Sony KV-1204A: Where to start?

[Popester]

A DVM could tell you if the on/off switch has continuity or not. The earlier point I was trying to make is if the crt is really weak or dead as far as emission goes, than fixing it to get it to power back up might not be worth your time and effort. Is a KV-1204A really from ‘77? I thought it would be earlier like ‘72 or ‘74. Regardless a manual will be needed and maybe someone here on the forum would sell you one or you could buy a downloadable file copy.

[Popester]

A lot of Sony sets used a derived power source that came off the flyback transformer. So the horizontal circuitry had to be running so the flyback could supply the other power sources that ran other things in the circuitry. Be very careful with the anode connection in these as it is coaxial. As I stated earlier these were very unique in their design. Not like the typical American made sets of the same time. Very reliable products. CRT’s tended to have a shorter lifespan but that was probably due to a brighter picture/contrast compared to a shadow mask type of CRT.

[ESigma25]

Originally Posted by Popester

A DVM could tell you if the on/off switch has continuity or not. The earlier point I was trying to make is if the crt is really weak or dead as far as emission goes, than fixing it to get it to power back up might not be worth your time and effort. Is a KV-1204A really from ‘77? I thought it would be earlier like ‘72 or ‘74. Regardless a manual will be needed and maybe someone here on the forum would sell you one or you could buy a downloadable file copy.

All the websites I was looking at said 1977 but it's probably an earlier model than that.

[Popester]

After typing in a Google search it does look like this is from '77 or '78 model year. Not sure if this used the SG613 HOT switch but they would short and take out a bunch of components. Check the HOT for a direct short, the damper diode, for a short, look for an inline fuse with a hard blow failure. HOT is usually mounted on a big heat sink and the damper diode will be near by maybe even soldered to the back of the transistor. I was thinking this was a earlier model, but they're numbering scheme didn't always make sense to me. I don't know if this has the SG613 or not but they were in the '75 model KV-1920, and KV-1722 sets. Not sure about the smaller ones. If the jug is good, it would be worthfixing as they are excellent sets and were so reliable. These sets used a HV block that was similar to a Zenith tripler. The casing could crack and arc to ground. I fixed one arcing to ground with epoxy glue and it's still working. That was on a KV-5200. It's hard to beat a Sony but they can be a bear to fix. Good luck and update as you get things going again.

[zeno]

This is an SG613 set, actually SG264 that IIRC subs to an SG613.
If the SG is shorted I would STRONGLY suggest not trying to fix it.
The regulator transistor & fuse are blown with it along with a few resistors.
Trouble is something else caused it almost always. If you dont find the cause
it will blow again right away or sometimes run perfect a while then blow.
In the day almost no shop would fix one. The ones that did charged flat rate $120 - $140 about double the usual rate. That was real $$ back then, see the price of cars !

73 Zeno
LFOD !