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Old 5th May 2011, 01:45 AM   #1
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Default Vintage Japanese tempo 35w4-50c5-12au6 help

Hey everyone Im new here and Im really having a tuff time with this little japanese amp i bought on ebay. So the story I got from the seller was the amp worked prior to him trying to install a new plug and after it was blowing fuses. So I got the amp and he had tried to install another two prong plug which I know is a shock hazzard so i went out to home depot and got a 3 prong and a installed it as well as all new tubes from a local tube shop here in denver. I made the assumption that he had wired the cord correctly so i did the same. Well the amp just keeps blowing fuses and 35w4 tubes so im currious if the plug is wired to the rectifier tube correctly. Im going to post pictures so hopefully you guys can help me out here cause im stuck on this one.

Thanks Guys

http://www.flickr.com/photos/80698781@N00/5688847698/
http://www.flickr.com/photos/80698781@N00/5688847670/

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Old 5th May 2011, 02:17 AM   #2
jfitz57 is offline jfitz57  United States
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Hi

The white wire should go to the negative side of the filter cap instead of the 35W4.
Do a search for "litebulb trick" or something like that, it will save you money on fuses and tubes
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Old 5th May 2011, 02:21 AM   #3
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Chris,

I don't see a power trafo in the photos. That makes the amp a DEATH TRAP, unless it's modified. Be grateful fuses and tubes failed, instead of you being killed.

That unit employs a 150 mA. series heater string. Japanese AC mains are lower voltage than those in North America. You need 10 W./150 Ω and 1/2 W./3.3 Ω resistors inserted into the series string to drop 23 Volts.

A $11.41 Triad N-68X isolation trafo from Allied Electronics (stock # 967-9502) will provide the protection necessary.

Replace all caps. in the unit. The 'lytics are undoubtedly bad and all the rest are suspect.

Check all resistors for drift out of tolerance. Replace as needed.
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Old 5th May 2011, 03:42 AM   #4
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Eli,

I know about the n68 transformer and plan on installing one shortly but from my understanding the issue is with pluging the two prong cord in wrong and creating a "hot chassis" so thats why I installed the grounded three prong.
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Old 31st December 2011, 02:32 AM   #5
rob55 is offline rob55  United States
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I’m an ignorant novice. I have recently acquired a 4” speaker attached to a 2x4x6 chassis with a tube complement of two 50C5 and one 12AU6. You can find pictures at https://plus.google.com/photos/10850...OGJmPH9-7HfogE How did all that get crammed in there? I guess it is true point to point. I assume it is some type or radio receiver.

Rattling a screw driver grounded to the chassis around to everything that looked like a cap brought no snap crackle or pop. I’m just going to tear the guts out. I want to convert it to a low watt guitar amp. One knob, kind of a combination of these two 1-12AU6; 1-50C5; 1-35W4 http://dogbarkmusic.com/Harm/harmony.pdf http://lectrolab.files.wordpress.com...ab_r203_r2.jpg Do you think there is enough room in there?

I plan to use the current cabinet. It is Bakelite. Not too many dials or knobs up front. The tube sockets are riveted in and do not appear scorched or chipped. I know I need to install a 1 to 1 isolation transformer as mentioned in this thread.. I think it will fit on top when all those other things are gone. I plan to put the ot on top too apparently with the core at right angle to the isolation transformer. That makes room underneath.


Assuming the ot and speaker are ok; it seems I can read ohms across the speaker to determine impedance, yes?
I want to put a out for a speaker cab on the back. Is there one that disconnects and reconnects the internal speaker just by inserting and removing the plug? If yes what is the part #? Where do I find it. I’m not connecting with Google on this question.I've been told one can do it with a shorting jack, but I think it leaves me with the internal speaker in series with the external speaker. I see switching jacks but can't find wiring diagrams.



Any and all advice appreciated. Thanks Rob
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Old 4th January 2012, 04:10 AM   #6
jfitz57 is offline jfitz57  United States
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Looks like maybe some kind of early wireless power line intercom or something with the R.F. can there.
Is it P-P ? If so I'd leave the output side alone and work on the input side.

Jim
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Old 4th January 2012, 04:50 AM   #7
kevinkr is offline kevinkr  United States
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Guitar amp thread so it gets moved to the I&A forum where it belongs.

Rob55 please start with the isolation transformer from the get go for safety.
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Old 4th January 2012, 10:28 PM   #8
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Quote:
Originally Posted by rob55 View Post
Im an ignorant novice. I have recently acquired a 4 speaker attached to a 2x4x6 chassis with a tube complement of two 50C5 and one 12AU6. You can find pictures at https://plus.google.com/photos/10850...OGJmPH9-7HfogE How did all that get crammed in there? I guess it is true point to point. I assume it is some type or radio receiver.

Rattling a screw driver grounded to the chassis around to everything that looked like a cap brought no snap crackle or pop. Im just going to tear the guts out. I want to convert it to a low watt guitar amp. One knob, kind of a combination of these two 1-12AU6; 1-50C5; 1-35W4 http://dogbarkmusic.com/Harm/harmony.pdf http://lectrolab.files.wordpress.com...ab_r203_r2.jpg Do you think there is enough room in there?

I plan to use the current cabinet. It is Bakelite. Not too many dials or knobs up front. The tube sockets are riveted in and do not appear scorched or chipped. I know I need to install a 1 to 1 isolation transformer as mentioned in this thread.. I think it will fit on top when all those other things are gone. I plan to put the ot on top too apparently with the core at right angle to the isolation transformer. That makes room underneath.


Assuming the ot and speaker are ok; it seems I can read ohms across the speaker to determine impedance, yes?
I want to put a out for a speaker cab on the back. Is there one that disconnects and reconnects the internal speaker just by inserting and removing the plug? If yes what is the part #? Where do I find it. Im not connecting with Google on this question.I've been told one can do it with a shorting jack, but I think it leaves me with the internal speaker in series with the external speaker. I see switching jacks but can't find wiring diagrams.



Any and all advice appreciated. Thanks Rob
your are ok for getting the impedance, add 20%.


Can't tell by the pictures whether you have room for the transformer with the speaker but I would guess it would all fit. The jack you want is a regular switched 1/4" jack like you would use on the input of the guitar amp. The output would be wired to the end terminal of the jack, go through the switch when a plug is not inserted, and the other terminal of the switch would go to the speaker and then to ground.

MONO CHASSIS MOUNT W/ N.C. SWITCH 1/4" JACK | AllElectronics.com
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Old 4th January 2012, 10:29 PM   #9
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Quote:
Originally Posted by jfitz57 View Post
Looks like maybe some kind of early wireless power line intercom or something with the R.F. can there.
Is it P-P ? If so I'd leave the output side alone and work on the input side.

Jim
No, it is a radio.
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Old 4th January 2012, 11:00 PM   #10
Minion is offline Minion  Canada
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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 .....
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