sylvania color set (23v rectangle) - Page 2 - Videokarma.org TV - Video

DaveWM · #16 02-02-2014, 12:27 PM

and here is the sylvania that the CRT is going into. better lighting this time and some shots with the back off.

https://www.youtube.com/watch?v=_nA3...ature=youtu.be

DaveWM · #17 02-05-2014, 03:42 PM

had a minor set back, after pulling the chassis and replacing ONE cap a .0056 1600v bumble bee, I decided to try it out again just to be sure everything still worked and the collapsing raster was fixed. I wanted to do this before the CRT swap since the chassis is extremely easy to pull and install.

well I had a LOT of noise in the signal, huge RF noise it seemed. this was both video and audio. I noticed that when I unplugged the set the audio would clean up perfectly for a second as the caps discharged the B+.

I had a hunch it was in the HV area (the only place that can make that much noise) so I removed the Horz out tube. bingo perfect sound. I used my prob and started messing with the HV wiring and when I touched the shunt tube cap the noise went away. I pulled the shunt tube cap and the wire (thin teflon looking thing) pullled right out of the cap. A few minutes later and I had the wire reattached and the issue was gone. I ma guessing it was arcing inside the cap contained enough that I could not locate it, but arcing all the same creating the RF noise.

So with the vert rock solid now (the 1600v BB would not open the eye even at 150v) I feel comfortable with pulling the CRT and moving on.

http://www.youtube.com/watch?v=PQX9L...re=c4-overview

DaveWM · #18 02-08-2014, 10:14 PM

http://www.youtube.com/watch?v=6BlgJLM7Muw

its coming alone nicely, should be able to get the chassis in tomorrow and see how the new CRT looks.

DaveWM · #19 02-09-2014, 10:35 AM

http://www.youtube.com/watch?v=G0oKeQYjPnY

CRT in and working

Kevin Kuehn · #20 02-09-2014, 11:31 AM

Nice work, Dave. I'm curious how hard would it be to put a more modern 23V CRT such as this one listed on ebay in a set of this vintage? http://www.ebay.com/itm/281262783191...%3AMEBIDX%3AIT Did most of the 23V tubes have bonded safety glass?

DaveWM · #21 02-09-2014, 11:38 AM

I don't think bonded glass vs. banded would make a difference. Pretty sure there is enough wiggle room for the CRT to fit. The thing I look for is delta gun and pin out.

Kevin Kuehn · #22 02-09-2014, 12:39 PM

It's hard to find specs on the 23V tubes. Someone told me recently that all the 23V were delta guns.

sampson159 · #23 02-09-2014, 02:33 PM

zenith made some 23v inline gun crts in the very late 70s

DaveWM · #24 02-09-2014, 03:25 PM

while adj the purity I noticed I had an intermittent focus pin connection. ground of the rivuts removed the back plate of the socket, used some solder braid to form a bridge from the old pin socket to the part that broke. Had to clean up the metal of course so the solder would stick but good to go now. pic is looking much better but will still take some tweeking.

TVTim · #25 02-09-2014, 05:16 PM

Lookin' really good there Dave. Nice clean looking set.

DaveWM · #26 02-09-2014, 05:44 PM

Thanks TVTim,

Just finished up posting a video of a prelim purity/convergence (done with live programming, will get the cross hatch out later to do it right).

One thing I plan to do is replace some of those bad 6GH8's one at a time and see what happens. One was in the pincushion I think that was the VERY weak testing one. I noticed in letter box mode there was quite a bit of pin cushion going on, so before I start tweeking the pin cushion coils I wanted to try a new strong 6GH8 and see what happens.

Carmine · #27 02-10-2014, 06:00 AM

Any chance you could show some pics along with the youtube links? I don't know about anyone else, but downloading video all the time is time consuming and data intensive for mobile phones. Some peoples work and other "non-private" computers also block/track youtube visits. Thanks.

DaveWM · #28 02-10-2014, 08:10 AM

Carmine, I will get some pics soon.

Another small issue. I started replacing some of the 6GH8's. when I replaced a weak on in the pic cushion (practically no emmisons), it started having issues, the pic grew dim, and the tube started to get REAL hot. I am checking around the pincushion circuit and see some suspect parts, so will be checking them and trying again. The pincushion correction is not right as is.

Carmine · #29 02-10-2014, 08:25 AM

Thanks. I enjoy following the threads and seeing the improvements, but youtube just isn't a practical option for me.

DaveWM · #30 02-11-2014, 05:03 PM

Picked up some NOS RCA 6GH8 tubes, replaced several in the set IIRC sync sep, pincushion,chroma amp, and 1st video. This cleared up a nagging sync issue and gives a good clean pic with excellent contrast control.

I also replaced a weak testing RF amp tube 6HQ5 on the tuner and cleaned the tuner. The tuner acted like it was dirty but it was not that bad. The new tube needed to be wiggled to get it to work. Maybe something in the tuner socket, I hope not as I don't want to go there. Anyway after the clean/new tube/wiggle the tuner is working much better.

The pincushion correction phasing works well, but the top still seems to have more bow in than the bottom which is completely straight. will have to look over the circuit and see if I can understand how it works. It uses a tube like the zeniths which inverts the signal for either the top or bottom, and I think just uses cap for the non inverted correction.

I am thinking maybe a screen resistor may have gotten toasted when if a tube shorted (common issue with 6GH8). I dont remember seeing any thing that odd when checking the resistance chart. Maybe just the way it is, would not even notice it with out a cross hatch or letter box programming.