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  #31  
Old 10-15-2012, 08:30 AM
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etype2 etype2 is offline
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Quote:
Originally Posted by jr_tech View Post
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"?

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jr
Yes. Only the 1220 "Premium model" had Skytune.
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  #32  
Old 10-15-2012, 09:20 AM
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Quote:
Originally Posted by etype2 View Post
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.
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  #33  
Old 10-15-2012, 11:54 PM
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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.
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  #34  
Old 10-16-2012, 01:44 AM
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I have had Sony color monitors that went "all white" (and then the protection circuits shut off the set) when electrolytic capacitors were bad.

Since you work on a lot of solid-state "newer" TVs, I highly recommend that you get an ESR meter for testing electrolytics. They are worth their weight in gold. I have a Creative Electronics one; they seem to come up on Ebay fairly often and sell for under $100 there. It is actually not that complex a device, just an oscillator and a circuit to measure the signal that comes through the capacitor being tested, I think. Decades ago, my co-worker duplicated the one we had in our shop in Illinois when they could not find any new ones to buy anymore.
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  #35  
Old 10-16-2012, 11:27 PM
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Tonight the set wouldn't start again, there were voltages missing in some places where I knew they should be, poked and prodded, checked Diodes and so on but nothing.
Finally I just took the soldering iron and soldered a lug on a terminal strip that I had poked previously when the set mysteriously started running, sure enough it started running again. The connection on the lug looked fine but maybe it was a cold solder joint somehow, I'll see tomorrow if it'll still run but it worked all evening while I was trying to figure out the video problem.

If I disconnect any of the RGB wires on the CRT socket board that particular color goes away so I know the CRT is responding, the Picture control grounds the Base of a small transistor and that seems to be working OK too.
I'm not sure how the brightness control works just yet.

I just found and bought a factory service manual for this thing on eBay so perhaps when I get that I may be able to figure this out.

I suspect bad caps too but without knowing which ones are in what circuit it could be difficult to figure out, I don't want to go through the expense of shotgunning them right now either, not until I see a picture on this thing.
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  #36  
Old 10-23-2012, 08:53 PM
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I bought a service manual for this set, now I can actually check some voltages and know what section I'm working on.
I also took the manual to the Electronics Store and bought a bunch of electrolytics, this isn't every cap in the set but it's enough to make a start and to have on hand if I find I need a particular one.

This whole pile of Caps was only $10, because they are very small values and voltages. One is only .47@10v, the tolerance on most is -10% to +150% so that gives a lot of wiggle room on those odd values.
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  #37  
Old 10-23-2012, 11:17 PM
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And this is why I hate working on Solid State gear.

I was rotating the set to get to the Horiz Hold control and the tip of my Soldering Iron came in contact with the metal chassis of the TV, pow, dead set, I wish I had had one or the other on an Isolation Transformer!

I figured I blew the fuse, there are two fuses in this thing and one circuit breaker but none of them blew.
Funny thing is nothing else seems to be shorted or blown either, the set just won't run, the CRT heaters don't light either despite being on a separate transformer which is getting AC voltage as far as I can tell, however the workings of this set are a bit confusing to say the least.

I did check the CRT to see if the heaters are still ok and they are so it's a power problem.

I do get a dial light however, and when the set is plugged in but switched off I can clearly hear the Horizontal Oscillator running, it winds down though when I switch it on.

The set was having a power supply problem to start with, it didn't want to power on cold first try, tonight I had to switch it on and off about three times before it would start so maybe I just finished off a bad Filter in the PS somewhere?

I can upload the PS portion of the schematic if anyone thinks they can assist me here, I would sure appreciate it!

This thing is from another planet, or so it seems.
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  #38  
Old 10-24-2012, 07:10 AM
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Yup.....Used to say that when I was 20 even, that Sony Trinitron sets were "alien"....and I have NEVER managed to bring one back.

Only RECENTLY claimed my ONE and only Sony victory....and it's an old 700U set I had sitting around for like 25 years. I had that 700U since I had JUST come from Hong Kong and wanted a real portable set since I wasn't stable yet. From a garage sale, it ran for maybe a year or two and then VERY suddenly had only a white raster. It's an old B/W set...but to this day the only Sony I have ever revived. My next one looks to be the 8-301W that I have MOSTLY running.
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  #39  
Old 10-25-2012, 01:41 AM
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Eric-

I first learned (the hard way!) what a "hot chassis" is when I was installing a little kit "frequency counter calibrator" into my Sony KV-1922, in 1980. I started to hook an oscilloscope probe's ground clip to the chassis when I got the big BANG! and the TV went dead. On mine, one or more of the main diodes after the power switch had blown.

I hope you can find a good deal on an isolation transformer if you do not already have one.
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  #40  
Old 10-25-2012, 06:51 AM
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Does a variac also serve as an isolation transformer? I have been trusting that I'm isolated by using a variac. My assumption being...that it's a big transformer.
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  #41  
Old 10-25-2012, 09:38 AM
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Quote:
Originally Posted by AiboPet View Post
Does a variac also serve as an isolation transformer? I have been trusting that I'm isolated by using a variac. My assumption being...that it's a big transformer.
It's a big AUTOtransformer, therefore not isolated. Better add an isolation
transformer between the variac and your load.
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  #42  
Old 10-25-2012, 09:57 AM
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Thanks. Will do.....kept thinking I was killing "two birds with one stone" with a variac. So far I don't work on many actual "chassis" sets at all (since I'm micro and solid state, mostly wall warts), but I do have a couple 9" sets and the older sets that do have AC plugs and real (such as they are) chassis.
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  #43  
Old 10-25-2012, 03:11 PM
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Quote:
Originally Posted by ChrisW6ATV View Post
Eric-

I first learned (the hard way!) what a "hot chassis" is when I was installing a little kit "frequency counter calibrator" into my Sony KV-1922, in 1980. I started to hook an oscilloscope probe's ground clip to the chassis when I got the big BANG! and the TV went dead. On mine, one or more of the main diodes after the power switch had blown.

I hope you can find a good deal on an isolation transformer if you do not already have one.

Hi Chris, I do have one, I haven't been using it much lately because of the voltage drop it causes, probably not an issue with the little Sony being as it doesn't have 30 tubes, also I have the Variac now that will compensate.

Too late now, I really wasn't thinking the Sony was a hot chassis, should have guessed by the shock I got while touching the bench and the set but I guess I thought I was touching a terminal and not the chassis.

This set has a lot of Top Hat Diodes, do they usually fail open? It's not blowing any fuses or smoking so I don't think anything is shorted but the B+ seems to be dead.

Now that I have a "nice" (cough) new Meter I can do some more testing. (See the test equipment forum for more on my new meter )
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  #44  
Old 10-25-2012, 09:28 PM
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Son of a...gun

Got my $20 worth out of my new meter tonight.

I finally figured out some basics on how the power supply works on this set and I didn't have any AC line voltage going in to it.

To make a long story short the Circuit Breaker is bad, it apparently blew out when I shorted the chassis and didn't reset, even though I pressed it a dozen times it never even made the slightest contact.

I would have figured this out sooner if the breaker wasn't such a PITA to access the lugs on without breaking anything else.
I finally got desperate and figured it HAD to be the breaker so I hooked a jumper across it and viola, it works again, this probably also explains the intermittent no start problem I was having as well.

Now I'm back to just having a white raster but at least I can continue recapping it, but enough for tonight, I can rest easier knowing I didn't ruin anything unobtanium.
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  #45  
Old 10-26-2012, 12:18 AM
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I felt I was so close

that I had to keep going.

I replaced a couple more caps in the AGC circuit with no results and then I remembered, I have a factory service manual! I can check some voltages.

It didn't take long to realize the 140+ supply to the Video board was missing, like zero volts.

The supply is on the same board I had recapped a few weeks ago and came off of one leg of a 4.7 Cap that I had replaced, it was zero at that end too, and no wonder, when I replaced the cap there is a wire that is also soldered to one of the lugs, it's supposed to be on the + lug, I had attached it to the - side!

I quickly switched it around and...Picture!

Did a little adjusting and here's the result.

Vertical is stretched out but the adjustment is underneath so I'll wait until I have it put back together before I adjust it.
I still need to repair or replace the Circuit breaker, anyone have a 1.25 Sony breaker? I may simply put a fuse across it.

When I get it finished I want to get a picture of it with Ted Baxter on screen, maybe a picture of Ted on WJM's 1210 playing on my 1210, that would be kind of cool.
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