Changing tube types, without changing the power trafo, could easily be a fool's errand. I again call attention to the very limited capability of the power "iron". There are only 2 A. of 6.3 VAC available. The EL84/6BQ5 draws 760 mA. of a heater current. A PP pair would leave only 480 mA. for the small signal tubes and that's not encouraging.
Now, that 1.2 A./5 VAC winding is interesting. Seeing what it's used for, by tracing, is important. It could be powering (as was suggested) 71A filaments. That winding is just hefty enough to power a pair of 5V6 heaters. Should that be feasible, 2 A. of 6.3 VAC should be quite adequate for the small signal tubes.
BTW, the 5AR4/GZ34 is the 2 A./5 VAC rectifier type with the lowest forward drop penalty. At the low B+ demand present here, an inexpensive Chinese 5AR4 rates to be OK.
Now, that 1.2 A./5 VAC winding is interesting. Seeing what it's used for, by tracing, is important. It could be powering (as was suggested) 71A filaments. That winding is just hefty enough to power a pair of 5V6 heaters. Should that be feasible, 2 A. of 6.3 VAC should be quite adequate for the small signal tubes.
BTW, the 5AR4/GZ34 is the 2 A./5 VAC rectifier type with the lowest forward drop penalty. At the low B+ demand present here, an inexpensive Chinese 5AR4 rates to be OK.
Probably cheaper to replace it or use a variac... OTOH, if it'll do 100V 50Hz, it would probably be fine at 120V 60Hz, no?
I know that, but one would think they would make one device that works in both places implying 50Hz capability, no?
"The frequency of electric current is 50 Hertz in Eastern Japan (including Tokyo, Yokohama, Tohoku, Hokkaido) and 60 Hertz in Western Japan (including Nagoya, Osaka, Kyoto, Hiroshima, Shikoku, Kyushu); however, most equipment is not affected by this frequency difference. A possible exception are timing devices such as clocks."
LMAO most equipment except linear supply powered devices designed for 60Hz running off 50Hz supply. They get HOT!
"The frequency of electric current is 50 Hertz in Eastern Japan (including Tokyo, Yokohama, Tohoku, Hokkaido) and 60 Hertz in Western Japan (including Nagoya, Osaka, Kyoto, Hiroshima, Shikoku, Kyushu); however, most equipment is not affected by this frequency difference. A possible exception are timing devices such as clocks."
LMAO most equipment except linear supply powered devices designed for 60Hz running off 50Hz supply. They get HOT!
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likely yes...
if you are restoring, make sure that you use the original tubes, otherwise that is no longer restoration but a redesign/rebuilt...
LMAO most equipment except linear supply powered devices designed for 60Hz running off 50Hz supply. They get HOT!
yes, a 50z traffo running off 60hz is cooler than a 60 hz traffo running on 50hz line....
but that depended on how far below the knee of the magnetization curves the traffo was run at...
True, but looking for the exact tubes is a burden especially DH types and are costly. I had given her the option and she is okay for a redesign if resources are not available and practical.
I will trace the connections and see the final image. Changing the trafo to work with 220v line will be most viable and putting a higher VA Trafo.
Looking at the unit, the 4pin outputs are supplied with 5v/1.2a tap, the driver 5 pin tubes are supplied by 6.3v/2a taps including panel lamp. the rectifier is supplied with 5v/2a with 22uf/350v dual section with 10H choke. the input transformer served as Interstage feeding the split phase to the outputs.
#80 must be the rectifier and 71A must be the 4 pin outputs but with 8k/10w pp opt isn't it overkill?
The problem is the input drivers (5 pins), maybe IDH triodes since filament are wired in parallel? i'm not familiar with 5 pin triodes..
I thought Hashimoto was started by ex-Sansui employees...
And I thought Hashimoto is a disease of the thyroid gland
...Best regards!
Yes almost similar but the only difference is the interstage trafo its 3657p and no input trafo but has additional 5pin tube that must be 76 too.
Thanks jazbo and all of you for the help. Now i know the only question now if the owner want to buy 71a, 76 and 80. Pricey tubes especially Globe types.
Thanks jazbo and all of you for the help. Now i know the only question now if the owner want to buy 71a, 76 and 80. Pricey tubes especially Globe types.
these tubes are still available and not so expensive compared to the more famous ones..
http://www.pmillett.com/tubebooks/tubedata/RC12.pdf
http://www.pmillett.com/tubebooks/tubedata/RC12.pdf
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