potential.
Raise the volume and it will clip early or it could be already modified one time.
Probably You are listening to half the Wattage the amp would produce, since the rail Voltages are at half potential.
Raise the volume and it will clip early or it could be already modified one time.
The previous owner could have converted it, if the transformer windings are available.
Measure the voltage on the main filter capacitors and check with the schematic.
Measure the voltage on the main filter capacitors and check with the schematic.
My guess is there is a way to set the voltage internally. One way to be sure is grab a schematic and see if voltages look right.
I have been fooled in the other direction with a turntable that was labeled 220volts and was really configured for 120.
I have been fooled in the other direction with a turntable that was labeled 220volts and was really configured for 120.
Appears that the amp was made for either 100V Japan or 230V Europe.
You seem to have the 230V unit. No sign of any transformer winding selection.
TEAC A-H500 Integrated Stereo Amplifier Manual | HiFi Engine
You seem to have the 230V unit. No sign of any transformer winding selection.
TEAC A-H500 Integrated Stereo Amplifier Manual | HiFi Engine
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Well, it definitely says it’s the 230 V version, and doesn’t appear to have been modified by previous owners. I don’t see anything obvious inside to switch voltage so maybe I should have a tech take a look at it. Would the Hz difference have any effect on the amp?
The 50 Hz line frequency rating just means it has a larger transformer and filter capacitors
than if it were rated for 60Hz. So that's actually good.
You just want to see if the DC power supply voltage measures per the schematic,
or about half that much. If it measures half what it should, then it's a 230V unit run on 120V.
If there are internal voltage regulators, they won't be working right if this is the case.
than if it were rated for 60Hz. So that's actually good.
You just want to see if the DC power supply voltage measures per the schematic,
or about half that much. If it measures half what it should, then it's a 230V unit run on 120V.
If there are internal voltage regulators, they won't be working right if this is the case.
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Lower frequency in an inductor means more current, so if a transformer was "cost-optimized" to be rated for 60Hz only, using it on 50Hz can make it saturate, in which case it will buzz and warm up.
But the other way around (50Hz transformer on 60Hz mains) means current is reduced, so it's safe.
But the other way around (50Hz transformer on 60Hz mains) means current is reduced, so it's safe.
Rather than sending it to a tech ($$$) or taking it apart, you could measure maximum wattage before clipping. If this is about the rated output power (half for 1 channel) then it has been modified previously.
Takes an analog VOM with a 50 vac scale or a 20 vac for small units, and a speaker. Turn up till it sounds cramped (clipping) then back off a little . Measure the AC voltage on speaker. P=(V^2)/Z where speaker impedance. Z is about 4/3 the speaker resistance.
I saw an analog VOM with 20 & 100 vac scales at Rural King farm supply last month for $27. You can check calibration by switching to 250 vac scale and testing a wall socket. Wall voltage 120 to 128, the unit is good.
If the output power is 1/4 or less of the rating, then either the transformer is wrong or the rail caps are dried up. 20 years after production both could be true.
Takes an analog VOM with a 50 vac scale or a 20 vac for small units, and a speaker. Turn up till it sounds cramped (clipping) then back off a little . Measure the AC voltage on speaker. P=(V^2)/Z where speaker impedance. Z is about 4/3 the speaker resistance.
I saw an analog VOM with 20 & 100 vac scales at Rural King farm supply last month for $27. You can check calibration by switching to 250 vac scale and testing a wall socket. Wall voltage 120 to 128, the unit is good.
If the output power is 1/4 or less of the rating, then either the transformer is wrong or the rail caps are dried up. 20 years after production both could be true.
Simpler to do, the manual specifies different transformers for either 220 or 100V options for the AC supply. They're toroidal type, so there won't be any multi-tapped transformers here. Check the parts list to see what you actually have but it wouldn't surprise me that you had a 100V model, working at 10% higher voltage than would normally be allowable or a "special" adapted with a local or US transformer.