Sony Trinitron KV-1921
 

I'll be getting one soon. What I'm wondering most of all is if it's one of those SG-613 sets. Also, is there anything else to watch out for?

SG-613 set or not, I'm stoked to finally be getting another 19" table set.

Anyone?

Well, here it is, arrived yesterday. It runs and the CRT seems strong but the raster shrinks and expands rapidly.

Manufactured September 1977, the same date seen on all those FBI anti-piracy warnings.

Thats either the last SG613 set or just after. I will look it up
tomorrow. Is the pulsating hrz, vert or both ?? Odds are its
just a 'lytic. The last SG613 sets were much more reliable
than the others. In other words the blew them much less often.
The rest of the set is quite reliable.

73 Zeno:smoke:

Good to know, and thanks in advance. The pulsating is horizontal and vertical.

That's one pretty TV set. I remember that style when they were new. Liked them in high school, like them now.

Be sure you are dealing with an SCC100 chassis first.
Sets is SG613. Uses a short lived modular chassis
thats very nice. Pulsing probably a cap in the PS but
some voltages need to be checked. DO NOT slip
on this set or you will loose the SG613 & other stuff.

73 Zeno:smoke:

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.

I used to have one just like that from '79. It had varactor push button tuning. It worked, but the high voltage had a really weird problem.

I have one of these with the push button channels. Made in 1979.

It's actually a really fantastic watch.

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 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:smoke:

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.

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...

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:smoke:

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.

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...

Super, thanks. Funny, I always thought electrolytics went bad faster if unused.

A common misconception - folks see the "shelf life" rating on a data sheet, note that it is shorter than the "endurance" (service) rating, and make the assumption. Hint: the shelf life is specified for storage at either 85 or 105 degrees Celcius, not room temperature (25 degrees C). NOBODY stores caps at either temp (185 degrees and 215 degrees Fahrenheit!!). The US DoD specifies storage at less than 35 degrees Celcius (95 degrees F) - big difference, and shelf life is magnitudes greater at the lower temps, as would be expected.

Over on DIYAudio, the threads are hilarious with the folks that can't/won't read a datasheet for capacitors or transistors. Most just don't want to admit they didn't know what they were looking at.

One thing I was always thankful for was an explanation of all the transistor parameters before learning the applications... Hie, Hfe, Hoe, VCeo, VCbo and others - all important, especially on the mid-terms exams. :yes::D

I learned most of my theory through various schools and bench experience in the 80s, but in 1995, I bought a copy of "The Art of Electronics" - best all-in-one theory and application text I've found. Not light reading, but a good way to have some "A-ha!" moments when things are explained clearly. Cool fact: I sold a service manual for a Transistor Analyzer to one of the authors (Horowitz) back in 2010.

I found the gouge for checking the SG-608 and SG-613's with an ohmmeter - they are in a couple of Sony Bulletins. I'll scan them this weekend when I get a chance. I may also make up a matrix that lists early Sony color sets by model and what HOT they use - the SCSs (SG-613, SG-608s) or transistors (2SC1316/2SC1034, etc.). That would go a long way for folks looking at potential Sony sets to save. Me, no problem with the SG-613 sets - I used to own two, and have some spares, except for the 2SC1034s. The best spares for Sonys are still some 4.7uF 250V caps.....and solder (for the later 80s sets with the bad IF solder connections).

Cheers,

I don't think I have seen any capacitor datasheets. I may have picked up that misconception from various posts here. I should try to get a bulk lot of capacitors then; ordering them individually would be a royal pain.

That book sounds pretty good to me. The way learn means I wouldn't read it cover to cover, but it would be great for occasional reference.

I'm not too concerned about what HOT the Sony sets use, not anymore. A big plus to me is that they made a lot of table sets, and I need another console like I need a hole in the head. I'll still take consoles if I like them enough though.

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.

Ah--The Sony GTO Line-timebase silicon switch 'Orrible bloody things!!.....

In UK, we had rather an infamous Sony model, the KV1810UB and KV1810 MkII.--Actually quite a compact neat set with great performance if the CRT was good

Both these sets used a SG-613 GTO in both the PSU stage and the horiz out. A Dry-Joint or failure of 19V rail would kill the horiz out GTO--the short then on the +B line would kill the PSU one...

These SG-613 were around £15 Each here, and a normal horiz-out transistor like a BU208 or BU508A maybe £1-2 at the time, so £30 in parts before you even started on one of these 1810's, Plus the so-called, 'Kit' of other crap you needed to change according to Sony, as a reliability measure--That didn't cure the blowing SG issues....

Wasn't long before a bright spark came up with a way to use a standard Horiz O/P Bipolar Transistor in place of both the PSU and Horiz-Out GTO's....

Involved changing the Drive Transformer for a type used with Horiz-Output Transistor, and deleting the original GTO drive circuit.
A BU508A was used quite successfully to sub the SG GTO with the alterations to drive it right by replacing the drive transformer by me for a number of these repairs, and was a good reliable conversion.
On a few of the earlier conversions, I retained the SG in the PSU (as I had sill a few around) and just modded the horiz-out stage. I kept one of those early ones for may years and no further trouble from it.

That must be the mod I heard a passing mention of. Where can I find instructions on how to do that?

Got a schematic of the mod, or a pix of a modd'ed set? Or a copy of the magazine article? That would be something, to get these old Sony sets going again on transistors instead of GCS'.

url?

...

Those modify the set to keep from blowing the SG608/SG613 - they don't show how to modify the set to use a bipolar transistor output.

Apparently, the February 1987 issue (page 252) of Television magazine (a UK publication aimed at TV repair engineers) has the modification. I found a 2007 posting referring to the article, but no article. I have several issues, bought when I was in England in 1987/1988, but my earliest is October 1987. I bought them as a novelty - each issue had a freebie taped to the cover, from wire ties to a resistor color code decoder, and one even had a silicon diode assortment, all BAT-series stuff.

It Really IS an easy mod....

Choose a Horiz Drive Tx from any popular set that uses a conventional Transistor.

Remove the Original Sony Tx and replace.

Only issue--The Sony uses the 19V rail (In the case of the 1810) to supply the drive stage. You'll Maybe have to alter the drive transistor and or the supply to it--To match that of the donor transformer, so if the Donor set uses a full (say 120V +B) to the drive Tx, then you'll need to supply the modded stage with that voltage, and change the drive transistor.

The Base circuit for the Horiz Out should also match that of the donor set.

Are you referring to the voltage going to the transistor's base leg?

Base to gate, Cathode to emitter, and Anode to Collector? Swap out driver transformer with one from a transistor set? Change the drive transistor to what? I've seen low and medium power horizontal drive transistors. Any problems with ringing or drive lines from the changed impedance of the output transistor?

Much more is needed - and I'm coming at this with over 30 years experience...

Sony used different gating methods in the SG608/SG613 sets, with some of the drive coming from another SCS, like the SG629. One size fits all isn't going to work in all sets - and the mod in the UK magazine was for the KV-1800UB, a set without a direct US analog.

Not a skeptic, just more detail is needed - not everyone here is overly familiar with the Sony circuit, much less one without a schematic....

Base to gate, Cathode to emitter, and Anode to Collector? Swap out driver transformer with one from a transistor set? Change the drive transistor to what? I've seen low and medium power horizontal drive transistors. Any problems with ringing or drive lines from the changed impedance of the output transistor?

Much more is needed - and I'm coming at this with over 30 years experience...

Sony used different gating methods in the SG608/SG613 sets, with some of the drive coming from another SCS, like the SG629. One size fits all isn't going to work in all sets - and the mod in the UK magazine was for the KV-1810UB, a set without a direct US analog, but probably close to the KV-1710, the FTC mandated 17" vs almost-18" screen.

Not a skeptic, just more detail is needed - not everyone here is overly familiar with the Sony circuit, much less one without a schematic....

eBay UK has a listing for the magazine:

http://www.ebay.co.uk/itm/TELEVISION.../161859718754?

but the seller doesn't ship internationally. :dammit:

OK Maybe I wasn't clear.....

All thats required is to Duplicate the Drive Circuit from the Donor set, the components around the drive Transformer, and Drive Transistor any series or parallel caps and resistors, these may affect the drive transformer tuning, and the components between the drive Tx and the Horz-Out Transistor.
Goes without saying--ALL the components of the original Gate Drive circuit of the SG will need to be removed.

The Horiz Out Transistor in any conventional--And these Sony sets--(Or GTO, MOSFET, IGBT--Whatever),--
is used as a switch, and as such is driven hard on each time its needed,(Important) the timing derived by the horiz osc/sync circuit, at 15.625KHz in case of UK sets....

The Transistor Must be driven Hard On (Taken Care of by the Drive Tx and its Base components --or it will dissipate excessive power in form of heat and self-destruct....

Ive not ever seen any 'impedance issues' --a Transistor driven hard on has low V C-E anyway--just like its Sony GTO equivalent.
No apparent issues at all.

Providing a suitable Horiz Output Transistor is chosen that has a suitable Voltage and Current Rating, is Driven accordingly--Then it will work.
(There's NO reason you couldnt use an IGBT or MOSFET if its a 'Horiz-Out' type from a very recent donor set....
I see no real issues providing the Donor drive scheme is applied in each case)

All thats needed is to COPY the Design of the Drive Circuit from the Donor set--Schematics for both are needed for this. The last one I converted--was over 25 years ago, but clearly remember it being very easy!

The UK Publication will refer to donor parts from UK sets with specific values of components For those parts, as such would not be suitable for USA engineers, and also worth considering the differences in tuning for the different line frequency between UK and US format sets.....
Stick to Donor parts from what you have around in your country--Follow the drive schematic of the donor--you wont go far wrong!

Really IS a Junk-Parts conversion job, using scrap chassis parts.....

I used a variety of different donor set parts, from Philips G8 and Thorn drive transformers--Whatever I had around actually. I doubt there would be any of these donors around in the US!

I received a reply from the seller - he now ships to the US.

But, from Alistairs description above, it isn't a mod so much as a mutilation/transplant/conversion of the horizontal sweep circuit of one transistorized set into a Sony. To me, a modification is a value change here or there, perhaps adding one or two components, but major surgery? Not for me.

Thanks for the info. If that's what it takes to get a near-mint SG-613 Trinitron running reliably, so be it. Looks like I have lots of studying to do.

or, recap, and replace the SG613 with an original, and replace the damper diode with the Sony suggested replacement for reliability. We did this in the 80s to Sonys we serviced, and had only one callback - for an unrelated CRT issue.

Most SG-613's we saw were killed by lightning strikes/surges. A V130LA10A or equivalent across the AC input would likely solve this. Honestly, most Sony's got the 4.7uF treatment - the 4.7uF 160V and the 4.7uF 250V caps would be bad, with high ESR and low value, nearly open. We kept a stock of 4.7uF 250V caps in stock to replace both the 160V and the 250V ones. I've got some 200 or so Sony service bulletins, and those 4.7uF caps are the only recurring parts in the bulletins. Most Sony bulletins are part number changes, so having them comment on any part as suspect makes you realize Sony also knew of the mass failures.

...

Reading the above suggests the USA versions of these period Sony sets with GCS/GTO's were more reliable than the UK KV1810....

Here, you could meticulously repair an 1810 according to Sony's own service-kit and two weeks later get the set back--All blown out again and with an irate customer to boot! They quickly gained the terrible reputation they have for being near unrepairable. Many places refused to even touch one, even if it wasn't dead.

--The UK sets--Really Were an absolute Abortion, they would blow with no warning and for no apparent reason, no surges, no lightning-strikes, they just died, leaving the customer facing huge bills.

Even Sony UK had issues with them at the time I gather.

--If you're lucky and have a worker--Do as suggested above--Re-cap etc, keep the SG, but if like here in UK you cant get any SG's these days cheaply--Then why not replace and modify--Its Hardly a 'Mutilation' or Major Surgery, merely the substitution of a drive Tx maybe the Drive transistor too, and some passive components, Take you less than half-hour once you thunk it through.....

Does the USA KV1921 set have a SG in both the PSU And in the Line stage, like the KV1810UB British Sony set,--ie, Two of 'em per set....?

The British model, probably uses a SG613 in the PSU, because of the 240 volt mains design. Possibly an early SWM design.

Your KV1810 is prob the same basic set as our KV1710 & or KV1910.
Early ones had 2 Sg613, later ones used 2SC867 in PS IIRC.
Sonys back then could have totally different chassii in the
same model #.
When these sets were new I did a stretch at Sony factory service.
I did smalls & few TV's. Policy was if you didnt find the cause of
a SG fail you changed the whole H/HV/V board. Customers were just
billed $120 labor + an SG & a few small parts total abt $160.
Problem #2 with Sony was they were a super arrogant company.
IF you got to talk to someone they treated you like you just
tracked dog shit into the house. They slowly improved in the '80s.

Nobody in our area would fix one. It was 2 50 mile round trips to Boston
to get one fixed. We refused TONS of them. Even if the symptom
wasnt "dead". After those sets the had a modular set with SG613
which was much more reliable. Then a one board with normal HOT
& an SG for a pin amp IIRC.

73 Zeno:smoke:

We never turned away a Sony, and actually got the mother lode from other shops that were afraid to touch them.

Sony had a nice set of bulletins you received when you ordered an SG613 from them. The bulletins went through all the pitfalls in replacing the SG613, from testing them, to changing the SID30-15 diode(s) to the upgraded diode. Actually, Andy summed this up in an earlier post.....

What most shops did was instead of ordering a SG613, they popped over to the supply house, bought an ECG276, popped it in, and prayed. No run-through of the suspect stuff that Sony suggested and no upgrade of the damper as suggested. The result was either success or failure - but most often failure.

We junked more Sonys due to bad CRTs (H-K short), mostly the 490BEB22 and the little 370? tubes as well. We had a 12" Sony with no back as a VCR monitor for years - it had no back because it was in a house fire and the back melted. Once removed, it wouldn't go back on, so we kept the set as a shop monitor. As I said in an earlier post, most SG608s and SG613s failed when a power surge occurred during a lightning strike. Most problems were with the 4.7uF caps - Rubycon and Marcons that would fail, and all 160V or 250V types. We replaced all of them with 250V caps - United Chemicons we got from one of the distributors for under a buck each.

I've seen lots of Sony's and the most problematic part ever has to be the MX0841's in the later CRT sets, followed by the caps in the early KVs, and then the STK regulator/audio in the late-80s sets. SG613s were like power supply diodes - understood to be the weak, shorting part in a Sony taking a power hit. 2SC867s and 2SC1034s went too, but the problem was really bad caps in just about all instances I've seen.