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Old 5th January 2012, 12:23 AM   #11
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Originally Posted by Minion View Post
It looks like an old Tube radio , I bought one at a garage sale a while back that I was going to use to salvage the power transformer but after openeing it I saw that it was directly mains powered with no power transformer at all which pissed me off and scared me thinking that they actually allowed this death trap to be sold in a store .......

PS: in Japan they also use a different voltage , generally 100v but 90v in some areas so there might be problems useing it in the US or europe .....
It is safe as a radio as there is no exposed circuit for a person to contact unlike a guitar amp which has that darn cord attached to it.
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Old 5th January 2012, 03:25 PM   #12
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Quote:
Originally Posted by Minion View Post
It looks like an old Tube radio , I bought one at a garage sale a while back that I was going to use to salvage the power transformer but after openeing it I saw that it was directly mains powered with no power transformer at all which pissed me off and scared me thinking that they actually allowed this death trap to be sold in a store .......

PS: in Japan they also use a different voltage , generally 100v but 90v in some areas so there might be problems useing it in the US or europe .....
There were a LOT of valve radio 'death traps' sold - some even used special resistive mains leads to drop the mains voltage (so no shortening, or replacing, the mains lead).

But I can't believe a guitar amp was ever made in such a way?.

BTW, I thought Japan had both 120V and 240V mains, depending where you were - it's why Japanese gear was always switchable, even relatively recently (VCR's etc.). Presumably this isn't the case any more?.
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Old 5th January 2012, 05:44 PM   #13
kevinkr is offline kevinkr  United States
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Originally Posted by Nigel Goodwin View Post
<snip>

BTW, I thought Japan had both 120V and 240V mains, depending where you were - it's why Japanese gear was always switchable, even relatively recently (VCR's etc.). Presumably this isn't the case any more?.
Japan has been on 100V mostly 60Hz with some 50Hz areas depending on where you are located for many decades, the switchable mains provision was for exported products. Like the U.S. few products for domestic sale have switchable mains.
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Old 5th January 2012, 11:05 PM   #14
Minion is offline Minion  Canada
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I picked up an old japanese tube amp last year that i used for parts and it had a japanese power xformer that had 90v and 100v ac primary taps on the transformer , it had a 235v 35ma, 6.3v 2a, 5v .5a secondary taps ......

when connected to a 115v source it gave me about an extra 25v on the 235v secondary but it made the 6.3v tap too high to use as heaters .......
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Old 6th January 2012, 08:58 AM   #15
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Originally Posted by kevinkr View Post
Japan has been on 100V mostly 60Hz with some 50Hz areas depending on where you are located for many decades, the switchable mains provision was for exported products. Like the U.S. few products for domestic sale have switchable mains.
I thought post WWII their infra structure was rebuilt by the USA and UK, each fitting their own mains voltages - and that was the main reason for Japanese equpment having customer adjustable mains switching.
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Old 11th January 2012, 02:24 PM   #16
shanx is offline shanx  Canada
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Just my 2 cents, I think you should determine whether (or why) you would want to do a complete tear down and rebuild of this vintage amp. It is not going to be a simple fix.
Safety Number#1 is absolute need to use an isolation transformer& Proper polarized wall plug.
Bleeder resistors should be placed across the power supply cap to safely discharge when the amp is turned off.
You have a dead short situation, and the output transformer also needs to be checked, and all the electrolytic caps replaced. You should probably sketch out the wiring, pull all the components out and verify what is still usable.
I would not even plug in replacement tubes until all supply voltages were double checked as correct at the sockets.
Don't want to be negative about it, but because something is vintage it does not necessarily mean it is of more value or even worth restoring..(IMO)
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