Sony Trin KV-1722, anything worthwhile?

[John in MA]

A guy I know has one of these sitting in his attic. I'm not after it, but he's wondering if it's worth trying to sell or if it should remain upstairs. My spidey senses tell me it's nothing special beyond a decent old TV. Thoughts?

[radiotvnut]

That sounds like a mid '70's model to me. The major issue with those '70's Sony's were that some of them used an oddball SCR in the horizontal output circuit. Those SCR's cost a fortune and are very easy to blow if you're not careful.

If it still works and if the CRT is in good shape; I'd say it would be a nice set to have around. I don't think theres much value on those sets at this time. It might bring $20-$25 from a collector of '70's TV sets. The average public would probably have to be paid to take it.

It seems that most consumers today want all the latest features for nothing and they are not interested in older sets. I have several sets from the mid '70's through the mid '80's (Zenith, RCA, Sony, etc.) that I couldn't sell for $5 each if I tried. So, I'll hang on to them for my own use. Ten years ago, these old sets would usually bring at least $65 on the used market.

[Findm-Keepm]

Originally Posted by radiotvnut

The major issue with those '70's Sony's were that some of them used an oddball SCR in the horizontal output circuit. Those SCR's cost a fortune and are very easy to blow if you're not careful.

Ah, yes, the veritable SG-613, actually a SCS (Silicon Controlled Switch). A real PITA circuit - compounded in the early days by Sams publishing an incorrect schematic, and technician's unfamiliarity with the circuit. Sony issued a ton of bulletins on these set, mostly reliability upgrades for the Horizontal and Verical Sweep circuits (the 2SC867 vertical outputs are expensive too!)

Several considerations - if the SG-613 is bad, they are still available - do not use an NTE replacement, they just aren't stout enough. Early ECG-276 devices were useable, but they are no more.

The 2SC867 has been upgraded to the 2SC867A, both NLA from Sony, but might still be available from a Sony distributor.

The CRTs were generally reliable, so if it comes on at all, hang on to it! I have it's 13" cousin, and it could be a daily watcher - comes on every time.

Attached are some service hints if you do wish to give it the ol' college try.

Cheers,

[kx250rider]

If it's clean, it's worthwhile. That was Sony's flagship TV that got them into the mainstream livingroom, in my opinion. However, as Findm-Keepm warns, you'll be into an expensive headache if you have a blown power supply. I fixed hundreds of those sets, and I wouldn't touch one today due to the cost of the SG-613. $70 each last time I asked, and that TV has two of them (one for horizontal output, and other for the B+ supply regulator). Later models used a transistor (2SC867), which was a lot cheaper, in the power supply.

So the answer is to see if it works, and if it's clean. If so, grab it! If not, it may still be worth saving for parts.

Charles