OK, found these really cheap so I picked them up to mess around with.

One is a KV1981R, I'm guessing early 80's, Stereo with audio video inputs on the back.
This set is nearly mint, the right speaker grille is bent a little but should pound out OK. It seems to work fine, the CRT is very strong with good gray scale within a few seconds of powering it up, it seems to be low mileage because there's not much dust or crud inside but the outside is yellowish with tobacco stains, it'll clean up but I'll have to strip it bare and wash it.

The second set is a KV1545R, it's one with the "Ball Bearing" control panel, bonus points since I already had the remote for it at home.
It's quite clean with a minor scruff on the top corner.

This one was sitting outside in the junk area for the last three weeks or more, I'm pretty sure it got rained on at least once early on but there doesn't seem to be any rust or ill effects.
I tried it last week when I was at the thrift and it didn't work so I left it, It was dry at that time.
I decided to pick it up this week, it was only $3.98 so little to lose.

It powers on for about a second, the HV hits and the green display comes on briefly, then it shuts down, not entirely though, the relay stays energized until you hit the power button a second time then it clicks off.

It won't power up again (the relay will click but no HV or display) until you unplug it and wait a few seconds, plug it back in and it'll repeat the sequence, seems to be going into auto shutdown?

OK Sony experts, what's wrong with it?

Here are some really lousy pictures.

Hello Eric,
I may even have the factory service for thst set.
one biggest things I find working on Sony is Bad Electrolytics.

Far as the picture tube goes those older sony pictures were good

I would check for bad contections also I'm thing this set has a scr regulator.

I was trying to remember it's been ten years since I've worked on a sony tv.

Got like 6 of them here at home

They wre one the best sets far as picture but alot people dreaded working on them

Hi Rich, would the bad Electros be in the power supply?

Our family's neighbor had one of those KV1981R sets. They had damn good pictures and I would always play nintendo on it with their kids. About the only thing I noticed about it was a little excess pincushion correction. Far as I know they still have it and its never been serviced.

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Hello Eric,
that is where I would check first in the powersupply area.
like I said sony's had a lot of bad caps

If I can find my notes on that set I bet I may have the fix.
My shop sold that set new and also did the warrenty for sony.

I even had beren trained on sony products in school Sony sent my class train manuals .

Years ago, someone gave me a KV1981R that they found at the dump. The speakers had been removed and the flyback transformer was arcing to the heatsink. Not knowing what kind of shape the tube was in, I junked the set.

I've also had the 19" version of that 15" set and I seem to remember having that shutdown problem. It's been a long time; but, I think the B+ regulator was shorted. The shorted regulator caused too much B+ voltage to be fed to the horizontal output stage; which, triggered the shutdown circuit. You can probably run the set through a variac and make it stay on for troubleshooting purposes.

I'll pull it apart when I get a moment or two.

I don't have a Variac but maybe my Dim-Bulb tester will do the job.

I took a DVD player out to the garage and hooked it to the 19" set, it works like new, a very bright CRT, Bright set to about 1/3 Picture about 1/2, Color is great and really good detail.

I was using my Isolation Transformer (also a Sony) since i needed two outlets and couldn't find a multi outlet extension cord.

The 19" set and the DVD player ran fine off the transformer, it's small and it drops the voltage slightly but they ran fine off it.

I decided to see if the 15" set would run using the drop from the transformer, sure enough it does, CRT is very strong on this one too, everything seemed to work but I got no sound from the speaker except possibly a slight hum.
It actually was the Isolation Transformer that was humming and it got loud, resonating off the bed of my truck, struggling with the load the set was putting on it.

The set seemed to be working fine still but it was clearly drawing too much current.

So what do you guys think, bad caps loading it down or bad regulator?
I guess I need to take the back off and see if anything gets hot, I don't want to blow the HOT though.

Here's some screen shots of the 19" set playing "The Mothers In Law" DVD, I might just clean this one up and make it my bedroom set!

i had one of those sonys last year.best picture i ever saw!crt was excellent.it was my garage watcher for awhile.i sold it and am kicking myself!when those sonys were good,they were great

Nice find! I like that 15" set... PM me if that one needs a home! It sounds like the HVR block might be leaky, and is putting it in shutdown.

Charles

I decided to see if the 15" set would run using the drop from the transformer, sure enough it does, CRT is very strong on this one too, everything seemed to work but I got no sound from the speaker except possibly a slight hum.
It actually was the Isolation Transformer that was humming and it got loud, resonating off the bed of my truck, struggling with the load the set was putting on it.

The set seemed to be working fine still but it was clearly drawing too much current.

So what do you guys think, bad caps loading it down or bad regulator?
I guess I need to take the back off and see if anything gets hot, I don't want to blow the HOT though.



The regulator transistors in those Sonys were a common problem - they'd short E-C, or go leaky B-C, giving you excess B+. Part number is MN8303 (preferred) or use a 2SC2581, and an NTE36 will do as well. Don't over torque the mounting screw when replacing them - the heat makes them expand somewhat and you'll be right back to square one if you torque too much. The driver transistor that feeds the regulator should be replaced as well when you replace the regulator - it'll check just fine, but go open on you, necessitating a call back. Other than that, most other problems were either audio related or bad remote functions - the IR Amplifier chip would short, pulling down the 12V line. OH - Get rid of any yellow glue in the regulator area too - it degrades with heat, turns brown, and becomes quite conductive. They are really good sets - I had a 17" one (KV-1746R) in my den for a few years.

Cheers,

I found some MN8303 online for cheap, like $7.00, worth taking a chance on.
I'll wait until I can take the back off and do a little checking though, probably wouldn't hurt to replace some of the small caps too.

On that 19", watch out for arcing flyback (internal). I had a number of those sets with blown power supplies, and it was caused by the FBT arcing internally once in awhile, and not quite enough to blow the HOT, but enough to blow the regulators. Also be sure to resolder the connections under the horiz drive transformer, and the nearby resistors. There is also a green dipped ceramic disc cap from the collector to base (IIRC) on the horizontal output transistor... That often shorts as well, mimicking a shorted output.

I replaced enough of those FBTs to still memorize the number: 1-439-351-12 :thumbsdn: Hopefully your set does not have that number, and if so, hopefully it was replaced in the '90s...

Charles

I brought the 15 incher in tonight and pulled the back off, lots of black dust but not bad overall, wetness was apparently minimal, more like light splattering than a soaking.

Running it off the Isolation transformer to drop the voltage and keep it running I get 139 volts across the main filter cap.

Measuring from filter negative to the Regulator I get .5v 12v and 0.0 volts, left to right looking at it face on.

Measured from chassis ground (a shield) I get -12v, 0.0v -12v
Nothing seems to be getting hot.

If I plug it into the wall and let it go into shutdown I get roughly half the voltage on the Regulator but I get about 166 volts on the Filter cap.

I'm not sure I'm measuring where I should, should I pull the Regulator and do a Diode check on it? The first two legs read pretty much shorted in circuit but that might be normal of course.

Here's a couple chassis shots.

BTW Charles, you are welcome to this set if you want it, you were supposed to get the Remote unit a long time ago! :yes:
I really just hated to see it going to waste in the open air back lot of a thrift store.

I'd like to see if I can trouble shoot it first for the fun of it, but if it gets complicated I'll be glad to turn it over to you.

The CRT looks very strong, it's not blue in person, the camera balance is a little off.
This is a solidly built little set and it has some heft to it, not yet the era of BPC.

P.S. I just put some batteries in the remote and it works!

Just curious but what is the "ball bearing" control panel?

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Just curious but what is the "ball bearing" control panel?

The control panel (and remote) buttons are small, rounded, shiny and silver... resembling the steel balls from ball bearings.

Hi Andy, I'm not sure where I Should be measuring?

I measured across the Filter cap and it was about 166 volts with the set plugged directly into the wall, it was on but in shutdown at the time.

With it powered up and running through the Isolation transformer (probably at 10 volts less than line) I Measured from chassis ground to the pins of the regulator and got no more than 12 volts on any pin and 139 volts across the Filter Cap.
I didn't see any hum bars on the screen but I didn't have a signal. just snow.

To tell if the regulator is working, you need to check the output voltage of the regulator. It's usually around 130-135v, and is probably labeled on the board. Is there a hum bar in the picture when you have it on a variac? If there is, the regulator isn't working.

The best place to check will probably be where the regulated B+ enters the flyback transformer. It will be the primary winding of the flyback with one end connected to the HOT collector and the other end will be the B+ input. There may also be a tap on the primary winding to provide the 200 volts to the video output stage. This is the way most solid state TV flyback transformers are connected.

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OK, line voltage is 117 coming out of the Iso Transformer with the set running, normal line voltage here is about 125v.

The 135v test point has 127v, not far off considering the low input voltage.

I pulled the regulator, not shorted, two legs check like a diode more or less, infinity one way, some resistance the other, the other two legs read pretty much infinity or at least in the megs.

The Flyback has some test points and marked voltage points too, the 135 is running 127 there also, there is a TP for 200v, I read 125 there, a 24v TP has zero but I don't know if I'm measuring from the correct point (chassis ground).

Also, hooked up a DVD player but couldn't get it to receive anything, tuner tunes up and down, picture flickers a bit when it jumps to UHF but no picture at all.

Also, no sound, no white noise, not a peep from the speaker even at full volume.

I'm starting to think maybe there's an open somewhere killing a voltage needed for these functions?

There are two fuses, both OK. Soldering looks good underneath.

If the Variac is on 117, and the 135 line is at 127, you have a load on it. Those regulate VERY well when working right, and you can keep 135 with as low as 95 or so line voltage. I'd check the two 10uF caps (160 or 250v?) near the regulator, and also keep in mind that the HVR block might be loading down the whole set if it's leaky internally.

Charles

Charles, Is the HVR the red thing in the 2nd anode line?
Any way to check it, it seems permanently attached to the Flyback.

I'll sub those caps you suggest, I already pulled the Filter and subbed it with no effect.

Update to my previous comments about no reception, I didn't have the r.f. Modulator plugged in, I found that out later last night when I was working on another set. I'll have to try this one again.


If the Variac is on 117, and the 135 line is at 127, you have a load on it. Those regulate VERY well when working right, and you can keep 135 with as low as 95 or so line voltage. I'd check the two 10uF caps (160 or 250v?) near the regulator, and also keep in mind that the HVR block might be loading down the whole set if it's leaky internally.

Charles

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I thought he said he was adjusting the variac for 139 on the filter cap (before the regulator).

I said Variac by mistake; he's using an isotap which was putting out 117.

Charles, Is the HVR the red thing in the 2nd anode line?
Any way to check it, it seems permanently attached to the Flyback.

I'll sub those caps you suggest, I already pulled the Filter and subbed it with no effect.



The HVR block is the red one mounted on the CRT shroud, with the FBT in and 2nd anode out, plus a small red overvoltage sensor wire (comes out behind it at the bottom). That goes to a plug on the board, which has a safety interlock. To check if the HVR is the problem, you can either unsolder that small wire from the HVR, or if you unplug from the board, you have to short the pins which have the interlock jumper in the plug. If the set stays on, and the B+ is still low, you have a leaky HVR. If it works fine, you have a faulty overvoltage sensor inside the HVR, and you can "get away with" leaving the wire disconnected "at risk", of course. But if the B+ is still pulled down, it will blow something FAST if you leave it on.

Charles

Thanks, I will check out these ideas and report back as soon as I can.
It's been pretty hectic around here though so I may have to wait a little while before I can get back to it.

I did decide to try getting a picture again, this time with the Modulator plugged in!

It works (with reduced line voltage) and has a great picture, the gray scale is off just a touch to the red side, I'm sure it'll adjust out easily.

I also noticed it cuts off the right side of the screen, look at the Peacock tail in the first picture, I don't know if this is related to it's problem or not but I don't think a Sony of this vintage left the factory like that.

Also there is no sound, none, nada, zip.

BTW, if you want a nice 1960's NBC Peacock opening, the Mothers In Law DVD set has one!

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