Mid-end DC integrated amplifier with ruler-flat frequency response and Pulse Power Supply.
Lower-end sibling of the terribly successful TA-F6B, the TA-F5 is the big version and the F5A a pared down, alternate and rare version.
Two gold-plated phono inputs (1x MM & 1x MC), Sony-made ICs (of course), clean cabling (if long...), a 4-gang attenuator from ALPS (of course), a solid diecast backplate which acts as heatsink, IC driver stage, NF tone controls, big (too big) meters plus (optional) solid AH-4A rack ears to perfect the real "pro" look of the late 1970s.
Also in : FET inputs, high-precision resistors and polypropylene caps for the MC/MM stage.
The circuit is close to that of the F6B, only downscaled and less powerful : DC, SEPP, OCL & OTL.
The Pulse Power Supply chops AC current at 20Khz as in the F6B or TA-N86B, even if the box is here finished in a more "homely" manner.
The TA-F5 is nothing really particular but clean, solid, all-metal and aluminium, long-lasting hifi with lots of power to boot.
And MC inputs, in 1977, weren't really that widespread on low-priced mid-end amps !
The TA-F5A version was export only : same structure and Pulse Power Supply but no 2nd phono input (and, hence, no MC cartridge head amp) and no stereo / reverse / mono switch - seemingly mainly a USA version.
The same distinction happened between the TA-F4 and TA-F4A but not between the much smaller and meter-less TA-F3A and its (even lower and obviously different) TA-F3 version which was closer to a TA-11 than a TA-F5.
Available much later in the US than elsewhere and therefore until much later as well. To follow the market trend regarding mid and low-mid segments, the next step was to :
a) bring the inputs closer to the faceplate to reduce cabling and go for the freon-filled Heat-Pipe (TA-F80, 1978 high-end)
b) put just as much power into much more compact an enclosure, as exemplarily exemplified with the TA-F55 and its even smaller Heat-Pipe (1979, mid end).
Then sell a lot of FH-7 's worldwide :)
This post will be updated with the TA-F5A service manual, at least for the parts identical between the two versions, and hopefully a proper image for the TA-F5A.