Stay away from??

[rca2000]

I'll try and explain this a bit more...others feel free to add more.

The aforementioned Sony sets with the "SG-613" GCS device (Gate controlled /turnoff switch), (occasionally an SG-264A was used) were VERY difficult to work on, because the GCS has ONE VERY bad attribute: it will SELF_DESTRUCT, if it loses gate drive--even if only for a BLINK of an eye !! Like an SCR,m they are turned on by a gate and STAY ON, until a reverse-pulse is applied to them. But, UNLIKE an SCR--a GCS can ALSO be turned OFF by that same gate---this makes them suitable for an amplifier ckt, at least a class C horizontal out ckt. Well.. "kind of suitable".


They, in reality, are NOT really suitable, because unlike a Bipolar transistor or even MOSFET or IGBT, they often fail in a horizontal ckt,. MUCH more than other devices, including tubes. Like a tube--when the drive is not there--they conduct "full-bore" , BUT UNLIKE a tube--they CANNOT handle this severe overload. Not even for a millisecond. Whereas all of use have seen an HOT "red-plate" because of even a slight loss of drive or such---we all KNOW they can "take it" for a short time, at least for awhile. Of course--this cannot be allowed to last--as it WILL kill the tube and more importantly its "load, meaning the flyback, in a short time if left this way. So, we go after the drive ckt, and fix it, and all is well. If, while chasing this problem down, there is a quick period of drive loss, we discover it, and correct it. if it last a few seconds or less--no harm is usually done.


BUT on a GCS horizontal ckt...ANY...and I mean ANY interruption or even reduction of the drive and ...BAM !! Out goes that GCS--WAY before you have time to discover why too !! They INSTANTLY short from "cathode" to "Anode", if that can really be considered the right terms for their elements. Think of all of the multitude of sets we have worked on over the years--with intermittent drive issues--usually, IF you catch and fix this in time-no harm is usually done, Sometimes, it may be a good idea to replace the H-out anyway, "just to be sure" all will be well, but often if you resolder the drive transformer of replace the cap in the base ckt--all will be well--for a long time.

But on these GCS Sonys---you get just ONE chance---to get EVERYTHING right--and I mean EVERYTHING !! Just a TINY problem with a glitch in the H-drive and BAM!! Out goes that GCS and fuse, and usually the B+ reg too and maybe more !! SO it was VERY difficult to fix one. Often, we would THINK we had one fixed, and POW !! Out it would go, ANd those Sony GCS'S were NOT cheap. Unlike Normal FET or Bipolar transistors, they did NOT get "cheaper" as time went on, either, and you could NOT use ANY other type than Sony !! If you id--you were SURE to be disappointed !! I fixed a FEW of these sets in years gone by--but do NOT really want to work on ANY more of them. By now--they are OLD, OVER 35 years I think--since Sony used them and I do NOT think ANY of the GCS sets would be fixable with all of those old caps. And Sony Trinitron tubes are NOT really known for their long-life, anyway...

So...STAY AWAY from Sony sets made from about 1973-1978 or so...unless you are a SEVERE masochist !! Maybe THIS will make things more clear for you all.

[andy]

...

[zeno]

Originally Posted by rca2000

I'll try and explain this a bit more...others feel free to add more. ETC........

Add to that the SG613 was about $25 plus the other parts damaged
every time you tried it you rolled the dice for $40 or more.
You could not return a "new defective" one. There were a few
common problems but the few people doing them kept
hush hush. When we were charging $50 the few Sony folks were getting
over $100 to do any Sony. There was a trouble shooting sheet for them, never seen one. Anyone got one? I didnt do many colors at
Sony, one of the guys advised me not to become the color TV
man unless I wanted a drinking problem. It was a specialized crew with
one of each doing
Color TV
B&W TV
Video
B&W TV
Audio
Radio & misc smalls
Parts man / janitor
one useless manager with a huge office
two gals for paperwork etc
We would drift around a bit when caught up or needed a change of pace.

73 Zeno

[ChrisW6ATV]

Originally Posted by zeno

The first Sony colors were not bad. The only thing odd
about them was they used separate HV & H sweep stages.
They switched to an SCR the SG613 abt '74 & they were
dogs to deal with...

73 Zeno

Originally Posted by rca2000

I'll try and explain this a bit more...others feel free to add more.

Thank you both for the detailed comments about those Sony sets. That number, SG-613, is very familiar to me. I may have even swapped out one in the past in some set; I have definitely seen it more than once. It looks like a TO-3 case but about 30% smaller, and narrower if I remember right.

[Zenith26kc20]

We fixed many of the gate switch Sonys. The key to getting them repaired was to break the set "in half". Using a square wave generator to feed a signal to the power supply enabled you to get it working. The horizontal stage failed repeatedly due to the horizontal drive IC starting slow. Somewhere are the rest of my notes but you had to use a variac on the set with the power supply disabled (jumpered) and at 18 volts of B+, the chip HAD to start producing horizontal drive. If it needed 20 or more it was bad. These sets had another problem. The 330 pf across the gate switch loved to short out.
I always wonder why Sony made such an insane TV.
The Zenith 9-160 modules could drive you nuts sometimes too. We had harness problems galore on those sets. THe 9-181 sets with "kick start" were somewhat fun. If the twist lok electrolytic opened up on the 181, the kick start would burn up after a few seconds.
And don't forget the Magnavox "Star" system with a AA battery in the tuner.....

[rca2000]

The 9-160 was a WALK IN THE PARK, compared to the GCS Sonys ! I fixed a WHOLE Bunch of them, for myself and others, "in the day" (Late 80's to mid-90's or so.) I ONLY had a few I could not fix. Often solder joints caused most of the problems with them. Saw a few bad B+ caps and 200 volt problems too. had ONE that would work FINE in a manual-tune set--but with the electronic tuner it would NOT tune--IIRC loss of a 7.5V or so flyback voltage line. Some bad fly's too....but overall--NOTHING like the GCS sets !! And the "startup" ckt on the 9-181 sets was not too bad---I recall a COUPLE that would NOT " Quench" the start pulse" and burn up that 1K resistor in a few sweconds, one was a bad quench transistor, and IIRC, ONE had a bad "puff" type cap. Of course--BOTH the 181 AND the 351 ATE flybacks !!

[rca2000]

Originally Posted by Zenith26kc20

I always wonder why Sony made such an insane TV.

I seem to recall them claiming that , at the time.....Bipolar transistors were NOT reliable enough for their "wide angle" deflection setups-.....and they did NOT want to go to a twin-SCR setup like RCA did., So, they came up with a "good idea"....so they thought.....and a service NIGHTMARE !! I had MUCH rather work on an RCA or other SCR sweep set !!

[Jon A.]

Originally Posted by Zenith26kc20

And don't forget the Magnavox "Star" system with a AA battery in the tuner.....

What's the problem with that one?

[rca2000]

Mainly....that they used that battery for memory retention, IIRC. IF it went dead the set lost ALL memory if powered down I think. ANd it was NOT a rechargeable battery either. The system control ckts. used I2L (integrated injection Logic) and the 1.5 volts was a logic voltage I think.

[TVTim]

Who would remember to change the battery inside of the television. I can't imagine many end users doing this.

[zeno]

Originally Posted by Zenith26kc20

I always wonder why Sony made such an insane TV.
The Zenith 9-160 modules could drive you nuts sometimes too. We had harness problems galore on those sets. THe 9-181 sets with "kick start" were somewhat fun. If the twist lok electrolytic opened up on the 181, the kick start would burn up after a few seconds.
And don't forget the Magnavox "Star" system with a AA battery in the tuner.....

I think the engineers got carried away & woudnt see the service
headaches. Remember that Sony suffered from arrogance.
As far as 9-160's go we did a ton with bad pc cons
& a few other things, but the beauty of it was you could whip
a new one in in a few minutes for abt $50 net. Done & on
to the next. Those were still busy days except in spring when
we would put more time in them.

73 Zeno

[zeno]

Originally Posted by rca2000

I seem to recall them claiming that , at the time.....Bipolar transistors were NOT reliable enough for their "wide angle" deflection setups-.....and they did NOT want to go to a twin-SCR setup like RCA did., So, they came up with a "good idea"....so they thought.....and a service NIGHTMARE !! I had MUCH rather work on an RCA or other SCR sweep set !!

AMEN ! To be honest I could never wrap my brain around the RCA
SCR, ITR sets but they never gave me trouble. It was bizarre but
reliable & serviceable. Also you could get help easily & without
being abused. All the US sets had great tech help if you needed it.
It took the Japanese years to learn that & to supply parts
in a timely manner.
Who used SCR's ? All I remember is Sony with the single GCS
and RCA, Philco & Heathkit with the RCA set-up. Did I forget any ??

73 Zeno

[radiotvnut]

I've seen some Wells-Gardner-built 25" consoles that had SCR's for the horizontal output. As I'm sure you know, the WG sets were built for a number of department stores.

[Zenith26kc20]

The problem with replacing the Star system battery was the cusomer would not call until it failed. It was a regular carbon/zinc battery. Once replaced one would have the fun job of programming every cable station the customer had programmed in before the failure. If I remember right, the 25 inch Star sets had vertical trouble also.
The only reason we "disliked" them was the amount of time it took to reprogram everything.
9-160 solder connections were no problem. The big problem was they would not always start. They would sit making an obscene noise for a few seconds which aggravated the customer to no end. If I remember right, that was mostly cured by clipping a resistor off the board in the front of the module. And, as mentioned those harness assemblies were aggravating. Also, a few burned up yoke plugs made customers mad from the smell and the famous 315 volt capacitor which opened causing half dark, half light picture. Other than the few problems that the System 3 sets had they were good performers.

[Jeffhs]

Originally Posted by Zenith26kc20

The problem with replacing the Star system battery was the cusomer would not call until it failed. It was a regular carbon/zinc battery. Once replaced one would have the fun job of programming every cable station the customer had programmed in before the failure. If I remember right, the 25 inch Star sets had vertical trouble also.
The only reason we "disliked" them was the amount of time it took to reprogram everything.

Most non-technical people do not realize or care that there is a battery in these TVs. Further, most televisions had (and still have) a warning on the back cover not to remove said back, due to high voltage and electric shock hazards. This warning is enough to scare most people into keeping their hands out of the innards of the TV, even to replace a battery.

Even if they knew there was any kind of battery in the set, most people would not have the faintest idea what it is there for, let alone how to replace it. When the battery in these Magnavox, et al. TVs finally failed, erasing all channel programming, I imagine most people just left it alone, changing the channels manually using the keypad on the remote.

There is also the possibility of the dead battery leaking in its holder inside the set, but again most set owners didn't know or care about it. (I wonder how many of these Magnavox Star System and other TVs have been found with defective backup cells that have leaked and corroded the contacts of the holder, when the set is being repaired due to some other problem. )

The same thing can and probably does happen all the time with today's flat panel TVs, which I'm sure also use backup batteries for channel memory and backup of other settings, although many FPs quit and are junked long before said battery fails. Remember, most non-technical people know only three things about their TVs: how to turn it on or off, how to adjust or mute the volume, and how to change the channels, once the set is installed and set up. They couldn't care less about backup batteries or anything else inside the television, so long as the set works properly.