Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Solid State CRT Televisions

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 12-19-2018, 08:34 PM
RetroHacker RetroHacker is offline
Electronics Accumulator
 
Join Date: Jan 2005
Location: Niskayuna, NY
Posts: 456
Sony LV-1901D. Don't just watch TV... record it and play it back later!

This is one of those things that I've always wanted. Not strictly sure why, since - let's face it - it isn't terribly useful. Sure, it's really neat, but that VCR only does Beta I, and even *I* don't have any tapes recorded in Beta I. Still, some switch in my brain told me I had to have this. And now I do. All 288 pounds of it. It's a beautiful machine, and seems well constructed. This particular unit is in really great cosmetic condition, some small chips of missing veneer on the bottom edges of the sides of the base, and some minor dings, but everything still looks great. All the knobs and doors are intact and present.

As one would expect, the VCR does not work. It'll need belts and lubrication before it'll ever run again. I'm pretty sure I won't have too much difficulty resurrecting it though - again, though, the motivation isn't real high there, since the machine won't play any of the Beta tapes I already have... but I'd love to see it running. There's a cassette stuck in it - no idea if it's something recorded on this set, or just a tape someone put in there in an attempt to test it in recent memory.

The television section, however, could use some attention. It looks as if the focus an G2 are just way out of whack, but the G2 adjustment on the neckboard does nothing (I haven't checked to see if the control itself is open yet). The CRT appears to still be pretty balanced in all three colors, I got a decent looking (if over-bright and blurry) color bar pattern out of it, and the white screen looks good. Purity could use a bit of help, but it's not terrible. Certainly not what I feared, as I know how old Sony tubes tend to get real dim and lose the red as they age. Focus control has some effect, but I'm not able to get the edges clear - only the center sharpens up, and that's with the control cranked all the way counterclockwise.

The faceplate is starting to delaminate in the upper right corner - that'll probably have to be investigated at some point as well. Has anyone done a cataract repair on a Trinitron before? I know I haven't.

I've done a bit of checking around, and I haven't found a Sam's Photofact on this - did they even make one? Or, perhaps a better question - was this TV chassis used in other sets? I would imagine this same basic chassis was in some table model set as well.

Any other VK'ers have one of these beasts? Anyone seen a failure like this? It almost seems like the HV is too high, throwing off the other voltages so I can't dial in the focus - but even then, I'd expect the G2 to have some effect. I wouldn't think it's a shorted CRT either, because all the colors are affected equally. I'll poke at it more later, but any advice would be appreciated.

https://i.imgur.com/Ukj2utc.jpg
https://i.imgur.com/fYBJr7p.jpg

-Ian
Reply With Quote
  #2  
Old 12-20-2018, 07:36 AM
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 3,282
I could have had a few of these but my squaw would have scalped me.
G-2 probably high due to open resistor on the low end of the pot.
Should be on the CRT PCB & value in the megs.
Manual a problem. For Sams look up the chassis number ( ex SCC-###-?? )
but I doubt they made it. Chassis tag is usually on the DGS shield.
OEM manual probably rare, ordered on a as needed basis.
Last chance is a similar Sams. Look up close SCC numbers til you find
it but you need access to a collection. After that a few pics posted here
& maybe I can find it. There are 2 chassis it could be but either should
be useful.

BTW this is a SG-613 chassis. One slip in the right place will wipe out
the hoz & power supply. Take extreme care !

73 Zeno
LFOD !
Reply With Quote
  #3  
Old 12-21-2018, 07:18 PM
RetroHacker RetroHacker is offline
Electronics Accumulator
 
Join Date: Jan 2005
Location: Niskayuna, NY
Posts: 456
Did a bit of poking at it tonight, and yes - there is an open 680K resistor on the neckboard. Looks to be 1/2 watt carbon comp. The bulk of the rest of the set is carbon film, but carbon comp have been used in this circuit, most likely due to carbon composition resistors being able to handle the higher voltage/pulses better than carbon film. I'll have to see what I can find as a suitable replacement.

I also see a couple of pretty sorry looking electrolytics on the power supply board that I'm going to change while I'm at it. I can see where they've leaked electrolyte, and I know they're not doing their job as they should - even thought this isn't the problem I'm seeing with the set.

-Ian
Reply With Quote
  #4  
Old 12-22-2018, 08:00 AM
RetroHacker RetroHacker is offline
Electronics Accumulator
 
Join Date: Jan 2005
Location: Niskayuna, NY
Posts: 456
My junk box surprises even me sometimes. I didn't have any 680K resistors in any of the little sorted bins (it's not that common a value), but I did some long searching through my box of "misc" resistors - mostly scavenged - and actually found a 1/2 watt carbon comp 680K resistor. It's kind of old and has drifted a bit (reads 780K on my meter), but it's the closest thing I had and probably close enough. Replaced the resistor and fired it up, and the G2 control works again! Took a fair bit of fiddling and adjusting, but I think I got it looking halfway decent.

https://i.imgur.com/PKnbD4X.jpg
https://i.imgur.com/ve88wQp.jpg

Purity isn't perfect, I need to adjust that:

https://i.imgur.com/B7Rb3Jj.jpg - red
https://i.imgur.com/yZBd0Fa.jpg - green
https://i.imgur.com/uBn9l4d.jpg - blue

Still needs more work, I still need to change some capacitors on the power supply board that look awful - but the set seems stable. I watched it for about an hour last night, and had no problems, no image instability, etc.

And there's a lot more that needs help - the sound doesn't work. In TV mode, I can hear only a faint static noise with the volume up all the way. In camera input mode, I can feed in audio and hear it, but it's weak and VERY distorted. Also, the tuner doesn't work - I can sort of see some noise that seems like part of the signal, but I can't get any color or sync on either the main or aux tuner. I haven't investigated these issues too deeply, but part of me wonders if the audio section and tuner draw power from the main TV chassis - those leaked out capacitors might have something to do with this.

And I messed with the Beta a bit, definitely needs belts, it kind of turns the tape reel a bit when you try to engage any of the transport controls, but fails very quickly. Eject sounds like it's attempting to put the tape back in the cassette but again, fails.

Another problem that I'll have to tackle at some point is the CRT cataracts. The worst spot is the upper right corner:
https://i.imgur.com/mvjMqiY.jpg

I've done cataract repair on normal tubes before, but I've never done a Sony, so I'd love to hear from someone who has. Is this one you can separate with heat, or do you need a hot wire? This looks different than the ordinary PVA material I'm used to, it seems almost like an oil? It's the worst in the upper right corner, here's a picture of what I'm dealing with. https://i.imgur.com/mvjMqiY.jpg
You can see how the faceplate is definitely delaminating, but it's doing so in a different manner than normal, looks like drops of water behind the glass.

In any event... progress!

-Ian
Reply With Quote
  #5  
Old 12-22-2018, 12:44 PM
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 3,282
Wow that jug looks strong ! Rare to find a '70s Sony with a good
one.
Purity looks like a few correction magnets fell off. They are small discs
sometimes on a plastic piece. They are taped to the CRT bell as
needed. You can use refrigerator seal gasket magnet for a sub.
Put near blotch & rotate & or flip over to get correction then tape down.
Had a few of these with cold joints at the SIF-DET-PRE AMP IC.
after that probably a 'lytic causing your audio woes...
Good Luck
73 Zeno
LFOD !
Reply With Quote
Audiokarma
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 10:17 PM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
ęCopyright 2012 VideoKarma.org, All rights reserved.