Sony KV-1710 horizontal osc - Videokarma.org TV - Video

andy · #1 07-04-2003, 07:52 PM

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kc8adu · #2 07-08-2003, 08:07 PM

i believe that one divides off main b+ to leak a startup voltage.
just enough to make it run somewhat till +12 comes up from the fly.
maybe the osc ic or whatever is loading it down?
been a while since i worked on one of those.
at least you dont have the sg-613 eater model.
sonys of that era had resistors that would have the coating crumbling off. some were fine and some would be way off.

andy · #3 07-08-2003, 09:26 PM

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#4 11-23-2007, 08:39 PM

I'm new to this site, you're my 1st reply!
If you still need repair help on that old Sony, I know what it is.
The "start-up" circuit on that chassis is complicated; 1 'lytic capacitor!
Your testing the old memory and it ain't what it use to be!
Here goes; the capacitor is a 10uF @ 160V or 250V on the PC Board directly under the CRT. Look at the schematic, it connects from raw B+ thru a resistor to the "+" side of the cap, the "--" side connects to the horiz osc B+ line. I think that was 12 or 18V. Totally simple, only 2 parts! Other makes used over a dozen parts to do the same thing!
It operates like this; when the set is 1st turned on, the raw B+ (150V I think) ramps up and the cap charges thru the resistor to the horiz osc B+ line. Since the cap is like a short circuit when not charged, that raw B+ is dumped thru the current limit resistor to bring up the horiz osc B+ close to normal. The horiz output circuit drives the HOT and the scan derived 18V supply takes over. The start-up cap charges and no current flows from it and the resistor anymore. Walla! Simple and effective!
I bought a KV-1710 from a Sony Dealer I worked at in 1974. We sold and serviced also. That's where I "fell-in-love" with Sony. My little Sister still uses that set in her Daughters' room to play games, etc. The set still looks brand new after 33 yrs. Instant on kept the CRT alive all these years!
Remember, 2 yrs later in '76, no more instant on! That TV won Sony an Emmy, the 1st time a TV got one! That was the most popular set of all times! It was on many commercials, TV episodes, talk shows. etc. That set was the 1st TV to make water look like water!
Anyway I'm rambling! Have fun and Happy Holidays... John

andy · #5 11-23-2007, 09:16 PM

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Stone3035 · #6 12-19-2008, 01:05 PM

I've had one of these sets kicking around for about 13 years. It still works, but has bad focus, and a dim picture. Anyone know if I can get an after-market CRT for this model (it's a 17").. and is the flyback, and focus resistor still available for this set??? I'd love to restore it for nostalgic purposes..

Thanks.

kx250rider · #7 12-19-2008, 01:10 PM

The CRT is a 470BEB22, and is a Sony exclusive. I think you can still have it rebuilt by Hawkeye, or VDC. I strongly doubt the flyback and HVR block would still be available, but you can probably find them used. I don't remember ever seeing a bad flyback on one of those, however. The HVR block usually cracks and arcs, but you can often clean it up and seal it with silicone rubber.

Charles

Stone3035 · #8 12-19-2008, 05:13 PM

FLyback and focus resistor are still OK. I was just curious if they were still available. Is it possible to breathe a bit of life back into the tube by momentarily zapping the R, G, and B cathodes with some higher voltage??? (isolated from the other circuits of course).. I heard using a megger on 1000 volts could work. Is this true??

radiotvnut · #9 12-19-2008, 05:36 PM

I would not zap this tube unless you have access to a decent CRT tester and have confirmed that the tube is bad. Poor focus and a dim picture is indeed a symptom of a weak tube; but, can often be compensated for by adjusting the G2 and focus controls. I've also seen TV's with a good tube that simply needed focus and G2 adjustments after someone had misadjusted these controls.

Stone3035 · #10 12-19-2008, 07:07 PM

I've tried all of those adjustments, with no avail. The tube will come a little brighter by increasing the G2 voltage, but with worse focus.. The focus can be corrected slightly, but not perfect.. I'm going to zap the cathodes with quick pulses...

andy · #11 12-20-2008, 06:41 PM

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Stone3035 · #12 12-20-2008, 11:29 PM

No focus resistor? Then what is the variable resistor block for above the flyback??

Findm-Keepm · #13 12-22-2008, 12:15 PM

I believe that's an H-Stat control - not a focus control. Please correct me if I'm wrong on this.

Cheers,

site123a · #14 12-22-2008, 12:59 PM

That's the HV block, it controls convergence...

Stone3035 · #15 12-22-2008, 01:25 PM

Oh that's what that is... I did notice that the convergence does change upon adjusting that pot.. How do I set that up? Do I measure the HV anode and adjust that pot until I get 23.3 KV as per the schematic? Then if the convergence is still out, I can adjust the purity magnetss at the CRT neck?? Is there anyway to adjust the focus, or is it pre-set? Where do I measure the focus voltage? I tried measuring G4, but I get 0 volts. The schematic says 165 Volts...