Ex National (Panasonic/Matsushita) domestic tape machine
I am very much "into" sustainability, a complete tape machine represents a LOT of embedded energy and to waste that embedded energy is a very bad thing, even worse is to bury it in landfill and subsequently poison our environment!
What is embedded energy?
Embedded energy is a measurement of the total energy that was used to create a component, a module or a complete piece of equipment originally.
So why has this National RS-760S become an "organ donor"?
Keep in mind this was a machine intended for the domestic market, the price conscious consumer. A fun machine to play around with (NOT for the professionals) but the Japanese decided to use sprocket reel tables which are partially made of plastic! Over the years, the plastic becomes brittle and breaks off. No longer will the reel be held in place and the machine becomes a noisy (as the reel tries to grip the reel table) heap of junk.
The machine actually was fully functional in all ways but this reel table problem made it pretty unsatisfactory to use and replacement reel tables are like "hens teeth" - it just wasn't worth the effort (for me anyway) to try and source a reel table.
But that said, they are a fun machine to record and playback those mysterious 1/4" tapes that might be lurking in the back cupboard or simply restore a machine for your "technology museum"
Brief background to National, Panasonic and Matsushita
Matsushita was begun by the Japanese industrialist Konosuke Matsushita. The Matsushita company initally used the branding NATIONAL for their premium products then in the 1980's moved to the branding NATIONAL PANASONIC and then further progressed to just PANASONIC.
To a certain extent, the branding on any Matsushita product gives an indication of its age - a "true original" Matsushita product from the 1960's or even 1970's should be branded NATIONAL
National Tape Recorder/Player SPARE PART
Part # QJI 0091 Main PCB
Main printed circuit board - fully populated/working
Although this could be used as a fully functional "drop-in" replacement board, it is far more likely to be of use as a "component farm"
Suits the Model: RS-760S (the onboard components will also suit other National/Panasonic machines e.g RQ-706S)
Made in Japan
Late 1960's - one of the early semiconductor based machines
CONDITION:
The printed circuit board remains fully populated (no components have been removed)
I have carefully removed ALL external interconnect wiring as I consider the most useful aspect of this main board will be as a "component farm" - a lot of very difficult (if not impossible) to obtain components from 50+ years ago
TESTING:
This PCB is known to be fully operational - the machine was heavily used during testing, failing no tests other than the issues with the take-up reel table, which bought about the demise of the machine.
Offered because of the rich component source this board can provide.
Because I believe this would be the main reason someone may want this board, I have carefully removed ALL external cabling to the board. It could still be installed as a complete/working board but that would entail a LOT of soldering, there are many connects to this board.
The board is single sided, components are readily accessible for de-soldering and all semi-conductor leads are nice and long.
So, here are the primary components of interest:
2x 2SB 348 (germanium PNP transistor, Ucb = 32V, Ic = 100mA)
6x 2SB 175 (germanium PNP transister, Ucb = 30V, Ic = 100mA)
6x 2SB 324 (germanium PNP transistor, Ucb = 32V, Ic = 100mA 220mW) ***
These transistor are types that can be thought of as the Japanese versions of the common AC126 & AC128's of the 1960's & 1970's period.
*** 99% sure about this due to schematic references but unable to inspect the casing easily due to the very tight fitting heatsinks on these devices
(used in the push-pull audio output section and the bias oscillator circuit)
2x interstage audio transformer type QLA-0017 (input to the push-pull output) ***
*** again 99% sure about this due to schematic references but these transformers are underneath the heatsinks and have heavy soldering on top, unable to easily identify them.
1x bias oscillator transformer QLB-0123
Very Large dual slide switch
The remaining components are "mundane" in nature although I see a few styro's in there.
I have included a photograph of the 706S schematic (single channel machine) which has a very similar design and component use to the RS-760S
The output transformers (T2) are NOT on this PCB but mounted separately and offered in a different advertisement
Since removal from the equipment, I have packed this board in sealed plastic and it will be supplied in this manner.
