Sony Trinitron KV-1921

[Jon A.]

Crap. I'll just leave it unplugged until I can dig into it.

I think I heard there are mods that make these things more reliable and allow them to use more common transistors.

[Findm-Keepm]

Originally Posted by Jon A.

Crap. I'll just leave it unplugged until I can dig into it.

I think I heard there are mods that make these things more reliable and allow them to use more common transistors.

Be sure to let Sony know if you do find that mod - Sony never issued any kind of mod in the SG-613 or SG-608 sets. It's a robust design, made weak by bad solder, bad caps and lightning strikes that juice the sets.

I'll see if I have the original service manual still - most of these sets were a cap swap (4.7uF@160V and 250V - we kept them in stock...), a bad chroma chip CX1-something, or a bad solder connection in the sweep area (which led to the 608/613 failing), and the occasional open cathode in the CRT, 490BEBP22 in most of the 19"ers.

Even in the 90s, the SG-613 from Sony was about 7 or 8 bux, far cheaper than a 6LQ6 was for tube sets. Most problems occurred when folks went with just the SCS and didn't look further, like the damper diode (SID30-15, subbed by Sony to another number - I can look it up) or the bad solder. You could power one up, check for proper drive, and know if you had it fixed before installing the SG-613. I think I've posted the Sony Bulletin on how to properly check the SCS out of circuit..

[zeno]

I remember the dampers opening up. Had a top hat style
wrapped in metal holder, new one was modern type.
When I worked at Sony SG613, some clocks, video
heads & a few other things were tracked. Seems at some
FSC's they were getting stolen. And the SG613 had
NO warranty, if a regular shop blew one they ate it.

73 Zeno

[Jon A.]

Originally Posted by Findm-Keepm

Be sure to let Sony know if you do find that mod - Sony never issued any kind of mod in the SG-613 or SG-608 sets. It's a robust design, made weak by bad solder, bad caps and lightning strikes that juice the sets.

I'll see if I have the original service manual still - most of these sets were a cap swap (4.7uF@160V and 250V - we kept them in stock...), a bad chroma chip CX1-something, or a bad solder connection in the sweep area (which led to the 608/613 failing), and the occasional open cathode in the CRT, 490BEBP22 in most of the 19"ers.

Even in the 90s, the SG-613 from Sony was about 7 or 8 bux, far cheaper than a 6LQ6 was for tube sets. Most problems occurred when folks went with just the SCS and didn't look further, like the damper diode (SID30-15, subbed by Sony to another number - I can look it up) or the bad solder. You could power one up, check for proper drive, and know if you had it fixed before installing the SG-613. I think I've posted the Sony Bulletin on how to properly check the SCS out of circuit..

I thought I heard a passing mention of a SG-613 mod on here somewhere, but who knows. I read so much here it kind of runs together.

I got that series of Japanese TV service manuals and only left out the one for Sony, thinking I'd never take on another one, who'd 'a thunk it. I'll just have to be extra cautious with this one and try to lay my hands on extra SG-613s. They should turn up all the time considering how sets that use them ate them so often.

I assume these were known for purity issues as well. I forgot to mention the image is darker at the top left, just like on my decade-newer KV-1926R.

[Findm-Keepm]

Originally Posted by Jon A.

I assume these were known for purity issues as well. I forgot to mention the image is darker at the top left, just like on my decade-newer KV-1926R.

A ure sign there is a bad cap - shading of the left hand side of the screen is a common B+ filter problem with Sonys.

Check the ESR on all the caps in the B+, vertical (save the 2SC867 or 2SC1034!!) and the horizontal sweep, and you'll likely fill a mug with bad caps. Sony used good caps, it's just age that kills them - they've met their 5,000 hour service life.

Even after getting a set running, we'd run through the caps, replacing any marginal caps. Nothing worse than a call back for one stinkin' cap...

[Jon A.]

Originally Posted by Findm-Keepm

Check the ESR on all the caps in the B+, vertical (save the 2SC867 or 2SC1034!!) and the horizontal sweep, and you'll likely fill a mug with bad caps. Sony used good caps, it's just age that kills them - they've met their 5,000 hour service life.

The caps probably went bad from lack of use. If I recall correctly, the fellow who gave me this set said it hadn't been used in about 20 years.

[Findm-Keepm]

Here's some tips for your set - the KV1920/KV1921 are similar sets - notice how most cures are by replacing a cap? Caps fail from use - most have a shelf life of 2X-3X the service life. Heat + ripple current are the two most common external failure sources...

[ChrisW6ATV]

Originally Posted by Findm-Keepm

Here's some tips for your set - the KV1920/KV1921 are similar sets - notice how most cures are by replacing a cap? Caps fail from use - most have a shelf life of 2X-3X the service life. Heat + ripple current are the two most common external failure sources...

Thank you for posting that list, Brian. I worked on commercial Sony color monitors for 20+ years until recently and kept a comparable list for them, but I never did much with consumer sets.

[zeno]

Best source of SG613 is junk sets. They either work or not,
dead shorted or OK.
Semis have an infant mortality. If it lasts a few minutes
its life expectancy jumps to near 100% for decades. So
if you got a Sony with a bad jug pull the SG613's &
? 2SC867's ? was it ? They are as good as new IMHO.
As long as you get any kind of raster they are fine.....

73 Zeno