Measuring from UK schematic but on US mains

patrickamory · 27th August 2007, 11:58 PM

Hi, I need to check voltages on my Radford amp... the (British) schematic only has one set of voltages marked, so I'm assuming these apply when using 220V mains. I live in the US and have the transformers wired for 125V. Is there a formula I can apply to the voltages on the schematic to find the correct readings when using 125V AC power?

mcs · 28th August 2007, 12:28 AM

If the transformer is wired for 125V mains, then all the voltages in the amp should be the same (apart from the transformer primary of course).

Best regards,

Mikkel C. Simonsen

patrickamory · 28th August 2007, 12:41 AM

Ah... really? I guess that makes sense. My Leak Stereo 20 schematic shows two sets of voltages, one for 220V mains, one for 110V, so that's why I expected it on the Radford too.

patrickamory · 28th August 2007, 03:35 AM

Indeed, all the voltages checked out just about perfectly as marked.

What does it mean in the schematic when it says 350 (at a point which measures 350VDC with a load hooked up), and then 170V in italics next to it? Is the 170V without a load, or something?

Sorry for all n00b questions

DigitalJunkie · 28th August 2007, 04:54 AM

It could mean that the figure in italics is an AC voltage (if you have a test-tone going into the amp.)

Or,perhaps a standby voltage? (Sometimes common on guitar amp schematics.)

27th August 2007, 11:58 PM	#1
patrickamory diyAudio Member Join Date: Jun 2007	Measuring from UK schematic but on US mains Hi, I need to check voltages on my Radford amp... the (British) schematic only has one set of voltages marked, so I'm assuming these apply when using 220V mains. I live in the US and have the transformers wired for 125V. Is there a formula I can apply to the voltages on the schematic to find the correct readings when using 125V AC power?

28th August 2007, 12:28 AM	#2
mcs diyAudio Member Join Date: Aug 2003 Location: Denmark	If the transformer is wired for 125V mains, then all the voltages in the amp should be the same (apart from the transformer primary of course). Best regards, Mikkel C. Simonsen __________________ My personal electronics website Remote control kits website

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28th August 2007, 12:41 AM	#3
patrickamory diyAudio Member Join Date: Jun 2007	Ah... really? I guess that makes sense. My Leak Stereo 20 schematic shows two sets of voltages, one for 220V mains, one for 110V, so that's why I expected it on the Radford too.

28th August 2007, 03:35 AM	#4
patrickamory diyAudio Member Join Date: Jun 2007	Indeed, all the voltages checked out just about perfectly as marked. What does it mean in the schematic when it says 350 (at a point which measures 350VDC with a load hooked up), and then 170V in italics next to it? Is the 170V without a load, or something? Sorry for all n00b questions

28th August 2007, 04:54 AM	#5
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	It could mean that the figure in italics is an AC voltage (if you have a test-tone going into the amp.) Or,perhaps a standby voltage? (Sometimes common on guitar amp schematics.)

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