Busted Sony 1210 Fixed!!

[Eric H]

Originally Posted by DavGoodlin

I have two TAB "Japanese Color TV service manual" volumes that cover the KV1200 and KV1201/12, since I have had a KV1210 for 30+ years I forget but I bleeve I had this problem. It sounds like you're on the right track. PM me If you want a scan emailed.

Thank you for the offer, lets wait and see what happens when I put the new Transistor in.

I replace the three electrolytics on the Osc board and fired it up with the Transistor removed to see what would happen, without the transistor in place I still get just a vertical line but it's now bright white and perfectly straight up and down, and it fills the entire height of the screen, the oscillator is clearly heard running.

I put the transistor back in just in case I had misread the Ohms readings but it still doesn't sweep, it does however reduce the brightness and make the line green and bendy so it's probably dragging the power supply down I would guess, the surprising thing is nothing smokes or pops with this shorted power transistor in place.
Hopefully I will get the replacement next week sometime.

Kind of an odd set that has the HV circuit separate from the H sweep, it's like some of the vintage sets that used an RF high voltage supply.

I have a sweep transistor in an old Panasonic 5" Pop Up set but it's rated at 50w where the one in the Sony is rated at 125w, it might last a few seconds if I packed it in Ice before I powered it up.

[DavGoodlin]

I'll second the horz drive board guess, especially around pincushion transformers. Don't overlook some total E-cap fails in this section also.

I have one of those and they are truly good receivers. Too bad a good tuner means nothing today. Bought a NEW CRT from Sony back in 1982 because it was the best looking set, by far, when used as a computer monitor.

[Eric H]

Thank you Charles!

I found this coupon folded and tucked into the ventilation slots.
It expired in 1985 so someone worked on this set around 1984-85.

Here's that address today, left of the Thai restaurant.

http://goo.gl/maps/ONjG

[jr_tech]

Early ad for sale on eBay describes the first 3 12" trinitron models and shows the fancy KV 1220:

http://www.ebay.com/itm/1970-SONYS-T...item4838fd03e5

Were the first year 12" models the only ones with the low location of the ch selector knobs and "sky tune"?

not affiliated,
jr

[etype2]

Originally Posted by jr_tech

Early ad for sale on eBay describes the first 3 12" trinitron models and shows the fancy KV 1220:

http://www.ebay.com/itm/1970-SONYS-T...item4838fd03e5

Were the first year 12" models the only ones with the low location of the ch selector knobs and "sky tune"?

not affiliated,
jr

Yes. Only the 1220 "Premium model" had Skytune.

[zenithfan1]

Originally Posted by etype2

Yes. Only the 1220 "Premium model" had Skytune.

Cool! Good to know, that's the one I have in my storage unit. I need to re-veneer the cabinet though.

[Eric H]

Well I have made some progress with this set.

I installed the NTE Transistor but still only had a vertical line on screen, did a little poking around and discovered I had left out the two plastic insulators that go over the screws for the transistor, I discovered this when I saw one of the insulators laying inside the Flyback cage.

I thought it something was amiss when I installed it but didn't know what until I discovered the case was at ground potential.

Anyway, fixed that problem and tried it again and now the set wouldn't turn on, got CRT heaters but no sound or HV, I figured I blew something up by leaving out the insulators but it had been running right before I shut it off, it had also been running with the old transistor installed the same way, in fact I wonder if it might have been fixed after I recapped the Oscillator board but I installed the T'sistor wrong? Well, not worth swapping it to find out now.

Checked fuses, checked voltages, had 114v on both of the large Transistors and nothing was smoking but it just didn't run.

Checked the Horiz Osc Transistor and it was good, finally I was just poking my meter around checking for B+ and I heard the HV crackle on, I have no idea what I did, checked the screen and now I have a full raster and good sound, however I don't have any video and the Brightness and Picture controls do nothing, the CRT is biased full on on all three guns, there may be a picture but I can't see it with the CRT turned full on.

Still working without a schematic, any ideas what would kick all three guns full on? Brightness control has zero effect.

[freakaftr8]

I have a 1201 and a 1220u. the 1220u works very nicely. Yes the SCR on the top of the set is vertical. THe bottom two are h out and pincushion or something to that realm. Bet your H out is open

[lnx64]

Hmm, should go there and ask for a TV repair. :P

Looks like a home now.

[6GH8cowboy]

Try rocking the horiz centering control (dead spot?) and check any jumpers. The H out trans could be open. If shorted you'd have less to look at. My gut feeling is a mechanical fault. good luck

[Eric H]

Alrighty then, I got a little time and decided to have another look at this little Sony.

As you recall from the beginning of this thread, this set only has a vertical line from top to bottom, this is somewhat unusual since most Flyback powered sets can't make any high voltage unless the horizontal sweep is working, this is an early Sony though so it might as well have come from the Saucer at Roswell as far me working on it's concerned, I recognize the CRT and the on/off switch but after that...

Anyhow, it was suggested that one of the two large TO style transistors under the flyback cage was probably the HO, now since I burned up my Digital Multimeter with the Diode scale on it a couple weeks ago I only have a vintage Digital Meter to use and only on Ohms.

First I disconnected one leg of the transistor closest to the edge of the flyback cage, the set didn't operate at all like that so that one must be an oscillator for the High voltage, connected it back and disconnected the other one, now the set runs exactly the same as it did so either this isn't doing anything or it's doing something that can't be seen with no raster.

I removed it and tested it with the Ohm meter, it checks about 1 ohm both ways between the case and the one leg, the other transistor is the same number and it doesn't check shorted like this so... I'm guessing this one is bad.
It's a C806A would I be right in guessing it's actually a 2SC806A?
I see Sony sells those for (gasp) $22.55 each!

NTE has an Equivalent NTE283 for $10.53 but I wonder if it would hold up?
Also is there anything else that would have made this one go bad.

I wouldn't mind the $22 if I knew it wouldn't go pop as soon as I turned it on.

[ChrisW6ATV]

Originally Posted by Eric H

It's a C806A would I be right in guessing it's actually a 2SC806A?
I see Sony sells those for (gasp) $22.55 each!

NTE has an Equivalent NTE283 for $10.53 but I wonder if it would hold up?

Eric-

Decades ago, I worked on one of the early 12-inch Sonys, probably the KV-1201 that I have the manual for. One of that set's numerous separate problems was a vertical-sweep problem, and I remember installing two replacement-type (ECG or other) output transistors. They lasted a short time (minutes to hours), then one or both blew again. I then bought the "real" Sony parts, and they were fine. One of the few or only times I had to have OEM transistors in a device to make it work.

Your set has a horizontal issue, not vertical, so with luck it will not have the same problem.

[mstaton]

I would try the NTE one first, and if it works maybe you can buy an original one later or buy 2 NTE's for the price of the Sony one so you can have an extra. You probably can get that locally. You can try Ford electronics in Buena park or Orvac's in Fullerton or Net electronics in Downey. Not exactly close to you but it's worth a shot.

[kx250rider]

Watch for dry electrolytics in the horizontal oscillator area. Also check and scope the the B+ to be sure it's is clean and free of AC and noise, and regulating at 130v (or 135 on some Sonys). If that's low or high, fix that problem first, or there will be more blown transistors. I can't remember any tips on that chassis, but 95% of the time, all trouble starts with dry electrolytics in the power supply and horizontal on 1960s-70s Sonys ;-) .

Charles

[Eric H]

I ordered an NTE283 this morning.
Turns out the cheapest source was my local Electronic supply house, $12.60 and no shipping, however it won't be here till next week sometime maybe.

Meanwhile I'll recap the oscillator board, there's one Electrolytic on there with the plastic sleeve shrunk halfway down the can, I'm guessing that's from heat and it wasn't made that way.